Bovine leukemia virus DNA in human breast tissue

Emerg Infect Dis. 2014 May;20(5):772-82. doi: 10.3201/eid2005.131298.


Bovine leukemia virus (BLV), a deltaretrovirus, causes B-cell leukemia/lymphoma in cattle and is prevalent in herds globally. A previous finding of antibodies against BLV in humans led us to examine the possibility of human infection with BLV. We focused on breast tissue because, in cattle, BLV DNA and protein have been found to be more abundant in mammary epithelium than in lymphocytes. In human breast tissue specimens, we identified BLV DNA by using nested liquid-phase PCR and DNA sequencing. Variations from the bovine reference sequence were infrequent and limited to base substitutions. In situ PCR and immunohistochemical testing localized BLV to the secretory epithelium of the breast. Our finding of BLV in human tissues indicates a risk for the acquisition and proliferation of this virus in humans. Further research is needed to determine whether BLV may play a direct role in human disease.

Keywords: DNA; United States; bovid; bovine; bovine leukemia virus; breast cancer; breast tissue; cancer; human; leukemia; lymphoma; viruses; zoonoses; zoonosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Cattle
  • DNA, Viral*
  • Female
  • Genes, Viral
  • Genome, Viral
  • Humans
  • Leukemia Virus, Bovine / genetics*
  • Mammary Glands, Human / virology*
  • Molecular Sequence Data
  • Proviruses*
  • Sequence Alignment
  • Viral Core Proteins / genetics
  • Viral Core Proteins / metabolism


  • DNA, Viral
  • Viral Core Proteins