Comparative analysis of the enveloped virions of two granulosis viruses of the armyworm, Pseudaletia unipuncta

Abstract

The enveloped virions of two strains of a granulosis virus, a synergistic Hawaiian (GVH) and a nonsynergistic Oregonian (GVO) strain which infect the armyworm, Pseudaletia unipuncta, were liberated from their capsules with 0.02 N NaOH and purified by filtration through membrane filters. The envelopes were solubilized with 0.1% Triton X-100. The enveloped virions, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), had 9 to 12 polypeptides, 3 of which were associated with the naked virion. The two strains differed in their electrophoretic patterns mainly in the presence of two heavy polypeptides (89,000 and 97,000 daltons) and a 52,000-dalton polypeptide in GVH and in the absence of the heavy polypeptides and the presence of a 57,000-dalton polypeptide in GVO. The two heavy polypeptides were sensitive to proteinase. Two two-dimensional electrophoreses (first dimension with agarose gel electrophoresis and second dimension with SDS-PAGE and immunoelectrophoresis) of the envelope of GVH resolved two polypeptides, 37,000 and 48,000 daltons, which were serologically related to the synergistic factor present in the capsule of GVH; however their molecular weights differed from that of the GVH synergistic factor. In GVO, no polypeptide serologically related to the synergistic factor was detected in the envelope. The enveloped virions purified by differential filtration were infectious when fed to armyworm larvae, but the naked virions, free of envelopes, were not infectious.