Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-30 (of 93 Records) |
Query Trace: Brault AC [original query] |
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Rio Negro virus infection, Bolivia, 2021
Loayza Mafayle R , Morales-Betoulle ME , Whitmer S , Cossaboom C , Revollo J , Loayza NM , Méndez HA , Chuquimia Valdez JA , Subieta FA , Espinoza Morales MX , Canedo Sánchez MV , Romero MER , Brault AC , Hugues HR , Mendez-Rico J , Malenfant JH , Shoemaker T , Klena JD , Montgomery JM , Marquina Salas JD . Emerg Infect Dis 2023 29 (8) 1705-1708 In May 2021, an agricultural worker originally from Trementinal, Argentina, sought treatment for febrile illness in Tarija, Bolivia, where he resided at the time of illness onset. The patient tested negative for hantavirus RNA, but next-generation sequencing of a serum sample yielded a complete genome for Rio Negro virus. |
Transmission of yellow fever vaccine virus through blood transfusion and organ transplantation in the USA in 2021: Report of an investigation
Gould CV , Free RJ , Bhatnagar J , Soto RA , Royer TL , Maley WR , Moss S , Berk MA , Craig-Shapiro R , Kodiyanplakkal RPL , Westblade LF , Muthukumar T , Puius YA , Raina A , Hadi A , Gyure KA , Trief D , Pereira M , Kuehnert MJ , Ballen V , Kessler DA , Dailey K , Omura C , Doan T , Miller S , Wilson MR , Lehman JA , Ritter JM , Lee E , Silva-Flannery L , Reagan-Steiner S , Velez JO , Laven JJ , Fitzpatrick KA , Panella A , Davis EH , Hughes HR , Brault AC , St George K , Dean AB , Ackelsberg J , Basavaraju SV , Chiu CY , Staples JE . Lancet Microbe 2023 4 (9) e711-e721 BACKGROUND: In 2021, four patients who had received solid organ transplants in the USA developed encephalitis beginning 2-6 weeks after transplantation from a common organ donor. We describe an investigation into the cause of encephalitis in these patients. METHODS: From Nov 7, 2021, to Feb 24, 2022, we conducted a public health investigation involving 15 agencies and medical centres in the USA. We tested various specimens (blood, cerebrospinal fluid, intraocular fluid, serum, and tissues) from the organ donor and recipients by serology, RT-PCR, immunohistochemistry, metagenomic next-generation sequencing, and host gene expression, and conducted a traceback of blood transfusions received by the organ donor. FINDINGS: We identified one read from yellow fever virus in cerebrospinal fluid from the recipient of a kidney using metagenomic next-generation sequencing. Recent infection with yellow fever virus was confirmed in all four organ recipients by identification of yellow fever virus RNA consistent with the 17D vaccine strain in brain tissue from one recipient and seroconversion after transplantation in three recipients. Two patients recovered and two patients had no neurological recovery and died. 3 days before organ procurement, the organ donor received a blood transfusion from a donor who had received a yellow fever vaccine 6 days before blood donation. INTERPRETATION: This investigation substantiates the use of metagenomic next-generation sequencing for the broad-based detection of rare or unexpected pathogens. Health-care workers providing vaccinations should inform patients of the need to defer blood donation for at least 2 weeks after receiving a yellow fever vaccine. Despite mitigation strategies and safety interventions, a low risk of transfusion-transmitted infections remains. FUNDING: US Centers for Disease Control and Prevention (CDC), the Biomedical Advanced Research and Development Authority, and the CDC Epidemiology and Laboratory Capacity Cooperative Agreement for Infectious Diseases. |
Intracellular diversity of WNV within circulating avian peripheral blood mononuclear cells reveals host-dependent patterns of polyinfection
Talmi-Frank D , Byas AD , Murrieta R , Weger-Lucarelli J , Rückert C , Gallichotte EN , Yoshimoto JA , Allen C , Bosco-Lauth AM , Graham B , Felix TA , Brault AC , Ebel GD . Pathogens 2023 12 (6) Arthropod-borne virus (arbovirus) populations exist as mutant swarms that are maintained between arthropods and vertebrates. West Nile virus (WNV) population dynamics are host-dependent. In American crows, purifying selection is weak and population diversity is high compared to American robins, which have 100- to 1000-fold lower viremia. WNV passed in robins leads to fitness gains, whereas that passed in crows does not. Therefore, we tested the hypothesis that high crow viremia allows for higher genetic diversity within individual avian peripheral blood mononuclear cells (PBMCs), reasoning that this could have produced the previously observed host-specific differences in genetic diversity and fitness. Specifically, we infected cells and birds with a molecularly barcoded WNV and sequenced viral RNA from single cells to quantify the number of WNV barcodes in each. Our results demonstrate that the richness of WNV populations within crows far exceeds that in robins. Similarly, rare WNV variants were maintained by crows more frequently than by robins. Our results suggest that increased viremia in crows relative to robins leads to the maintenance of defective genomes and less prevalent variants, presumably through complementation. Our findings further suggest that weaker purifying selection in highly susceptible crows is attributable to this higher viremia, polyinfections and complementation. |
Combating West Nile virus disease - time to revisit vaccination
Gould CV , Staples JE , Huang CY , Brault AC , Nett RJ . N Engl J Med 2023 388 (18) 1633-1636 It is time to revisit the need for human West Nile virus (WNV) vaccines. Since its initial detection in the United States in 1999, WNV has become the leading cause of domestic arthropod-borne viral (arboviral) disease. Spread by infected culex-species mosquitoes, WNV has caused more than 55,000 reported cases of human disease, more than 27,000 of them neuroinvasive, and 2600 deaths between 1999 and 2021, according to data from the Centers for Disease Control and Prevention (CDC). WNV is also an ongoing public health threat in many areas of the world; the largest recorded outbreak in Europe occurred in 2018. |
Increase in Colorado tick fever virus disease cases and effect of COVID-19 pandemic on behaviors and testing practices, Montana, 2020
