New potent and broadly effective antibodies against HIV found

A team of researchers at and associated with the International AIDS Vaccine Initiative (IAVI), The Scripps Research Institute, the biotechnology company Theraclone Sciences and Monogram Biosciences Inc., a LabCorp company, report in the current issue of Nature the isolation of 17 novel antibodies capable of neutralizing a broad spectrum of variants of HIV, the virus that causes AIDS.

The new antibodies, large protein molecules that bind to pathogens and flag them for destruction, were isolated from blood serum samples collected in a continuing global search for broadly neutralizing antibodies (bNAbs) launched by IAVI.

They should provide researchers with a new set of targets for the design of vaccine candidates that can elicit similar antibodies to protect people from contracting HIV. Some of the bNAbs blocked HIV infection of cells as much as 10 to 100 times as potently as previously discovered bNAbs.

“Most antiviral vaccines depend on stimulating the antibody response to work effectively,” said Dennis Burton, a professor of immunology and microbial science and director of the IAVI Neutralizing Antibody Center at The Scripps Research Institute in La Jolla, Calif. Professor Burton, one of the senior authors of the study, is also a member of the Ragon Institute, in Cambridge, Mass.

“Because of HIV’s remarkable variability, an effective HIV vaccine will probably have to elicit broadly neutralizing antibodies. This is why we expect that these new antibodies will prove to be valuable assets to the field of AIDS vaccine research.”

Only a minority of people who are HIV-positive begin to produce bNAbs after several years of infection. Animal studies suggest that such antibodies could block HIV infection if they were elicited by a preventive vaccine.

Researchers prize bNAbs because their structural and biochemical analysis can reveal how to achieve a preventive vaccine. Specifically, scientists expect that they can use information about how bNAbs bind to HIV to construct immunogens—the active ingredients of vaccines—that elicit similar antibodies.

The potency of bNAbs matter because a highly potent antibody could confer such protection at relatively low levels.

“Solving the neutralizing antibody problem is perhaps the greatest challenge facing the field today,” said IAVI’s chief scientific officer, Wayne Koff. “IAVI concluded many years ago that unlocking the information stored in bNAbs was going to be essential to the fulfillment of our mission—ensuring the design and development of broadly effective AIDS vaccines.

This is why we support several laboratories around the world that are designing novel vaccine candidates on the basis of what we’re learning from such antibodies. We have no doubt that these new bNAbs will contribute a great deal to our own immunogen design efforts and, we hope, those of other researchers working on AIDS vaccines.”

In that regard, the new bNAbs are encouraging. Many of them bind hitherto unknown molecular structures, or epitopes, on the surface of HIV. This means that they could significantly broaden the target options researchers have in designing vaccines to elicit similar antibodies.

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Acne drug prevents HIV breakout

Acne drug prevents HIV breakout

Johns Hopkins scientists have found that a safe and inexpensive antibiotic in use since the 1970s for treating acne effectively targets infected immune cells in which HIV, the virus that causes AIDS, lies dormant and prevents them from reactivating and replicating.

The drug, minocycline, likely will improve on the current treatment regimens of HIV-infected patients if used in combination with a standard drug cocktail known as HAART (Highly Active Antiretroviral Therapy), according to research published now online and appearing in print April 15 in The Journal of Infectious Diseases.

"The powerful advantage to using minocycline is that the virus appears less able to develop drug resistance because minocycline targets cellular pathways not viral proteins," says Janice Clements, Ph.D., Mary Wallace Stanton Professor of Faculty Affairs, vice dean for faculty, and professor of molecular and comparative pathobiology at the Johns Hopkins University School of Medicine.

"The big challenge clinicians deal with now in this country when treating HIV patients is keeping the virus locked in a dormant state," Clements adds. "While HAART is really effective in keeping down active replication, minocycline is another arm of defense against the virus."

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