Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-25 (of 25 Records) |
Query Trace: Crabtree M[original query] |
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A Pan-respiratory Antiviral Chemotype Targeting a Transient Host Multiprotein Complex (preprint)
Muller-Schiffmann A , Michon M , Lingappa AF , Yu SF , Du L , Deiter F , Broce S , Mallesh S , Crabtree J , Lingappa UF , Macieik A , Muller L , Ostermann PN , Andree M , Adams O , Schaal H , Hogan RJ , Tripp RA , Appaiah U , Anand SK , Campi TW , Ford MJ , Reed JC , Lin J , Akintunde O , Copeland K , Nichols C , Petrouski E , Moreira AR , Jiang IT , DeYarman N , Brown I , Lau S , Segal I , Goldsmith D , Hong S , Asundi V , Briggs EM , Phyo NS , Froehlich M , Onisko B , Matlack K , Dey D , Lingappa JR , Prasad MD , Kitaygorodskyy A , Solas D , Boushey H , Greenland J , Pillai S , Lo MK , Montgomery JM , Spiropoulou CF , Korth C , Selvarajah S , Paulvannan K , Lingappa VR . bioRxiv 2021 18 We present a small molecule chemotype, identified by an orthogonal drug screen, exhibiting nanomolar activity against members of all the six viral families causing most human respiratory viral disease, with a demonstrated barrier to resistance development. Antiviral activity is shown in mammalian cells, including human primary bronchial epithelial cells cultured to an air-liquid interface and infected with SARS-CoV-2. In animals, efficacy of early compounds in the lead series is shown by survival (for a coronavirus) and viral load (for a paramyxovirus). The drug target is shown to include a subset of the protein 14-3-3 within a transient host multi-protein complex containing components implicated in viral lifecycles and in innate immunity. This multi-protein complex is modified upon viral infection and largely restored by drug treatment. Our findings suggest a new clinical therapeutic strategy for early treatment upon upper respiratory viral infection to prevent progression to lower respiratory tract or systemic disease. Copyright The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. |
Exposure of Egyptian rousette bats (Rousettus aegyptiacus) and a little free-tailed bat (Chaerephon pumilus) to alphaviruses in Uganda
Kading RC , Borland EM , Mossel EC , Nakayiki T , Nalikka B , Ledermann JP , Crabtree MB , Panella NA , Nyakarahuka L , Gilbert AT , Kerbis-Peterhans JC , Towner JS , Amman BR , Sealy TK , Miller BR , Lutwama JJ , Kityo RM , Powers AM . Diseases 2022 10 (4) The reservoir for zoonotic o'nyong-nyong virus (ONNV) has remained unknown since this virus was first recognized in Uganda in 1959. Building on existing evidence for mosquito blood-feeding on various frugivorous bat species in Uganda, and seroprevalence for arboviruses among bats in Uganda, we sought to assess if serum samples collected from bats in Uganda demonstrated evidence of exposure to ONNV or the closely related zoonotic chikungunya virus (CHIKV). In total, 652 serum samples collected from six bat species were tested by plaque reduction neutralization test (PRNT) for neutralizing antibodies against ONNV and CHIKV. Forty out of 303 (13.2%) Egyptian rousettes from Maramagambo Forest and 1/13 (8%) little free-tailed bats from Banga Nakiwogo, Entebbe contained neutralizing antibodies against ONNV. In addition, 2/303 (0.7%) of these Egyptian rousettes contained neutralizing antibodies to CHIKV, and 8/303 (2.6%) contained neutralizing antibodies that were nonspecifically reactive to alphaviruses. These data support the interepidemic circulation of ONNV and CHIKV in Uganda, although Egyptian rousette bats are unlikely to serve as reservoirs for these viruses given the inconsistent occurrence of antibody-positive bats. |
Discovery and Characterization of Bukakata orbivirus ( Reoviridae:Orbivirus ), a Novel Virus from a Ugandan Bat.