Soto RA , Baldry E , Vahey GM , Lehman J , Silver M , Panella A , Brault AC , Hughes HR , Fitzpatrick KA , Velez J , Biggerstaff BJ , Wolff B , Randolph J , Ruth LJ , Staples JE , Gould CV . Emerg Infect Dis 2023 29 (3) 561-568 In 2020, Montana, USA, reported a large increase in Colorado tick fever (CTF) cases. To investigate potential causes of the increase, we conducted a case-control study of Montana residents who tested positive or negative for CTF during 2020, assessed healthcare providers' CTF awareness and testing practices, and reviewed CTF testing methods. Case-patients reported more time recreating outdoors on weekends, and all reported finding a tick on themselves before illness. No consistent changes were identified in provider practices. Previously, only CTF serologic testing was used in Montana. In 2020, because of SARS-CoV-2 testing needs, the state laboratory sent specimens for CTF testing to the Centers for Disease Control and Prevention, where more sensitive molecular methods are used. This change in testing probably increased the number of CTF cases detected. Molecular testing is optimal for CTF diagnosis during acute illness. Tick bite prevention measures should continue to be advised for persons doing outdoor activities. |
Laboratory evaluation of RealStar Yellow Fever Virus RT-PCR kit 1.0 for potential use in the global yellow fever laboratory network
Basile AJ , Niedrig M , Lambert AJ , Meurant R , Brault AC , Domingo C , Goodman CH , Johnson BW , Mossel EC , Mulders MN , Velez JO , Hughes HR . PLoS Negl Trop Dis 2022 16 (9) e0010770 BACKGROUND: Early detection of human yellow fever (YF) infection in YF-endemic regions is critical to timely outbreak mitigation. African National Laboratories chiefly rely on serological assays that require confirmation at Regional Reference Laboratories, thus delaying results, which themselves are not always definitive often due to antibody cross-reactivity. A positive molecular test result is confirmatory for YF; therefore, a standardized YF molecular assay would facilitate immediate confirmation at National Laboratories. The WHO-coordinated global Eliminate Yellow Fever Epidemics Laboratory Technical Working Group sought to independently evaluate the quality and performance of commercial YF molecular assays relevant to use in countries with endemic YF, in the absence of stringent premarket assessments. This report details a limited laboratory WHO-coordinated evaluation of the altona Diagnostics RealStar Yellow Fever Virus RT-PCR kit 1.0. METHODOLOGY AND PRINCIPAL FINDINGS: Specific objectives were to assess the assay's ability to detect YF virus strains in human serum from YF-endemic regions, determine the potential for interference and cross-reactions, verify the performance claims as stated by the manufacturer, and assess usability. RNA extracted from normal human serum spiked with YF virus showed the assay to be precise with minimal lot-to-lot variation. The 95% limit of detection calculated was approximately 1,245 RNA copies/ml [95% confidence interval 497 to 1,640 copies/ml]. Positive results were obtained with spatially and temporally diverse YF strains. The assay was specific for YF virus, was not subject to endogenous or exogenous interferents, and was clinically sensitive and specific. A review of operational characteristics revealed that a positivity cutoff was not defined in the instructions for use, but otherwise the assay was user-friendly. CONCLUSIONS AND SIGNIFICANCE: The RealStar Yellow Fever Virus RT-PCR kit 1.0 has performance characteristics consistent with the manufacturer's claims and is suitable for use in YF-endemic regions. Its use is expected to decrease YF outbreak detection times and be instrumental in saving lives. |
Prolonged shedding of Zika virus in human semen is associated with male reproductive tract inflammation.
Vogt MB , McDonald EM , Delorey M , Mead PS , Hook SA , Hinckley AF , Werre SR , Brault AC , Duggal NK . J Infect Dis 2022 226 (7) 1140-1150 Zika virus (ZIKV) is a mosquito-borne flavivirus that causes congenital defects. Sexual transmission of ZIKV was confirmed in a recent epidemic; however, mechanisms behind ZIKV infection and persistence in the male reproductive tract are unknown. Previously, we found that ∼33% of men with symptomatic ZIKV infections shed ZIKV RNA in semen, and some men shed ZIKV RNA for >3 months. Here, we evaluated the semen of 49 ZIKV-infected men to identify immune factors correlating with long-term ZIKV shedding in semen and ZIKV-infected cell types in semen. We found prolonged ZIKV RNA shedding in semen was associated with male reproductive tract inflammation, indicated by higher leukocyte counts and inflammatory cytokine concentrations in semen of long-term versus short-term shedders. Additionally, we found ZIKV RNA in seminal leukocytes and epithelial cells. This study of human semen from ZIKV-infected men provides critical insights into impacts of ZIKV on male reproductive tract health. |
Evaluation of Whatman FTA cards for the preservation of yellow fever virus RNA for use in molecular diagnostics.
Davis EH , Velez JO , Russell BJ , Basile AJ , Brault AC , Hughes HR . PLoS Negl Trop Dis 2022 16 (6) e0010487 Yellow fever virus (YFV) is a flavivirus that frequently causes outbreaks of hemorrhagic fever in Africa and South America and is considered a reemerging public health threat. Accurate diagnosis of yellow fever (YF) disease is critical as one confirmed case constitutes an outbreak and may trigger a mass vaccination campaign. Highly sensitive and specific molecular diagnostics have been developed; however, these assays require maintenance of cold-chain during transport of specimens to prevent the degradation of viral RNA prior to testing. Such cold-chain requirements are difficult to meet in some regions. In this study, we investigated Whatman FTA cards as an alternative stabilization method of YFV RNA for use in molecular diagnosis. Using contrived specimens, linear regression analysis showed that RNA detection from a single 6mm FTA card punch was significantly less sensitive than traditional RNA extraction; however, pooling RNA extracted from two FTA punches significantly lowered the limit of detection to be equal to that of the traditional RNA extraction gold standard. In experiments addressing the ability of FTA card methodology to stabilize YFV RNA at variable temperature, RNA could be detected for more than two weeks following storage at 25°C. Even more promising, YFV RNA was detectable on cards held at 37°C from two days to over two weeks depending on viral input. FTA cards were also shown to stabilize YFV RNA at high humidity if cards were desiccated prior to inoculation. These results support that FTA cards could be cost effective and easy to use in molecular diagnosis of YF, preserving viral RNA to allow for positive diagnoses in situations where maintaining cold-chain is not feasible. |
Genomic Evaluation of the Genus Coltivirus Indicates Genetic Diversity among Colorado Tick Fever Virus Strains and Demarcation of a New Species.
