Abstract
Chemical properties of a small spherical virus, which was recently isolated in Yamanashi prefecture, were investigated and compared with those of Ina isolate of Bombyx densonucleosis virus (DNV). Negative stained virions of Yamanashi isolate had a diameter of 24nm. A few of them had several projection-like structure. The nucleic acid in the intact virion was determined to be single-stranded (ss) DNA by diphenylamine reaction, formaldehyde reaction and acridine orange staining. Since the DNA was extracted as double-stranded (ds) DNA under conditions of appro priate high salt or even fairly low salt buffer, it was presumed that complementary ssDNA was con tained in separate virions, and two complementary ssDNAs in different particles were joined together by complementary base paring. The viral DNA of Yamanashi isolate was resolved in agarose gel electrophoresis into two closely migrating bands (MW: 4.0×106 (DNA I) and 3.8×106 (DNA II), respectively as dsDNA), while only one band was formed for the viral DNA of Ina isolate. When both DNA I and II were digested with several restriction endonuceases, the electro-pherograms of these fragments were clearly different from each other. Using SDS-PAGE, six structural proteins were detected from dissociated highly purified virions. Yamanashi isolate may consist of two different DNVs which have three structural proteins, and are clearly different from Ina isolate of Bombyx DNV.
