THE USE OF MOLECULAR GENETIC METHODS TO DETECT HOMO- AND HETEROZYGOUS ALLELES OF THE β-TUBULIN GENE IN PARASITIC NEMATODES HAEMONCHUS CONTORTUS

The article presents data on the use of molecular genetic tests to diagnose the occurrence of mutant alleles in the β-tubulin gene in parasitic nematodes Haemonchus contortus that lead to the formation of genetically determined resistance to benzimidazoles. The studies were conducted on parasitic nematodes isolated from the gastrointestinal tracts of sheep raised in the Stavropol Territory and the Republic of Ingushetia. On these sheep farms, regular deworming of the entire small cattle with benzimidazole preparations was carried out. To establish the taxonomic affiliation of the studied helminths, a nested PCR was performed followed by a restriction analysis of the obtained amplicons. DNAs belonging to H. contortus nematodes were subsequently studied by the multiplex PCR to identify homo- and heterozygous alleles of the β-tubulin gene in the nematode genotype. The reaction used two pairs of species-specific primers different combinations of which made it possible to detect the presence or absence of single-nucleotide substitutions in the β-tubulin gene. These single-nucleotide substitutions which cause the resistance to benzimidazole drugs are a recessive trait. The technique we use can be applied to timely identify the initial stages of the formation of a resistant genotype in a population of parasitic nematodes of the Trichostrongylidae family at the herd level.