A member of the CAP protein superfamily, Hc -CAP-15, is important for the parasitic-stage development of Haemonchus contortus

Background The CAP superfamily proteins are distributed widely in eukaryotes and play crucial roles in various biological processes. However, very little is known about their functions in parasitic nematodes, including Haemonchus contortus , a socioeconomically important parasitic nematode. We have therefore studied a member of the CAP protein family of H. contortus , named Hc- CAP-15, with the aim to explore its roles in regulating the parasitic developmental process. Methods The conservation and phylogenetic relationships, spatial expression and temporal transcription profiles of Hc -CAP/ cap - 15 , as well its biological function during parasite development were investigated using bioinformatics, immunofluorescence, real-time PCR and RNA interference (RNAi). Results Hc -CAP-15 was found to be a single-domain CAP protein consisting of four conserved motifs that is localized in the cuticle, intestine and oocyte of adult worms. Hc-cap-15 was transcribed at all developmental stages of H. contortus , with the highest transcription level in parasitic fourth-stage larvae (L4s). Silencing of Hc-cap-15 resulted in a significant increase in the body length of L4s. Conclusions The results suggested that Hc -CAP-15 is important for the development of H. contortus . Our findings provide a basis for further study of the functions of the CAP family proteins in H. contortus and related parasitic nematodes. Graphical Abstract