Size Differences in the Ribonucleic Acids of Feline Leukaemia Viruses

Electrophoretic analysis of native and denatured RNA of feline leukaemia virus (FeLV) has revealed small but significant size differences between the RNAs of a number of FeLV isolates. The mol. wt. of the denatured or subunit RNA has been estimated to range from 2·2 to 2·6 × 106 in the different isolates, each of which belonged to one or more FeLV subgroups (A, B and C). The RNA of subgroup A virus was smaller than that of subgroup B virus, while the RNA of subgroup C virus appeared to be intermediate in size between the RNAs of A and B subgroup viruses. Size differences were, however, also found between RNAs of FeLV isolates of a single subgroup (A), indicating that no simple relationship exists between RNA size and virus subgroup.