Cloning and characterization of the densoviruses susceptible gene +nsd-2 in the silkworm, Bombyx mori

Abstract

Recently, a silkworm gene responsible for the susceptibility to BmDNV-2 (a parvo-like virus) has been discovered and designated as +nsd-2, which encodes a 12-pass transmembrane protein. BmDNV-Z, isolated in Zhenjiang of China, has a high homology with BmDNV-2 in serological characteristics and genome structure. However, it is still uncertain whether +nsd-2 is also responsible for susceptibility to BmDNV-Z. In this study, we cloned +nsd-2 gene from Chinese silkworm strain (HuaBa35) that is
susceptible to BmDNV-Z. DNA sequencing confirmed that +nsd-2 from HuaBa35 is the same with that from NO.908 susceptible to BmDNV-2. RT-PCR analysis showed that the gene +nsd-2 was only expressed in
larval midgut and widely expressed in every instar of larva. Bioinformatic study showed that +nsd-2 is a putative amino acid transporter with three glycosylation sites and located on chromosome 11. In addition, +nsd-2 gene was also expressed by baculovirus expression system in Sf9 cell. Our analysis will contribute to the detailed investigation on the infection mechanism of BmDNV.