Respiratory syncytial virus (RSV) is a common respiratory virus that usually causes mild, cold-like symptoms. However, RSV can cause serious illness or death in premature or very young infants and people over age 65, highlighting a critical need for vaccines in these populations.
Journey to a Better Vaccine
After NIH scientists identified RSV as a human pathogen in 1957, researchers tested multiple vaccines that proved unsuccessful, leading scientists to explore RSV surface proteins as a vaccine target for pregnant people (to protect the newborn) and the elderly.
Scientists identified the RSV fusion “F” protein, a surface protein that helps the virus infect human cells.
NIAID researchers found mice exposed to the RSV F protein produced a more protective immune response compared to mice exposed to other surface proteins.
Two forms of the RSV F protein were identified, later determined to be the prefusion and postfusion states.
NIAID scientists locked the RSV F protein in its prefusion state, which was a more protective vaccine candidate. Read more below.
Vaccine candidates using the locked RSV prefusion F protein began Phase 3 clinical trials.
Two States of the RSV F Protein
Preclinical Findings Show Promise for Prefusion F Protein Vaccines
NIAID found animals vaccinated with prefusion F protein developed a more potent immunity than those vaccinated with the postfusion F protein. This discovery led scientists toward finding a way to prevent the F protein from transitioning from its prefusion state to its postfusion state.