Precursor polypeptides of adult T-cell leukaemia virus: detection with antisera against isolated polypeptides gp68, p24 and p19.

Sera of individuals infected with adult T-cell leukaemia virus (ATLV) react predominantly with the polypeptides gp68, p24 and p19. These polypeptides were isolated from ATLV-infected MT-2 cells and virus. The radioiodinated polypeptides were used to quantify respective antibodies in individual ATLV carrier sera. Heteroantisera prepared in rabbits against isolated polypeptides facilitated studies on the biosynthesis of the core and envelope polypeptides of ATLV. Pulse-chase experiments revealed a polypeptide of mol. wt. 48 000 (48K) as the precursor to the core polypeptides p24 and p19. A 28K polypeptide related to p19 appeared to be an early side-product of the gag gene or a translate of a defective viral message. Antiserum to the putative env gene product gp68 recognized gp68, gp66 and small amounts of gp62. In tunicamycin-treated cells gp68, gp66 and gp62 were no longer synthesized, but a 54K polypeptide reacted with antiserum to gp68. Polypeptide p54 is structurally related to gp68 and therefore apparently represents the unglycosylated form of gp68. Moreover, the apparent mol. wt. of p54 and p48 agree with those predicted for respective env and gag precursors from the nucleotide sequence of an ATLV provirus.