Genetic analysis of the 3' untranslated region of the bovine SLC11A1 gene reveals novel polymorphisms

Polymorphisms in microsatellites at the 3' untranslated region (3'UTR) of the SLC11A1 (solute carrier family 11 member A1) gene have been associated with natural resistance to Brucella abortus and Mycobacterium bovis infection in livestock species. Here, we carried out an individual genetic analysis of the two microsatellites present at the 3'UTR SLC11A1 gene in 254 Bos taurus purebred, 125 B. indicus purebred and 54 B. taurus × B. indicus crossbred cattle. The genotyping by capillary electrophoresis showed the presence of four alleles (157, 159, 161 and 163) for the first microsatellite (MS1) and six alleles (175, 177, 179, 181, 183 and 185) for the second microsatellite (MS2). The alleles 159 and 175 were the most frequent in all breeds analyzed. B. taurus showed the most homogeneous haplotype and genotype for both microsatellites, whereas B. indicus showed the most heterogeneous haplotype and genotype. Two novel variants (alleles 161 and 163) within the MS1 are reported as well as novel variants in MS2 in Holstein breed. The knowledge of the polymorphisms distribution in both microsatellites at the 3'UTR of the SLC11A1 gene in cattle breeds is useful for future experimental design to evaluate the association between reported genotypes and natural resistance to pathogens infection.

Association of an IRF3 putative functional uORF variant with resistance to Brucella infection: A candidate gene based analysis of InDel polymorphisms in goats

Brucellosis is an important zoonotic disease caused by infection with Brucella spp. It generates major economic losses in livestock production worldwide. Goats are the principal hosts of B. melitensis, the main infection agent of caprine and human brucellosis. The selection of resistance-related genes is considered one of the best long-term means to improve control to bacterial infection in domestic ruminants. We performed a candidate gene association study to test if six short insertion/deletion polymorphisms (InDels) at bacterial-infection related genes influence the resistance to Brucella infection in female creole goats. InDels (IRF3-540: rs660531540, FKBP5-294: rs448529294, TIRAP-561: rs657494561, PTPRT-588: rs667380588, KALRN-989: rs667660989 and RAB5a-016: rs661537016) were resolved by PCR-capillary electrophoresis in samples from 64 cases and 64 controls for brucellosis. Allelic frequencies were significantly different between cases and controls at IRF3-540 and KALRN-989 (p = 0.001 and 0.005). Indeed, the minor alleles (a and k) at InDels IRF3-540 and KALRN-989 were more frequent among controls than cases, providing evidence that these alleles confer protection against Brucella infection. Moreover, IRF3-540 a-containing genotypes (Aa and aa) were associated with absence of Brucella-specific antibodies in goats (p = 0.003; OR = 3.52; 95% CI = 1.55-7.96), and more specifically, a-allele was associated with resistance to Brucella infection in a dose-dependent manner. Also, we observed that the IRF3-540 deletion (a-allele) extends a conserved upstream ORF by 75 nucleotides to the main ORF, and thus it may decrease gene expression by reducing translation efficiency from the main ORF. These results suggest a potential functional role of IRF3-540 deletion in genetic resistance to Brucella infection in goats.

Association of TNF rs668920841 and INRA111 polymorphisms with caprine brucellosis: A case-control study of candidate genes involved in innate immunity

Caprine brucellosis is an infectious, contagious zoonotic disease caused by Brucella melitensis. Multiple factors, including host genetics, can influence the outcome of the exposure to Brucella; and it is expected that genetic variants that affect the host innate immune response could have a key role in Brucella infection and pathogenesis. In this study, we evaluated if polymorphisms in innate immunity-related genes are associated with results of Brucella infection in goats. Nine polymorphisms within interferon gamma (IFNG), tumor necrosis factor (TNF), MyD88 innate immune signal transduction adaptor (MYD88), interleukin 10 (IL10) and IL-10 receptor subunit alpha (IL10RA) genes and two molecular markers (BMS2753 and INRA111) were resolved by PCR-capillary electrophoresis in samples from 81 seronegative and 61 seropositive goats for brucellosis. A heterozygous genotype at INRA111, a microsatellite near the VRK serine/threonine kinase 2 (VRK2) gene, was associated with absence of Brucella-specific antibodies in goats naturally exposed to the pathogen (P = .004). Conversely, variants in the TNF gene (rs668920841) and near the IFN gamma receptor 1 (IFNGR1) gene (microsatellite BMS2753) were significantly associated with presence of Brucella-specific antibodies at allelic (P = .042 and P = .046) and genotypic level (P = .012 and P = .041, respectively). Moreover, an in silico analysis predicted a functional role of the insertion-deletion polymorphism rs668920841 on the transcriptional regulation of the caprine TNF gene. Altogether, these results contribute to the identification of genetic factors that have a putative effect on the resistance / susceptibility phenotype of goats to Brucella infection.