Isolation and characterization of entomopox virions from virus-containing inclusions of Amsacta moorei (Lepidoptera: Arctiidae)

Preparations of Amsacta moorei entomopox virions were obtained from virus-containing inclusions (VCI) by using a carbonate-thioglycolate solution (pH 10.7–11.5). The virions possessed a uniform coat (“halo”) surrounding the viral envelope and exhibited an RNA polymerase activity. The “halo” could be removed by prolonged exposure to the carbonate-thioglycolate solution. Virions obtained by this treatment, however, possessed low infectivity and no detectable RNA polymerase activity. Removal of the “halo” by trypsin resulted in virions which possessed RNA polymerase activity and relatively high infectivity.Preparations of particles with and without the “halo” were similar in percent DNA, protein per OD₂₆₀, number of particles per OD₂₆₀, and RNA polymerase activity. Particles without the “halo,” however, were less dense (1.262 g/cm³) in CsCl than those with the “halo” (1.282 g/cm³) and 15–45 times more infective.Parallel studies of “nonhaloed” Amsacta virions (trypsin-treated) and vaccinia virions showed that both viruses contained similar amounts of protein per OD₂₆₀, but Amsacta virions contained only 36% of the DNA found in vaccinia.