More than a decade ago, an insect virus was detected and isolated from hypertrophied salivary glands of both male and female house flies, Musca domestica, in Florida. The virus was described initially as a non-occluded, enveloped, rod-shaped, dsDNA virus (Coler et al. 1993). The symptoms caused by the Musca domestica salivary gland hypertrophy virus (MdSGHV) resembled the symptoms of a virus detected in the tsetse flies Glossina pallidipes (GpSGHV) and in G. morsitans (Whitnall 1934, Burtt 1945). However, unlike the majority of dsDNA insect viruses, the SGHVs infected, and induced cytopathic effects in, selected adult tissues. In tsetse flies, infection with SGHV causes salivary gland enlargement (hyperplasia, Jaenson 1978), testicular degeneration, and ovarian abnormalities (Jura et al. 1988, Feldmann et al. 1992, Sang et al. 1998, Sang et al. 1999). In recent years, the tsetse SGHV has infected virtually all tsetse fly-rearing colonies in both Europe and Africa, and symptomatic expression of the virus has decimated tsetse fly colonies used for the sterile insect technology program (SIT). In 2005, our lab resumed research on the MdSGHV to understand the biology of the SGHV group and to provide support for the International Atomic Energy Agency’s (IAEA) effort to develop virus-free tsetse fly colonies.

(A) Healthy salivary glands (sg) and (B) hypertrophied salivary glands induced by MdSGHV infection.

Virus Biology

Introduction