Sheep Protein May Prevent HIV Infection in Newborns
Early treatment with a protein that normally signals pregnancy in sheep
may block the development of AIDS in babies born to HIV-infected
mothers.
The protein, dubbed interferon tau by researchers at Texas A&M
University's Institute of Biosciences and Technology (IBT),
normally signals the reproductive system of female sheep that
pregnancy has begun. When given to newborn lambs infected with
ovine lentivirus, however, it appears to block the virus from
reproducing and keeps an AIDS-like disease called lymphocytic
infectious pneumonia from developing.
"We've been able to show that if we begin treating infected
lambs right after they're born and treat them for 50 days, we can
block progression of the disease," says reproductive biologist Fuller
W. Bazer, director of IBT.
Laboratory studies conducted by Bazer and colleagues at
IBT and other places suggest that interferon tau also blocks the
reproduction of HIV in cultures of human cells.
About one baby in four born to HIV-infected mothers (as many
as 800 a year) become infected with the virus, according to the
Pediatric AIDS Foundation. Researchers suspect that most of them
become infected during the birth process.
"We think that using the sheep protein might be worth
consideration during that period (immediately after birth), because
the immune system of the newborn human is not very well developed,"
Bazer says. "The system might not even recognize the sheep protein
as a treatment."
Interferon tau is one of a family of interferons that also
includes interferon alpha, beta and gamma. They're called
interferons because they interfere with the ability of viruses to
use the genetic information they carry to reproduce in infected
cells. At one time, medical scientists thought interferons might be
the "magic bullet" that would cure viral diseases like AIDS and
stop the uncontrolled growth of cancer tumors.
"Unfortunately, that hasn't proven to be true," Bazer says.
A major problem with other interferons has been that while
they do have powerful antiviral and antitumor properties, powerful
doses also damage other cells and cause serious side effects. So
far, they have been most effective in treating leukemia, a cancer-
like disease of the blood.
Tests of interferon tau's toxicity on laboratory-grown cell
cultures suggest, however, that it is much less toxic than other
interferons, Bazer says. The researchers were able to administer
doses of interferon tau as much as 40 times stronger than the other
interferons before similar cell damage took places.
The effectiveness of interferon tau in blocking the
development of lymphocytic infectious pneumonia in lambs appears to
depend on beginning treatment soon after birth. Bazer expects the
same approach would be necessary for it to be effective against
HIV.
"It seems like it's only effective during that period when the
virus is in the macrophage and they're undergoing a high rate of
replication," he says.
At this point, the ultimate usefulness of interferon tau isn't
yet clear, Bazer says. He is working with researchers at the USDA
and Texas A&M's Agricultural Research and Extension Center in San
Angelo, Texas, to explore its application to diseases of sheep and
other agricultural animals. Dr. Andres de la Concha is the scientist
there who has conducted the experiments with lambs.
A California-based biotechnology company
preparing to begin clinical tests of its effectiveness in treating
multiple sclerosis.
-30-
Contact:
Kay Kendall, Communications Chief
Texas A&M University's Institute of Biosciences & Technology
2121 W. Holcombe Blvd, Houston TX 77030-3303
Tel. 713-677-7736, Fax 713-677-7512
Email: [email protected]
http://www.tamu.edu/ibt/ibt.htm
RSS