Detection and titration of bluetongue virus in Culicoides insect cell culture by an antigen-capture enzyme-linked immunosorbent assay.

Bluetongue virus (BTV) infects sheep, cattle and other ruminants and is transmitted by Culicoides spp. of biting midges. Virus is typically isolated and characterized by infection of susceptible vertebrate cells that undergo detectable and measurable cytopathic effects. Cell lines derived from C. sonorensis may be useful for virus isolation and studies to better understand BTV replication in the insect vector. However, their use is hampered because BTV infection does not produce significant cytopathic effects in these insect cell cultures. Detection of virus replication in these cells typically requires co-cultivation with susceptible vertebrate cell culture. This report describes the use of an antigen-capture enzyme-linked immunosorbent assay (Ag-Cap ELISA) for direct detection and titration of BTV in cultures of a Culicoides cell line. This assay should facilitate use of this cell line for virus isolation, titration and studies of BTV replication.