Experimental HIV Vaccine Shows Breakthrough Promise In Primate Study

An experimental HIV vaccine candidate developed by LJI, Scripps Research and IAVI generated high levels of broadly neutralising antibodies in primates, researchers said. Tested on rhesus macaques, the vaccine prompted antibody production in about 44% of animals. The findings, published in Nature, mark a major step after 14 years of research aimed at preventing HIV infection.

An experimental HIV vaccine candidate has delivered encouraging results in a preclinical study involving primates, offering fresh hope in the long-standing effort to prevent HIV infection. Developed by scientists from the La Jolla Institute for Immunology (LJI), Scripps Research and the International AIDS Vaccine Initiative (IAVI), the vaccine is designed to stimulate the production of rare broadly neutralising antibodies capable of combating HIV despite its rapid mutations. According to LJI, it is the first HIV vaccine candidate to generate high levels of these virus-fighting antibodies in primates.

“This feels like a huge success,” said Shane Crotty, chief scientific officer at LJI, who co-led the research with Scripps Research professor William Schief. “We constructed a successful vaccine from the ground up, which required a deep understanding of the immune system.”

The vaccine works by guiding the maturation of B cells, the immune cells responsible for producing antibodies. B cells begin in a naïve state and mature after recognising parts of a pathogen, enabling them to generate antibodies that bind to the pathogen and help prevent infection. As they mature, B cells refine these antibodies to improve their ability to target vulnerable sites on viruses.

Overcoming HIV’s complex defence mechanisms

Scientists said HIV has remained a formidable challenge because it employs multiple strategies to evade the immune system. The virus surrounds itself with constantly shifting sugar molecules, known as glycans, allowing it to escape detection by immune cells. It also mutates at an extraordinary rate and changes its shape while infecting human cells, making previously produced antibodies ineffective.

“The worldwide diversity of HIV mutations is extraordinary. Even the diversity within one individual person living with HIV is dramatic,” said Patrick Madden, an LJI instructor who served as study co-first author along with Jon Steichen, an investigator at Scripps Research.

Researchers said these characteristics rarely allow B cells enough time to develop potent broadly neutralising antibodies. To overcome this challenge, the team traced the development of HIV-targeting B cells in reverse to understand how they evolved after exposure to specific parts of the virus. They found that early exposure to portions of HIV’s outer envelope protein prompted the development of broadly neutralising antibodies. These viral antigens became the foundation for designing the vaccine molecules.

Source : https://www.freepressjournal.in/india/experimental-hiv-vaccine-shows-breakthrough-promise-in-primate-study