South African researchers said on Friday they were encouraged by results from two HIV studies indicating that vaccines might one day be effective in controlling viral levels and even preventing infections.

Preliminary data from a clinical trial involving 480 uninfected people, half of them in South Africa, found that the majority of participants experienced a positive immune response after being given the HVTN 204 vaccine.

A healthy immune system can help ward off HIV infection, while those with compromised immunity are often more susceptible to contracting the virus.

"This is really good news. This is an important milestone, but we still have a long way to go," Gavin Churchyard, the study's principal investigator, said at a briefing sponsored by the South African AIDS Vaccine Initiative in Johannesburg.

Churchyard, who heads South Africa's Aurum Institute for Health Research, added that the vaccine's side-effects generally had been mild to moderate for those involved in the trial.

A separate clinical trial of a DNA vaccine developed by Finland's FIT Biotech showed equally promising early results in a smaller HIV-positive group, most of which was made up of residents from Soweto, the black township south of Johannesburg.

Some 5.5 million South Africans, or about 12 percent of the total population, are infected with HIV, and 1,000 die each day from AIDS, making the country a frontline for HIV vaccine research.

Dr. Eftyhia Vardas, the principal investigator for the Finnish vaccine trial in South Africa, said the vaccine helped patients maintain low viral loads and steady CD4 cell counts, both key to keeping HIV from progressing into full-blown AIDS.

The studies provided a bit of blue sky in a field of AIDS research that has generally been a huge disappointment. Previous vaccine trials that have reached the critical third phase, when effectiveness is measured, have all failed.

While some AIDS scientists have turned their attention to other potential preventative weapons -- microbicidal creams and mass male circumcision for example -- others continue to pursue the vaccine route, though admittedly with lowered expectations.

Churchyard said that vaccines, if successfully developed, would more likely be of therapeutic rather than preventative value, taking their place alongside the anti-retrovirals that have become the cornerstone of current HIV treatment.

Adolescents whose parents are infected or have died from HIV/AIDS cope significantly better emotionally if they have a strong social support system in place, according to research published today in the American Journal of Public Health.

Adolescents affected by HIV are a "very unique group with added challenges and barriers, compared to adolescents in the general population," lead researcher Dr. Sung-Jae Lee from University of California, Los Angeles, noted in comments to Reuters Health. They clearly benefit from having people around them who care about them, and value and love them, the researcher added.

The relationship between social support and emotional well-being are well established. And a lack of support, both real and perceived, has been linked to emotional distress, behavioral problems and poor mental health.

Lee's team examined the effect of social support on the feelings and behavior of 413 adolescent boys and girls from 307 predominantly African American and Latino families in which one or both parents had HIV/AIDS. The average age of the adolescents was 14.7 years.

During the 2-year study period, adolescents who reported having more social support providers displayed significantly lower levels of depression and fewer behavior problems over time than adolescents with fewer social support providers.

"In spite of all the challenges, having additional social support providers contributed to better mental health (e.g., lower depression)," Lee said. "This has significant implications" for future prevention programs for HIV-affected adolescents, the researcher added.

However, adolescents reporting more negative role model influence in their lives had more problem behaviors. "Given the multi-layered nature of social support, programs targeting HIV-affected adolescents should focus on how various social support factors influence each other," Lee suggested.

The study also found that, regardless of the level of social support, adolescents' depression and behavior problems all declined over time. The protective effects of social support also tended to decline over time.

"Research on the relationship between mental and behavioral outcomes and social support among HIV-affected adolescents is limited," Lee points out, "and our findings point to the need for future prevention programs to facilitate better social support for this unique group of adolescents."

SOURCE: American Journal of Public Health, October 2007.

The introduction and widespread use of highly active antiretroviral therapy (HAART) in the United States has led to "dramatic decreases" in hospitalizations among HIV-infected infants and children younger than 5 years old, new evidence suggests.

However, the decrease in hospital use has been less noteworthy among HIV-infected adolescent.

Dr. Athena P. Kourtis from the Centers for Disease Control and Prevention, Atlanta and colleagues used the National Inpatient Sample database to analyze trends in hospital use by HIV-infected children and adolescents in the 10 years between 1994 (before HAART) and 2003 (after widespread HAART use).

According to the team's report in the journal Pediatrics, there were an estimated 3,420 hospitalizations of HIV-infected children aged 18 or younger in 2003 compared with 11,785 in 1994 -- a decrease of 71 percent.

As mentioned, this decrease was more marked among infants and pre-school children (94 percent for boys and 92 percent for girls) than among adolescents (decrease of 47 percent for boys and increase of 23 percent among girls between 15 and18 years of age).

The inpatient fatality rates for HIV-infected children also fell from 5.0 percent in 1994 to 1.8 percent in 2003.

The data show that hospitalizations for several HIV-related conditions are much less common in the HAART era compared with the pre-HAART era. These include bacterial pneumonia caused by Pneumocystis jiroveci; general bacterial infections; sepsis, serious systemic infections; fungal infections; brain infections (encephalitis); and failure to thrive.

No significant changes were observed in the number of hospitalizations for two other common opportunistic infections -- Pneumococcus or cytomegalovirus infections.

