Bovine leukemia viral DNA found on human breast tissue is genetically related to the cattle virus

Bovine leukemia virus (BLV) infection is widespread in cattle and associated with B cell lymphoma. In a previous study we demonstrated that bovine leukemia viral DNA was detected in human breast tissues and significantly associated with breast cancer. Our current study aimed to determine whether BLV DNA found in humans and cattle at the same geographical region were genetically related. DNA was extracted from the breast tissue of healthy (n = 32) or cancerous women patients (n = 27) and from the blood (n = 30) of cattle naturally infected with BLV, followed by PCR-amplification and partial nucleotide sequencing of the BLV env gene. We found that the nucleotide sequence identity between BLV env gene fragments obtained from human breast tissue and cattle blood ranged from 97.8 to 99.7% and grouped into genotype 1. Thus, our results further support the hypothesis that this virus might cause a zoonotic infection.