Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-22 (of 22 Records) |
Query Trace: Kading R[original query] |
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Micro‒global positioning systems for identifying nightly opportunities for Marburg virus spillover to humans by Egyptian Rousette bats
Amman BR , Schuh AJ , Akurut G , Kamugisha K , Namanya D , Sealy TK , Graziano JC , Enyel E , Wright EA , Balinandi S , Lutwama JJ , Kading RC , Atimnedi P , Towner JS . Emerg Infect Dis 2023 29 (11) 2238-2245 Marburg virus disease, caused by Marburg and Ravn orthomarburgviruses, emerges sporadically in sub-Saharan Africa and is often fatal in humans. The natural reservoir is the Egyptian rousette bat (ERB), which sheds virus in saliva, urine, and feces. Frugivorous ERBs discard test-bitten and partially eaten fruit, potentially leaving infectious virus behind that could be consumed by other susceptible animals or humans. Historically, 8 of 17 known Marburg virus disease outbreaks have been linked to human encroachment on ERB habitats, but no linkage exists for the other 9 outbreaks, raising the question of how bats and humans might intersect, leading to virus spillover. We used micro‒global positioning systems to identify nightly ERB foraging locations. ERBs from a known Marburg virus‒infected population traveled long distances to feed in cultivated fruit trees near homes. Our results show that ERB foraging behavior represents a Marburg virus spillover risk to humans and plausibly explains the origins of some past outbreaks. |
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. |
Subgenomic flavivirus RNA (sfRNA) associated with Asian lineage Zika virus identified in three species of Ugandan bats (family Pteropodidae).
Fagre AC , Lewis J , Miller MR , Mossel EC , Lutwama JJ , Nyakarahuka L , Nakayiki T , Kityo R , Nalikka B , Towner JS , Amman BR , Sealy TK , Foy B , Schountz T , Anderson J , Kading RC . Sci Rep 2021 11 (1) 8370 Serological cross-reactivity among flaviviruses makes determining the prior arbovirus exposure of animals challenging in areas where multiple flavivirus strains are circulating. We hypothesized that prior infection with ZIKV could be confirmed through the presence of subgenomic flavivirus RNA (sfRNA) of the 3' untranslated region (UTR), which persists in tissues due to XRN-1 stalling during RNA decay. We amplified ZIKV sfRNA but not NS5 from three experimentally-infected Jamaican fruit bats, supporting the hypothesis of sfRNA tissue persistence. Applying this approach to 198 field samples from Uganda, we confirmed presence of ZIKV sfRNA, but not NS5, in four bats representing three species: Eidolon helvum (n = 2), Epomophorus labiatus (n = 1), and Rousettus aegyptiacus (n = 1). Amplified sequence was most closely related to Asian lineage ZIKV. Our results support the use of sfRNA as a means of identifying previous flavivirus infection and describe the first detection of ZIKV RNA in East African bats. |
Genomic characterization of 99 viruses from the bunyavirus families Nairoviridae, Peribunyaviridae, and Phenuiviridae, including 35 previously unsequenced viruses.
Kapuscinski ML , Bergren NA , Russell BJ , Lee JS , Borland EM , Hartman DA , King DC , Hughes HR , Burkhalter KL , Kading RC , Stenglein MD . PLoS Pathog 2021 17 (3) e1009315 Bunyaviruses (Negarnaviricota: Bunyavirales) are a large and diverse group of viruses that include important human, veterinary, and plant pathogens. The rapid characterization of known and new emerging pathogens depends on the availability of comprehensive reference sequence databases that can be used to match unknowns, infer evolutionary and pathogenic potential, and make response decisions in an evidence-based manner. In this study, we determined the coding-complete genome sequences of 99 bunyaviruses in the Centers for Disease Control and Prevention's Arbovirus Reference Collection, focusing on orthonairoviruses (family Nairoviridae), orthobunyaviruses (Peribunyaviridae), and phleboviruses (Phenuiviridae) that either completely or partially lacked genome sequences. These viruses had been collected over 66 years from 27 countries from vertebrates and arthropods representing 37 genera. Many of the viruses had been characterized serologically and through experimental infection of animals but were isolated in the pre-sequencing era. We took advantage of our unusually large sample size to systematically evaluate genomic characteristics of these viruses, including reassortment, and co-infection. We corroborated our findings using several independent molecular and virologic approaches, including Sanger sequencing of 197 genome segments, and plaque isolation of viruses from putative co-infected virus stocks. This study contributes to the described genetic diversity of bunyaviruses and will enhance the capacity to characterize emerging human pathogenic bunyaviruses. |
Possibility for reverse zoonotic transmission of SARS-CoV-2 to free-ranging wildlife: A case study of bats.
