Molecular Characterization and Pathogenesis of the Baculovirus Anprnpv Causing Tiger Band Disease in Antheraea Proylei (Oak Tasar Silkworm)

Abstract The temperate oak tasar silkworm Antheraea proylei is frequently infested by tiger band disease caused by Antheraea proylei nucleopolyhedro virus (AnprNPV). The disease is characterised by dark tiger-like strips across the body of the silkworm, causing an increased mortality and poor seed cocoon recovery. The study confirms that the spread of the disease is particularly high in autumn seasons pertaining to high temperature and humidity conditions. The virus displays a higher copy number in the fatbody tissue and is also able to spread and multiply in various development stages such as egg, larvae, pupa and moth of infected A. proylei silkworms. To check the cross-infectivity of the virus on the silkworm species Antheraea pernyi, A. frithi and Samiaricini and some other lepidopteran species (Phalera raya, Hablaea peura, Pieris canidiaand P. brassicae), virus inoculum was introduced into early-stage larvae. All the silkworm species died acquiring the infection, whereas inoculation into other lepidopteran pests did not have any impact on their survival, indicating the host range of this virus was limited to the silkworm clade. The virus follows a transovum vertical transmission route where hatched larvae laid by infected mother moths were found to contain virus. The surface of eggs is identified to be the potential source of infection since poorly washed eggs displayed the presence of virus on the outer surface whereas was absent in the inner contents of the surface-washed eggs. Hence, a surface disinfection method with 0.2% sodium hypochlorite has been devised from this study that can prevent the occurrence and spread of this virus. Similarly, a PCR as well as an qRT-PCR method has been developed for detection of the virus during early stages of infection in A. proylei silkworms.