Molecular characterization of Chittoor (Batai) virus isolates from India

BACKGROUND & OBJECTIVES: Chittoor virus (CHITV) belongs to genus Orthobunyavirus, family Bunyaviridae. It has been isolated from various species of mosquitoes and pig from different parts of India. Five isolates of CHITV were characterized at the molecular level and compared with other Batai viruses (BATV) to find out any kind of reassortment in their genome. METHODS: Complete nucelocapsid (S), glycoprotein (M) and partial RNA polymerase (L) segments of CHITV were amplified and sequenced. These sequences were compared with those of Batai viruses, isolated from different geographical locations in Asia, Africa and Europe. RESULTS: Phylogenetic analysis revealed CHITV as a variant of BATV. High level of conservation was seen among the CHITV isolates studied. The CHITV sequences showed clustering in one lineage with the sequences from Japan and Malaysia, however, BATV sequences from Europe and Africa formed a separate phylogenetic lineage. INTERPRETATION & CONCLUSIONS: The study indicates the presence of a single genotype of CHITV circulating in India, despite the involvement of different hosts in the natural cycle by this virus. Analysis of the sequences of the S, M and L segments of genome indicated that the virus has not undergone any reassortment. This virus has not caused any epidemic involving humans, however, replication of the virus in different mosquito and vertebrate hosts species suggests that it is a cause of concern.