Immunological cross-reactions of the major internal protein component from “slow” viruses of sheep

Abstract The major p27 polypeptides of the sheep “slow” viruses, visna, maedi, and progressive pneumonia, were compared by radioimmunoassay. The immunologic relatedness among these viral proteins was determined from the competition of homologous- and heterologous-disrupted virions with iodinated visna virus p27 for visna antisera. The p27 antigens of visna virus and maedi virus were indistinguishable from each other and were partially related to p27 of progressive pneumonia virus.