Scientists discover HIV neutralising antibodies

SA - the Good News, 22 October 2012

Medical research on two women living with HIV has found that they developed antibodies which were able to kill at least 88% of the virus. This ground-breaking discovery provides an important new approach that could be useful in making an AIDS vaccine.

The study, performed by members of the Centre for the Aids Programme of Research in South Africa (CAPRISA) consortium, involves scientists from Wits University, the National Institute for Communicable Diseases (NICD) in Johannesburg, the University of KwaZulu-Natal and the University of Cape Town, who have been studying, over the last five years, how certain HIV-infected people develop very powerful antibody responses. "The women developed a neutralising antibody that was able to destroy at least 88% of the virus in their bodies. Broadly neutralising antibodies are considered to be the key to making an AIDS vaccine. This discovery provides new clues on how vaccines could be designed to elicit broadly neutralising antibodies. The world needs an effective AIDS vaccine to overcome the global scourge of AIDS," said Professor Salim Abdool Karim, Director of CAPRISA and President of the Medical Research Council, in his comments on the significance of the finding.

Through long-term follow-up laboratory studies on these two women, the team led by Wits researchers and Centre for HIV and STI at the NICD of the National Health Laboratory Service based scientists Dr Penny Moore and Professor Lynn Morris, discovered that a sugar (known as a glycan) on the surface protein coat of the virus at a specific position (referred to as position 332) forms a site of vulnerability in the virus and enables the body to mount a broadly neutralising antibody response. "Understanding this game of 'cat and mouse' between HIV and the immune response of the infected person has provided valuable insights into how neutralising antibodies arise," said Moore.

Analysis of a large number of other viruses from throughout the world, performed in collaboration with scientists from the University of North Carolina and Harvard University, suggest that the vulnerability at position 332 may be present at the time of infection in about two thirds of subtype C viruses (the subtype most common in Africa). Hence, if a vaccine is developed to target this glycan only, it may not be able to uniformly neutralise all subtype C viruses; as a result AIDS vaccines may need to attack multiple targets on the virus.