Hughes HR , Velez JO , Fitzpatrick K , Davis EH , Russell BJ , Lambert AJ , Staples JE , Brault AC . Diseases 2021 9 (4) The type species of the genus Coltivirus, Colorado tick fever virus (CTFV), was discovered in 1943 and is the most common tick-borne viral infection in the Western US. Despite its long history, very little is known about the molecular diversity of viruses classified within the species Colorado tick fever coltivirus. Previous studies have suggested genetic variants and potential serotypes of CTFV, but limited genetic sequence information is available for CTFV strains. To address this knowledge gap, we report herein the full-length genomes of five strains of CTFV, including Salmon River virus and California hare coltivirus (CTFV-Ca). The sequence from the full-length genome of Salmon River virus identified a high genetic identity to the CTFV prototype strain with >90% amino acid identity in all the segments except segment four, suggesting Salmon River virus is a strain of the species Colorado tick fever coltivirus. Additionally, analysis suggests that segment four has been associated with reassortment in at least one strain. The CTFV-Ca full-length genomic sequence was highly variable from the prototype CTFV in all the segments. The genome of CTFV-Ca was most similar to the Eyach virus, including similar segments six and seven. These data suggest that CTFV-Ca is not a strain of CTFV but a unique species. Additional sequence information of CTFV strains will improve the molecular surveillance tools and provide additional taxonomic resolution to this understudied virus. |
The host range restriction of bat-associated no-known-vector flaviviruses occurs post-entry.
Charles J , Tangudu CS , Nunez-Avellaneda D , Brault AC , Blitvich BJ . J Gen Virol 2021 102 (9) Most flaviviruses are transmitted horizontally between vertebrate hosts by haematophagous arthropods. Others exhibit host ranges restricted to vertebrates or arthropods. Vertebrate-specific flaviviruses are commonly referred to as no-known-vector (NKV) flaviviruses and can be separated into bat- and rodent-associated NKV flaviviruses. Rio Bravo virus (RBV) is one of eight recognized bat-associated NKV (B-NKV) flaviviruses. Studies designed to identify the genetic determinants that condition the host range restriction of B-NKV flaviviruses have never been performed. To investigate whether the host range restriction occurs at the level of attachment or entry, chimeric flaviviruses were created by inserting the pre-membrane and envelope protein genes of RBV into the genetic backbones of yellow fever virus (YFV) and Zika virus (ZIKV), two mosquito-borne flaviviruses associated with human disease. The chimeric viruses infected both vertebrate and mosquito cells. In vertebrate cells, all viruses produced similar mean peak titres, but the chimeric viruses grew more slowly than their parental viruses during early infection. In mosquito cells, the chimeric virus of YFV and RBV grew more slowly than YFV at early post-inoculation time points, but reached a similar mean peak titre. In contrast, the chimeric virus of ZIKV and RBV produced a mean peak titre that was approximately 10-fold lower than ZIKV. The chimeric virus of YFV and RBV produced an intermediate plaque phenotype, while the chimeric virus of ZIKV and RBV produced smaller plaques than both parental viruses. To conclude, we provide evidence that the structural glycoproteins of RBV permit entry into both mosquito and vertebrate cells, indicating that the host range restriction of B-NKV flaviviruses is mediated by a post-attachment/entry event. |
Fatal Human Infection with Evidence of Intrahost Variation of Eastern Equine Encephalitis Virus, Alabama, USA, 2019.
Hughes HR , Velez JO , Davis EH , Laven J , Gould CV , Panella AJ , Lambert AJ , Staples JE , Brault AC . Emerg Infect Dis 2021 27 (7) 1886-1892 Eastern equine encephalitis virus (EEEV) is an arbovirus in the family Togaviridae, genus Alphavirus, found in North America and associated with freshwater/hardwood swamps in the Atlantic, Gulf Coast, and Great Lakes regions. EEEV disease in humans is rare but causes substantial illness and death. To investigate the molecular epidemiology and microevolution of EEEV from a fatal case in Alabama, USA, in 2019, we used next-generation sequencing of serum and cerebrospinal fluid (CSF). Phylogenetic inference indicated that the infecting strain may be closely related to isolates from Florida detected during 2010-2014, suggesting potential seeding from Florida. EEEV detected in serum displayed a higher degree of variability with more single-nucleotide variants than that detected in the CSF. These data refine our knowledge of EEEV molecular epidemiologic dynamics in the Gulf Coast region and demonstrate potential quasispecies bottlenecking within the central nervous system of a human host. |
Chimeric Zika viruses containing structural protein genes of insect-specific flaviviruses cannot replicate in vertebrate cells due to entry and post-translational restrictions.
Tangudu CS , Charles J , Nunez-Avellaneda D , Hargett AM , Brault AC , Blitvich BJ . Virology 2021 559 30-39 Long Pine Key virus (LPKV) and Lammi virus are insect-specific flaviviruses that phylogenetically affiliate with dual-host flaviviruses. The goal of this study was to provide insight into the genetic determinants that condition this host range restriction. Chimeras were initially created by replacing select regions of the Zika virus genome, including the premembrane and envelope protein (prM-E) genes, with the corresponding regions of the LPKV genome. Of the four chimeras produced, one (the prM-E swap) yielded virus that replicated in mosquito cells. Another chimeric virus with a mosquito replication-competent phenotype was created by inserting the prM-E genes of Lammi virus into a Zika virus genetic background. Vertebrate cells did not support the replication of either chimeric virus although trace to modest amounts of viral antigen were produced, consistent with suboptimal viral entry. These data suggest that dual-host affiliated insect-specific flaviviruses cannot replicate in vertebrate cells due to entry and post-translational restrictions. |
Discordant Clinical Outcomes in a Monozygotic Dichorionic-Diamniotic Twin Pregnancy with Probable Zika Virus Exposure. Case Report.
