Immunoglobulin classes of antibodies in the sera of buffaloes infected with Toxocara vitulorum

Serum samples of buffalo calves naturally infected with Toxocara vitulorum uere fractionated by means of 'Sephadex' G-200 gel-filtration. On gel-filtration, the buffalo sera separated into three main peaks sometimes with two minor peaks between peaks-1 and -2 as were those of other domestic animals. IgM and X₂-macroglobulins were eluted mostly with the peak-1 and the trough following this peak. The IgG's were eluted largely with the peak-2 and the trough following this peak. On further fractionation the bulked and concentrated eluates of peak-2 resolved into two subclasses consisting of IgG₂ and IgC₁. The antibody activity of these classes was examined by the enzyme-liked immunosorbent, gel-diffusion, in vitro larval precipitin and passive cutaneous anaphylaxis techniques (ELISA, GPT, IVP, PCA). A phosphate buffered saline extract of infective T. vitulorum eggs was used as the antigen. The ELISA activity was distributed throughout the peaks-1 and -2, the trough between these peaks and that following peak-2. The GPT and IVP antibodies were present in the IgG_l and not in IgG₂ the immunoglobulin subclasses constituting the peak-2. The PCA activity was confined largely to the ascending part of peak-1 in the sera collected during the prepatent and patent phases of the infection whereas this activity was mostly confined to two minor peaks preceding peak-2 in the sera collected from days 174 of birth but after the experimental infection with 50,000-100,000 infective eggs on day 160.