Expression of Caenorhabditis elegans-expressed Trans-HPS, partial aminopeptidase H11 from Haemonchus contortus

• We expressed an enzymatic region of Haemonchus contortus H11 using Caenorhabditis elegans.
• Crude Trans-HPS could be recognized by bacterial antibodies of both full-length H11 and HPS.
• Immunization with crude Trans-HPS extract led to 37.71% reduction in faecal egg count in goats.
• Immunization with crude Trans-HPS extract led to 24.91% reduction in worm burden in goats.

Aminopeptidase H11 present in the surface of intestine microvilli in Haemonchus contortus was identified as the most effective antigen candidate. However, its recombinant forms produced in Escherichiacoli, insect cells and yeast could not provide promising protection against H. contortus challenge, probably due to the inappropriate glycosylation and/or conformational folding. Herein, partial H11 containing the potential zinc-binding domain and two predicted glycosylation sites (nt 1 bp–1710 bp, Trans-HPS) was subcloned downstream of 5′ flanking region of Caenorhabditis elegans cpr-1 gene in pPD95.77 vector, with the deletion of GFP gene. The recombinant was expressed in C. elegans and verified by blotting with anti-H11 and anti-Trans-HPS rabbit polyclonal antibodies and anti-His monoclonal antibody. Stably inherited Trans-HPS in worm descendants was achieved by integration using UV irradiation. Immunization with the crude Trans-HPS extracted from transgenic worms resulted in 37.71% reduction in faecal egg counts (FEC) (P < 0.05) and 24.91% reduction in worm burden, but an upward curve with moderate rate of daily FEC in goats. These results suggested an apparent delay against H. contortus egg-laying in goats, which differed from that with bacteria-origin form of partial H11 (nt 670 bp–1710 bp, HPS) (26.04% reduction in FEC and 18.46% reduction in worm burden). These findings indicate the feasibility of sufficient C. elegans-expressed H11 for the immunological research and vaccine development.

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