Abstract
Abstract
Freeze/thaw (F/T) extracts of gradient purified concentrates of baboon endogenous retrovirus (BEV) depress phytohemagglutinin (PHA)-induced blastogenic transformation of human, baboon, and mouse lymphocytes. Extracts of normal fetal dog thymus cells (vehicle for virus replication), pelleted virus cores, spent tissue culture medium, and virus suspension buffers were not depressive. Sephacryl S-200 chromatography of BEV F/T extracts yielded two peaks of suppressive activity; peak A, eluted in the region of relatively high protein concentration with the 45,000-dalton ovalbumin marker, was highly labile, but not cytotoxic. Peak B, eluted between cytochrome c and DNP alanine markers, contained no detectable protein and appeared to consist of two components; one cytotoxic and highly labile and a second, noncytotoxic and relatively stable. A polyvalent antiserum to BEV proteins precipitated components of the BEV F/T extract and peaks A and B, but failed to abrogate immunodepression.
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