Mercado M , Daza M , Moore CA , Valencia D , Rico A , Álvarez-Diaz DA , Brault AC , Fitzpatrick K , Mulkey SB . Trop Med Infect Dis 2020 5 (4) Prenatal exposure to Zika virus (ZIKV) is associated with congenital anomalies of the brain and the eye and neurodevelopmental sequelae. The spectrum of disease outcomes may relate to timing of infection as well as genetic and environmental factors. Congenital infections occurring in twin pregnancies can inform the clinical spectrum of these conditions and provide unique information regarding timing of infection and in utero environment with disease pathophysiology. Herein, we report a monozygotic dichorionic-diamniotic twin pregnancy with probable prenatal ZIKV exposure identified through the Colombian ZIKV disease surveillance system. Multidisciplinary clinical evaluations were provided to the twins during their first three years of life through a national program for children with in utero ZIKV exposure. Laboratory evidence of congenital infection as well as microcephaly, brain, eye, and neurodevelopmental compromise related to prenatal ZIKV infection were identified in only one infant of the twin pregnancy. This is the first report of monozygotic twins discordant for Zika-associated birth defects. The evaluation of the pathophysiology of discordance in disease outcome for congenital infections in twin pregnancies may lead to a better understanding of potential complex environmental and genetic interactions between the mother, her offspring, and an infectious exposure. |
Development of diagnostic microsphere-based immunoassays for Heartland virus
Basile AJ , Horiuchi K , Goodman CH , Kosoy O , Panella AJ , Velez JO , Pastula DM , Brault AC , Staples JE , Calvert AE . J Clin Virol 2020 134 104693 BACKGROUND: Heartland virus (HRTV), a recently reclassified member of the genus Bandavirus, family Phenuiviridae, was first isolated in 2009 from a Missouri farmer exhibiting leukopenia and thrombocytopenia with suspected ehrlichiosis. Since then, more HRTV cases have been diagnosed, and firstline laboratory diagnostic assays are needed to identify future infections Objectives. We sought to develop rapid and reliable IgM and IgG microsphere immunoassays (MIAs) to test sera of patients suspected of having HRTV infection, and to distinguish between recent and past infections. STUDY DESIGN: Heartland virus antigen was captured by an anti-HRTV monoclonal antibody covalently bound to microspheres. Antibodies in human sera from confirmed HRTV-positive and negative cases were reacted with the microsphere complexes and detected using a BioPlex® 200 instrument. Assay cutoffs were determined by receiver operator characteristic analysis of the normalized test output values, equivocal zones for each assay were defined, and sensitivities, specificities, accuracies, and imprecision values were calculated. RESULTS: Sensitivities, specificities and accuracies of the IgM and IgG MIAs were all >95 %. Both tests were precise within and between assay plates, and cross-reactivity with other arboviruses was not observed. CONCLUSIONS: HRTV IgM and IgG MIAs are accurate and rapid first-line methods to serologically identify recent and past HRTV infections. |
Global perspectives on arbovirus outbreaks: A 2020 snapshot
Kading RC , Brault AC , Beckham JD . Trop Med Infect Dis 2020 5 (3) When this special issue was first conceived in early 2019, we never anticipated that the publication of this collection of articles would be happening during a pandemic. While this outbreak collection is focused on viruses transmitted by arthropods, its release concurrent with the SARS-CoV-2 pandemic and international health emergency provides an appropriate context in which to draw attention to research focused on other high-consequence, epidemic-causing viruses that may be next to emerge on the global stage. |
Zika virus replication in myeloid cells during acute infection is vital to viral dissemination and pathogenesis in a mouse model
McDonald EM , Anderson J , Wilusz J , Ebel GD , Brault AC . J Virol 2020 94 (21) Zika virus (ZIKV) can establish infection in immune privileged sites such as the testes, eye and placenta. Whether ZIKV infection of white blood cells is required for dissemination of the virus to immune privileged sites has not been definitively shown. To assess whether initial ZIKV replication in myeloid cell populations is critical for dissemination during acute infection, recombinant ZIKVs were generated that could not replicate in these specific cells. ZIKV was cell-restricted by insertion of a complementary sequence to a myeloid-specific microRNA in the 3'untranslated region. Following inoculation of a highly sensitive immunodeficient mouse model, crucial immune parameters, such as quantification of leukocyte cell subsets, cytokine and chemokine secretion, and viremia were assessed. Decreased neutrophil numbers in the spleen were observed during acute infection with myeloid-restricted ZIKV that precluded the generation of viremia and viral dissemination to peripheral organs. Mice inoculated with a non-target microRNA control ZIKV demonstrated increased expression of key cytokines and chemokines critical for neutrophil and monocyte recruitment and increased neutrophil influx in the spleen. In addition, ZIKV-infected Ly6C(hi) monocytes were identified in vivo in the spleen. Mice inoculated with myeloid-restricted ZIKV exhibited similar trends as PBS-sham inoculated mice, including a lack of inflammatory cytokine production and a decrease in Ly6C(hi) ZIKV RNA positive monocytes.ImportanceMyeloid cells, including monocytes, play a crucial role in immune responses to pathogens. Monocytes have also been implicated as "Trojan horses" during viral infections, carrying infectious virus particles to immune privileged sites and/or to sites protected by physical blood-tissue barriers, such as the blood-testis barrier and the blood-brain barrier. In this study, we found that myeloid cells are crucial to Zika virus (ZIKV) pathogenesis. By engineering ZIKV clones to encode myeloid-specific microRNA target sequences, viral replication was inhibited in myeloid cells by harnessing the RNAi pathway. Severely immunodeficient mice inoculated with myeloid-restricted ZIKV did not demonstrate clinical signs of disease and survived infection. Furthermore, viral dissemination to peripheral organs was not observed in these mice. Lastly, we identified Ly6C(mid/hi) murine monocytes as the major myeloid cell population that disseminates ZIKV. |
Movement of St. Louis encephalitis virus in the Western United States, 2014- 2018.
