Determination of amino acid motifs present in the antigen-binding site of BoLA-DRB3 alleles in a Holstein population of La Pampa y su asociación con mastitis

Abstract

The intensity of the immune response
is regulated by amino acid motifs in antigen recognition
sites (ARS) present in the pockets of
Major Histocompatibility Complex molecules.
The objective of this work was to study the association
between these motifs and resistance/
susceptibility to mastitis measured by somatic
cell counts (SCC) in milk from Holstein cattle
from the province of La Pampa. The population
was divided into: 1) case group with high SCC
and presence of mastitis (≥ 250,000 cells/ml
susceptibility) and 2) control group under SCC
(< 250,000 cells/ml resistant). From a sample of
128 animals, 40 were genotyped for the second
exon of BoLA-BRB3 gene by direct sequencing
technique, 20 cows for each group. A total of 24
alleles were detected in the analyzed population.
Gene frequencies of amino acid motifs of
the five pockets (1, 4, 6, 7 and 9) from ARS in
the two groups of animals were calculated. Test
Odds Ratio (OR) Woolf-Haldane was used to
study the association. No significant differences
between amino acid motifs of pockets 1, 4, 7
and 9 between groups with high and low SCC
were found. However, the T 11 Y 30 motif in
pocket 6 (found in BoLA-DRB3 * 0601, * 0901
and * 4401 alleles) showed a significant OR
value = 0.11 (p = 0.03). This suggests an association
between this motif with a lower risk of
developing mastitis. The role of amino acid motif
T 11Y 30 in animal immune response should be
validated in independent populations