Bovine leukemia virus

[Guest guest]

This IS an interesting question, but the question goes

beyond raw milk -- the virus is found in meat too. Viruses

don't usually live all that long outside a live animal, I wonder

how long they survive in meat and milk? I don't think this

is a " raw milk " issue though, because most folks don't

drink raw milk, and it says it is present in " much of marketed

beef and dairy products " .

http://breast-cancer-research.com/content/3/S1/A14

Bovine leukemia virus (BLV) is an oncogenic retrovirus that commonly infects

cattle and causes a B cell leukemia/lymphoma in ‰ of 1% of infected cattle. BLV

is present in much of marketed beef and dairy products, and breast cancer

incidence is greatest in countries with high consumption of bovine foodstuffs.

We were therefore interested in determining whether humans were infected with

BLV, and whether it might play a role in breast cancer. In previous studies we

found that many humans had antibodies to BLV envelope glycoprotein (gp51) and

capsid protein (p24), suggesting humans might possibly be infected with BLV. We

used immunohistochemistry (IHC) and in situ PCR (IS-PCR) to detect viral protein

and proviral DNA, respectively, as signs of infection in surgically excised

human breast tissue sections.

-- Heidi Jean

[Guest guest]

> This IS an interesting question, but the question goes

> beyond raw milk -- the virus is found in meat too. Viruses

Also, there seems to be some split on opinion - someone said BLV is zoonotic

and incapable of transfer to humans, this summary of research seems to

indicate otherwise........

Bovine Leukemia Virus Infection and Human Breast Cancer Risk

Gertrude Buehring, Ph.D.

University of California, Berkeley

------------------------------------------------------------------------

The purpose of the research proposed here is to determine whether infection

of a woman's breast tissue with bovine leukemia virus (BLV) makes it more

likely that she will develop breast cancer. Our interest in this question

stems from the fact that breast cancer in the mouse is caused by a virus,

MMTV, which is transmitted from mother to nursing baby mice via the milk.

The MMIV system provides proof that a naturally occurring cancer can be

caused by a virus in a food source. Since the main source of milk for humans

is cows, a bovine virus might be a likely candidate for a milk-transmitted

agent of human breast cancer.

Bovine leukemia virus (BLV) is a cancer causing virus of cattle which can be

transmitted from cow to calf via the milk. BLV commonly infects dairy and

beef cattle and is found in the marketed milk and meat of these animals.

Most infected cattle are healthy and are not removed from the herd.

Consumption of non-pasteurized dairy products or undercooked beef could

possibly allow transmission of infectious virus to humans. BLV can infect

other species including sheep and goats naturally, and several species

experimentally including non-human primates. BLV can also infect the cells

of many species cultured in flasks, including cells from humans and other

primates. We recently discovered that BLV infects the breast cells of cows

naturally and causes these cells to behave more like cancer cells. This

indicates that this " leukemia " virus can target more than just blood cells.

Our preliminary data suggests that humans can become infected with BLV. We

found 53% of the humans tested have antibodies to BLV in their blood, which

is an indication of exposure to BLV. We also detected BLV proteins and DNA

in human breast tissues removed by surgery, which suggests these tissues

were infected by BLV. The research proposed here is to ascertain whether the

presence of BLV DNA and proteins in breast tissues correlates with the

patient's diagnosis of breast cancer. Breast cancer tissues from 10 women

and normal tissue from 169 controls with no history of breast neoplasms will

be tested by in situ-polymerase chain reaction for proviral BLV DNA and by

immunohistochemistry for BLV capsid protein. The association between the

presence of BLV DNA/protein and patient diagnosis will be analyzed

statistically. If frequency of BLV infection is shown to be significantly

different in malignant breast tissue versus normal controls, this will

justify the launching of a larger prospective study designed to determine

whether BLV can cause some cases of breast cancer. The ultimate impact of

the project could be to reduce breast cancer incidence by preventing human

infection with BLV through elimination of the virus in cattle, interception

of its transmission from cattle to humans, or vaccinations of humans.