Swetnam DM , Stuart JB , Young K , Maharaj PD , Fang Y , Garcia S , Barker CM , Smith K , Godsey MS , Savage HM , Barton V , Bolling BG , Duggal N , Brault AC , Coffey LL . PLoS Negl Trop Dis 2020 14 (6) e0008343 St. Louis encephalitis virus (SLEV) is a flavivirus that circulates in an enzootic cycle between birds and mosquitoes and can also infect humans to cause febrile disease and sometimes encephalitis. Although SLEV is endemic to the United States, no activity was detected in California during the years 2004 through 2014, despite continuous surveillance in mosquitoes and sentinel chickens. In 2015, SLEV-positive mosquito pools were detected in Maricopa County, Arizona, concurrent with an outbreak of human SLEV disease. SLEV-positive mosquito pools were also detected in southeastern California and Nevada in summer 2015. From 2016 to 2018, SLEV was detected in mosquito pools throughout southern and central California, Oregon, Idaho, and Texas. To understand genetic relatedness and geographic dispersal of SLEV in the western United States since 2015, we sequenced four historical genomes (3 from California and 1 from Louisiana) and 26 contemporary SLEV genomes from mosquito pools from locations across the western US. Bayesian phylogeographic approaches were then applied to map the recent spread of SLEV. Three routes of SLEV dispersal in the western United States were identified: Arizona to southern California, Arizona to Central California, and Arizona to all locations east of the Sierra Nevada mountains. Given the topography of the Western United States, these routes may have been limited by mountain ranges that influence the movement of avian reservoirs and mosquito vectors, which probably represents the primary mechanism of SLEV dispersal. Our analysis detected repeated SLEV introductions from Arizona into southern California and limited evidence of year-to-year persistence of genomes of the same ancestry. By contrast, genetic tracing suggests that all SLEV activity since 2015 in central California is the result of a single persistent SLEV introduction. The identification of natural barriers that influence SLEV dispersal enhances our understanding of arbovirus ecology in the western United States and may also support regional public health agencies in implementing more targeted vector mitigation efforts to protect their communities more effectively. |
"Submergence" of Western equine encephalitis virus: Evidence of positive selection argues against genetic drift and fitness reductions.
Bergren NA , Haller S , Rossi SL , Seymour RL , Huang J , Miller AL , Bowen RA , Hartman DA , Brault AC , Weaver SC . PLoS Pathog 2020 16 (2) e1008102 Understanding the circumstances under which arboviruses emerge is critical for the development of targeted control and prevention strategies. This is highlighted by the emergence of chikungunya and Zika viruses in the New World. However, to comprehensively understand the ways in which viruses emerge and persist, factors influencing reductions in virus activity must also be understood. Western equine encephalitis virus (WEEV), which declined during the late 20th century in apparent enzootic circulation as well as equine and human disease incidence, provides a unique case study on how reductions in virus activity can be understood by studying evolutionary trends and mechanisms. Previously, we showed using phylogenetics that during this period of decline, six amino acid residues appeared to be positively selected. To assess more directly the effect of these mutations, we utilized reverse genetics and competition fitness assays in the enzootic host and vector (house sparrows and Culex tarsalis mosquitoes). We observed that the mutations contemporary with reductions in WEEV circulation and disease that were non-conserved with respect to amino acid properties had a positive effect on enzootic fitness. We also assessed the effects of these mutations on virulence in the Syrian-Golden hamster model in relation to a general trend of increased virulence in older isolates. However, no change effect on virulence was observed based on these mutations. Thus, while WEEV apparently underwent positive selection for infection of enzootic hosts, residues associated with mammalian virulence were likely eliminated from the population by genetic drift or negative selection. These findings suggest that ecologic factors rather than fitness for natural transmission likely caused decreased levels of enzootic WEEV circulation during the late 20th century. |
Bourbon virus in wild and domestic animals, Missouri, USA, 2012-2013
Jackson KC , Gidlewski T , Root JJ , Bosco-Lauth AM , Lash RR , Harmon JR , Brault AC , Panella NA , Nicholson WL , Komar N . Emerg Infect Dis 2019 25 (9) 1752-1753 Since its recent discovery, Bourbon virus has been isolated from a human and ticks. To assess exposure of potential vertebrate reservoirs, we assayed banked serum and plasma samples from wildlife and domestic animals in Missouri, USA, for Bourbon virus-neutralizing antibodies. We detected high seroprevalence in raccoons (50%) and white-tailed deer (86%). |
On the Fly: Interactions Between Birds, Mosquitoes, and Environment That Have Molded West Nile Virus Genomic Structure Over Two Decades.
