Polypeptide synthesis in Junín virus-infected BHK-21 cells.

Analysis by immune precipitation and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of intracellular [35S]-methionine-labelled specific Junín virus polypeptides demonstrated synthesis of the nucleoprotein (Np64) between 24 to 96 hr post-infection (p.i.). Two glycoproteins with apparent molecular weights (Mr) of 72,000 (Gp72) and 38,000 (Gp38) were detected by pulse labelling with [35S]-methionine or sugar precursor at about 48 hr p.i. The rate of synthesis of Gp38 increased up to 96 hr p.i. with concomitant decrease of Gp72. During pulse-chase experiments, Gp72 was cleaved to Gp38. These results suggest that Gp72 may be a precursor of the envelope structural glycoprotein. Using sera to virion fractions we found that Gp72 and Gp38 did not share antigenic determinants with Np64. We also identified a 200,000 Mr polypeptide (P200) in infected cells. The possibility that P200, Gp72 and Np64 are virus coded products is discussed.