FDA Approves First Diagnostic Assay to Detect Both HIV Antigen and Antibodies

/USNewswire/ -- The U.S. Food and Drug Administration today approved the first assay to detect both antigen and antibodies to Human Immunodeficiency Virus (HIV). This assay is approved for use as an aid in the diagnosis of HIV-1/HIV-2 infection in adults including pregnant women. It is also the first assay for use as an aid in the diagnosis of HIV-1/HIV-2 infection in children as young as two years old.

The highly sensitive assay is intended to be used as an aid in the diagnosis of HIV-1/HIV-2 infection, including acute or primary HIV-1 infection. Since it actually detects the HIV-1 virus (specifically the p24 antigen) in addition to antibodies to HIV, the ARCHITECT HIV Ag/Ab Combo assay can be used to diagnose HIV infection prior to the emergence of antibodies. Most tests used today in the diagnostic setting detect HIV antibodies only. Although direct detection of the virus itself by nucleic acid testing is available, it is not widely used in diagnostic settings.

HIV is the virus that can lead to acquired immune deficiency syndrome, or AIDS. HIV damages a person's body by destroying specific blood cells, called CD4+ T cells, which are crucial to helping the body fight diseases. Two types of HIV have been identified: HIV-1 and HIV-2. HIV-1 is responsible for most HIV infections throughout the world. HIV-2 is found primarily in West Africa; however, cases of HIV-2 infection have been reported in North America and Europe.

The Centers for Disease Control and Prevention report that approximately 18 million people in the United States are tested for HIV each year. Most recent CDC estimates are that there are about 56,000 new HIV infections in the United States each year. In addition, there are more than 1 million people living with HIV in the United States, according to CDC.

"The approval of this assay represents an advancement in our ability to better diagnose HIV infection in diagnostic settings where nucleic acid testing to detect the virus itself is not routinely used," said Karen Midthun, M.D., acting director of FDA's Center for Biologics Evaluation and Research. "It provides for more sensitive detection of recent HIV infections compared with antibody tests alone."

The ARCHITECT HIV Ag/Ab Combo assay is not intended to be used for routine screening of blood donors. However, it is approved as a donor screening assay for HIV-1/HIV-2 infection in urgent situations where licensed blood donor screening tests are unavailable or their use is impractical.

The ARCHITECT HIV Ag/Ab Combo assay will be used in clinical laboratories and in public health laboratories, and is the first assay approved in the United States to detect HIV antigen and antibodies simultaneously.

The ARCHITECT HIV Ag/Ab Combo assay is manufactured by Abbott Laboratories, Abbott Park, Illinois.

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FDA Approves Donor Screening Test for Antibodies to HIV

/PRNewswire/ -- The U.S. Food and Drug Administration today announced approval of the Abbott Prism HIV O Plus assay, as a screening tool designed to detect the presence of certain antibodies to HIV. The assay is one of five assays that run on the fully automated Abbott Prism System.

There are two types of HIV. HIV type 1 consists of various subgroups, including group M, the most common subgroup of the virus in the United States, and group O, found primarily in Cameroon and other areas of West Africa.

HIV type 2 is found mostly in West Africa. Both types have been detected in the United States and Europe.

The Abbott Prism HIV O Plus assay detects antibodies to HIV type 1, groups M and O, and HIV type 2. It is the second donor screening test licensed for the detection of antibodies to HIV type 1, group O.

The Abbott Prism HIV O Plus assay is licensed to screen donated blood and blood specimens from other living donors for these specific types of HIV and subgroups of HIV type 1. The assay is also licensed to screen specimens from organ donors when specimens are obtained while the donor's heart is still beating and from cadavers. Positive results from the screening test require confirmation from supplemental tests.

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Study Suggests Blood Test for Alzheimer’s Possible

Researchers have revealed a direct relationship between two specific antibodies and the severity of Alzheimer’s disease symptoms, raising hopes that a diagnostic blood test for the devastating disorder is within reach.

Researchers from the University of Georgia, the Charlie Norwood VA Medical Center in Augusta and the Medical College of Georgia compared antibody levels in blood samples from 118 older adults with the participant’s level of dementia. The team, whose results appear in the current edition of Journal of Gerontology: Medical Sciences, found that the concentration of two specific proteins that are involved in the immune response increases as the severity of dementia increases.

“We found a strong and consistent relationship between two particular antibodies and the level of impairment,” said study co-author L. Stephen Miller, professor and director of clinical psychology training in the UGA Franklin College of Arts and Sciences. “The finding brings us closer to our ultimate goal of developing a blood test that can diagnose Alzheimer’s disease or potentially identify if someone is at higher risk for the disease.”

Miller’s co-authors include Jennifer S. Wilson, a former undergraduate student in the UGA Honors program who is now pursing graduate studies at Emory University; Shyamala Mruthinti, research pharmacologist at the VA Medical Center and adjunct professor at MCG; and Jerry Buccafusco, director of the MCG Alzheimer’s Research Center. The team focused on antibodies that the body creates in response to two proteins that are associated with Alzheimer’s disease. One protein, known as amyloid-beta, forms the plaques that are evident in the brains of people with Alzheimer’s upon autopsy. The other protein, known as RAGE, is involved in the normal aging process but is expressed at higher levels in the brains of people with Alzheimer’s.

In a previous study that compared a group of people with Alzheimer’s disease to a healthy control group, Mruthinti and her colleagues found that anti-amyloid beta and anti-RAGE antibodies are significantly higher in the group with Alzheimer’s. The team’s latest study expands on that finding to reveal a direct relationship between severity of Alzheimer’s disease and levels of the two antibodies in the blood.

“Alzheimer’s is an inflammatory disease of the brain, and these two antibodies give us a way to measure that inflammation,” Mruthinti said. “Using them as an early diagnostic marker may allow us to start drug treatment early, when it’s most effective, to increase the patient’s quality of life.”

While optimistic about their findings, the researchers caution that it could still be years before a diagnostic test based on their work is clinically available. The study found that the relationship between the two antibodies and Alzheimer’s severity persists even after controlling for patient age and total antibody levels. To further test the strength of the relationship, the researchers are now working with a sample that controls for other factors that have the potential to influence levels of the two antibodies, such as diabetes and heart disease. Buccafusco and his colleagues are also working to decrease the cost and time involved in the test.

“We’re in the process of trying to reduce the test to a one-day procedure, whereas right now it takes three to four days,” Buccafusco said. “But even now, our test is orders of magnitude cheaper than having people come in every few months to get a functional MRI or PET scan to try to discern brain plaques.”

The team is targeting the two proteins themselves as a possible treatment for Alzheimer’s disease. Mruthinti explains that, individually, amyloid-beta and RAGE proteins don’t provoke an immune response. The trouble begins when the two bind and the immune system attacks, resulting in constant state of inflammation that damages the brain. The researchers recently developed a way to measure levels of amyloid beta-RAGE complex, and preliminary data using transgenic mice that express Alzheimer’s symptoms suggest that an antigen they created to boost the body’s natural immune response to the complex can reduce the formation of the brain plaques.

“The amyloid beta-RAGE complex cuts off the connections between neurons,” Mruthinti explained, “but our hope is that we can protect those connections by preventing those plaques from forming.”

The research was funded by a Merit Review Award from the Veterans Administration to principal investigator Mruthinti and by the Medical College of Georgia Alzheimer’s Research Center.

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