Kupe Virus, a New Virus in the FamilyBunyaviridae, GenusNairovirus, Kenya

We have previously described isolation and preliminary identifi cation of a virus related to Dugbe virus (DUGV), family Bunyaviridae, genus Nairovirus.Six isolates of the virus were obtained from pools of Amblyomma gemma and Rhipicephalus pulchellus ticks collected from hides of cattle in Nairobi, Kenya, in October 1999.We report results of further characterization of this virus, including growth kinetics in cell culture and full-length genome sequencing and genetic characterization, which show it to be distinct from DUGV.We suggest that this is a new virus in the family Bunyaviridae, genus Nairovirus, and we propose that it be designated Kupe virus.T he genus Nairovirus in the family Bunyaviridae com- prises 7 species groups containing primarily tick-borne viruses, some of which have been identifi ed as human or animal pathogens.The genome of the nairoviruses consists of 3 segments of negative-sense, single-stranded RNA, small (S), medium (M), and large (L), which encode the nucleocapsid protein, glycoproteins (Gn and Gc), and viral polymerase, respectively.Additionally, an M segmentencoded nonstructural protein, NS M , was recently identifi ed in the nairovirus Crimean-Congo hemorrhagic fever virus (CCHFV) (1).In recent years, nucleotide and amino acid sequence information has become available so that additional characterization of these viruses is possible, including further analysis of relationships among members of the genus.Full-length sequence data are now available for CCHFV, Hazara virus (HAZV) and Dugbe virus (DUGV), and partial sequences are available for many other members of the genus.CCHFV, which ranges from sub-Saharan Africa to western People's Republic of China, is currently the most well characterized member of the genus.DUGV, also well characterized, is commonly isolated in surveillance studies conducted in Africa and appears to be endemic in most of the drier parts of this continent.DUGV is transmitted by ticks to vertebrates, including humans, and causes a mild febrile illness and thrombocytopenia (2).In a recent survey of ticks infesting market livestock in Nairobi, Kenya, we identifi ed 26 isolates of DUGV and additionally obtained several isolates of a virus that was identifi ed as a nairovirus related most closely to DUGV (3).We report further characterization of the K611 isolate of this virus, including the full-length genome.Our fi ndings suggest that this is a new virus in the genus Nairovirus, and we propose that it be designated Kupe virus (Kupe is the Kiswahili word for tick). Materials and MethodsIsolates of viruses were obtained from pools of ticks collected at abattoirs in Nairobi, Kenya, as described (3).The K611 isolate used in this study was obtained from a pool of Amblyomma gemma ticks in October 1999. Characterization of Viruses in Cell Culture and MiceGrowth of Kupe virus and DUGV was tested in Vero (African green monkey kidney), LLC-MK 2 (rhesus monkey kidney), BHK (baby hamster kidney), SW-13 (human adrenal cortex carcinoma), HeLa (human cervical adenocarcinoma), HUH-7 (human hepatocarcinoma), and C6/36 (Aedes albopictus mosquito) cells in culture.Growth kinetics of the 2 viruses were compared in a 13day growth curve in which cells were infected at a multiplicity of infection of 0.01 and aliquots removed daily.Virus titers were assayed on Vero cell monolayers in Kupe Virus, a New Virus in the Family Bunyaviridae, Genus Nairovirus, Kenya