We observed relevant differences in the frequency of DRB1 locus alleles between the groups studied (p = 0.0477), with the DRB1*09 allele showing greater probabilistic relevance in the group with primary EBV infection (residues x2: 2.4538), the DRB1*03 allele being more relevant in the serological transition group (residues x2: 2.8528) and the DRB1*16 allele being more relevant in the group with past EBV infection (residues x2: 2.6223) (Figure 3A and Table 2). Here, HLA-DRB1 is linked to Epstein-Barr virus infection.