Abstract

Understanding of the responsive and interactive mechanism between the host cells and Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is crucial to the diagnosis of CPV-caused disease and the development of new control measures. In this report, we employed suppression subtractive hybridization to compare differentially expressed genes in the midguts of CPV-infected and normal silkworm larvae. 36 genes and 20 novel ESTs were obtained from 2 reciprocal subtractive libraries. Three up-regulated genes (ferritin, rpL11 and alkaline nuclease) and 3 down-regulated genes (serine protease, trypsin-like protease and inhibitor of apoptosis protein) were identified by quantitative real¬time PCR. The transcript differences of these 6 genes at 6, 12, 24, 48 and 72 h post-inoculation both in CPV-infected and normal midguts were compared. Our results indicated that ferritin and rpL11 were increased during the early stage (6-12h p.i.) of CPV infection, whereas alkaline nuclease was increased during the late stage (24-72h p.i.) of CPV infection. The expression of serine protease and trypsin-like protease is decreased at 24-72 h after CPV infection, while the expression of inhibitor of apoptosis protein is decreased throughout the infective stage. Our results provide new clues for investigating the molecular mechanism of BmCPV infection.

Key words: Bombyx mori, cytoplasmic polyhedrosis virus, midgut, suppression subtractive hybridization, quantitative real-time PCR.