Molecular Weights of Lepidopteran Baculovirus DNAs: Derivation by Electron Microscopy

Abstract

Mol. wt. estimates have been derived for the covalently-closed circular DNAs extracted from seven nuclear polyhedrosis and three granulosis viruses by a comparison of their contour length with that of the replicative form of f1 bacteriophage DNA. The length of the circular DNA molecules was uniform for each of the ten viruses studied. The mol. wt. values obtained ranged from 58 × 10⁶ to 94 × 10⁶ although all but two values were within the range 69 × 10⁶ to 81 × 10⁶. There appeared to be two major size classes within the latter range. The mol. wt. of the three granulosis virus DNAs were from 68 × 10⁶ to 71 × 10⁶ while the nuclear polyhedrosis virus DNAs spanned the full range. Thus, the distribution of mol. wt. values obtained from covalently-closed DNAs isolated from baculoviruses was not consistent with the division of the group into nuclear polyhedrosis and granulosis viruses.