Experimental vaccination with GP300 (thrombospondin-like protein) against the bovine lungwurm Dictyocaulus viviparus.

Abstract

GP300 is a thrombospondin-like immunodominant and phosphorylcholine (PC) containing glycoprotein of Dictyocaulus viviparus and related nematodes. Antibodies induced by a primary D. viviparus infection or vaccination are mainly directed against the PC moiety of GP300 (Kooyman et al., 2009). IgE antibodies specific for GP300 correlate with protection against infection (Kooyman et al., 2002) In the following experiment, protection against a challenge infection with 500 L3 Dictyocaulus viviparus larvae was measured after administration of a vaccine consisting of 100 μg purified thrombospondin-like protein and Quill A. The vaccine does elicit an antibody response consisting of IgE, IgG1 and IgG2, but differences in protection between a vaccinated and an adjuvant control group could not be demonstrated. Clinical signs did not improve in the vaccinated group. A strong positive correlation between IgG2 and total worm counts was demonstrated. First, this positive correlation consisted between the IgG2 antibody reaction against the native GP300 and total worm counts. Later this correlation consisted between the IgG2 antibody reaction against protein backbone of GP300 and total worm counts. In general, immune reactions against the native GP300 are more abundant than those against the protein backbone of GP300 alone. More detailed investigation of the antibody response is needed in order to draw a final conclusion about the suitability of GP300 as a vaccine against parasitic bronchitis caused by Dictyocaulus viviparus.