Duggal NK , Langwig KE , Ebel GD , Brault AC . J Med Entomol 2019 56 (6) 1467-1474 West Nile virus (WNV) was first identified in North America almost 20 yr ago. In that time, WNV has crossed the continent and established enzootic transmission cycles, resulting in intermittent outbreaks of human disease that have largely been linked with climatic variables and waning avian seroprevalence. During the transcontinental dissemination of WNV, the original genotype has been displaced by two principal extant genotypes which contain an envelope mutation that has been associated with enhanced vector competence by Culex pipiens L. (Diptera: Culicidae) and Culex tarsalis Coquillett vectors. Analyses of retrospective avian host competence data generated using the founding NY99 genotype strain have demonstrated a steady reduction in viremias of house sparrows over time. Reciprocally, the current genotype strains WN02 and SW03 have demonstrated an inverse correlation between house sparrow viremia magnitude and the time since isolation. These data collectively indicate that WNV has evolved for increased avian viremia while house sparrows have evolved resistance to the virus such that the relative host competence has remained constant. Intrahost analyses of WNV evolution demonstrate that selection pressures are avian species-specific and purifying selection is greater in individual birds compared with individual mosquitoes, suggesting that the avian adaptive and/or innate immune response may impose a selection pressure on WNV. Phylogenomic, experimental evolutionary systems, and models that link viral evolution with climate, host, and vector competence studies will be needed to identify the relative effect of different selective and stochastic mechanisms on viral phenotypes and the capacity of newly evolved WNV genotypes for transmission in continuously changing landscapes. |
N-linked glycosylation of the West Nile virus envelope protein is not a requisite for avian virulence or vector competence
Maharaj PD , Langevin SA , Bolling BG , Andrade CC , Engle XA , Ramey WN , Bosco-Lauth A , Bowen RA , Sanders TA , Huang CY , Reisen WK , Brault AC . PLoS Negl Trop Dis 2019 13 (7) e0007473 The N-linked glycosylation motif at amino acid position 154-156 of the envelope (E) protein of West Nile virus (WNV) is linked to enhanced murine neuroinvasiveness, avian pathogenicity and vector competence. Naturally occurring isolates with altered E protein glycosylation patterns have been observed in WNV isolates; however, the specific effects of these polymorphisms on avian host pathogenesis and vector competence have not been investigated before. In the present study, amino acid polymorphisms, NYT, NYP, NYF, SYP, SYS, KYS and deletion (A'DEL), were reverse engineered into a parental WNV (NYS) cDNA infectious clone to generate WNV glycosylation mutant viruses. These WNV glycosylation mutant viruses were characterized for in vitro growth, pH-sensitivity, temperature-sensitivity and host competence in American crows (AMCR), house sparrows (HOSP) and Culex quinquefasciatus. The NYS and NYT glycosylated viruses showed higher viral replication, pH and temperature sensitivity than NYP, NYF, SYP, SYS, KYS and A'DEL viruses in vitro. Interestingly, in vivo results demonstrated asymmetric effects in avian and mosquito competence that were independent of the E-protein glycosylation status. In AMCRs and HOSPs, all viruses showed comparable viremias with the exception of NYP and KYS viruses that showed attenuated phenotypes. Only NYP showed reduced vector competence in both Cx. quinquefasciatus and Cx. tarsalis. Glycosylated NYT exhibited similar avian virulence properties as NYS, but resulted in higher mosquito oral infectivity than glycosylated NYS and nonglycosylated, NYP, NYF, SYP and KYS mutants. These data demonstrated that amino acid polymorphisms at E154/156 dictate differential avian host and vector competence phenotypes independent of E-protein glycosylation status. |
Duration of seminal Zika viral RNA shedding in immunocompetent mice inoculated with Asian and African genotype viruses.
McDonald EM , Duggal NK , Delorey MJ , Oksanish J , Ritter JM , Brault AC . Virology 2019 535 1-10 Prior to the emergence of Asian genotype Zika virus (ZIKV) in the Western hemisphere, sexual transmission in humans was documented. Sexual transmission by African genotype ZIKVs has not been assessed in laboratory animal models, due to rapid and high mortality rates of immunodeficient mice following inoculation. To overcome these limitations, immunocompetent C57Bl/6 mice were used to longitudinally assess Asian and African genotype ZIKV sexual transmission potential. Furthermore, to determine if enhanced pathogenesis of African genotype ZIKVs is due to structural determinants, PRVABC59 prM/E was replaced with African MR766 prM/E (chimeric ZIKV). The African genotype and chimeric ZIKV elicited greater pathogenic effects in the male reproductive tract and generated higher viremias. Yet, the duration, magnitude and efficiency of seminal shedding of infectious virus and viral RNA were similar between chimeric-, African and Asian genotype ZIKV-inoculated mice. These data show that increased male reproductive tract pathology does not increase sexual transmission potential. |
Mutations present in a low-passage Zika virus isolate result in attenuated pathogenesis in mice
Duggal NK , McDonald EM , Weger-Lucarelli J , Hawks SA , Ritter JM , Romo H , Ebel GD , Brault AC . Virology 2019 530 19-26 Zika virus (ZIKV) infection can result in neurological disorders including Congenital Zika Syndrome in infants exposed to the virus in utero. Pregnant women can be infected by mosquito bite as well as by sexual transmission from infected men. Herein, the variants of ZIKV within the male reproductive tract and ejaculates were assessed in inoculated mice. We identified two non-synonymous variants at positions E-V330L and NS1-W98G. These variants were also present in the passage three PRVABC59 isolate and infectious clone relative to the patient serum PRVABC59 sequence. In subsequent studies, ZIKV E-330L was less pathogenic in mice than ZIKV E-330V as evident by increased average survival times. In Vero cells, ZIKV E-330L/NS1-98G outcompeted ZIKV E-330V/NS1-98W within 3 passages. These results suggest that the E-330L/NS1-98G variants are attenuating in mice and were enriched during cell culture passaging. Cell culture propagation of ZIKV could significantly affect animal model development and vaccine efficacy studies. |
Comparative fitness of West Nile virus isolated during California epidemics
