Abstract

Haemonchus contortus is one of the most prevalent gastrointestinal nematodes in all ecosystems in Mexico, where sheep are raised on pasture, and it poses a significant threat. This study aimed to examine the surgical isolation of a Mexican H. contortus strain, its morphological and molecular characterization, and the maintenance of this strain for future research. Biological behavior and some phenotypic aspects of the adults were considered. Fecal samples were obtained from naturally infected sheep, larval cultures were performed, and a nematode-free lamb was infected. Once the infection was established, the donor sheep were euthanized, the adults recovered, and H. contortus females and males were selected. A surgical transfer from H. contortus adult to the abomasum of a receptor lamb was performed, and the beginning of the egg excretion was confirmed three days post-transfer; fecal cultures from the receptor lamb were conducted to verify the purity of the strain. After three lambs were infected with 3000, 5000, and 10,000 L3, the pre-patent period, prolificacy, and measurements of the adult stages of the strain were studied. The molecular characteristics were evaluated by qPCR; primers were designed based on NCBI genomic DNA sequences of H. contortus to amplify a 176 bp fragment, and the amplicon was sequenced for taxonomic identification. The results of this study describe biological characteristics and some phenotypic aspects of the adults, as well as eggs and infective larvae, and molecular characteristics of the isolated strain, and establish a successful methodology for isolating and maintaining a pure strain of H. contortus (FESC-strain); it can be used as a reference in experimental infections or anthelmintic resistance studies.

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