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 toBmDNV-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-2from 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.

Key words: BmDNV-Z, +^nsd-2, RT-PCR, transporter protein, baculovirus expression.

Abbreviation

DNV, Densoviruses; BmDNVs, bombyx mori densoviruses; PCR,polymerase chain reaction; MCS, multiple cloning sites; SDS-PAGE, sodium dodecyl sulfate- polyacrylamide gel electrophoresis; LB, Lysogeny broth; HTTM,horizontally transferred transmembrane domain; RFLP, restriction fragment length polymorphism.