Serological study on the transmission of a granulosis virus of the armyworm,Pseudaletia unipuncta (Lepidoptera: Noctuidae), to other lepidopterous species

The synergistic (Hawaiian) strain of a granulosis virus (GV) from the armyworm, Pseudaletia unipuncta, was transmitted to Spodoptera exigua, Autographa californica, and Trichoplusia ni. The viruses isolated from these hosts were tested by radial double-immunodiffusion (RDD) and immunoelectrophoresis (IE) for their relationship to the original virus. Untreated and heat-treated virus inclusion bodies (capsules) were compared for their antigenic properties but no differences were detected. The antiserum elicited against the whole capsule was more sharply specific for the antigenic determinants than the one elicited against the dissolved capsule proteins. The viruses obtained from S. exigua and T. ni elicited precipitin lines that differed from those of the P. unipuncta GV in their electrophoretic mobility with the one-trough IE method; however, with the two-trough method, the lines fused indicating that the antigens were identical. The major precipitin line indicating identity of the viruses wasthat produced by the synergistic factor (SF) purified from the capsule proteins of the synergistic GV strain. The presence of SF in the GV produced in alternate hosts indicated that its production was virus directed. The SF was not detected in the GVs of Laspeyresia pomonella and Pieris rapae and in the nonsynergistic Oregonian GV of P. unipuncta. A field-collected GV from S. exigua exhibited a different precipitin pattern from that of the synergistic GV, but one of the precipitin lines shared partial relationship to the SF.