Fagre AC , Lee JS , Kityo RM , Bergren NA , Mossel EC , Nakayiki T , Nalikka B , Nyakarahuka L , Gilbert AT , Peterhans JK , Crabtree MB , Towner JS , Amman BR , Sealy TK , Schuh AJ , Nichol ST , Lutwama JJ , Miller BR , Kading RC . Viruses 2019 11 (3) While serological and virological evidence documents the exposure of bats to medically-important arboviruses, their role as reservoirs or amplifying hosts is less well-characterized. We describe a novel orbivirus (Reoviridae:Orbivirus) isolated from an Egyptian fruit bat (Rousettus aegyptiacus leachii) trapped in 2013 in Uganda and named Bukakata orbivirus. This is the fifth orbivirus isolated from a bat, however genetic information had previously only been available for one bat-associated orbivirus. We performed whole-genome sequencing on Bukakata orbivirus and three other bat-associated orbiviruses (Fomede, Ife, and Japanaut) to assess their phylogenetic relationship within the genus Orbivirus and develop hypotheses regarding potential arthropod vectors. Replication kinetics were assessed for Bukakata orbivirus in three different vertebrate cell lines. Lastly, qRT-PCR and nested PCR were used to determine the prevalence of Bukakata orbivirus RNA in archived samples from three populations of Egyptian fruit bats and one population of cave-associated soft ticks in Uganda. Complete coding sequences were obtained for all ten segments of Fomede, Ife, and Japanaut orbiviruses and for nine of the ten segments for Bukakata orbivirus. Phylogenetic analysis placed Bukakata and Fomede in the tick-borne orbivirus clade and Ife and Japanaut within the Culicoides/phlebotomine sandfly orbivirus clade. Further, Bukakata and Fomede appear to be serotypes of the Chobar Gorge virus species. Bukakata orbivirus replicated to high titers (10(6)(-)10(7) PFU/mL) in Vero, BHK-21 [C-13], and R06E (Egyptian fruit bat) cells. Preliminary screening of archived bat and tick samples do not support Bukakata orbivirus presence in these collections, however additional testing is warranted given the phylogenetic associations observed. This study provided complete coding sequence for several bat-associated orbiviruses and in vitro characterization of a bat-associated orbivirus. Our results indicate that bats may play an important role in the epidemiology of viruses in the genus Orbivirus and further investigation is warranted into vector-host associations and ongoing surveillance efforts. |
Confirmation of Zika virus infection through hospital-based sentinel surveillance of acute febrile illness in Uganda, 2014-2017
Kayiwa JT , Nankya AM , Ataliba IJ , Mossel EC , Crabtree MB , Lutwama JJ . J Gen Virol 2018 99 (9) 1248-1252 Zika virus (ZIKV), transmitted by Aedes species mosquitoes, was first isolated in Uganda in 1947. From February 2014 to October 2017, the Uganda Virus Research Institute, in collaboration with the US Centers for Diseases Control and Prevention, conducted arbovirus surveillance in acute febrile illness (AFI) patients at St Francis hospital in Nkonkonjeru. Three hundred and eighty-four serum samples were collected and tested for IgM antibodies to yellow fever virus (YFV), West Nile virus (WNV), dengue virus (DENV), chikungunya virus (CHIKV) and ZIKV. Of the 384 samples, 5 were positive for ZIKV IgM. Of these five, three were confirmed by plaque reduction neutralization test (PRNT) to be ZIKV infections. Of the remaining two, one was determined to be a non-specific flavivirus infection and one was confirmed to be alphavirus-positive by reverse transcriptase polymerase chain reaction (RT-PCR). This study provides the first evidence of laboratory-confirmed ZIKV infection in Uganda in five decades, and emphasizes the need to enhance sentinel surveillance. |
Neutralizing antibodies against flaviviruses, Babanki virus, and Rift Valley fever virus in Ugandan bats
Kading RC , Kityo RM , Mossel EC , Borland EM , Nakayiki T , Nalikka B , Nyakarahuka L , Ledermann JP , Panella NA , Gilbert AT , Crabtree MB , Peterhans JK , Towner JS , Amman BR , Sealy TK , Nichol ST , Powers AM , Lutwama JJ , Miller BR . Infect Ecol Epidemiol 2018 8 (1) 1439215 Introduction: A number of arboviruses have previously been isolated from naturally-infected East African bats, however the role of bats in arbovirus maintenance is poorly understood. The aim of this study was to investigate the exposure history of Ugandan bats to a panel of arboviruses. Materials and methods: Insectivorous and fruit bats were captured from multiple locations throughout Uganda during 2009 and 2011-2013. All serum samples were tested for neutralizing antibodies against West Nile virus (WNV), yellow fever virus (YFV), dengue 2 virus (DENV-2), Zika virus (ZIKV), Babanki virus (BBKV), and Rift Valley fever virus (RVFV) by plaque reduction neutralization test (PRNT). Sera from up to 626 bats were screened for antibodies against each virus. Results and Discussion: Key findings include the presence of neutralizing antibodies against RVFV in 5/52 (9.6%) of little epauletted fruit bats (Epomophorus labiatus) captured from Kawuku and 3/54 (5.6%) Egyptian rousette bats from Kasokero cave. Antibodies reactive to flaviviruses were widespread across bat taxa and sampling locations. Conclusion: The data presented demonstrate the widespread exposure of bats in Uganda to arboviruses, and highlight particular virus-bat associations that warrant further investigation. |
Mosquitoes of northwestern Uganda
Mutebi JP , Crabtree MB , Kading RC , Powers AM , Ledermann JP , Mossel EC , Zeidner N , Lutwama JJ , Miller BR . J Med Entomol 2018 55 (3) 587-599 Despite evidence of arbovirus activity in northwestern Uganda (West Nile Sub-region), there is very limited information on the mosquito fauna of this region. The only published study reported 52 mosquito species in northwestern Uganda but this study took place in 1950 and the information has not been updated for more than 60 yr. In January and June 2011, CO2 baited-light traps were used to collect 49,231 mosquitoes from four different locations, Paraa (9,487), Chobe (20,025), Sunguru (759), and Rhino Camp (18,960). Overall, 72 mosquito species representing 11 genera were collected. The largest number of distinct species was collected at Chobe (43 species), followed by Paraa (40), Sunguru (34), and Rhino Camp (25). Only eight of the 72 species (11.1%) were collected from all four sites: Aedes (Stegomyia) aegypti formosus (Walker), Anopheles (Cellia) funestus group, Culex (Culex) decens group, Cx. (Culex) neavei Theobald, Cx. (Culex) univittatus Theobald, Cx. (Culiciomyia) cinereus Theobald, Cx. (Oculeomyia) poicilipes (Theobald), and Mansonia (Mansonoides) uniformis (Theobald). Fifty-four species were detected in northwestern Uganda for the first time; however, these species have been detected elsewhere in Uganda and do not represent new introductions to the country. Thirty-three species collected during this study have previously been implicated in the transmission of arboviruses of public health importance. |
Epidemiology of sapovirus infections in a birth cohort in Peru.
