Brugia pahangi infections in cats: antibody responses which correlate with the change from the microfilaraemic to the amicrofilaraemic state.

The humoral responses of eight cats infected with Brugia pahangi to somatic antigens from all life-cycle stages were examined quantitatively by ELISA and qualitatively by immunoblotting for almost a year post infection. Six cats spontaneously became amicrofilaraemic: their production of IgG antibodies against somatic antigens of microfilariae, adults, and infective larvae was not statistically higher than that of the two cats which remained microfilaraemic. However, immunoblotting revealed that those cats which spontaneously became amicrofilaraemic selectively recognized certain microfilarial, adult and infective larval somatic antigens prior to disappearance of microfilariae from the peripheral circulation. The data suggest that selective recognition of antigens by some cats is responsible for the production of antibodies which may then promote microfilarial death.