Research Article

Antibody is responsible for the passive transfer of immunity to mice from rabbits, rats or mice vaccinated with attenuated Schistosoma japonicum cercariae

N. A. Moloneya1 and G. Webbea1

a1 London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT


Sera from rabbits, rats and mice multiply-vaccinated with attenuated cercariae of Schistosoma japonicum conferred high levels of resistance against challenge to naive recipient mice (up to 97, 64 and 60% respectively). Vaccinated rabbit and rat sera were given before challenge and vaccinated mouse serum 5 days after challenge. To show that the protective factors in these sera were antibodies, vaccinated rabbit and mouse sera were fractionated by protein A-Sepharose and the fractions precipitated by 50% ammonium sulphate. The protein A-Sepharose binding or non-binding fractions in vaccinated rabbit serum transferred approximately equal levels of significant resistance to mice, suggesting that both the IgG and non-IgG components of vaccinated rabbit serum are protective. The major part of the protective activity in vaccinated mouse serum was transferred to recipients by the protein A-Sepharose binding fraction, i.e. the IgG antibodies. Heat inactivation of sera at 56 °C for 3 h affected the protective capacity of vaccinated rat sera, but not that of vaccinated rabbit or mouse sera.

(Accepted October 05 1989)