Immuno-fluorescent studies on Balantidium coli

Abstract

In order to perform the fluorescent antibody test with a pig strain of Balantidium coli, 2 rabbits were injected with a suspension of ciliates, to provide immune sera. They received 80,000 cells in 8 divided doses given at intervals of 7 days, then 30,000 cells in 3 doses and lastly of 20,000 cells in 2 doses together with Freund adjuvant. Blood samples were taken a week after the last injection of each series and afterwards tested by the indirect fluorescent antibody technique. The blood samples taken 2 weeks after the last injection of the 3rd series gave a positive fluorescent antibody test. There was some non-specific fluorescence when fixed balantidia were used as antigen and in sections of ciliates fixed in osmic acid and embedded in gelatin. No non-specific fluorescence was found when living balantidia were used as antigen. Serum samples of naturally infected pigs were tested for the presence of antibodies against B. coli by the indirect fluorescent antibody test: no antibodies were detected.