Bovine leukemia virus linked to breast cancer in Australian women and identified before breast cancer development

PLoS One. 2017 Jun 22;12(6):e0179367. doi: 10.1371/journal.pone.0179367. eCollection 2017.


Bovine leukemia virus (BLV), a common virus of cattle globally, was believed for decades not to infect humans. More recent techniques (in situ PCR and DNA sequencing) enabled detection of BLV in human breast tissue, and determination of its significant association with breast cancer in a US population. Using similar techniques to study 96 Australian women, we report here detection of retrotranscribed BLV DNA in breast tissue of 40/50(80%) of women with breast cancer versus 19/46(41%) of women with no history of breast cancer, indicating an age-adjusted odds ratio and confidence interval of 4.72(1.71-13.05). These results corroborate the findings of the previous study of US women with an even higher odds ratio for the Australian population. For 48 of the subjects, paired breast tissue samples, removed 3-10 years apart in two unrelated procedures, were available. For 23/31 (74%) of these, in which the first specimen was diagnosed as nonmalignant (benign or premalignant) and the second as malignant, BLV was already present in benign breast tissue years 3-10 years before the malignancy was diagnosed. This is consistent with the supposition of a causative temporal relationship between BLV infection and subsequent development of cancer.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Australia / epidemiology
  • Base Sequence
  • Breast Neoplasms / epidemiology
  • Breast Neoplasms / pathology*
  • Breast Neoplasms / virology*
  • Carcinogenesis*
  • DNA, Viral / genetics
  • Dairy Products / virology
  • Diet, High-Fat / adverse effects
  • Female
  • Humans
  • Leukemia Virus, Bovine / genetics
  • Leukemia Virus, Bovine / physiology*
  • Middle Aged
  • Red Meat / virology
  • Time Factors


  • DNA, Viral

Grants and funding

This research was supported by a Research Enabling Grant from the University of California, Berkeley and the James and Margaret Lawson Research Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.