Nucleic acid sequence relationships among "slow" viruses of sheep.

Abstract The RNA genomes of the sheep “slow” viruses, visna, maedi, and progressive pneumonia, were compared by nucleic acid hybridization. The homology among these viral RNAs was determined from the extent competition of homologous viral RNA-cDNA hybrids by heterologous RNA and from the thermal stability of homologous and heterologous RNA-cDNA hybrids. The 70 S RNAs of visna and maedi virus were indistinguishable but only partially homologous to that of progressive pneumonia virus.