Fig. 2

Association study to determine the significance of the detection frequency of the BoLA-DRB3 allele compared with those of 682 alleles from low-risk spreaders and 1138 alleles from high-risk spreaders.. BLV-positive cows were diagnosed using an anti-BLV antibody ELISA Kit (JNC, Tokyo, Japan), which is used to detect anti-Env gp51 antibodies from serum samples, according to the manufacturer’s instructions. BLV-positive cows were subjected to BLV proviral load calculation using the BLV-CoCoMo-qPCR-2 system (RIKEN Genesis, Kanagawa, Japan) [32]. The 910 BLV-infected cows were classified into two groups: (i) cows with proviral load over 10,000 as high-risk BLV spreader cows (N = 569), and (ii) cows with proviral load under 10,000 as low-risk BLV spreader cows (N = 341). Fisher’s exact test was performed for estimating p values and odds ratios (ORs) were used for detecting the association of each BoLA-DRB3 allele and BLV proviral load, using R version 3.4.2 statistical analysis software [43]. The X-axis shows the allele number for BoLA-DRB3 and the Y-axis shows the minus multiplied common logarithm for p values. The alleles with p values < 0.00217 (0.05/23 alleles, the statistical significance threshold) were determined to be resistant when OR > 1 and susceptible when OR < 1