Sanchez GJ , Mayta H , Pajuelo MJ , Neira K , Xiaofang L , Cabrera L , Ballard SB , Crabtree JE , Kelleher D , Cama V , Bern C , Oshitani H , Gilman RH , Saito M . Clin Infect Dis 2017 66 (12) 1858-1863 Background: Sapovirus is one of the primary viral causes of acute gastroenteritis, especially in settings where rotavirus vaccination has been implemented. The characteristics and impact of natural infection at the community level, however, have not been well documented. Methods: Stool samples were analyzed from 100 children randomly selected from a community-based birth cohort study in Peru. All diarrheal and one non-diarrheal stools collected trimonthly from children up to two years of age (n=1669) were tested for sapovirus detection. Viral shedding duration was determined by testing additional weekly samples (n=440), collected before and after a sapovirus positive sample. Results: The incidence of sapovirus infection in the first and second year of life was 4.3 and 11.1 per 100-child months, respectively. By two years of age, 82% of children had at least one sapovirus infection, and 64% had at least one sapovirus-associated diarrhea episode. The median shedding period was 18.5 days. In 112 of 175 infections, 14 genotypes from four genogroups (GI, GII, GIV and GV) were determined. Among genogroups, GI viruses were more frequently found in symptomatic infections than in asymptomatic infections (OR: 3.1 [CI: 1.3-7.4]). Fifty-nine children had serial sapovirus infections but only three had repeated infection of the same genotype. Conclusions: Sapovirus was frequently detected in children with acute gastroenteritis at the community level during the first two years of life. Serial sapovirus infections by multiple genotypes in a child suggest genotype-specific immunity from each infection, which need to be taken into account for vaccine development. |
Arboviruses isolated from mosquitoes collected in Uganda, 2008-2012
Mossel EC , Crabtree MB , Mutebi JP , Lutwama JJ , Borland EM , Powers AM , Miller BR . J Med Entomol 2017 54 (5) 1403-1409 A large number of arthropod-borne viruses are endemic to East Africa. As a part of the process of undertaking a systematic characterization of the mosquito fauna of Uganda, we examined mosquitoes collected from 2008 through early 2012 for known and novel viruses. In all, 8,288 mosquito pools containing 157,554 mosquitoes were tested. Twenty-nine isolations of 11 different viruses were made from mosquitoes of nine distinct species and from pools identified only to genus Culex. Identified viruses were from family Togaviridae, alphaviruses Sindbis and Babanki viruses; family Rhabdoviridae, hapaviruses Mossuril and Kamese viruses; family Flaviviridae, flaviviruses West Nile and Usutu viruses; family Phenuiviridae, phlebovirus Arumowot virus; and family Peribunyaviridae, orthobunyaviruses Witwatersrand, Pongola, and Germiston viruses. In addition, a novel orthobunyavirus, provisionally named Mburo virus, was isolated from Coquillettidia metallica (Theobald). This is the first report of Babanki, Arumowot, and Mossuril virus isolation from Uganda. |
Pilot intervention study of household ventilation and fine particulate matter concentrations in a low-income urban area, Dhaka, Bangladesh
Weaver AM , Parveen S , Goswami D , Crabtree-Ide C , Rudra C , Yu J , Mu L , Fry AM , Sharmin I , Luby SP , Ram PK . Am J Trop Med Hyg 2017 97 (2) 615-623 Fine particulate matter (PM2.5) is a risk factor for pneumonia; ventilation may be protective. We tested behavioral and structural ventilation interventions on indoor PM2.5 in Dhaka, Bangladesh. We recruited 59 good ventilation (window or door in ≥ 3 walls) and 29 poor ventilation (no window, one door) homes. We monitored baseline indoor and outdoor PM2.5 for 48 hours. We asked all participants to increase ventilation behavior, including opening windows and doors, and operating fans. Where permitted, we installed windows in nine poor ventilation homes, then repeated PM2.5 monitoring. We estimated effects using linear mixed-effects models and conducted qualitative interviews regarding motivators and barriers to ventilation. Compared with poor ventilation homes, good ventilation homes were larger, their residents wealthier and less likely to use biomass fuel. In multivariable linear mixed-effects models, ventilation structures and opening a door or window were inversely associated with the number of hours PM2.5 concentrations exceeded 100 and 250 mug/m3. Outdoor air pollution was positively associated with the number of hours PM2.5 concentrations exceeded 100 and 250 mug/m3. Few homes accepted window installation, due to landlord refusal and fear of theft. Motivators for ventilation behavior included cooling of the home and sunlight; barriers included rain, outdoor odors or noise, theft risk, mosquito entry, and, for fan use, perceptions of wasting electricity or unavailability of electricity. We concluded that ventilation may reduce indoor PM2.5 concentrations but, there are barriers to increasing ventilation and, in areas with high ambient PM2.5 concentrations, indoor concentrations may remain above recommended levels. |
An integrated genomic and transcriptomic survey of mucormycosis-causing fungi.