Olival KJ , Cryan PM , Amman BR , Baric RS , Blehert DS , Brook CE , Calisher CH , Castle KT , Coleman JTH , Daszak P , Epstein JH , Field H , Frick WF , Gilbert AT , Hayman DTS , Ip HS , Karesh WB , Johnson CK , Kading RC , Kingston T , Lorch JM , Mendenhall IH , Peel AJ , Phelps KL , Plowright RK , Reeder DM , Reichard JD , Sleeman JM , Streicker DG , Towner JS , Wang LF . PLoS Pathog 2020 16 (9) e1008758 The COVID-19 pandemic highlights the substantial public health, economic, and societal consequences of virus spillover from a wildlife reservoir. Widespread human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also presents a new set of challenges when considering viral spillover from people to naïve wildlife and other animal populations. The establishment of new wildlife reservoirs for SARS-CoV-2 would further complicate public health control measures and could lead to wildlife health and conservation impacts. Given the likely bat origin of SARS-CoV-2 and related beta-coronaviruses (β-CoVs), free-ranging bats are a key group of concern for spillover from humans back to wildlife. Here, we review the diversity and natural host range of β-CoVs in bats and examine the risk of humans inadvertently infecting free-ranging bats with SARS-CoV-2. Our review of the global distribution and host range of β-CoV evolutionary lineages suggests that 40+ species of temperate-zone North American bats could be immunologically naïve and susceptible to infection by SARS-CoV-2. We highlight an urgent need to proactively connect the wellbeing of human and wildlife health during the current pandemic and to implement new tools to continue wildlife research while avoiding potentially severe health and conservation impacts of SARS-CoV-2 "spilling back" into free-ranging bat populations. |
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. |
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. |
Comparative vector competence of North American Culex pipiens and Culex quinquefasciatus for African and European lineage 2 West Nile viruses
Romo H , Papa A , Kading R , Clark R , Delorey M , Brault AC . Am J Trop Med Hyg 2018 98 (6) 1863-1869 West Nile virus (WNV) is a mosquito-borne flavivirus that is phylogenetically separated into distinct lineages. Lineage 1 (L1) and lineage 2 (L2) encompass all WNV isolates associated with human and veterinary disease cases. Although L1 WNV is globally distributed, including North America, L2 WNV only recently emerged out of sub-Saharan Africa into Europe and Russia. The spread of L2 WNV throughout and beyond Europe depends, in part, on availability of competent vectors. The vector competence of mosquitoes within the Culex genus for WNV is well established for L1 WNV but less extensively studied for L2 WNV. Assessing the vector competence of North American Culex mosquitoes for L2 WNV will be critical for predicting the potential for L2 WNV emergence in North America. We address the vector competence of North American Culex pipiens and Culex quinquefasciatus for L2 WNV. Both mosquito species were highly competent for each of the L2 WNV strains assessed, but variation in infection, dissemination, and transmission was observed. An L2 WNV strain (NS10) isolated during the Greek outbreak in 2010 exhibited a reduced capacity to infect Cx. pipiens compared with other L2 WNV strains. In addition, a South African L2 WNV strain (SA89) displayed a significantly shorter extrinsic incubation period in Cx. quinquefasciatus compared with other L2 WNV strains. These results demonstrate that North American Culex mosquito species are competent vectors of African and European L2 WNV and that emergence of L2 WNV is unlikely to be hindered by poor competence of North American vectors. |
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. |
Rapid and specific detection of Asian- and African-lineage Zika viruses.
