Milestone in Combating Aids: First Component of HIV Vaccine Developed
Scientists at California
Institute of Technology (Caltech) in association with Rockefeller University
have come up with the first component of a possible HIV vaccine.It follows the process of the vaccines normally given to prevent various
diseases. It introduces a small amount of the virus insufficient to cause
illness but good enough to create antibodies to fight the attack of the virus.
This will be done by preventing new infections by blocking the entry of the
virus into the target cells.
To do this, the human body makes antibodies that target the HIV envelope protein, the sole viral protein on the surface of HIV. Different strains of HIV all have similar envelope structures, and human antibodies are specialized to attack specific regions of the envelope. Antibodies that are effective against many different strains of HIV are called broadly neutralizing antibodies, or bNAbs, for their ability to quell a broad spectrum of HIV viruses, according to Pamela Bjorkman, the David Baltimore Professor of Biology and Bioengineering.
The team first engineered a piece of the HIV envelope to remove glycans, a sugar that HIV uses to shield vulnerable regions like V3 from antibodies. After exposing V3, the researchers then added glycans to other regions that are more variable between strains, covering them up in order to ensure that the test animals would produce antibodies specific to the V3 region. Then, the team placed approximately 70 of these identically engineered envelopes (that contain no viral genetic material) on a carrier particle and injected it into the animal models.
This engineered complex caused the animals to create the correct bNAb precursors specific to the V3 region on HIV. Furthermore, adding the engineered envelope to the carrier particle ensured a large response from the animals’ immune systems. When exposed to an actual HIV virus, the precursor bNAbs developed by this initial inoculation were able to see past the virus’s shielding glycans to target its vulnerable regions.
The team is now focused on the next step: a dose of the vaccine that would enable precursors to mature into bNAbs.