During investigations into the outbreak of encephalitis in 1996 in the Kerala state in India, an arbovirus was isolated from a Culex tritaeniorhynchus mosquito pool. It was characterized as a Japanese encephalitis and West Nile virus cross-reactive arbovirus by complement fixation test. A plaque reduction-neutralization test was performed using hyperimmune sera raised against the plaque-purified arbovirus isolate. The sera did not show reactivity with Japanese encephalitis virus and were weakly

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... reactive with West Nile virus. Complete open reading frame sequence analysis characterized the arbovirus as Bagaza virus (BAGV), with 94.80 % nucleotide identity with African BAGV strain DakAr B209. Sera collected from the encephalitic patients during the acute phase of illness showed 15 % (8/53) positivity for anti-BAGV neutralizing antibodies. This is the first report of the isolation of BAGV from India. The presence of anti-BAGV neutralizing antibodies suggests that the human population has been exposed to BAGV. The GenBank/EMBL/DDBJ accession number of the Indian Bagaza virus isolate sequenced in this paper is EU684972. A supplementary figure showing the phylogenetic analysis of BAGV based on nucleocapsid, membrane, non-structural (NS) 1, NS2, NS3, NS4 and NS5 gene sequences is available with the online version of this paper.