期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：4
页码：1989-1993
DOI：10.1073/pnas.75.4.1989
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A number of variant-specific surface antigens (VSSAs) were purified from clones of Trypanosoma brucei and T. congolense and tested for immunological crossreactivity. Anti-VSSA sera were clone-specific when tested by indirect immunofluorescence of living trypanosomes, but they were not clone-specific when tested by radioimmunoassay with purified 125I-labeled VSSAs. In this double-antibody radioimmunoassay every VSSA tested was precipitated by the homologous and all heterologous anti-VSSA sera. Any unlabeled VSSA could inhibit the heterologous precipitation reactions by 100%. The homologous precipitation reactions were effectively inhibited only by unlabeled homologous VSSA. Crossreactions between different VSSA molecules were also revealed by microcomplement fixation tests. The results confirm the presence, in VSSAs, of variable determinants specific to individual VSSAs and also show crossreacting determinants in all VSSAs tested, including those isolated from different species of trypanosomes. These results contrast with previous studies which failed to find evidence for immunological crossreactivity between different VSSA molecules. We suggest that the crossreacting determinants in VSSAs may represent common structural regions. The existence of such regions would have considerable implication for the development of theories and experiments concerning the mechanism of antigenic variation in African trypanosomes.