Worwa G , Hutton AA , Brault AC , Reisen WK . PLoS Negl Trop Dis 2019 13 (2) e0007135 West Nile virus (WNV) has been circulating in California since its first detection in 2003, causing repeated outbreaks affecting public, wildlife and veterinary health. Epidemics of WNV are difficult to predict due to the multitude of factors influencing transmission dynamics among avian and mosquito hosts. Typically, high levels of WNV amplification are required for outbreaks to occur, and therefore associated viral strains may exhibit enhanced virulence and mortality in competent bird species resulting in increased mosquito infection prevalence. In our previous study, most WNV isolates made from California during 2007-08 showed increased fitness when competed in House Finches (HOFI, Haemorhous mexicanus) and Culex tarsalis Coquillett mosquitoes against COAV997-5nt, a genetically marked recombinant virus derived from a 2003 California strain. Herein, we evaluated the competitive fitness of WNV strains isolated during California epidemics in 2004, 2005, 2007, 2011 and 2012 against COAV997-5nt. These outbreak isolates did not produce elevated mortality in HOFIs, but replicated more efficiently than did COAV997-5nt based on quantification of WNV RNA copies in sera, thereby demonstrating increased competitive fitness. Oral co-infections in Cx. tarsalis resulted in similar virus-specific infection and transmission rates, indicating that outbreak isolates did not have a fitness advantage over COAV997-5nt. Collectively, WNV isolates from outbreaks demonstrated relatively greater avian, but not vector, replicative fitness compared to COAV997-5nt, similar to previously characterized non-outbreak isolates of WNV. Our results indicated that ecological rather than viral factors may facilitate WNV amplification to outbreak levels, but monitoring viral phenotypes through competitive fitness studies may provide insight into altered replication and transmission potential among emerging WNV strains. |
Restriction of Zika virus infection and transmission in Aedes aegypti mediated by an insect-specific flavivirus
Romo H , Kenney JL , Blitvich BJ , Brault AC . Emerg Microbes Infect 2018 7 (1) 181 Previous studies demonstrated an insect-specific flavivirus, Nhumirim virus (NHUV), can suppress growth of West Nile virus (WNV) and decrease transmission rates in NHUV/WNV co-inoculated Culex quinquefasciatus. To assess whether NHUV might interfere with transmission of other medically important flaviviruses, the ability of NHUV to suppress viral growth of Zika virus (ZIKV) and dengue-2 virus (DENV-2) was assessed in Aedes albopictus cells. Significant reductions in ZIKV (100,000-fold) and DENV-2 (10,000-fold) were observed in either cells concurrently inoculated with NHUV or pre-inoculated with NHUV. In contrast, only a transient 10-fold titer reduction was observed with an alphavirus, chikungunya virus. Additionally, restricted in vitro mosquito growth of ZIKV was associated with lowered levels of intracellular ZIKV RNA in NHUV co-inoculated cultures. To assess whether NHUV could modulate vector competence for ZIKV, NHUV-inoculated Aedes aegypti were orally exposed to ZIKV. NHUV-inoculated mosquitoes demonstrated significantly lower ZIKV infection rates (18%) compared to NHUV unexposed mosquitoes (51%) (p < 0.002). Similarly, lower ZIKV transmission rates were observed for NHUV/ZIKV dually intrathoracically inoculated mosquitoes (41%) compared to ZIKV only inoculated mosquitoes (78%) (p < 0.0001), suggesting that NHUV can interfere with both midgut infection and salivary gland infection of ZIKV in Ae. aegypti. These results indicate NHUV could be utilized to model superinfection exclusion mechanism(s) and to study the potential for the mosquito virome to impact transmission of medically important flaviviruses. |
Heartland virus epidemiology, vector association, and disease potential
Brault AC , Savage HM , Duggal NK , Eisen RJ , Staples JE . Viruses 2018 10 (9) First identified in two Missouri farmers exhibiting low white-blood-cell and platelet counts in 2009, Heartland virus (HRTV) is genetically closely related to severe fever with thrombocytopenia syndrome virus (SFTSV), a tick-borne phlebovirus producing similar symptoms in China, Korea, and Japan. Field isolations of HRTV from several life stages of unfed, host-seeking Amblyomma americanum, the lone star tick, implicated it as a putative vector capable of transstadial transmission. Laboratory vector competence assessments confirmed transstadial transmission of HRTV, demonstrated vertical infection, and showed co-feeding infection between A. americanum. A vertical infection rate of 33% from adult females to larvae in the laboratory was observed, while only one of 386 pools of molted nymphs (1930) reared from co-feeding larvae was positive for HRTV (maximum-likelihood estimate of infection rate = 0.52/1000). Over 35 human HRTV cases, all within the distribution range of A. americanum, have been documented. Serological testing of wildlife in areas near the index human cases, as well as in widely separated regions of the eastern United States where A. americanum occur, indicated many potential hosts such as raccoons and white-tailed deer. Attempts, however, to experimentally infect mice, rabbits, hamsters, chickens, raccoons, goats, and deer failed to produce detectable viremia. Immune-compromised mice and hamsters are the only susceptible models. Vertical infection augmented by co-feeding transmission could play a role in maintaining the virus in nature. A more complete assessment of the natural transmission cycle of HRTV coupled with serosurveys and enhanced HRTV disease surveillance are needed to better understand transmission dynamics and human health risks. |
Infection of epididymal epithelial cells and leukocytes drives seminal shedding of Zika virus in a mouse model
McDonald EM , Duggal NK , Ritter JM , Brault AC . PLoS Negl Trop Dis 2018 12 (8) e0006691 While primarily a mosquito-borne virus, Zika virus (ZIKV; genus Flavivirus in the Flaviviridae family) is capable of being sexually transmitted. Thirty to fifty percent of men with confirmed ZIKV infection shed ZIKV RNA in their semen, and prolonged viral RNA shedding in semen can occur for more than 6 months. The cellular reservoir of ZIKV in semen is unknown, although spermatozoa have been shown to contain ZIKV RNA and antigen. Yet, spermatozoa are not a requisite for sexual transmission, as at least one case of ZIKV sexual transmission involved a vasectomized man. To determine the cellular reservoirs of ZIKV in semen, an established animal model of sexual transmission was used. The majority of virus detected in the seminal fluid of infected mice during the peak timing of sexual transmission was from the supernatant fraction, suggesting cell-free ZIKV may be largely responsible for sexual transmission. However, some ZIKV RNA was cell-associated. In the testes and epididymides of infected mice, intracellular staining of ZIKV RNA was more pronounced in spermatogenic precursors (spermatocytes and spermatogonia) than in spermatids. Visualization of intracellular negative strand ZIKV RNA demonstrated ZIKV replication intermediates in leukocytes, immature spermatids and epididymal epithelial cells in the male urogenital tract. Epididymal epithelial cells were the principal source of negative-strand ZIKV RNA during the peak timing of sexual transmission potential, indicating these cells may be the predominant source of infectious cell-free ZIKV in seminal fluid. These data promote a more complete understanding of sexual transmission of ZIKV and will inform further model development for future studies on persistent ZIKV RNA shedding. |
