High levels of benzimidazole resistance and β-tubulin isotype 1 SNP F167Y in Haemonchus contortus populations from Ceará State, Brazil

[Display omitted] •High levels of benzimidazole resistance as shown by EHT.•Real-time PCR can be used for benzimidazole resistance diagnosis.•Resistance at SNP F167Y prevailed over SNP F200Y in the studied area.•Albendazole and oxfendazole use may influence specific resistant SNP frequencies. Haemon...

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Published in:	Small ruminant research Vol. 146; pp. 48 - 52
Main Authors:	Santos, Jessica Maria Leite dos, Monteiro, Jomar Patrício, Ribeiro, Wesley Lyeverton Correia, Macedo, Iara Tersia Freitas, Araújo Filho, José Vilemar de, Andre, Weibson Paz Pinheiro, Araújo, Paulo Ricardo Monteiro, Vasconcelos, Janaelia Ferreira, Freitas, Edilson Pereira de, Camurça-Vasconcelos, Ana Lourdes Fernandes, Vieira, Luiz da Silva, Bevilaqua, Claudia Maria Leal
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-01-2017
Subjects:	Anthelmintic resistance Benzimidazoles Nematodes Real-time PCR Sheep Nematodes Anthelmintic resistance Sheep Benzimidazoles Real-time PCR
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Summary:	[Display omitted] •High levels of benzimidazole resistance as shown by EHT.•Real-time PCR can be used for benzimidazole resistance diagnosis.•Resistance at SNP F167Y prevailed over SNP F200Y in the studied area.•Albendazole and oxfendazole use may influence specific resistant SNP frequencies. Haemonchus contortus is the most prevalent parasitic nematode in tropical areas, and anthelmintic resistance is a global problem. Our objective was to characterize benzimidazole (BZ) resistance in gastrointestinal nematode populations in Ceará State, Brazil, using the egg hatch test (EHT) and in H. contortus populations using quantitative real-time polymerase chain reaction (qPCR). Twenty locations were surveyed, and fecal samples were collected from a minimum of 40 animals from each farm and pooled. Five thousand L3 from each farm were used to infect single animals at Embrapa (Brazilian Agricultural Research Company) to provide a source of eggs for both phenotypical and molecular tests. The mean EHT was 2.46μg/ml (±0.58μg/ml), and BZ resistance was detected at all surveyed locations. The mean resistant allelic frequencies at positions F200Y and F167Y were 34.16% (±12.13%) and 58.31% (±18.89%), respectively. The resistant allelic frequencies at F167Y were higher than those at F200Y in most studied locations. We also investigated the possibility that specific BZ utilization may influence resistant allelic frequencies. We selected three nematode populations based on the resistant SNP prevalence at F200Y and F167Y as follows: higher frequency at SNP F200Y, higher frequency at SNP F167Y and similar frequencies at both positions. Anthelmintic treatments included two BZs (oxfendazole and albendazole) and ivermectin. Three animals per population per treatment were infected with 5000 L3, and nematode eggs were collected for molecular test before and after anthelmintic treatments. The results showed preferential selection of SNP F167Y in response to oxfendazole, an increase in resistant SNP frequencies in general in response to albendazole and little change in relation to pre-treatment situations in response to ivermectin. Our results confirm that BZ resistance is common. The resistant allele at SNP F167Y in H. contortus prevails in Ceará State, and we provide evidence that this result may be due to the utilization of oxfendazole in recent years.
ISSN:	0921-4488 1879-0941
DOI:	10.1016/j.smallrumres.2016.11.023