Studies on the chemical properties of “flacherie virus isolated by Furuta” in the silkworm, Bombyx mori

Abstract

Chemical properties on a small flacherie virus, “flacherie virus isolated by Furuta” (FVF), were investigated and compared to those of Ina-flacherie virus (Bombyx-DNV). The purified FVF had a diameter of 22nm, and the bouyant density in CsCl was found to be 1.40. The nucleic acid in the intact virion was determined to be single-stranded DNA by diphenylamine reaction, formaldehyde reaction and acridine orange staining. Moreover, it was supposed that complementary single-stranded DNA (plus and minus) was contained in separate virions, since the DNA was extracted as double-stranded DNA under conditions of appropriate high-salt buffer and elevated temperature. Four structural proteins, one major protein (VP1) with a molecular weight (MW) of about 50, 000 and the other three minor proteins (VP2, VP3 and VP4) with MWs of about 57, 000, 70, 000 and 77, 000 were found in FVF by SDS-PAGE. These compositions were closely similar to those of Bombyx-DNV. Immunological investigation using Bombyx-DNV antiserum also showed that both FVF and Bombyx DNV are identical virus, or both are closely similar strain to each other.