Chotiwan N , Brewster CD , Magalhaes T , Weger-Lucarelli J , Duggal NK , Ruckert C , Nguyen C , Garcia Luna SM , Fauver JR , Andre B , Gray M , Black WCth , Kading RC , Ebel GD , Kuan G , Balmaseda A , Jaenisch T , Marques ETA , Brault AC , Harris E , Foy BD , Quackenbush SL , Perera R , Rovnak J . Sci Transl Med 2017 9 (388) Understanding the dynamics of Zika virus transmission and formulating rational strategies for its control require precise diagnostic tools that are also appropriate for resource-poor environments. We have developed a rapid and sensitive loop-mediated isothermal amplification (LAMP) assay that distinguishes Zika viruses of Asian and African lineages. The assay does not detect chikungunya virus or flaviviruses such as dengue, yellow fever, or West Nile viruses. The assay conditions allowed direct detection of Zika virus RNA in cultured infected cells; in mosquitoes; in virus-spiked samples of human blood, plasma, saliva, urine, and semen; and in infected patient serum, plasma, and semen samples without the need for RNA isolation or reverse transcription. The assay offers rapid, specific, sensitive, and inexpensive detection of the Asian-lineage Zika virus strain that is currently circulating in the Western hemisphere, and can also detect the African-lineage Zika virus strain using separate, specific primers. |
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. |
Predicting the mosquito species and vertebrate species involved in the theoretical transmission of Rift Valley fever virus in the United States
Golnar AJ , Turell MJ , LaBeaud AD , Kading RC , Hamer GL . PLoS Negl Trop Dis 2014 8 (9) e3163 Rift Valley fever virus (RVFV) is a mosquito-borne virus in the family Bunyaviridiae that has spread throughout continental Africa to Madagascar and the Arabian Peninsula. The establishment of RVFV in North America would have serious consequences for human and animal health in addition to a significant economic impact on the livestock industry. Published and unpublished data on RVFV vector competence, vertebrate host competence, and mosquito feeding patterns from the United States were combined to quantitatively implicate mosquito vectors and vertebrate hosts that may be important to RVFV transmission in the United States. A viremia-vector competence relationship based on published mosquito transmission studies was used to calculate a vertebrate host competence index which was then combined with mosquito blood feeding patterns to approximate the vector and vertebrate amplification fraction, defined as the relative contribution of the mosquito or vertebrate host to pathogen transmission. Results implicate several Aedes spp. mosquitoes and vertebrates in the order Artiodactyla as important hosts for RVFV transmission in the U.S. Moreover, this study identifies critical gaps in knowledge which would be necessary to complete a comprehensive analysis identifying the different contributions of mosquitoes and vertebrates to potential RVFV transmission in the U.S. Future research should focus on (1) the dose-dependent relationship between viremic exposure and the subsequent infectiousness of key mosquito species, (2) evaluation of vertebrate host competence for RVFV among North American mammal species, with particular emphasis on the order Artiodactyla, and (3) identification of areas with a high risk for RVFV introduction so data on local vector and host populations can help generate geographically appropriate amplification fraction estimates. |
Mosquitoes used to draw blood for arbovirus viremia determinations in small vertebrates
Kading RC , Biggerstaff BJ , Young G , Komar N . PLoS One 2014 9 (6) e99342 Serial samples from the same individuals may be required for certain virological studies, however, some small animals cannot easily be blood-sampled. Therefore, we evaluated the use of Culex quinquefasciatus Say and Aedes albopictus Skuse mosquitoes as "biological syringes" to draw blood for virus titer determinations in small vertebrates. Groups of chicks (Gallus gallus), hamsters (Mesocricetus auratus), and house sparrows (Passer domesticus) were experimentally infected with West Nile virus (WNV) or Highlands J virus (HJV). In general, good correlation was seen between mosquito- and syringe-derived blood samples at titers ≥5.0 log10 pfu/mL serum as compared with titers <5.0 log10 pfu/mL serum for chicks, hamsters, and sparrows. Ninety-two percent (24/26) of sparrows with virus titers >105 pfu/mL serum had mosquito- and syringe-derived titers within one log of each other. Sparrow viremia profiles generated from single mosquito blood meals and syringe were not significantly different (p>0.05). This technique is valuable for assessing the roles of small vertebrates in the ecologies of arboviruses, and could be used in applications beyond virology and infectious diseases, when <10 microL of whole blood is required. |