Chibucos MC , Soliman S , Gebremariam T , Lee H , Daugherty S , Orvis J , Shetty AC , Crabtree J , Hazen TH , Etienne KA , Kumari P , O'Connor TD , Rasko DA , Filler SG , Fraser CM , Lockhart SR , Skory CD , Ibrahim AS , Bruno VM . Nat Commun 2016 7 12218 Mucormycosis is a life-threatening infection caused by Mucorales fungi. Here we sequence 30 fungal genomes, and perform transcriptomics with three representative Rhizopus and Mucor strains and with human airway epithelial cells during fungal invasion, to reveal key host and fungal determinants contributing to pathogenesis. Analysis of the host transcriptional response to Mucorales reveals platelet-derived growth factor receptor B (PDGFRB) signaling as part of a core response to divergent pathogenic fungi; inhibition of PDGFRB reduces Mucorales-induced damage to host cells. The unique presence of CotH invasins in all invasive Mucorales, and the correlation between CotH gene copy number and clinical prevalence, are consistent with an important role for these proteins in mucormycosis pathogenesis. Our work provides insight into the evolution of this medically and economically important group of fungi, and identifies several molecular pathways that might be exploited as potential therapeutic targets. |
Etiological role and repeated infections of sapovirus among children aged less than two years in a cohort study in a peri-urban community of Peru.
Liu X , Jahuira H , Gilman RH , Alva A , Cabrera L , Okamoto M , Xu H , Windle HJ , Kelleher D , Varela M , Verastegui M , Calderon M , Sanchez G , Sarabia V , Ballard SB , Bern C , Mayta H , Crabtree JE , Cama V , Saito M , Oshitani H . J Clin Microbiol 2016 54 (6) 1598-1604 Human sapovirus has been shown to be one of the most important etiologies in pediatric patients with acute diarrhea. However, very limited data are available about the causative roles and epidemiology of sapovirus in community settings. A nested matched case-control study within a birth cohort study of acute diarrhea in a peri-urban community in Peru from 2007 to 2010 was conducted to investigate the attributable fraction (AF) and genetic diversity of sapovirus. By quantitative reverse transcription real-time polymerase chain reaction (RT-qPCR), sapovirus was detected in 12.4% (37/299) of diarrheal and 5.7% (17/300) of non-diarrheal stools (p=0.004). Sapovirus AF (7.1%) was higher in the second (13.2%) than the first year (1.4%) of life of children. Ten known genotypes and one novel cluster (n=5) within four genogroups (GI, GII, GIV and GV) were identified by phylogenetic analysis of partial VP1 gene. Further sequence analysis of full VP1 gene revealed a possible novel genotype, tentatively named as GII.8. Notably, symptomatic reinfections with different genotypes within the same (n=3) or different genogroups (n=5) were observed in eight children. Sapovirus exhibited high attributable burden for acute gastroenteritis especially in the second year of life of children in a Peruvian community. Further large-scale studies are needed to understand better the global burden, genetic diversity, and repeated infections of sapovirus. |
Modelling subject-specific childhood growth using linear mixed-effect models with cubic regression splines
Grajeda LM , Ivanescu A , Saito M , Crainiceanu C , Jaganath D , Gilman RH , Crabtree JE , Kelleher D , Cabrera L , Cama V , Checkley W . Emerg Themes Epidemiol 2016 13 1 BACKGROUND: Childhood growth is a cornerstone of pediatric research. Statistical models need to consider individual trajectories to adequately describe growth outcomes. Specifically, well-defined longitudinal models are essential to characterize both population and subject-specific growth. Linear mixed-effect models with cubic regression splines can account for the nonlinearity of growth curves and provide reasonable estimators of population and subject-specific growth, velocity and acceleration. METHODS: We provide a stepwise approach that builds from simple to complex models, and account for the intrinsic complexity of the data. We start with standard cubic splines regression models and build up to a model that includes subject-specific random intercepts and slopes and residual autocorrelation. We then compared cubic regression splines vis-a-vis linear piecewise splines, and with varying number of knots and positions. Statistical code is provided to ensure reproducibility and improve dissemination of methods. Models are applied to longitudinal height measurements in a cohort of 215 Peruvian children followed from birth until their fourth year of life. RESULTS: Unexplained variability, as measured by the variance of the regression model, was reduced from 7.34 when using ordinary least squares to 0.81 (p < 0.001) when using a linear mixed-effect models with random slopes and a first order continuous autoregressive error term. There was substantial heterogeneity in both the intercept (p < 0.001) and slopes (p < 0.001) of the individual growth trajectories. We also identified important serial correlation within the structure of the data (rho = 0.66; 95 % CI 0.64 to 0.68; p < 0.001), which we modeled with a first order continuous autoregressive error term as evidenced by the variogram of the residuals and by a lack of association among residuals. The final model provides a parametric linear regression equation for both estimation and prediction of population- and individual-level growth in height. We show that cubic regression splines are superior to linear regression splines for the case of a small number of knots in both estimation and prediction with the full linear mixed effect model (AIC 19,352 vs. 19,598, respectively). While the regression parameters are more complex to interpret in the former, we argue that inference for any problem depends more on the estimated curve or differences in curves rather than the coefficients. Moreover, use of cubic regression splines provides biological meaningful growth velocity and acceleration curves despite increased complexity in coefficient interpretation. CONCLUSIONS: Through this stepwise approach, we provide a set of tools to model longitudinal childhood data for non-statisticians using linear mixed-effect models. |
Studies on the species composition and relative abundance of mosquitoes of Mpigi District, Central Uganda
Mayanja M , Mutebi JP , Crabtree MB , Ssenfuka F , Muwawu T , Lutwama JJ . J Entomol Zool Stud 2014 2 (5) 317-322 Prediction of arboviral disease outbreaks and planning for appropriate control interventions require knowledge of the mosquito vectors involved. Although mosquito surveys have been conducted in different regions of Uganda since the mid 30's such studies have not been carried out in Mpigi District. In October 2011, we conducted mosquito collections in Mpigi district to determine species composition and relative abundance of the different species. The survey was conducted in four villages, Njeru, Ddela, Kiwumu and Nsumbain Kammengo sub-county, Mpigi district, Uganda. CDC light traps baited with dry ice (carbon dioxide) were used to capture adult mosquitoes. A total of 54,878 mosquitoes comprising 46 species from eight genera were collected. The dominant species at all sites was Coquilletidia (Coquilletidia) fuscopennata Theobald (n=38,059, 69%), followed by Coquillettidia (Coquillettidia) metallica Theobald (n=4,265, 7.8%). The number of species collected varied from 17 in the genus Culex to 1 in the genus Lutzia. Of the 46 species identified, arboviruses had previously been isolated from 28 (60.9%) suggesting a high potential for arboviral transmission and/or maintenance in Mpigi District. |
Detection of Entebbe Bat Virus After 54 Years.