Kourtis and colleagues hope these data can be used to "examine our progress;" assess the health care needs of specific HIV-infected groups, such as adolescents, and for specific HIV-related conditions, such as pneumococcus and CMV; and "define future policies in an era of competing health care priorities."

SOURCE: Pediatrics, August 2007.

In a study conducted at two major HIV centers in Singapore, rapid HIV self-tests were used improperly, or the results were interpreted incorrectly, by individuals at risk for HIV infection or those who were already infected.

The major problem was collecting an adequate blood sample, Dr. Vernon J. Lee of Tan Took Seng Hospital in Singapore and co-investigators report in the Journal of Acquired Immune Deficiency Syndromes. In addition, a significant number of study subjects were unable to interpret results or interpreted them incorrectly.

Lee's team tested the Abbott Determine HIV 1/2 test in 350 subjects, 88 of whom were known to be HIV-positive. Before testing, 90 percent said the test steps were easy to understand and the instructions were easy to read and follow.

However, Lee and colleagues found that 85 percent of participants failed to perform all of the steps correctly or were unable to perform the test at all. As a result, invalid results occurred in 56 percent of cases.

Twelve percent were unable to correctly interpret the test results, including 2 percent who incorrectly interpreted positive results and 7 percent who incorrectly interpreted negative results. However, Lee and associates found the test itself, when properly used, was similar in accuracy to the manufacturer's claims.

The investigators found that "blood sampling via fingerprick and collection via a capillary tube was difficult for participants."

The subjects who were known to be HIV-positive correctly performed the test and interpreted the results more often, which might reflect their "exposure to and experience with blood tests."

Inconvenience and long waiting times were cited by 18 percent of participants as deterrents to being tested for HIV at health-care centers.

The researchers conclude that the "implementation of self-testing should be reconsidered until kit design and downstream issues have been adequately addressed."

SOURCE: Journal of Acquired Immune Deficiency Syndromes, August 1, 2007.

A drug used to treat people infected with the AIDS virus has shown promise as a possible future weapon against cancer, U.S. researchers said on Friday.

Scientists at the U.S. National Cancer Institute examined how drugs called protease inhibitors, usually given in combination with other drugs to fight the human immunodeficiency virus, or HIV, performed against several types of cancer including non-small cell lung cancer.

In a study published in the journal Clinical Cancer Research, the scientists tested whether protease inhibitors would slow cancer cell growth in the laboratory and in mice. Three of six drugs they tried inhibited cancer cell growth.

The most effective of the drugs was nelfinavir, sold by Roche Holding AG as Viracept, the researchers said. The drug also slowed the growth of both drug-sensitive and drug-resistant breast cancer cells, they added.

The researchers have started an initial clinical trial to test nelfinavir in cancer patients.

Viracept won marketing approval in Europe in 1998. It was cleared for use a year earlier in the United States, where it is sold by Pfizer Inc..

The two other protease inhibitors that inhibited growth of cancer cells were ritonavir, sold by Abbott Laboratories Inc as Norvir, and saquinavir, sold by Roche as Invirase.

The researchers examined protease inhibitors because they affect a protein involved in the development of many cancer types. In people with HIV, such drugs can slow the spread of the virus in the body and reduce the risk of developing AIDS-related illnesses.

A new HIV-fighting drug from Merck & Co. appears superior to options for patients who have stopped responding to available drugs, federal regulators said Friday.

The Food and Drug Administration said Merck's studies of Isentress show the drug is safe and effective to treat HIV patients who have developed a resistance to other medications.

Roughly 1 million people in the U.S. are HIV positive, according to the Centers for Disease Control. FDA has cleared 30 different HIV treatments since 1987, and they are typically prescribed in combination to suppress the virus, which cripples the immune system and causes death if not treated.

The agency posted its review of the drug to the FDA Web site ahead of a Wednesday meeting, where outside experts are scheduled to vote on the drug's safety and effectiveness. FDA is not required to follow the experts' recommendations, though it usually does.

The agency granted the drug priority review status earlier this year, meaning staffers would finish the review in six months, four months earlier than usual. A decision is expected mid-October.

If approved, Isentress would be the first in a new class of HIV treatments called integrase inhibitors that block the virus from infecting cells and reproducing.

Government scientists said Isentress has a favorable safety profile, with rash and elevated levels of creatine in the blood reported as the most common side effects.

Merck reported 13 deaths among 900 patients who took Isentress in a clinical study although the FDA said the deaths were not related to the drug.

Isentress would compete with Pfizer's Selzentry, another novel HIV treatment the FDA approved last month for drug-resistant HIV patients. Merck's drug could be more attractive to doctors and patients because it appears to have fewer side effects.

Selzentry's label carries a warning that the drug can cause liver damage and advises patients to see a doctor immediately if they develop an allergic reaction. FDA cleared the drug on the condition that the company conduct follow-up studies to look at the effects of long-term use.

On Wednesday, the FDA will ask its outside experts whether Merck should be required to conduct post-marketing studies on Isentress.

Merck shares rose 51 cents, or 1 percent, to $50.17 Friday.