RESUMEN
In previous work, we found significant associations of horse polymorphic microsatellite and immunity-related (IR) gene markers with Rhodococcus equi infection of foals. Here, a statistically significant association between a single nucleotide polymorphism (SNP) within the interleukin 7 receptor-encoding gene (IL7R) with high R. equi burden in transtracheal aspirates was found (Fisher's F = 0.043, odds ratio: 8.00, 95% confidence interval: 1.127-56.795). Further positional and/or functional candidate genes investigated TLR2, IL13, IL17A, IL28R, TACE/ADAM 17 and GBP1, were not associated with infection in this study. SNPs analysed were found by sequencing and appropriate restriction fragment length polymorphism markers were developed. Their associations with R. equi infection were tested by genotyping thoroughbred foals from the original study. The association was confirmed by analysing genotypes composed with genes previously reported to be associated with R. equi infection in the same group.
Asunto(s)
Infecciones por Actinomycetales/veterinaria , Enfermedades de los Caballos/inmunología , Inmunidad/genética , Polimorfismo de Nucleótido Simple , Receptores de Interleucina-7/genética , Rhodococcus equi/inmunología , Infecciones por Actinomycetales/genética , Infecciones por Actinomycetales/microbiología , Animales , Frecuencia de los Genes , Predisposición Genética a la Enfermedad/genética , Genotipo , Enfermedades de los Caballos/genética , Enfermedades de los Caballos/microbiología , Caballos , Polimorfismo de Longitud del Fragmento de Restricción , Rhodococcus equi/aislamiento & purificación , Análisis de Secuencia de ADN , Tráquea/microbiologíaRESUMEN
In previous work, we found significant associations of horse chromosome 15 (ECA15) microsatellite markers HMSO1 and HTG06 with two horse infections, Rhodococcus equi and Lawsonia intracellularis, respectively. Interleukin-1 beta subunit and interleukin-1 receptor antagonist encoding genes (IL1B and IL1RN) could be considered as candidate genes underlying the associations reported. Therefore, we identified single nucleotide polymorphisms (SNPs) within three interleukin-1 beta functionally related genes: IL1B, IL1RN and Casp1 (interleukin-1 beta converting enzyme/caspasel encoding gene). Using appropriate restriction fragment length polymorphism (PCR-RFLP) and/or single strand conformation polymorphism (PCR-SSCP) markers, their associations with the two infections by genotyping foals from the original study were tested. In addition, the physical localization of one of the two closely located genes, IL1RN, was re-assessed by fluorescence in-situ hybridization (FISH). A statistically significant association between an intronic SNP of the Casp1 gene with R. equi infection was found. The IL1RN gene was localized to 15q13-q14 in agreement with its originally reported physical position.