Kading RC , Kityo R , Nakayiki T , Ledermann J , Crabtree MB , Lutwama J , Miller BR . Am J Trop Med Hyg 2015 93 (3) 475-7 Entebbe bat virus (ENTV; Flaviviridae: Flavivirus), closely related to yellow fever virus, was first isolated from a little free-tailed bat (Chaerephon pumilus) in Uganda in 1957, but was not detected after that initial isolation. In 2011, we isolated ENTV from a little free-tailed bat captured from the attic of a house near where it had originally been found. Infectious virus was recovered from the spleen and lung, and the viral RNA was sequenced and compared with that of the original isolate. Across the polypeptide sequence, there were 76 amino acid substitutions, resulting in 97.8% identity at the amino acid level between the 1957 and 2011 isolates. Further study of this virus would provide valuable insights into the ecological and genetic factors governing the evolution and transmission of bat- and mosquito-borne flaviviruses. |
Epidemiology of meningitis in an HIV-infected Ugandan cohort
Rajasingham R , Rhein J , Klammer K , Musubire A , Nabeta H , Akampurira A , Mossel EC , Williams DA , Boxrud DJ , Crabtree MB , Miller BR , Rolfes MA , Tengsupakul S , Andama AO , Meya DB , Boulware DR . Am J Trop Med Hyg 2014 92 (2) 274-9 There is limited understanding of the epidemiology of meningitis among human immunodeficiency virus (HIV)-infected populations in sub-Saharan Africa. We conducted a prospective cohort study of HIV-infected adults with suspected meningitis in Uganda, to comprehensively evaluate the etiologies of meningitis. Intensive cerebrospiral fluid (CSF) testing was performed to evaluate for bacterial, viral, fungal, and mycobacterial etiologies, including neurosyphilis,16s ribosomal DNA (rDNA) polymerase chain reaction (PCR) for bacteria, Plex-ID broad viral assay, quantitative-PCR for HSV-1/2, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Toxoplasma gondii; reverse transcription-PCR (RT-PCR) for Enteroviruses and arboviruses, and Xpert MTB/RIF assay. Cryptococcal meningitis accounted for 60% (188 of 314) of all causes of meningitis. Of 117 samples sent for viral PCR, 36% were EBV positive. Among cryptococcal antigen negative patients, the yield of Xpert MTB/RIF assay was 22% (8 of 36). After exclusion of cryptococcosis and bacterial meningitis, 61% (43 of 71) with an abnormal CSF profile had no definitive diagnosis. Exploration of new TB diagnostics and diagnostic algorithms for evaluation of meningitis in resource-limited settings remains critical. |
First detected Helicobacter pylori infection in infancy modifies the association between diarrheal disease and childhood growth in Peru
Jaganath D , Saito M , Gilman RH , Queiroz DM , Rocha GA , Cama V , Cabrera L , Kelleher D , Windle HJ , Crabtree JE , Checkley W . Helicobacter 2014 19 (4) 272-9 BACKGROUND: In endemic settings, Helicobacter pylori infection can occur shortly after birth and may be associated with a reduction in childhood growth. MATERIALS AND METHODS: This study investigated what factors promote earlier age of first H. pylori infection and evaluated the role of H. pylori infection in infancy (6-11 months) versus early childhood (12-23 months) on height. We included 183 children near birth from a peri-urban shanty town outside of Lima, Peru. Field-workers collected data on socioeconomic status (SES), daily diarrheal and breast-feeding history, antibiotic use, anthropometrics, and H. pylori status via carbon 13-labeled urea breath test up to 24 months after birth. We used a proportional hazards model to assess risk factors for earlier age at first detected infection and linear mixed-effects models to evaluate the association of first detected H. pylori infection during infancy on attained height. RESULTS: One hundred and forty (77%) were infected before 12 months of age. Lower SES was associated with earlier age at first detected H. pylori infection (low vs middle-to-high SES Hazard ratio (HR) 1.59, 95% CI 1.16, 2.19; p = .004), and greater exclusive breast-feeding was associated with reduced likelihood (HR 0.63, 95% CI 0.40, 0.98, p = .04). H. pylori infection in infancy was not independently associated with growth deficits (p = .58). However, children who had their first detected H. pylori infection in infancy (6-11 months) versus early childhood (12-23 months) and who had an average number of diarrhea episodes per year (3.4) were significantly shorter at 24 months (-0.37 cm, 95% CI, -0.60, -0.15 cm; p = .001). DISCUSSION: Lower SES was associated with a higher risk of first detected H. pylori infection during infancy, which in turn augmented the adverse association of diarrheal disease on linear growth. |
Deletion of the NSm virulence gene of Rift Valley fever virus inhibits virus replication in and dissemination from the midgut of Aedes aegypti mosquitoes.
