The study aims to evaluate the dynamics of simultaneous infection by Haemonchus contortus and Haemonchus placei in sheep, with emphasis in competition or crossing between both species. This study also aims to standardize molecular techniques for identification of H. contortus and H. placei species, their hybrids and detection the mutation in albendazole resistant gene (at residue 200 of the isotype 1 ²-tubulin gene). In the first trial, the animals of group 1 (n=6) will be infected, initially, with 2,000 infective larvae (L3) of H. placei and 11 days later, with 2,000 L3 of H. contortus. In order to produce L3 to infect animals of group 2 (n=12), fecal cultures will be made using fecal samples from each animal of group 1. This procedure will allow evaluating if hybrids are produced and if they are able to infect successfully sheep. All animals of groups 1 and 2 will be sacrificed to quantification and identification of the parasites to determine if there was competition between species, as well as the hybrid production. Worm free animals (n=6) will be kept as a control group. In a second trial, a group of 32 worm free sheep will be infected with H. placei (n=16) or H. contortus (n=16). Initially, these animals (so-called permanent) will be grazing in worm free pasture. Then, this pasture will be gradually contaminated by eggs and larvae originated from the infected sheep (permanent). Thus, these animals will be exposed to natural re-infections and will be sacrificed regularly. Tracer sheep will be introduced in paddocks, periodically, until the end of the trial with the purpose to evaluate the real level of pasture contamination (dynamics of infection) of each Haemonchus species and the possible hybrid production in conditions of natural infection. These tracer animals will be immunosuppressed to reduce the immune response. Morphometric and molecular analyzes will be applied to accurately identify parasites of both species and hybrids. Molecular techniques will be tested for suitable identification of species and possible hybrid production, as well as gene flow occurrence between these species, particularly those related to albendazole resistance.
News published in Agência FAPESP Newsletter about the scholarship: