Vaccine Stops Vaginal Transmission of HIV-Like Virus

[Guest guest]

This just scares me!!

http://dailynews./h/nm/20010723/hl/vaccine_1.html

Monday July 23 5:44 PM ET

Vaccine Stops Vaginal Transmission of HIV-Like Virus

By Amy Norton

NEW YORK (Reuters Health) - For the first time, scientists have used

a modified polio vaccine virus to at least partially block the

vaginal transmission of an HIV (news - web sites)-like virus in

monkeys. They say the achievement opens up the possibility of

developing an HIV vaccine that stops the virus at its point of entry

during sex.

In experiments with monkeys that had been vaccinated against simian

immunodeficiency virus (SIV), a cousin to HIV, all remained healthy

up to one year after being exposed to SIV through vaginal

transmission. Two of seven monkeys given the vaccine were completely

protected from infection, while two others had lower levels of virus

in their blood, suggesting at least partial protection.

In a ``control'' group of monkeys that did not get the vaccine, all

became infected and half developed symptoms within a year.

Monkeys normally develop an AIDS (news - web sites)-like illness

within 12 to 18 months of infection with the SIV strain used in the

study, Dr. Andino of the University of California, San

Francisco, told Reuters Health.

He and his colleagues report their findings in the August 2nd issue

of the Journal of Virology.

A number of HIV vaccines are under development, including ones now in

human trials. The one used in this study is different, Andino

explained, in that it triggers an immune response in mucosal tissue--

the type that lines the vagina and rectum and could serve as a first

line of defense against sexually transmitted HIV.

``Mucosal surfaces may be the key to preventing infection,'' Andino

said in an interview.

To create their vaccine, Andino and his colleagues started with the

Sabin oral polio vaccine, which is known to elicit an immune system

response in mucosal tissue. They added fragments of genetic

information from SIV to the vaccine, which allows it to present SIV

proteins to the monkey's immune system, priming it to quickly attack

SIV after infection.

If further animal research pans out, Andino said the next step would

be to test the effects of adding HIV genetic fragments to the Sabin

vaccine. This oral polio vaccine is no longer used in the US, due to

rare instances in which the vaccine has caused polio.

Still, Andino said that adding some HIV gene fragments to the vaccine

would be safe. And, he added, since the Sabin vaccine is known to

confer long-lasting immunity and is cheap and easy to administer, an

HIV vaccine based on it could be ideal for the developing nations

being ravaged by AIDS.

But there remain many unknowns, including whether HIV and SIV sexual

transmission are similar enough for these monkey findings to

translate to humans.

``It's possible,'' Andino said, ``that HIV is more sneaky.''

SOURCE: Journal of Virology 2001;75:7435-7452.