Caprine arthritis-encephalitis virus is distinct from visna and progressive pneumonia viruses as measured by genome sequence homology.

Competitive inhibition of hybridization between (125)I-labeled caprine arthritis-encephalitis viral RNA and homologous cDNA by heterologous viral RNA shows that the caprine retrovirus shares <20% genome sequence homology with visna and progressive pneumonia viruses. These viruses, however, are indistinguishable in immunodiffusion reactions involving the major structural protein (p28).