HIV and AIDS Research: IX International Conference on AIDS Highlights
The following are several summaries from studies supported by the National Institute of Allergy and Infectious Diseases (NIAID). All information from these summaries is embargoed until presentation time. To pursue these or related stories, call the NIAID Office of Communications at (301) 402-1663.
NIAID, a component of the National Institutes of Health (NIH), supports research on AIDS, tuberculosis, allergies, immunology and infectious diseases. NIH is an agency of the U.S. Public Health Service, part of the U.S. Department of Health and Human Services.
Screening Test for HIV Catches Early Infection Oral, Monday, June 7, 3 p.m. (9 a.m. EDT)
A blood test that looks for a protein part of HIV called p24 can help detect newly infected patients, allowing them to work with health care providers to pursue appropriate treatment. In a study of 2,120 blood samples taken from adults treated in the Emergency Medicine Department of The Johns Hopkins Hospital, NIAID-supported investigators found that the p24 test detected HIV infections in six patients who did not yet show antibodies to the virus. Standard HIV screening tests that rely on HIV antibodies, such as ELISA, did not detect the infections.
Unlike HIV antibodies, which can develop from two to six months after infection, p24 is present in blood in measurable levels during the first six weeks and at the end stage of infection. In addition to the six patients, the study investigators detected with the p24 test two patients with end-stage disease. Patients with p24 but without HIV antibodies are seen at low, but significant frequency in emergency departments (ED) in high-risk areas, the investigators conclude.
Newly infected patients have primary or acute HIV infection and can develop symptoms similar to the flu or mononucleosis or skin rash, diarrhea or neurological complications.
Note: NIAID is conducting a study, Division of AIDS Treatment Research Initiative (DATRI) 002, to see if AZT therapy will benefit such newly infected people. Call 1-800-TRIALS-A for more information.
Detection of p24 Antigenemia in HIV Seronegative Patients Attending an Urban Hospital Emergency Department." S.J. Clark, D.R. Howard, E.S. Daar, G.D. Kelen, G.M. Shaw and T.C. Quinn of the University of Alabama, Birmingham; Abbott Labs, Chicago, Ill.; University of California Medical Center, Los Angeles; Johns Hopkins Medical Institution, Baltimore, Md.; and NIAID, Bethesda, Md.
Diagnosing HIV Infection in Newborns Oral, Monday, June 7, 5 p.m. (11 a.m. EDT)
By using two serologic tests together, health care providers can determine if a one-month-old newborn has acquired an HIV infection from his or her mother, report NIAID-supported investigators. Such early detection of true HIV infection allows children to be followed carefully and treated appropriately at the earliest possible time.
The two tests, the modified p24 antigen assay and the IgA immunoblot assay, are commercially available. The p24 test detects one of HIV's structural proteins, p24 antigen, rather than antibodies to HIV. The protein is present in the blood of infected people in measurable levels early in infection and then declines until AIDS develops when it then increases. The IgA test looks for the presence of an antibody, immunoglobulin A (IgA), made by infected infants to fight HIV. IgG can be passed to children during pregnancy, whether or not they become infected with HIV, during pregnancy and will show up in screening tests for HIV antibodies after birth. However, IgA cannot be passed from the mother to the infant, and its presence in the infant indicates that the child is infected.
In the United States, infected mothers have about a 24 percent risk of passing HIV to their children before or during birth. In developing countries, such perinatal transmission rates can rise as high as 50 percent.
For the study, scientists compared the two tests alone and together when screening blood samples taken sequentially from infants born to HIV-infected mothers. When used together, the two tests accurately detected HIV infection in 78 children and the absence of infection in 130 children. The children ranged in age from one week to older than one year. Alone, the ability of the IgA test to detect antibody ranged from 20 percent among those one week to three-months old to 98.5 percent among those older than 12 months. When tested on three-month-olds, the p24 alone had a sensitivity of 100 percent, but declined to 79.6 percent among children older than one year.
"An Algorithm for the Early Diagnosis of Perinatally Acquired HIV-1 Infection Using the IgA Immunoblot Assay and the Modified p24 Antigen Assay." T.C. Quinn, R. Kline, R. Livingston, A. Carella, M. Moss, N. Hutton of NIAID and The Johns Hopkins University, Baltimore, Md.
Smoking Drugs, Advanced Disease Associated with Pneumonia Among HIV Patients Poster, Tuesday, June 8, 11:30 a.m. (5:30 a.m. EDT)
Smoking crack, marijuana or other drugs, not tobacco, is significantly associated with bacterial pneumonia among HIV-infected individuals, report NIH researchers. The findings do not support prior suggestions that drug users could reduce their risk of HIV infection by switching from injecting to smoking drugs. Furthermore, investigators suggest that health care providers must account for use of such drugs by HIV-infected patients when prescribing pneumonia-prevention therapies.
The results stem from the AIDS Links to Intravenous Drug Experience (ALIVE) study which follows 2,921 injection drug users at risk for or already infected with HIV. Based at The Johns Hopkins School of Public Health, ALIVE is supported by the National Institute of Drug Abuse and NIAID. When ALIVE began in 1988, 24 percent of the participants had HIV.
Also predictive of pneumonia among study patients: levels of the immune system CD4+ T cells of 200 or less per cubic millimeter of blood and age between 30 to 40 years. HIV targets and kills CD4+ T cells. For this study, investigators matched 40 patients who had pneumonia with 197 who did not from a group of HIV-infected drug users participating in the cohort study since 1988. More than 87 percent of the group smoked tobacco cigarettes.
"Risk Factors For Bacterial Pneumonia Among HIV Seropositive Intravenous Drug Users." Waleska Teixeria Caiaffa, M.D, David Vlahov, Ph.D., Neil M.H. Graham, M.D., Liza Solomon, Dr.P.H., Kenrad E. Nelson, M.D., Alvaro Munoz, Ph.D., et al., of the Department of Epidemiology at The Johns Hopkins School of Public Health, Baltimore, Md.
Nevirapine Effective Against HIV Oral, Thursday, June 10, 6 p.m. (noon EDT)
Nevirapine, an experimental drug that interferes with HIV's ability to replicate in the laboratory, also can curtail the virus in patients who receive 400 milligrams (mg.) daily, according to NIAID-supported investigators. This drug, alone and in combination, currently is under investigation in several NIAID studies.
For the trial, AIDS Clinical Trials Group 164/168, the investigators enrolled HIV-infected patients with counts of the immune system cell, CD4+ T, of 400 cells or less per cubic millimeter of blood who had measurable levels of the HIV protein, p24. HIV targets and kills CD4+ T cells.
Of 10 patients receiving at least eight weeks of therapy, 50 percent had sustained reductions in their p24 levels. Moreover, those whom investigators have followed for 16 or more weeks have maintained their lower p24 levels. Previous trials of nevirapine have found that doses of 200 mg. or less had an impact on HIV of limited duration. The virus becomes resistant to the drug at all doses administered.
"Antiviral Activity of Nevirapine at 400 mg. in P24 Antigen Positive Adults." Diane Havlir, M.D., of the University of California, San Diego, and the ACTG 164 and 168 study teams.