Mouse mammary tumor like virus sequences in breast milk from healthy lactating women
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Mouse mammary tumor virus (MMTV) has been a long standing candidate as a potential cause of some human breast cancers. Forty years ago, electron microscopic images of MMTV-like particles were identified in milk from 5% of healthy lactating women. These observations, however, have not been confirmed by modern methods. The purpose of this study was to confirm the presence of MMTV-like DNA sequences in human milk from normal lactating women. Standard and in situ PCR analyses were conducted on DNA extracted from fresh breast milk samples collected from a group of 91 healthy lactating women volunteers. The MMTV-like viral positive PCR products were sequenced and a phylogenetic tree was constructed to compare these sequences. Immunohistochemistry analyses were performed on breast milk cells using polyclonal rabbit antibodies against affinity-purified MMTV envelope glycoproteins 52/36. MMTV-like envelope gene sequences were identified by PCR in 5% (4/91) of breast milk samples from healthy lactating women volunteers. These observations were confirmed by in situ PCR and immunohistochemistry using MMTV gp52/36 antibodies. These findings confirm the presence of MMTV-like gene sequences in human milk. As MMTV is transmitted via milk from mouse mothers to their newborn pups to cause mammary tumors when they become adults, this indicates a means of transmission of this virus in humans.
KeywordsMouse mammary tumor virus MMTV MMTV-like virus Envelope protein Hormonal influence PCR
We would like to thank Dinh Tran from St. Vincent’s Hospital for his help in the cell marker staining performed in this study.
Conflict of interest
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