Vaccination with recombinant paramyosin against the bovine lungworm Dictyocaulus viviparus considerably reduces worm burden and larvae shedding

Abstract

BackgroundThe lungworm Dictyocaulus viviparus, causing parasitic bronchitis in cattle, induces a temporary protective immunity that prevents clinical disease. A radiation-attenuated larvae based vaccine is commercially available in a few European countries, but has the disadvantages of a live vaccine. As a recombinant subunit vaccine would overcome these disadvantages, the parasite’s muscle protein paramyosin (PMY) was tested as a recombinant vaccine antigen.MethodsD. viviparus-PMY was recombinantly expressed in Escherichia coli as a glutathione-S-transferase (GST)-fused protein. Emulsified in adjuvant Saponin Quil A, the protein was given intramuscularly into calves. Two independent recombinant PMY (rPMY) vaccination trials with negative control groups (first trial: adjuvant only; second trial: non-fused GST) as well as an additional positive control group in the second trial, using the Bovilis©Dictol live vaccine to verify vaccination results, were performed. To determine the vaccination success, shedding of larvae as well as worm burden and worm sizes were analyzed. Additionally, ELISA-based determination of development of immunglobulins IgM, IgA, IgE, IgG as well as the subclasses IgG1 and IgG2 was performed. To analyze PMY localization in the bovine lungworm, immunohistochemical staining of adult worms was carried out.ResultsImmunohistochemical staining revealed that PMY is part of the bovine lungworm’s pharyngeal and body wall muscles. Vaccination with rPMY resulted in 47% [geometric mean: 67%] and 57% (geometric mean: 71%) reduction of larvae shedding in the first and second vaccination trial, respectively. Worm burden was reduced by 54% (geometric mean: 86%) and 31% (geometric mean: 68%), respectively, and worms of rPMY-vaccinated cattle were significantly shorter in both trials. Furthermore, ELISAs showed a clear antibody response towards rPMY with exception of IgE for which titers could not be detected. After challenge infection, rPMY antibodies were only exceptionally elevated among study animals indicating PMY to be a hidden antigen.ConclusionsEven though vaccination with the attenuated live vaccine was with 94% (geometric mean: 95%) reduction in larvae shedding and 93% (geometric mean: 94%) reduction in worm burden superior to rPMY vaccination, results using the latter are promising and show the potential for further development of a recombinant PMY-based vaccine against the bovine lungworm.

Vaccination of calves with yeast‐ and bacterial‐expressed paramyosin from the bovine lungworm Dictyocaulus viviparus

“…Individual LPG values for each animal were added to a cumulative value. Geometric mean (GM) calculations were performed as described previously .…”

“…Development of antibodies to rPMY was assessed for each subclass (IgM, IgA, IgE, IgG, IgG1 and IgG2) as described recently by Strube et al . with the following conditions for detection of IgM, IgA, IgG, IgG1 and IgG2: all serum samples were used as a 1:40 dilution and secondary antibodies as a 1 : 1000 dilution. Plate coating with rPMY corresponded to vaccinations (trial 1: EcPMY; trials 2 and 3: PpPMY).…”

“…Paramyosin (PMY), commonly known as a muscle protein of invertebrates including D. viviparus , has been considered as a promising vaccine candidate as it is transcribed throughout all developmental stages of bovine lungworms . PMY of D. viviparus displays immunomodulatory functions by binding to collagen and IgG , similar to those described for Taenia crassiceps ‐PMY .…”

“…Indeed, Strube et al . demonstrated in two vaccine trials in cattle already a geometric mean (GM) protection level of 86% regarding worm burden during a first and 68% during a second vaccination trial using recombinant Escherichia coli ‐expressed PMY. Furthermore, GM cumulative larvae counts were reduced by 67% and 71%, respectively.…”

Proteomic identification of Galectin-11 and 14 ligands from Haemonchus contortus

“…Correspondingly, 45% of the glycoproteins that the two galectins bound were membrane proteins of the adult stage of H. contortus, and included vitelline, myosin and M13 protein (neprilysin); these proteins have been previously assessed as vaccine candidates (Knox 2011;Strube et al 2015;Tellam et al 2002). This evidence would indicate that other putative glycoproteins identified here by these ruminant galectins might facilitate the identification of new intervention targets and, thus, warrant further investigation.…”