Variation in the ovine C-type lectin dectin-1 gene (CLEC7A)

Dectin-1 is a pattern-recognition receptor that predominantly recognizes β-glucans from fungi, plants and bacteria. It is therefore implicated in immunological defenses against pathogens that have β-glucans. In this study, variation in exons 4–6 of the ovine dectin-1 gene (CLEC7A) was investigated. These exons encode the putative domain for β-glucan recognition. Three, three and four unique PCR-single-strand conformational polymorphism (PCR-SSCP) patterns were detected in exons 4, 5 and 6, respectively. DNA sequencing also revealed three, three and four different nucleotide sequences for the respective exons. All of these sequences were unique, but shared high sequence homology with the CLEC7A cDNA sequences from sheep, cattle and pigs. Either one, or a combination of two sequences was found for each exon in each sheep. This suggests that these sequences represent allelic variants of the ovine CLEC7A gene, although only defined within the exons investigated. The sequence data confirmed four single nucleotide polymorphisms (SNPs) in exon 4, two in exon 5 (with one at the intronic boundary) and three in exon 6. Of these SNPs, the two in exon 4 and two in exon 6 would result in amino acid substitutions. The variation detected here may have an impact on the recognition of β-glucans and therefore affect the ovine immune response.