Bovine leukemia virus DNA in human breast tissue.
Bottom Line: 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.Further research is needed to determine whether BLV may play a direct role in human disease.
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.
Related in: MedlinePlus
Mentions: Nested IS-PCR was used to identify the cell type in which the PCR product was localized. Figure 3 shows IS-PCR results obtained by using tax primers for the BLV-negative human sample (no. 143), 1 of the BLV-positive samples (no. 010), the positive and negative cell line controls, and a BLV tax-positive bovine mammary gland sample. The site of the amplified BLV DNA was the secretory mammary epithelium, identified by an anatomic pathologist (H.M.J.). Table 5 summarizes the results for L-PCR and IS-PCR (tax) testing of the 6 tissue samples that were studied in depth.