Detection of antibodies in Brugia pahangi-infected cats by counter immunoelectrophoresis, indirect fluorescent antibody test and enzyme-linked immunosorbent assay.

In cats infected with Brugia pahangi, antibodies first appeared against the larvae (L3), then against the adults (L5) and the microfilariae (mf). Homologous antigens were better than antigens prepared from heterologous species (Dirofilaria immitis, Dipetalonema viteae, Litomosoides carinii and Onchocerca gutturosa) in detecting antibodies to B. pahangi in the infected cats by indirect fluorescent antibody test (IFAT). Metabolic products of L5, but not L3 or mf, of B. pahangi were antigenic and were used in the enzyme-linked immunosorbent assay (ELISA) for detection of antibodies. Using various homologous antigens, IFAT was found to be more sensitive than counter immunoelectrophoresis and ELISA in the detection of antibodies in the infected cats. The best antigen was cryosections of L3, with a positivity rate of 81%. However, using L3, L5 and mf antigens in IFAT, a total positivity of 97% was obtained.