Negative-strand RNA viruses (NSRVs) are associated with animals, plants, and insects (vectors and non-vectors). NSRV families associated with insects are Bunyaviridae (BVae) and Rhabdoviridae (RVae). An insect [non-vector] rhabdovirus (RhV), sigma virus (SV), discovered in Drosophila, is the only insect RhV with its genome sequenced to date. The genome of SV, like those of other NSRVs consists of unpaired, negative sense RNA that encodes five (N, P, M, G, and L) proteins. One protein, the nucleocapsid (N) protein is a structural protein that binds with the viral genome. The N protein of SV is more related to those of insect-associated RhVs than to those of other RhVs. However, the evolutionary relationship between the N proteins of SV and other NSRVs is unknown. Since SV and BVae have similar genomes, encode similar proteins and occur in insects, we hypothesize that SV and BVae evolved from a similar ancestor. Alternatively, SV and BVae evolved from different ancestors. Our objectives were to determine 1) the percent homology between the N proteins of SV and insect-associated BVae and 2) the phylogenetic relationship among SV and insect-associated BVae and RVae. Alignment of the N protein sequence of SV with those of the insect-associated genera of BVae: Bunyavirus, Tospovirus, and Phlebovirus, using ClustalW, revealed that the N proteins of SV and BVae are related. The N protein sequence of SV is more conserved (10-14%) within the Bunyavirus than in other BVae genera (4-11%). The Phylogenetic Analysis Using Parsimony (PAUP) program revealed that BVae probably arose from RVae and SV is more closely related to BVae than to RVae. Therefore, SV and BVae may have evolved from a similar ancestor.
Support from the National Science Foundation, IBN 9514583 and 9986076 to POL is gratefully acknowledged.
Species 1: Mononegavirales Rhabdoviridae (sigma virus)
Species 2: Diptera Drosophilidae Drosophila (vinegar fly)
Keywords: insect rhabdovirus, phylogenetic relationship
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA