ASSOCIATIONS OF CANDIDATE GENES INVOLVED IN SUSCEPTIBILITY TO MAP INFECTION IN HOLSTEIN COWS

The understanding of the genes associated with MAP infection is fundamental to evaluate them in to breeding schemes and control the disease. The aim of this study was to investigate the genetic variability within a pool of 8 genes and achieve a study of association with MAP infection in a population of Holstein cattle classified as MAP-positive and MAP-negative using both ELISA and faecal cultural results. A case-control study was designed by using a total of 324 German Holstein cows from 15 different farms tested for paratuberculosis using faecal culture. In addition the plasma was tested for MAP antibody by ELISA. Buffy coat was used for isolation of DNA. The genes were investigated for genetic variability by PCR and sequencing. Twenty SNPs were genotyped and finally 9 SNPs were included in the association study. The SNP rs43390642 in the WNT2 promoter region was significantly associated with MAP infection using both faecal and ELISA diagnostic test. The linkage disequilibrium with the SNP rs134692583 in DLD might suggest a combined mechanism of action of these neighbour genes into MAP infection. Significant association was also found between the faecal culture status of the animals and allele variants of the SNP AY518738S04:g.521G>A in NOD2. The other SNPs within the genes: LAMB1, PRDM1, SOCS5, PTGER4 and IL10 showed no associations. This study clarifies the involvement of the investigated loci in MAP infection. The identification of SNPs associated with MAP infection is the first step to set up marker assisted selection programmes to improve the health status by breeding.