Progress and challenges for developing vaccines against gastrointestinal nematodes of ruminants

Gastrointestinal nematodes (GINs) infect sheep, goats and cattle, causing huge economic losses to the breeding industry worldwide. The current major control method is the usage of anthelmintic drugs, however, the widespread issue of parasite anthelmintic resistance means that this approach is becoming unsustainable. Vaccination has been regarded as a long-term and sustainable intervention strategy for controlling these parasitoses. In the past several decades, substantial progress has been made in developing vaccines against GINs infection in grazing ruminants. Many natural proteins of GINs have been identified as effective candidate antigens, which could induce a high level of protective immunity against these GINs infection in ruminants, but the recombinant forms of these native antigens have not achieved satisfactory immunoprotective effects. This review summarizes the progress and challenges for developing vaccines against the main GINs, including Haemonchus contortus, Ostertagia ostertagi, Teladorsagia circumcincta, Cooperia oncophora and Trichostrongylus colubriformi, as well as provides a perspective on promoting the progress of commercially viable recombinant subunit vaccines.