Kading RC , Crabtree MB , Bird BH , Nichol ST , Erickson BR , Horiuchi K , Biggerstaff BJ , Miller BR . PLoS Negl Trop Dis 2014 8 (2) e2670 BACKGROUND: Previously, we investigated the role of the Rift Valley fever virus (RVFV) virulence genes NSs and NSm in mosquitoes and demonstrated that deletion of NSm significantly reduced the infection, dissemination, and transmission rates of RVFV in Aedes aegypti mosquitoes. The specific aim of this study was to further characterize midgut infection and escape barriers of RVFV in Ae. aegypti infected with reverse genetics-generated wild type RVFV (rRVF-wt) or RVFV lacking the NSm virulence gene (rRVF-DeltaNSm) by examining sagittal sections of infected mosquitoes for viral antigen at various time points post-infection. METHODOLOGY AND PRINCIPAL FINDINGS: Ae. aegypti mosquitoes were fed an infectious blood meal containing either rRVF-wt or rRVF-DeltaNSm. On days 0, 1, 2, 3, 4, 6, 8, 10, 12, and 14 post-infection, mosquitoes from each experimental group were fixed in 4% paraformaldehyde, paraffin-embedded, sectioned, and examined for RVFV antigen by immunofluorescence assay. Remaining mosquitoes at day 14 were assayed for infection, dissemination, and transmission. Disseminated infections were observed in mosquitoes as early as three days post infection for both virus strains. However, infection rates for rRVF-DeltaNSm were statistically significantly less than for rRVF-wt. Posterior midgut infections in mosquitoes infected with rRVF-wt were extensive, whereas midgut infections of mosquitoes infected with rRVF-DeltaNSm were confined to one or a few small foci. CONCLUSIONS/SIGNIFICANCE: Deletion of NSm resulted in the reduced ability of RVFV to enter, replicate, and disseminate from the midgut epithelial cells. NSm appears to have a functional role in the vector competence of mosquitoes for RVFV at the level of the midgut barrier. |
Multiple norovirus infections in a birth cohort in a Peruvian periurban community
Saito M , Goel-Apaza S , Espetia S , Velasquez D , Cabrera L , Loli S , Crabtree JE , Black RE , Kosek M , Checkley W , Zimic M , Bern C , Cama V , Gilman RH . Clin Infect Dis 2014 58 (4) 483-91 BACKGROUND: Human noroviruses are among the most common enteropathogens globally, and are a leading cause of infant diarrhea in developing countries. However, data measuring the impact of norovirus at the community level are sparse. METHODS: We followed a birth cohort of children to estimate norovirus infection and diarrhea incidence in a Peruvian community. Stool samples from diarrheal episodes and randomly selected nondiarrheal samples were tested by polymerase chain reaction for norovirus genogroup and genotype. Excretion duration and rotavirus coinfection were evaluated in a subset of episodes. RESULTS: Two hundred twenty and 189 children were followed to 1 and 2 years of age, respectively. By 1 year, 80% (95% confidence interval [CI], 75%-85%) experienced at least 1 norovirus infection and by 2 years, 71% (95% CI, 65%-77%) had at least 1 episode of norovirus-associated diarrhea. Genogroup II (GII) infections were 3 times more frequent than genogroup 1 (GI) infections. Eighteen genotypes were found; GII genotype 4 accounted for 41%. Median excretion duration was 34.5 days for GII vs 8.5 days for GI infection (P = .0006). Repeat infections by the same genogroup were common, but repeat infections by the same genotype were rare. Mean length-for-age z score at 12 months was lower among children with prior norovirus infection compared to uninfected children (coefficient: -0.33 [95% CI, -.65 to -.01]; P = .04); the effect persisted at 24 months. CONCLUSIONS: Norovirus infection occurs early in life and children experience serial infections with multiple genotypes, suggesting genotype-specific immunity. An effective vaccine would have a substantial impact on morbidity, but may need to target multiple genotypes. |
Isolation and molecular characterization of Fikirini rhabdovirus, a novel virus from a Kenyan bat.
