Heteroduplex study of the sequence relations between RD-114 and baboon viral RNAs

Abstract

The regions of sequence homology and nonhomology between the RNA genomes of RD-114 and baboon endogenous type C viruses were mapped by an EM heteroduplex study. Short complementary[c]DNA copies (about 150-200 nucleotides in length) of RD-114 RNA were prepared by an endogenous synthesis; labels of poly(dT) were attached to the 3'' ends of the cDNA molecules by a reaction catalyzed by deoxynucleotidyl terminal transferase. The cDNA-poly(dT) was hybridized to RD-114 RNA and to baboon viral RNA dimer (50-70 S) units, and the positions of the poly(dT) labels were observed by EM. With RD-114, labels were distributed uniformly along the genome. With baboon virus RNA (monomer length, 9.5 kilobases [kb]), the regions of high homology with RD-113 cDNA were observed to lie in the intervals from 1.5-2.5 kb and from 3.7-5.5 kb from the 5'' end. The relations of these heteroduplex maps to the known antigenic similarities and differences among the several viral proteins and to the genetic maps of the viruses are discussed.