Abstract
The genome of Choristoneura fumiferana nuclear polyhedrosis virus (CfMNPV) contained reiterated sequences interdispersed in 4 locations. These regions, termed RS, were found in EcoRI fragments A, F, E and B. The sequences were identified by hybridization of the fragment EcoRI-A to a Southern blot of EcoRI-digested viral DNA. Further confirmation and more precise localization of the RS sequences was obtained by hybridization of nick-translated 32P-labeled EcoRI-E fragment to Southern blots of viral DNA digested with EcoRI, BamHI, XbaI and BglII. Hybridization of 32P-labeled EcoRI-E to HindIII blots of viral DNA revealed the presence of a ladder consisting of 8 fragments. The 3 fragments of the ladder with the lowest sizes represented the HindIII fragments, O, PQ and R. The other 5 fragments were submolar in amount, in that they could not be seen in ethidium bromide-stained gels and probably represented minor virus variants that arose after passage of virus in larvae. Each variant was distinguished from the others by an additional insertion of 210 base-pairs into the EcoRI-B fragment of the genome.