Kading RC , Gilbert AT , Mossel EC , Crabtree MB , Kuzmin IV , Niezgoda M , Agwanda B , Markotter W , Weil MR , Montgomery JM , Rupprecht CE , Miller BR . J Gen Virol 2013 94 2393-8 Zoonotic and vector-borne pathogens have comprised a significant component of emerging human infections in recent decades, and bats are increasingly recognized as reservoirs for many of these disease agents. To identify novel pathogens associated with bats, we screened tissues of bats collected in Kenya. Virus isolates were identified by next generation sequencing of viral nucleic acid preparations from the infected cell culture supernatant and characterized. Here we report the identification of Fikirini rhabdovirus, a novel rhabdovirus isolated from a bat, Hipposideros vittatus, captured along the Kenyan coast. |
Identification of host blood from engorged mosquitoes collected in western Uganda using cytochrome oxidase I gene sequences.
Crabtree MB , Kading RC , Mutebi JP , Lutwama JJ , Miller BR . J Wildl Dis 2013 49 (3) 611-26 Emerging infectious disease events are frequently caused by arthropod-borne viruses (arboviruses) that are maintained in a zoonotic cycle between arthropod vectors and vertebrate wildlife species, with spillover to humans in areas where human and wildlife populations interface. The greater Congo basin region, including Uganda, has historically been a hot spot for emergence of known and novel arboviruses. Surveillance of arthropod vectors is a critical activity in monitoring and predicting outbreaks of arboviral disease, and identification of blood meals in engorged arthropods collected during surveillance efforts provides insight into the ecology of arboviruses and their vectors. As part of an ongoing arbovirus surveillance project we analyzed blood meals from engorged mosquitoes collected at five sites in western Uganda November 2008-June 2010. We extracted DNA from the dissected and triturated abdomens of engorged mosquito specimens. Mitochondrial cytochrome c oxidase I gene sequence was amplified by PCR and sequenced to identify the source of the mosquito host blood. Blood meals were analyzed from 533 engorged mosquito specimens; 440 of these blood meals were successfully identified from 33 mosquito species. Species identifications were made for 285 of the 440 identified specimens with the remainder identified to genus, family, or order. When combined with published arbovirus isolation and serologic survey data, our results suggest possible vector-reservoir relationships for several arboviruses, including Rift Valley fever virus and West Nile virus. |
Inactivation of infectious virus and serological detection of virus antigen in Rift Valley fever virus-exposed mosquitoes fixed with paraformaldehyde
Kading R , Crabtree M , Miller B . J Virol Methods 2013 189 (1) 184-8 Formaldehyde is routinely used to fix tissues in preparation for pathology studies, however concerns remain that treatment of tissues with cellular fixatives may not entirely inactivate infectious virus particles. This concern is of particular regulatory importance for research involving viruses that are classified as select agents such as Rift Valley fever virus (RVFV). Therefore, the specific aims of this study were to 1) assay RVFV-exposed Aedes aegypti mosquitoes fixed in 4% paraformaldehyde for the presence of infectious RVFV particles at various time points following infection and 2) demonstrate the utility of immunofluorescence assay (IFA) for the detection of RVFV antigen in various tissues of paraformaldehyde-fixed mosquitoes. Mosquitoes were administered an infectious blood meal containing one of two strains of RVFV, harvested at various time points following infection, intrathoracically-inoculated with 4% paraformaldehyde, and fixed overnight at 4 degrees C. The infection status of a subset of mosquitoes was verified by IFA on leg tissues prior to fixation, and infectivity of RVFV in fixed mosquito carcasses was determined by Vero cell plaque assay. Paraformaldehyde-fixed mosquitoes harvested 14 days post infection were also paraffin-embedded and sectioned for detection of RVFV antigen to particular tissues by IFA. None of the RVFV-exposed mosquitoes tested by Vero cell plaque assay contained infectious RVFV after fixation. Furthermore, incubation of mosquito sections with trypsin prior to antibody staining is recommended for optimal visualization of RVFV antigen in infected mosquito tissues by IFA. |
Mosquitoes of western Uganda
Mutebi JP , Crabtree MB , Kading RC , Powers AM , Lutwama JJ , Miller BR . J Med Entomol 2012 49 (6) 1289-306 The mosquito fauna in many areas of western Uganda has never been studied and is currently unknown. One area, Bwamba County, has been previously studied and documented but the species lists have not been updated for >40 yr. This paucity of data makes it difficult to determine which arthropod-borne viruses pose a risk to human or animal populations. Using CO2 baited-light traps, from 2008 through 2010, 67,731 mosquitoes were captured at five locations in western Uganda including Mweya, Sempaya, Maramagambo, Bwindi (BINP), and Kibale (KNP). Overall, 88 mosquito species, 7 subspecies, and 7 species groups in 10 genera were collected. The largest number of species was collected at Sempaya (65 species), followed by Maramagambo (45), Mweya (34), BINP (33), and KNP (22). However, species diversity was highest in BINP (Simpson's Diversity Index 1-D = 0.85), followed by KNP (0.80), Maramagambo (0.79), Sempaya (0.67), and Mweya (0.56). Only six species Aedes (Aedimorphus) cumminsii (Theobald), Aedes (Neomelaniconion) circumluteolus (Theobald), Culex (Culex) antennatus (Becker), Culex (Culex) decens group, Culex (Lutzia) tigripes De Grandpre and De Charmoy, and Culex (Oculeomyia) annulioris (Theobald), were collected from all five sites suggesting large differences in species composition among sites. Four species (Aedes (Stegomyia) metallicus (Edwards), Anopheles (Cellia) rivulorum Leeson, Uranotaenia (Uranotaenia) chorleyi (Edwards), and Uranotaenia (Uranotaenia) pallidocephala (Theobald) and one subspecies (Aedes (Stegomyia) aegypti formosus (Walker)) were collected in Bwamba County for the first time. This study represents the first description of the mosquito species composition of Mweya, Maramagambo, BINP, and KNP. A number of morphological variations were noted regarding the postspiracular scales, hind tibia, and sternites that make Culex (Culex) neavei (Theobald) challenging to identify. At least 50 species collected in this study have previously been implicated in the transmission of arboviruses of public health importance suggesting a high potential for maintenance and transmission of a wide variety of arboviruses in western Uganda. |
Infection and transmission of Rift Valley fever viruses lacking the NSs and/or NSm genes in mosquitoes: potential role for NSm in mosquito infection.
