The isolation of 17 novel antibodies against HIV by a team of institutional and industry researchers sponsored by the US-based International AIDS Vaccine Initiative (IAVI) has opened up new possibilities for designing effective vaccines against the disease.

The new antibodies are capable of neutralising a broad spectrum of variants of the human immunodeficiency virus, while some of them blocked HIV infection of cells up to 10-100 times more potently than previously discovered broadly neutralizing antibodies (bNAbs), the researchers reported in the latest issue of Nature.

“Because of HIV’s remarkable variability, an effective HIV vaccine will probably have to elicit broadly neutralising antibodies,” noted Dennis Burton, professor of immunology and microbial science as well as director of the IAVI Neutralizing Antibody Center at The Scripps Research Institute in La Jolla, US.

“This is why we expect that these new antibodies will prove to be valuable assets to the field of AIDS vaccine research,” added Professor Burton, one of the authors of the study published in Nature on “Broad neutralisation coverage of HIV by multiple highly potent antibodies”.

The research team included scientists from and associated with IAVI and the non-profit Scripps Research Institute as well as US-based companies Theraclone Sciences and Monogram Biosciences (part of diagnostic specialist Laboratory Corporation of America).

Isolating bNAbs

Theraclone Science’s I-STAR discovery platform, which harnesses the power of the immune system to identify rare antibodies in human blood cells, was used to isolate the bNAbs against HIV.  Monogram Biosciences conducted the relevant neutralisation assays.

The serum samples from which the bNAbs described in Nature were isolated represented the top 1% of all the samples gathered by IAVI and its partners, in terms of the number of HIV variants they neutralised and the potency with which they did so, the Scripps Research Institute said.

The 17 new bNAbs were isolated from four HIV-positive individuals as part of an ongoing global effort by IAVI, focused on identifying antibodies that neutralise subtypes of HIV found mainly in developing countries.

The initiative had previously generated three potent bNAbs, two of which (PG9 and PG16) were isolated by the same research team in 2009 and described in the journal Science. 

Greatest challenge

Only a minority of people who are HIV-positive start to produce bNAbs after several years of infection, the Scripps Research Institute pointed out. Animal studies suggest these antibodies could block HIV infection if elicited by a preventive vaccine. 

“Solving the neutralising antibody problem is perhaps the greatest challenge facing the field today,” commented IAVI chief scientific officer Wayne Koff.

Many of the newly discovered bNAbs bind to hitherto unknown epitopes on the surface of the human immunodeficiency virus. This means that they could significantly broaden the target options available to researchers in designing vaccines to elicit similar antibodies, the Scripps Research Institute explained.