Biochemical and biological variation of Cydia pomonella (codling moth) granulosis virus.

Cydia pomonella granulosis viruses (CpGV) from three different sources were compared biochemically and biologically. Restriction enzyme profiles of a CpGV isolated in Mexico and propagated for 9 years in a laboratory in Darmstadt, Germany (CpGV-MD) were compared with those of the same isolate propagated for 9 years at a Berkeley, California, laboratory (CpGV-MB). Only one of six enzymatic digests revealed a difference in the DNAs, which were subsequently calculated to be 99.94% homologous. No differences were found in molecular weights of enveloped virion polypeptides with SDS-polyacrylamide gel electrophoresis. In contrast, the restriction profiles of a CpGV isolated in Russia (CpGV-R) differed from that of CpGV-MB and CpGV-MD in five of six enzymatic digests due to what appeared to be a deleted fragment of DNA of about 1 x 10(6) in the CpGV-R genome. SDS-PAGE indicated a small difference in mobility of a high-molecular-weight protein in CpGV-R as compared to CpGV-MB and CpGV-MD. Two low-molecular weight proteins present in both CpGV-MD and CpGV-MB were missing completely in CpGV-R. Southern blot hybridization of restriction endonuclease gels using (32)P-labeled CpGV-MB DNA showed homology for all three isolates. A radioimmune protein blot assay revealed no differences in serological reactivity among the three CpGVs. LD(50) values for first and fifth instar larvae showed CpGV-MB and CpGV-MD to have similar virulence, while CpGV-R had significantly less.