Human Immunodeficiency Virus (HIV), the virus that causes AIDS, is a difficult disease to treat; researchers have spent over three decades trying to create a vaccine. Developing a vaccine for HIV is complicated because the unique marker on the surface of HIV, called “Env“, rapidly mutates and is covered by a protective layer of sugar molecules, making it difficult for the immune system to effectively attack.
Three studies were published in Cell and Science on June 18th, each exploring how to get B cells to produce effective antibodies against HIV. The results indicate that the immune system can produce antibodies against HIV, but it needs to be taught how to make effective ones through “a series of shots—each consisting of a different engineered protein designed to push the immune system, step by step, toward the production of protective antibodies that will work against virtually all HIV strains” (Dr. Francis Collins, NIH).
Image Source: Science Photo Library – SCIEPRO
The first study, conducted by the Scripps Research Institute, tested a nanoparticle, called eOD-GT8 60mer, in mice genetically-modified to produce human antibodies that are designed to activate specific types of B cells that are capable of producing precursors of effective antibodies against HIV. The nanoparticle, not “native” immune system proteins, effectively “primed” the immune system to fight HIV infections, and is a good candidate to be the first in a sequence of HIV immunizations. The second study, conducted by researchers at Rockefeller University with teams from Scripps and Weill Medical College at Cornell, confirmed the promising results of the first study and tested the same molecule in mice with the more matured B cells of the later stages of HIV. They found that nanoparticle wasn’t as effective in these mice, indicating the need for an additional step in the immunization process. The third study, conducted by the Weill College of Medicine, tested immunizations with a common protein found on the surface of HIV, called BG505 SOSIP, in rhesus macaque and rabbit models. In both models, the immunizations prompted the production of antibodies capable of neutralizing a moderately resistant strain of HIV with limited results.
These studies show that an effective HIV treatment will likely require a series of immunizations: one to coax the immune system into producing broadly neutralizing antibodies and another to help produce more mature, specific antibodies.
Feature Image Source: Syringe and Vaccine by NIAID