SIV evades vaccine antibodies in monkeys
For years, scientists have assumed that a protective vaccine’s only job is to stimulate moderate levels of antibodies that will serve to neutralize the invading virus.
"We were surprised because we expected the virus that breaks through to be resistant to the vaccine-induced antibodies," Cynthia Derdeyn, Ph.D., senior author and professor of pathology and laboratory medicine at Emory University School of Medicine and Yerkes National Primate Research Center, said. "We need to know more about whether antibodies are present and protective on the mucosal surfaces where transmission occurs, and whether active vaccination might be increasing susceptibility to infection."
Recent studies demonstrate that experimental vaccines provide many monkeys against repeated SIV invasions. These new results are confusing and sobering for many researchers because this new discovery shows that SIV can evade the vaccine-induced antibodies without any mutation.
"There is a protective effect, but it's incomplete," Derdeyn said. "So we want to know what's happening in those animals where the virus gets through the barrier."
Further details are available in PNAS dated on Aug. 10, 2015.