Genotypic variation among wild isolates of Heliothis spp nuclear polyhedrosis viruses from different geographical regions.

Ten nuclear polyhedrosis viruses infecting insect hosts in the genus Heliothis and isolated in different geographical regions of the world were characterized using restriction endonuclease analysis. Digestion of the dsDNA genomes with BamHI, EcoRI, and HindIII resulted in fragmentation profiles which separated the wild-type isolates into two major genotypes, corresponding with the morphology of the virion (multiply embedded major genotypes, corresponding with the morphology of the virion (multiply embedded vs singly embedded). Isolates within each major genotype have similar fragmentation profiles, showing only slight differences in the number and size of several fragments, and thus represent variants of the major genotype. Submolar fragments present in a number of the digests suggests that these wild-type isolates might themselves consist of two or more genotypic variants. The significance of this genotypic heterogeneity is discussed.