Bluetongue Virus Infection in Salivary Glands of Culicoides Variipennis

Abstract

Bluetongue virus (BTV) multiplies in the invertebrate host culicodies variipennis and is transmitted by this biting fly to wild and domestic ruminants; e.g., see review. Virus replication in the salivary gland of nonbloodfed flies was similar to that for cultured cells. This report describe observations on BTV-infected salivary gland cells from bloodfed flies.Two-day-old female flies, which had been given a blood meal on normal rabbits when the flies were one day old, were inoculated either with normal or BTV-infected cell culture fluids into the hemocoel. Flies were maintained alternately on water and 10% sugar solution for 14-21 days when salivary glands were removed and processed for viewing in thin section.Viroplasms in association with macrotubules, fibrils, and progeny virions were observed in the cytoplasm of infected salivary gland cells (Fig. 1). Large numbers of macrotubules were observed and they often occupied large areas of the cell. Macrotubules most often appeared in bundles of linear array and had an ordered appearance.