A new class of murine retroviruses: Immunological and biochemical comparison of novel isolates from Mus cervicolor and Mus caroli (original) (raw)

A new murine retrovirus (designated M432) isolated from the Southeast Asian mouse species, Mus cervicolor, has been characterized with respect to its protein composition, RNA genome, and certain of its immunologic properties. The M432 virus contains a magnesium-dependent reverse transcriptase (MW 70,000) and at least five other viralassociated proteins (MW.s 65,000, 32,000, 24,000, 16,000, and 12,000). The two largest structural proteins (designated gp65 and gp32) are glycosylated and are components of the virion surface. The major internal protein is p24, while p12 is the major viral phosphoprotein. A radioimmunoassay developed for the p24 protein detects this antigen in cultured cells infected with M432 as well as in tissues of animals from the species Mus musculus which were inoculated at birth with the M432 virus. A second retrovirus (designated M832) isolated from cultured cells of another Southeast Asian murine species, Mus caroli, is related by several criteria to the M432 virus. An antiserum to the polymerase of M432 cross-reacts with the reverse transcriptase of M832; similarly, the radioimmunoassay for the M432-p24 protein detects a cross-reactive antigen in cells producing M832. Using nucleic acid hybridization techniques, a partial sequence homology (-25%) can be detected between the RNA genomes of the two new isolates. By morphologic, immunologic, and biochemical criteria, the M432 and M832 viruses are unrelated to known type C and type B viruses isolated from mice and appear, then, to be members of a new class of genetically transmitted murine retroviridae.