United Press International; Thursday May 14 5:33 PM EDT
Lori Valigra

A study of 42 babies and a mother thought to have cleared the AIDS virus suggests they may not have had the virus in the first place. The study, published in Thursday's issue of the journal Science, suggests the misclassifications resulted from laboratory contamination of test specimens, mislabeling or other mixed up.

The findings contradict earlier suspicions of the existence of such "transient" HIV infections in which a person gets infected for a short while and then gets over it.

"Can the body eliminate HIV? I don't think we have proof of that yet," said Dr. Lisa Frenkel, associate professor of pediatrics and laboratory medicine at the University of Washington in Seattle, and lead author of the Science report. In the mid 1990s, several research groups, including one at the University of California at Los Angeles, suggested that a small percentage of infants who tested positive for HIV were later mysteriously cleared of all signs of the virus.

But Frenkel said her study found no evidence such transient infections exist. The earlier cases could have been mistakes in labeling specimens or laboratory contamination.

"I think the Frenkel research confirms what most experts feel, that if transient infection occurs, it is extremely rare," said Dr. Stephen Spector, chairman of the executive committee of the Pediatric AIDS Clinical Trials Group, which is supported by the National Institutes of Health. Spector also is professor of pediatrics at the University of California at San Diego.

"Even the best-documented case of transient AIDS at UCLA has been called into question," Spector said. "It may have been a transient infection, but if so, it is a very extraordinary case."

Frenkel and her colleagues studied 42 infants and one mother who were suspected of having transient HIV infections. All 43 people had originally shown evidence of HIV infection on one or more occasions. But later tests did not find evidence of HIV.

The infants were from five, multi-center trials across the United States. The research was supported by the U.S. Public Health Service and two private organizations, the Pediatric AIDS Foundation and the Foster Foundation. The current research started a few years ago, when Frenkel and her colleagues were studying the resistance of HIV to the AIDS drug AZT. They encountered a mother who had two positive HIV tests. Her baby tested positive three times. During later testing, HIV could not be found in either of their blood specimens. The researchers thought they had a case of transient HIV infection in both the mother and baby.

The scientists re-analyzed the specimens of the mother and baby, plus 41 other infants thought to have transient HIV infections. In the case of the mother and her infant, they found that their viruses looked different, and that one of the viruses was a strain used in laboratories.

In 20 of the other 41 infant cases, they could not find the gene for the envelope, the outside coating of the virus used to evaluate how genes are related. The tests suggested that the patients' specimens had become contaminated with HIV in the laboratory.

In another six cases they found patient specimens were mixed up in the lab. And in 17 cases they found the envelope of the virus in the child's specimen was not related to that of the envelope in the virus from the mother's specimen.

"By using a rigorous genetic standard in examining all the supposed cases of transient HIV-1 infection we could find from a large number of cases, we couldn't prove transient infection in any of them," Frenkel said. "Either the specimens were mixed up, or there was contamination from one specimen to another in the laboratory."

To confirm transient HIV-1 infection, virus strains in the donor must be genetically linked to virus strains in the recipient. So the genomic sequence of the virus in a baby should be related to the mother, according to Frenkel.

Frenkel said that there is a 1-percent to 2-percent false positive rate in laboratories, which is normal. To help decrease errors, the researchers recommended using separate laboratories to test donor and recipient specimens. Babies typically get HIV either shortly before or during birth. In 1996, there were 440 deaths in the United States caused by pediatric AIDS (children 13 years of age and younger), according to the HIV/AIDS Surveillance Report of the Centers for Disease Control and Prevention (CDC) in Atlanta. In the same year, there were 3,450 people living with pediatric AIDS.

Frenkel, Spector and other AIDS experts said mothers should get HIV tests at centers that specialize in such testing. And they should get more than one type of AIDS test on more than one occasion.

Referrals and other information are available from the CDC's National HIV/AIDS Hotline at 1-800-342-2437 in English, 1-800-344-7432 in Spanish and 1-800-243-7889 for the hearing impaired.

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