Urine Test Shows HIV
Infection When Blood
Test Does Not
By Maggie Fox
Reuters Health Correspondent
WASHINGTON (Reuter) - Some people show evidence of infection with the AIDS virus in their urine even though their blood shows no sign of infection, researchers said Thursday.
The team at Clinical Reference Laboratory (CRL) said one out of every 1,000 people they tested showed antibodies to the virus in their urine, which indicates they were exposed to it at some point.
But the people, who were considered at a low risk of HIV, did not have the infection in their blood. This could mean they were exposed to the virus -- usually through sexual intercourse -- but somehow fought it off, the researchers said.
"The results suggest that people being tested for HIV antibody should have both their blood and urine screened," Dr. Robert Stout, president of CRL, said in a statement.
The CRL study tested blood and urine samples from more than 50,000 people considered at low risk of HIV infection.
It found 19 of them, or about one in 3,000, had evidence of HIV in their blood. That is about the same as the rate found in the general population.
The urine test, developed by California-based Calypte Biomedical Corp. and approved by the U.S. Food and Drug Administration (FDA) in June, found all but one of these.
But when 25,000 of the volunteers who had negative blood tests took the urine test, 24 of the samples tested positive for antibodies to HIV in the urine.
Antibodies are produced by the body to fight infection, and are a good way to see if a virus of bacteria has tried to infect someone.
In this case, a specific antibody to HIV known as Immunoglobulin A antibody, or IgA, was found. It is produced in the mucous membranes -- which are found in the mouth, nose and throat and also the genital tract.
Other studies have also found some people have antibodies in the urine but not the blood, but they were done in groups considered at high risk of HIV infection. This is the first one done in a low-risk group, CRL, which released the findings in a statement, said.
Stout said a big question was whether the body was able to stop the infection in the mucous membranes. Most people are infected through sex, which is logical because the mucous membranes are fairly porous and an easy way for a virus to get into the body.
Perhaps the infection was stopped cold, or somehow restricted, or compartmentalized, in the mucous membranes. If so, the way this was done could be mimicked in a vaccine.
"The study of individuals that have been able to recognize, compartmentalize, or eliminate the virus may prove very useful for the development of vaccine candidates," Stout said.
Dr. R. Scott Hitt, chairman of the Presidential Advisory Council on HIV/AIDS, said it was clear more studies are needed on people who have antibodies in their urine but not their blood.
"Increased prevention efforts for HIV infection must include more accurate means for determination of those in all risk categories who have been exposed to the virus, and it should be the responsibility of public health officials to undertake every avenue to ensure that an individual at risk for HIV knows his or her status," Hitt said.
"Only by this process of earlier and accurate screening can we provide the best possible treatment therapies."
Calypte stock was up more than $1 on the news, at 3 1/3.