• Porcine zona pellucida;
  • low-dose immunization;
  • anti-zona antibody titration

ABSTRACT: The antigenic potency of porcine zona pellucida has been studied in the rabbit using low-dose immunization (50, 100, 200, and 400 zonae per injection), and the subsequent level of anti-zona antibodies was determined. The antibody titers as determined by the indirect immunofluorescence test (IF) and the zona precipitation reaction (PR) were 1:640 and 1:80, respectively, after immunization with 100 zonae. There was no difference in antibody titers between the immunization of 400 suspended zonae and 400 heat-treated zonae. Injection of homogenized porcine ovary also resulted in titers of 1:640 and 1:80 (IF and PR, respectively). Immunization, however, with only 50 isolated zonae did not produce a measurable antibody titer. Immunization with 1200 intact or heat-treated zonae resulted in transient infertility.

The present study demonstrated that the limiting quantity of zonae required for detectable antibody production was between 1.65 μg and 3.30 μg zona protein as monitored by immunofluorescence and immunoprecipitation assays. To induce an antifertility effect, at least 40 μg of zona material was necessary.