ABSTRACT
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.
Subject(s)
Arenaviridae/metabolism , Arenaviruses, New World/metabolism , Peptide Biosynthesis , Viral Proteins/biosynthesis , Animals , Arenaviruses, New World/genetics , Cell Line , Cricetinae , Glycoproteins/biosynthesis , RNA, Viral/analysis , Viral Proteins/immunologyABSTRACT
In the Junin virus-infected cell, there is a soluble antigen (SAg), which we have detected by complement fixation. PAGE of purified SAg revealed two polypeptides with molecular weights of 20,000 and 25,000. An antigenically identical component, which was demonstrated by complement fixation and immunodiffusion tests and which had the same electrophoretic profile as SAg, was found after proteolytic breakdown of purified virions. SAg is an internal component of the virion, since it is unable to stimulate neutralizing antibodies and it can be obtained from viral particles whose envelopes have been removed by Triton X-100 treatment. The antigenic determinant apparently resides in the major nonglycosylated polypeptide (nucleoprotein P64), since the proteolytic degradation product is obtained in quantity and it is nonglycosylated.
Subject(s)
Antigens, Viral , Arenaviridae/immunology , Arenaviruses, New World/immunology , Complement Fixation Tests , Viral Proteins/immunology , Animals , Cell Line , Cricetinae , Epitopes , Glycoproteins/immunology , Molecular Weight , Virion/immunologyABSTRACT
Polyacrylamide gel electrophoresis of purified Junin virus revealed six distinct structural polypeptides, two major and four minor ones. Four of these polypeptides appeared to be covalently linked with carbohydrate. The molecular weights of the six proteins, estimated by coelectrophoresis with marker proteins, ranged from 25,000 to 91,000. One of the two major components (number 3) was identified as a nucleoprotein and had a molecular weight of 64,000. It was the most prominent protein and was nonglycosylated. The other major protein (number 5), with a molecular weight of 38,000, was a glucoprotein and a component of the viral envelope. The location on the virion of three additional glycopeptides with molecular weights of 91,000, 72,000, and 52,000, together with a protein with a molecular weight of 25,000, was not well defined.
