Approaches in Identification of Putative Reservoirs/Hosts of Rift Valley Fever Virus (RVF) in Kenya

Abstract

Background: Rift Valley Fever (RVF) is a mosquito borne viral zoonosis, first reported in the Rift Valley of Kenya in 1931. In the last major outbreak of 2006/2007 in Kenya, Baringo, Garissa, and Kilifi districts were major hotspots with mortality of approximately 300 human and 40,000 livestock.

Methodology: Blood fed mosquitoes sampled during the outbreak were cryopreserved. Heads and abdomens of single cryopreserved blood fed mosquitoes (n = 213) (Aedes, Culex, Anopheles and Mansonia genera) were screened for RVF virus by cell culture, and RT-PCR. Putative vertebrate hosts of the virus were determined by amplification and sequencing of blood meal cytochrome c oxidase I (COI). The resultant sequences were annotated through a bioinformatic pipeline suite comprising of 1) BioEdit for initial cleaning and development of consensus sequences 2) Basic Local Alignment Search Tool (BLAST) searches against GenBank nr database to identify putative homologues of the sequences and 3) Barcode of Life Data Systems (BOLD) for COI.

Results: The results of the in silico analyses implicated 3 species in 2 genera as putative vectors of the virus. Among 12 blood meal samples positive for RVFV 6 were drawn from Garissa samples and implicated goats, human and donkey while the rest were from Baringo and implicated sheep and goats as putative hosts.

Conclusion: The analyses demonstrate the potential application of bioinformatics approaches when integrated to wet lab tools as accurate and effective in identification of the vertebrate hosts of RVF, with potential application in public health initiatives in understanding vector borne pathogen epidemiology, and enabling control.