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Circulation, evolution and transmission of ngari and bunyamwera orthobunya viruses in Northern Kenya

Year: 2014
Type: article
Abstract: Background: Although genetic drift/reassortment seems to occur frequently in the Bunyaviridae family, the epidemiological consequences of these evolutionary events are poorly understood. Moreover, these viruses have been isolated from a range of mosquito species but the actual role of the associated mosquito species in the maintenance, transmission and evolution of the virus in the environment remains unclear. Our objective was to understand the dynamics of circulation, reassortment and transmission of Bunyamwera and Ngari viruses in Kenya. Methods & Materials: Selected Bunyamwera and Ngari virus isolates from previous surveillance exercises in Kenya were cultured in Vero cells to prepare viral stocks. Total RNA was isolated from culture and specific primers designed against the genome segments using Bunyamwera/Batai virus sequences in Genebank. Sequencing was performed in ABI 3700 genetic analyzer and phylogenetic analysis using MEGA v5.2. Sequences were compared with selected members of the Orthobunyavirus genus isolated from different geographical locations. For vector competence, female mosquitoes were exposed to blood-virus mixture (1010 Pfu/ml). Engorged mosquitoes were transferred to clean cages and maintained with sucrose solution at 28oC for 14 days. A sub-set of experimental mosquitoes were killed by freezing at days 7 and 14 and virus assayed in both legs and body separately by plaque assay. Results: We identified isolates of both viruses which were relatively conserved regardless of the species or region of isolation with the Kenyan Ngari isolates clustering closest with the Ngari strains associated with the 1997-1998 hemorrhagic fever outbreaks in East Africa. Aedes aegypti was refractory to Ngari virus but susceptible to Bunyamwera virus and could be a competent vector for Bunyamwera virus. Anopheles gambiae was susceptible to both Ngari and Bunyamwera viruses but lower dissemination rates for the later. This may have been possibly due to genetic reassortment and warrants further investigation. This has major implication in light of continued animal trade and travel especially into malaria endemic regions where Anopheles gambiae is more prevalent. Conclusion: Our results underscore the need to continually monitor emergent arboviral genotypes circulating within particular regions as well as vectors mediating these transmissions in order to preempt and prevent their adverse effects.
DOI: 10.1016/j.ijid.2014.03.900
Language: English
Field: Medicine
Open Access status: gold
Estimated APC paid: $2,900
OpenAlex ID: W2020917331
FWCI:
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Cited by: 1
Related to: 10