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. |
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. |
Prevalence of antibodies to alphaviruses and flaviviruses in free-ranging game animals and nonhuman primates in the greater Congo basin
Kading RC , Borland EM , Cranfield M , Powers AM . J Wildl Dis 2013 49 (3) 587-99 Vector-borne and zoonotic pathogens have comprised a significant proportion of the emerging infectious diseases in humans in recent decades. The role of many wildlife species as reservoirs for arthropod-borne viral pathogens is poorly understood. We investigated the exposure history of various African wildlife species from the Congo basin to mosquito-borne flaviviruses and alphaviruses by testing archived serum samples. Sera from 24 African forest buffalo (Syncerus caffer nanus), 34 African elephants (Loxodonta africana), 40 duikers (Cephalophus and Philantomba spp.), 25 mandrills (Mandrillus sphinx), 32 mountain gorillas (Gorilla beringei beringei), five Grauer's gorillas (Gorilla beringei graueri), two L'Hoest's monkeys (Cercopithecus lhoesti), two golden monkeys (Cercopithecus kandti), and three chimpanzees (Pan troglodytes) sampled between 1991 and 2009 were tested for antibodies against chikungunya virus (CHIKV), o'nyong-nyong virus (ONNV), West Nile virus (WNV), dengue 2 virus (DENV-2), and yellow fever virus (YFV) by plaque reduction neutralization test. Specific neutralizing antibodies against ONNV were found in African forest buffalo in the Democratic Republic of the Congo (DRC) and Gabon, duikers in the DRC, and mandrills in Gabon, providing novel evidence of enzootic circulation of ONNV in these countries. African forest buffalo in the DRC and Gabon also demonstrated evidence of exposure to CHIKV, WNV, and DENV-2, while mandrills in Gabon were antibody positive for CHIKV, DENV-2, WNV, and YFV. All of the elephants tested had a strong neutralizing antibody response to WNV. We also document results from a survey of gorillas for arboviruses, of which 4/32 (13%) had antibody to an alphavirus or flavivirus. Overall, our results demonstrate a high prevalence of neutralizing antibodies against multiple arboviruses in wildlife in equatorial Africa. |
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. |
Studies on the origin of Culex pipiens pipiens form molestus in New York City
Kading RC . J Am Mosq Control Assoc 2012 28 100-5 Culex pipiens pipiens is comprised of two forms: Cx. pipiens pipiens form pipiens and Culex pipiens pipiens form molestus. One population of Cx. p. pipiens form molestus in the United States, located in the 91st Street sewer of New York City (NYC), has been relatively well-characterized. The objective of this review is to summarize the results of multiple independent studies on Cx. p. pipiens form molestus in NYC and present the current understanding of the origin of this population. While solid evidence exists supporting the genetic differentiation and population structuring between Cx. p. pipiens form pipiens and form molestus in NYC, the possibility that the 91st St. sewer population of form molestus was founded by local aboveground Cx. p. pipiens form pipiens cannot be ruled out based on available data to date. Future studies in the US should include sympatric populations of both forms of Cx. p. pipiens from around the world in order to provide the necessary context to resolve these phylogenetic relationships. |
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. |
Host selection of potential West Nile virus vectors in Puerto Barrios, Guatemala, 2007
Kading RC , Reiche AS , Morales-Betoulle ME , Komar N . Am J Trop Med Hyg 2012 88 (1) 108-15 The selection of vertebrate hosts by Culex mosquitoes relative to West Nile virus (WNV) transmission in neotropical countries such as Guatemala is not described. This study determined the feeding patterns of Cx. quinquefasciatus and Cx. nigripalpus and estimated the relative contribution of two common and frequently infected wild bird species, Turdus grayi and Quiscalus mexicanus, to WNV transmission. Engorged mosquitoes were collected from rural and urban habitats after the dry and wet seasons in the Department of Izabal in 2007. Host selection by Cx. nigripalpus varied significantly between urban and rural habitats. Both Cx. quinquefasciatus and Cx. nigripalpus fed predominantly on chickens and other domestic animals. Blood meals from wild birds were rare, accounting for 1.1% of blood meals identified from Cx. quinquefasciatus and 6.5% of blood meals from Cx. nigripalpus. Transmission of WNV by these two mosquito species may be dampened by extensive feeding on reservoir-incompetent hosts. |
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