Effect of syngeneic anti-idiotypic antibody on influenza virus neuraminidase antibody response

Influenza viruses possess two major surface glycoproteins - hemagglutinin (HA) and neuraminidase (NA). Py203, a monoclonal antibody (Ab) specific for the neuraminidase of the PR8 (H1N1) influenza virus, was used to prepare syngeneic monoclonal anti-idiotypic (anti-Id) Abs. From a BALB/c mouse immunized with Py203 (anti-N1), we obtained RM1, a monoclonal anti-Id Ab. The Py203-Id was detected in a significant fraction of immunoglobulins (Igs) in the primary and secondary responses elicited by PR8 (H1N1) and X31 (H3N2) viruses. In animals injected with minute amounts of RM1 and subsequently boosted with an identical dose of RM1, no detectable anti-NA activity was noted, but a significant increase in Py203-Id-bearing Igs was observed. In the sera of animals injected with minute amounts of RM1 and subsequently boosted with PR8 (H1N1) or X31 (H3N2) viruses, an increase in anti-NA activity and in the level of Py203-Id was noted. Animals injected with large amounts of RM1 and boosted with PR8 and X31 showed a marked suppression of the Py203-Id but no alteration in the anti-NA response. The anti-Id recognizes an idiotope (the Py203 idiotope) shared by antibodies specific for the N1 and N2 neuraminidase variants.