Why Some HIV Vaccines Fail

August 1, 2005

 

Vaccines against HIV have not been notably effective, and Duke Medical Center's Barton Haynes and his colleagues may have discovered one reason why. The researchers have reported evidence that some HIV vaccines may have failed because they induce a class of antibodies that a patient's own immune system is programmed to destroy.

Vaccines work by triggering the immune system to produce such antibodies, which lie in wait to attack and destroy invaders such as viruses. Many vaccines consist of weakened viruses or pieces of viruses, such as the virus' outer protein "envelope," that biologically instruct the immune system how to prepare antibodies to fight the virus.

The Duke team reported in an online article in the journal Science Express, the Web version of Science, that certain broadly protective antibodies, which recognize and latch onto a characteristic HIV protein, resemble antibodies made in autoimmune diseases. In autoimmune diseases, the immune system attacks the body's own tissues. In most people, the immune system destroys these types of antibodies to prevent attacks against the body.

"The fundamental problem in all of HIV vaccine research has been that when you inject the envelope of the HIV virus into people or animals, no broadly neutralizing antibodies--those antibodies that kill most HIV strains--are made," says Haynes. "This provides a plausible explanation for why [those] antibodies have not been made."

The results provide a new goal for future HIV research, he says. Vaccine research can now focus on designing vaccines that induce antibodies that will more effectively attack the virus without themselves being destroyed. "We now have a window into how to study HIV vaccines from the host side of the problem."