Madeline McCurry-Schmidt talking about the new HIV vaccine’s success in preclinical study.
The new vaccine works by intervening in a process called B cell maturation. B cells make antibodies. Like many immune cells, B cells have an early “naive” stage before they are ready to make antibodies. B cells start to mature once they get the signal that a pathogen, such as a virus, is trying to attack. B cells see pieces of that pathogen’s molecular structure and start producing antibodies that can bind to that structure and halt infection.
It can take a little while for B cells to find the right “bullseye” on a pathogen. But B cells keep trying. As they mature, B cells tweak their antibody production, refining antibody structures to bind to a pathogen in just the right, vulnerable spots.
Scientists describe B cell development as a training process or bootcamp. In most cases, the body is left with a well-honed B cell army.
HIV is hard to beat because it doesn’t give B cells a chance to develop effective antibodies. The first problem is that HIV disguises itself from the immune system. The virus is wrapped in an ever-shifting cloak of sugar molecules, called glycans. This lets HIV sneak undetected past human cells, which are also covered in glycans.
The second big problem is that HIV mutates very quickly. “The worldwide diversity of HIV mutations is extraordinary. Even the diversity within one individual person living with HIV is dramatic,” says LJI Instructor Patrick Madden, Ph.D., who served as study co-first author with Jon Steichen, Ph.D., an institute investigator at Scripps Research.
The third problem is that HIV changes its shape when it infects human cells. Even if B cells get a glimpse of its viral structure—snap!—the structure changes.
Taken together, these problems rarely give B cells a chance to hone their antibody responses against HIV. Even if a B cell manages to make neutralizing antibodies, the virus can mutate or change its shape, rendering those antibodies useless.
I love it when someone explains science in a simple language that I can understand.