Title: Diversity in Haemonchus contortus: A case study from Sudan
Khalid Mohammedsalih1,2,3, Amna Khalafalla2, Ahmed Bashar1, Jürgen Krücken3, Georg von Samson-Himmelstjerna3
1Faculty of Veterinary Science, University of Nyala, P.O. Box 155, Nyala, Sudan
2Faculty of Veterinary Medicine, University of Khartoum, P.O. Box 32, Khartoum North, Sudan
3Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany
Corresponds to Khalid Mohammedsalih, Faculty of Veterinary Science, University of Nyala, P.O. Box 155, Nyala, Sudan. Email: firstname.lastname@example.org, Tel: +249115948886.
Haemonchus contortus is a major parasitic gastrointestinal nematode species affecting small ruminants health and results in great economic losses worldwide. The control of haemonchosis has mainly depended on the use of anthelmintics (e.g. benzimidazoles), but the excessive and the prolonged use of these drugs has resulted in the development of resistance. Development of benzimidazoles resistance is confirmed when a single nucleotide polymorphism (SNP) occurred in each of codon F167Y (TTC/TAC), E198A (GAA/GCA) or F200Y (TTC/TAC) of β-tubulin isotype 1 gene of H. contortus. Basically, our goal here was to detect the presence of each of the three mentioned mutations in Haemonchus from goats isolated from four different South Darfur (Sudan) study areas using PCR, gene sequencing and pyrosequencing assays. All the tested samples (n=34) confirmed as H. contortus when species-specific PCR performed. The allele frequencies were 3% and 7% at codon F167Y and F200Y, respectively. These values were below the threshold for resistance development (>10%). Quantification of alleles using pyrosequencing assays at the position of codon E198A was failed in all tested samples, and sequence mismatches were detected when Sanger sequencer adopted. The findings of this first study of SNPs in the β-tubulin isotype 1 gene of H. contortus populations from Sudan suggest that mutations were not occurred at codon F167Y and F200Y, and both codons were excluded as a cause of benzimidazole resistance in South Darfur. With codon E198A, the study recommends the establishment of a new molecular protocol for allele frequency measurement.
Haemonchus contortus, benzimidazole resistance, sequence mismatches, goat, Sudan