Suppression of hyaluronidase reduces invasion and establishment of Haemonchus contortus larvae in sheep
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RESEARCH ARTICLE
Open Access
Suppression of hyaluronidase reduces invasion and establishment of Haemonchus contortus larvae in sheep Xiangshu Yang1,2†, Sawar Khan1†, Xiaochao Zhao1, Jiayan Zhang1,2, Ayesha Nisar1 and Xingang Feng1*
Abstract Haemonchus contortus is a hematophagous endoparasite of small ruminants, which is responsible for huge economic losses in livestock sector. Hyaluronidase produced by infective larvae of H. contortus can degrade hyaluronic acid present in the host’s abomasal tissue. Thus, it facilitates larval tissue invasion and early establishment. We herein explored this ability of hyaluronidase in H. contortus, and tested whether hyaluronidase is utilized as a virulence factor by H. contortus while establishing the infection. We first successfully blocked the hyaluronidase gene in L3 larvae by RNA interference (RNAi), which was subsequently confirmed by qPCR, enzymatic activity, and immunohistochemistry assays. Using these larvae we then conducted in vivo and in vitro assays on sheep to assess the effects of hyaluronidase suppression on larval invasion and establishment of infection. The in vivo assay showed a significant drop in worm burden in siRNA treated group in comparison to control group. During in vitro assay we applied an ovine ex vivo model where siRNA treated group of larvae showed significantly reduced invasion of the abomasal tissue explants as compared to control group. These findings indicate that hyaluronidase plays a key role in host’s tissue invasion and larval establishment, and it is used as a virulence factor by H. contortus while establishing the infection. As an invasive virulence molecule, its functional research is thus conducive to the prevention of haemonchosis. Keywords: Haemonchus contortus, hyaluronidase, RNA interference, virulence factor, ex vivo tissue explants, in vivo Introduction Haemonchus contortus is an important gastrointestinal parasitic nematode of domestic and wild small ruminants whose origin is traced back to an assemblage of antelopes in Africa during the late Tertiary period [1–3]. It feeds on blood while living in the host’s abomasum and causes an infection called haemonchosis (a pathological condition characterized by anaemia, weight loss, and even mortality in infected animals), thereby leading to serious economic losses [4–6]. Currently, the prevention and *Correspondence: [email protected] † Xiangshu Yang and Sawar Khan contributed equally to this work 1 Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, People’s Republic of China Full list of author information is available at the end of the article
control of H. contortus is based on application of drugs such as macrocyclic lactones, salicylanilides, and benzimidazoles. Recently, a vaccine named B arbervax® (http:// barber vax.com.au/) was also launched as alternative to chemical control of H. contortus. This parasite has shown a great ability to develop re
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