Crabtree MB , Kent Crockett RJ , Bird BH , Nichol ST , Erickson BR , Biggerstaff BJ , Horiuchi K , Miller BR . PLoS Negl Trop Dis 2012 6 (5) e1639 BACKGROUND: Rift Valley fever virus is an arthropod-borne human and animal pathogen responsible for large outbreaks of acute and febrile illness throughout Africa and the Arabian Peninsula. Reverse genetics technology has been used to develop deletion mutants of the virus that lack the NSs and/or NSm virulence genes and have been shown to be stable, immunogenic and protective against Rift Valley fever virus infection in animals. We assessed the potential for these deletion mutant viruses to infect and be transmitted by Aedes mosquitoes, which are the principal vectors for maintenance of the virus in nature and emergence of virus initiating disease outbreaks, and by Culex mosquitoes which are important amplification vectors. METHODOLOGY AND PRINCIPAL FINDINGS: Aedes aegypti and Culex quinquefasciatus mosquitoes were fed bloodmeals containing the deletion mutant viruses. Two weeks post-exposure mosquitoes were assayed for infection, dissemination, and transmission. In Ae. aegypti, infection and transmission rates of the NSs deletion virus were similar to wild type virus while dissemination rates were significantly reduced. Infection and dissemination rates for the NSm deletion virus were lower compared to wild type. Virus lacking both NSs and NSm failed to infect Ae. aegypti. In Cx. quinquefasciatus, infection rates for viruses lacking NSm or both NSs and NSm were lower than for wild type virus. CONCLUSIONS/SIGNIFICANCE: In both species, deletion of NSm or both NSs and NSm reduced the infection and transmission potential of the virus. Deletion of both NSs and NSm resulted in the highest level of attenuation of virus replication. Deletion of NSm alone was sufficient to nearly abolish infection in Aedes aegypti mosquitoes, indicating an important role for this protein. The double deleted viruses represent an ideal vaccine profile in terms of environmental containment due to lack of ability to efficiently infect and be transmitted by mosquitoes. |
Transmission of West Nile virus by Culex quinquefasciatus Say infected with Culex flavivirus Izabal
Kent RJ , Crabtree MB , Miller BR . PLoS Negl Trop Dis 2010 4 (5) e671 BACKGROUND: The natural history and potential impact of mosquito-specific flaviviruses on the transmission efficiency of West Nile virus (WNV) is unknown. The objective of this study was to determine whether or not prior infection with Culex flavivirus (CxFV) Izabal altered the vector competence of Cx. quinquefasciatus Say for transmission of a co-circulating strain of West Nile virus (WNV) from Guatemala. METHODS AND FINDINGS: CxFV-negative Culex quinquefasciatus and those infected with CxFV Izabal by intrathoracic inoculation were administered WNV-infectious blood meals. Infection, dissemination, and transmission of WNV were measured by plaque titration on Vero cells of individual mosquito bodies, legs, or saliva, respectively, two weeks following WNV exposure. Additional groups of Cx. quinquefasciatus were intrathoracically inoculated with WNV alone or WNV+CxFV Izabal simultaneously, and saliva collected nine days post inoculation. Growth of WNV in Aedes albopictus C6/36 cells or Cx. quinquefasciatus was not inhibited by prior infection with CxFV Izabal. There was no significant difference in the vector competence of Cx. quinquefasciatus for WNV between mosquitoes uninfected or infected with CxFV Izabal across multiple WNV blood meal titers and two colonies of Cx. quinquefasciatus (p>0.05). However, significantly more Cx. quinquefasciatus from Honduras that were co-inoculated simultaneously with both viruses transmitted WNV than those inoculated with WNV alone (p = 0.0014). Co-inoculated mosquitoes that transmitted WNV also contained CxFV in their saliva, whereas mosquitoes inoculated with CxFV alone did not contain virus in their saliva. CONCLUSIONS: In the sequential infection experiments, prior infection with CxFV Izabal had no significant impact on WNV replication, infection, dissemination, or transmission by Cx. quinquefasciatus, however WNV transmission was enhanced in the Honduras colony when mosquitoes were inoculated simultaneously with both viruses. |
Arbovirus surveillance of mosquitoes collected at sites of active Rift Valley fever virus transmission: Kenya, 2006-2007
Crabtree M , Sang R , Lutomiah J , Richardson J , Miller B . J Med Entomol 2009 46 (4) 961-4 Mosquitoes collected during an outbreak of Rift Valley fever in Kenya from December 2006 to February 2007 were tested to isolate other mosquito-borne arboviruses circulating in the region. Twenty-seven virus isolations were made comprising seven viruses from three arbovirus families. |
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