Characterization of excretory‐secretory products of adult Dictyocaulus viviparus and the antibody response to them in infection and vaccination

Abstract

In vitro released products of the adult stage of the bovine lungworm. Dictyocaulus viviparus, were characterized according to their SDS-PAGE profile, glycosylation pattern, in vitro synthesis and antigenicity in the context of infection and vaccination with irradiated larvae. Biosynthetic labelling experiments with 35S-methionine indicated active synthesis of ES throughout this time. There was, however, little incorporation of 3H-glucosamine into ES products, and lectin affinity chromatography and glycopeptidase F digestion identified only one glycosylated component. Immunoprecipitation of 125I-labelled ES products with sera from calves patently infected with D. viviparus demonstrated that all of these, with the exception of two components, are antigenic to the bovine host. One of those not immunoprecipitated was shown to be host serum albumin carried over into culture. A limited degree of cross-reactivity between nematode species was observed, with a D. viviparus female-specific antigen of 290 kDa being recognized by serum antibody from calves infected with the gastrointestinal nematodes Cooperia oncophora and Ostertagia ostertagi. Calves vaccinated with irradiated larvae of D. viviparus, despite not being exposed to the adult stage of the parasite, also showed some recognition of adult ES products. This might suggest that vaccination with irradiated larvae operates against both pre-pulmonary and pulmonary stages of the infection.