Adjuvant effect of anti-idiotypic antibodies to Yersinia pestis lipopolysaccharide.

Rabbit anti-idiotypic antibodies (anti-Id-ab) against Yersinia pestis lipopolysaccharide (LPS) were obtained with monoclonal immunoglobulins. Their complementary character to the original antigen was confirmed by immunohistochemical analysis and ELISA and gel precipitation tests. The anti-Id-ab were shown to possess all essential properties of Ab2beta subtype. Both in-vitro and in-vivo experiments demonstrated a pronounced adjuvant activity of anti-Id-ab without the toxic effect characteristic of Y. pestis LPS. Combined immunisation with anti-Id-ab plus the FI capsular antigen led to a significant increase in the protective immune response against experimental acute challenge with virulent Y. pestis.