Hytrosaviruses: Structure and Genomic Properties
Adly M. M. Abd-Alla, Drion G. Boucias and Max Bergoin
from: Insect Virology (Edited by: Sassan Asgari and Karyn N. Johnson). Caister Academic Press, U.K. (2010)
Hytrosaviruses are the only insect virus group that elicit salivary gland hypertrophy symptoms in their respective host. Salivary gland hypertrophy viruses (SGHVs) have been identified from several dipteran species, including the tsetse fly Glossina pallidipes (GpSGHV), the house fly Musca domestica (MdSGHV), and the narcissus bulb fly Merodon equestris (MeSGHV). The main characteristics of the hytrosaviruses are: (i) they produce non-occluded, enveloped, rod-shaped virions that measure 550-1000 nm in length and 80-100 nm in diameter; (ii) they possess a large circular double-stranded DNA (dsDNA) genome ranging in size from 120-190 kbp and having G+C ratios ranging from 28-44%; (iii) they cause overt salivary gland hypertrophy symptoms, testicular degeneration and ovarian abnormalities in dipteran adults. Although sharing several important features with other large DNA viruses (baculoviruses, nudiviruses, ascoviruses, and nimaviruses), such as producing rod-shaped, enveloped virions replicating in the nucleus, and possessing a large, circular, double-stranded DNA genome, GpSGHV and MdSGHV (and MeSGHV) differ significantly in several respects from these already-classified viruses. In this chapter, the discovery of the hytrosaviruses and their pathological impact on their host will be discussed and their genomic organization and relation to the other large DNA viruses will be reviewed read more ...