Experimental RSV Vaccine Shows Promise in Mice

An experimental vaccine shows promise for protecting mice from the respiratory syncytial virus (RSV), the pathogen that most commonly causes the chest infection bronchiolitis in young children. The vaccine, developed at Boston Children’s Hospital, contains key immune-stimulating molecules, called adjuvants, along with a fragment of a protein that RSV uses to enter cells, called F protein.

In a study of the vaccine, 12 newborn mice, aged 4 to 7 days old, were injected with the vaccine or a saline solution, and were then exposed to RSV seven weeks later. Approximately two weeks after RSV exposure, the virus was found in the lungs of the mice that were given saline, but not in the vaccinated mice. The concentration of RSV in the noses of the vaccinated mice was also 100 times lower than in the control mice, suggesting the virus had more effectively infected the upper airways of the unvaccinated mice. The researchers also looked at the vaccinated mice’s immune response to RSV. “The adjuvant combination robustly enhanced antibody and useful T-cell responses and indicated protection against RSV infection in infant mice,” said Ofer Levy, MD, PhD, director of the precision vaccines program and senior physician in pediatrics in the division of infectious diseases at Boston Children’s Hospital.

When tested in human blood cells taken from newborns, the vaccine also generated a favorable immune response. However, one limitation of the study is that the mice were adults by the time the experiment ended. In people, RSV causes bronchiolitis in young children. The immune response of the mice at several weeks old, when they were adults, may therefore not apply to young children.

The researchers hope to next test the vaccine in nonhuman primates and then people.