The presence of benzimidazole resistance mutations in Haemonchus placei from US cattle

Sympatric species distribution, genetic diversity and population structure of Haemonchus isolates from domestic ruminants in Pakistan

“…Although sheep and goats are the preferred hosts for H. contortus, the prevalence of H. contortus infection (38.5%) was found to be relatively higher next only to H. placei (46.2%) in Pakistani cattle. These results are in contrast to the reports from Brazil and United States where H. placei was the predominant species with a frequency of >90% (Brasil et al, 2012;Chaudhry et al, 2014). However, a much higher frequency of H. contortus infection in cattle (61.9%) had been reported in Tunisia (Akkari et al, 2013).…”

“…The relative predominance of different sympatric Haemonchus species among ruminant hosts appears to depend on the kind of livestock management system prevailing in different regions. In cattle pastures with single-species grazing, H. placei was found to predominate while pastures with rotational or co-grazing of multiple ruminant species, significant level of H. contortus infections in cattle do occur (Chaudhry et al, 2014). In small holder production system of Pakistan where co-grazing of sheep, goat and cattle are common, the relatively higher prevalence of H. contortus infection in cattle could have been derived from grazing areas contaminated by infected sheep and/or goat.…”

“…Three mutations within this gene resulting in substitutions of amino acids have been reported (F167Y, E198A and F200Y), of which F200Y has been consistently found to differ between drug susceptible and drug resistant populations (Clark et al, 2005;Von Samson-Himmelstjerna et al, 2007;Rufener et al, 2009). F200Y is also the predominant benzimidazole associated polymorphism in numerous trichostrongylid nematodes (Winterrowd et al, 2003;Almeida et al, 2010;Chaudhry et al, 2014). The frequency of resistant alleles at F200Y locus in the present study was found to be lower than reported for Brazilian isolates and is comparable to the frequency in Brazilian farms with little usage of benzimidazole drugs (Brasil et al, 2012).…”

“…However, it needs to be mentioned that very few molecular genotyping studies of H. placei on ␤ tubulin isotype1 loci related to benzimidazole resistance have been reported. Recently, Chaudhry et al (2014) reported the presence of benzimidazole resistance mutations at F200Y locus in H. placei isolates from US cattle. The absence of E198A single nucleotide polymorphism (SNP) in Pakistani isolates could be due to its rarity of association with benzimidazole resistance (Von Samson-Himmelstjerna et al, 2007, 2009.…”

Genetic evidence for the spread of a benzimidazole resistance mutation across southern India from a single origin in the parasitic nematode Haemonchus contortus

“…The thermo-cycling parameters of isotype-1 b-tubulin consisted of an initial 98°C for 30 s followed by 35 cycles of 98°C for 10 s, 59°C for 30 s and 72°C for 1 min with a single final extension cycle of 72°C for 5 min. Amplicons were cloned into a PJET 1.2/BLUNT vector (Thermo Scientific, USA) and sequenced using previously described procedures (Chaudhry et al, 2014). Sequences were aligned with H. contortus isotype-1 b-tubulin sequences (GenBank Accession Number X67489) and edited using Geneious Pro 5.4 software (version 5.6) 2.6.…”