Bunyavirus taxonomy: Limitations and misconceptions associated with the current ICTV criteria used for species demarcation
Blitvich BJ , Beaty BJ , Blair CD , Brault AC , Dobler G , Drebot MA , Haddow AD , Kramer LD , LaBeaud AD , Monath TP , Mossel EC , Plante K , Powers AM , Tesh RB , Turell MJ , Vasilakis N , Weaver SC . Am J Trop Med Hyg 2018 99 (1) 11-16 The International Committee on Taxonomy of Viruses (ICTV) has implemented numerous changes to the taxonomic classification of bunyaviruses over the years. Whereas most changes have been justified and necessary because of the need to accommodate newly discovered and unclassified viruses, other changes are a cause of concern, especially the decision to demote scores of formerly recognized species to essentially strains of newly designated species. This practice was first described in the seventh taxonomy report of the ICTV and has continued in all subsequent reports. In some instances, viruses that share less than 75% nucleotide sequence identity across their genomes, produce vastly different clinical presentations, possess distinct vector and host associations, have different biosafety recommendations, and occur in nonoverlapping geographic regions are classified as strains of the same species. Complicating the matter is the fact that virus strains have been completely eliminated from ICTV reports; thus, critically important information on virus identities and their associated biological and epidemiological features cannot be readily related to the ICTV classification. Here, we summarize the current status of bunyavirus taxonomy and discuss the adverse consequences associated with the reclassification and resulting omission of numerous viruses of public health importance from ICTV reports. As members of the American Committee on Arthropod-borne Viruses, we encourage the ICTV Bunyavirus Study Group to reconsider their stance on bunyavirus taxonomy, to revise the criteria currently used for species demarcation, and to list additional strains of public and veterinary importance. |
Generation of a Lineage II Powassan Virus (Deer Tick Virus) cDNA Clone: Assessment of Flaviviral Genetic Determinants of Tick and Mosquito Vector Competence.
Kenney JL , Anishchenko M , Hermance M , Romo H , Chen CI , Thangamani S , Brault AC . Vector Borne Zoonotic Dis 2018 18 (7) 371-381 The Flavivirus genus comprises a diverse group of viruses that utilize a wide range of vertebrate hosts and arthropod vectors. The genus includes viruses that are transmitted solely by mosquitoes or vertebrate hosts as well as viruses that alternate transmission between mosquitoes or ticks and vertebrates. Nevertheless, the viral genetic determinants that dictate these unique flaviviral host and vector specificities have been poorly characterized. In this report, a cDNA clone of a flavivirus that is transmitted between ticks and vertebrates (Powassan lineage II, deer tick virus [DTV]) was generated and chimeric viruses between the mosquito/vertebrate flavivirus, West Nile virus (WNV), were constructed. These chimeric viruses expressed the prM and E genes of either WNV or DTV in the heterologous nonstructural (NS) backbone. Recombinant chimeric viruses rescued from cDNAs were characterized for their capacity to grow in vertebrate and arthropod (mosquito and tick) cells as well as for in vivo vector competence in mosquitoes and ticks. Results demonstrated that the NS elements were insufficient to impart the complete mosquito or tick growth phenotypes of parental viruses; however, these NS genetic elements did contribute to a 100- and 100,000-fold increase in viral growth in vitro in tick and mosquito cells, respectively. Mosquito competence was observed only with parental WNV, while infection and transmission potential by ticks were observed with both DTV and WNV-prME/DTV chimeric viruses. These data indicate that NS genetic elements play a significant, but not exclusive, role for vector usage of mosquito- and tick-borne flaviviruses. |
Zika Virus Shedding in Semen of Symptomatic Infected Men.
Mead PS , Duggal NK , Hook SA , Delorey M , Fischer M , Olzenak McGuire D , Becksted H , Max RJ , Anishchenko M , Schwartz AM , Tzeng WP , Nelson CA , McDonald EM , Brooks JT , Brault AC , Hinckley AF . N Engl J Med 2018 378 (15) 1377-1385 BACKGROUND: Zika virus (ZIKV) is an emerging mosquito-borne flavivirus that has been linked to adverse birth outcomes. Previous reports have shown that person-to-person transmission can occur by means of sexual contact. METHODS: We conducted a prospective study involving men with symptomatic ZIKV infection to determine the frequency and duration of ZIKV shedding in semen and urine and to identify risk factors for prolonged shedding in these fluids. Specimens were obtained twice per month for 6 months after illness onset and were tested by real-time reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay for ZIKV RNA and by Vero cell culture and plaque assay for infectious ZIKV. RESULTS: A total of 1327 semen samples from 184 men and 1038 urine samples from 183 men were obtained 14 to 304 days after illness onset. ZIKV RNA was detected in the urine of 7 men (4%) and in the semen of 60 (33%), including in semen samples from 22 of 36 men (61%) who were tested within 30 days after illness onset. ZIKV RNA shedding in semen decreased substantially during the 3 months after illness onset but continued for 281 days in 1 man (1%). Factors that were independently associated with prolonged RNA shedding included older age, less frequent ejaculation, and the presence of certain symptoms at the time of initial illness. Infectious ZIKV was isolated from 3 of 78 semen samples with detectable ZIKV RNA, all obtained within 30 days after illness onset and all with at least 7.0 log10 ZIKV RNA copies per milliliter of semen. CONCLUSIONS: ZIKV RNA was commonly present in the semen of men with symptomatic ZIKV infection and persisted in some men for more than 6 months. In contrast, shedding of infectious ZIKV appeared to be much less common and was limited to the first few weeks after illness onset. (Funded by the Centers for Disease Control and Prevention.). |
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