RESUMO
BACKGROUND: Epstein-Barr virus (EBV) has been implicated in the development of breast cancer (BC) since 1995. It is classified into A/B genotypes, C/D subtypes, and F/f variants according to variations in its genome. AIM: To determine the distribution difference of EBV types between BC patients and healthy controls in Egypt and to detect the association between different EBV types and BC characteristics. METHODS: Three hundred and sixty-two participants (142 BC patients and 220 controls) were enrolled in this study. All participants were screened for EBV infection by determination of viral-capsid-IgG antibodies in their sera. EBNA-1 gene was detected by PCR in tumor biopsies of seropositive patients and in peripheral blood mononuclear cells of controls. A/B genotyping of EBV was performed by nested-PCR targeting the EBNA-2 gene. C/D subtypes and F/f variants were identified by Restriction fragment length polymorphism at BamHI-I W1/I1 and BamHI-F regions of EBV genome, respectively. RESULTS: Among 362 participants, 300(82.9%) were EBV-seropositive, including 120/142(84.5%) of the BC patients and 180/220(81.8 %) of the controls. EBNA-1 gene was positive in 54(45%) of seropositive BC patients and in 38(21.1%) of seropositive controls. There was a significant association of EBNA-1 gene with breast cancer (OR=3.05, 95%CI=1.84-5.07). Moreover, EBNA-1 gene positivity was significantly associated with the more aggressive tumors. Genotype-A and prototype-F were predominant among patients (90.4%, 100%, respectively) as well as among controls (91.7%, 100%, respectively) with no statistical significant association with BC risk. However, subtype-D was significantly more frequent in patients (95.6%) than in controls (64.7%) and was significantly associated with a higher BC risk as compared to subtype-C (OR=11.7, 95%CI=2.4-57.08). Subtype-D was significantly associated with higher grades tumors (100% among grade III), with progesteron receptor-negative tumors and with HER2-positive tumors (100% for each). The combined genotypes that significantly associated with BC risk were ADF (OR=4.9) and BDF (OR=5.5). CONCLUSIONS: Subtype-D of EBV could be the only EBV type implicated in BC development among Egyptian females and associated more with poor prognosis.