Identification of structural proteins of Bombyx mori parvo-like virus (China Zhenjiang isolate).

OBJECTIVE Bombyx mori parvo-like virus is a type of virus containing two single-stranded linear DNA molecules (VD1, VD2). In the present work, the structural proteins of B. mori parvo-like virus (China Zhenjiang isolate) (BmDNV-Z) were identified. METHODS The virions were purified by cesium chloride density gradient centrifugation from the feces of B. mori larvae infected with BmDNV-Z and analyzed by SDS-PAGE, Western blotting and MALDI-TOF/mass spectometry. RESULTS There were seven polypeptides of the virions, named P1 to P7, which reacted with the anti-virion serum. In addition, two polypeptides, P5 and P6, were recognized by the antibody against a viral protein encoded by VD1-ORF3. CONCLUSION The results showed that the viral polypeptides were mainly composed of 7 proteins named P1 to P7. Western blotting with anti-virion serum indicated that structural proteins P5, P6 and P7 had molecular weights of around 50, 55 and 130 kDa, respectively. They were the major immunogens of the virion. Among them, P5 and P6 were coded by VD1-ORF3 and P7 was encoded by VD2-ORF1. Taken together, three viral structural proteins encoded by VD1-ORF3 and VD2-ORF1 were identified in BmDNV-Z for the first time.