Advac, LLC, a vaccine research company founded by Sang-Moo Kang, a professor in the Institute for Biomedical Sciences at Georgia State University, has received $225,000 from the National Institutes of Health to develop a safer, more effective vaccine for human respiratory syncytial virus.

RSV is a common respiratory virus that can cause serious complications in infants and older adults. It is the leading cause of hospitalization among children less than one year old in the United States.

A vaccine was designed to protect infants and toddlers against the virus in the 1960s, but a large portion of those who were immunized went on to develop a heightened infection, known as enhanced respiratory disease. Many of the children were hospitalized, and two immunized toddlers died. Today, there is still no FDA-approved vaccination for RSV.

Kang plans to assess the safety and efficacy of two promising vaccines that would not induce enhanced respiratory disease. One will use an inactivated split virus—a virus that is killed with chemicals, then split apart—rather than an inactivated whole virus. This is the same method used to create the seasonal flu vaccine, but it has not successfully been developed in an RSV vaccine. Kang’s preliminary data show it is effective, safer and less likely to trigger enhanced respiratory disease.

Kang has also found that vaccines containing virus-like particles (VLP), which are engineered to resemble viruses but do not contain the viral genome, offer protection against RSV by controlling the replication of the virus in the lungs without causing detectable enhanced respiratory disease. He plans to test an RSV VLP vaccine formulated in combination with split RSV vaccine in mice. He believes that the combined approach may boost the vaccine’s efficacy without compromising safety.

He will also further study a unique adjuvant, a substance that enhances the body’s immune response to the vaccine and improves its effectiveness. Licensed adjuvants cannot prevent or reverse the RSV vaccine-induced enhanced respiratory disease in animals. But Kang has demonstrated that certain adjuvants—known as toll-like receptor (TLR) agonist combination adjuvants—can make the vaccine not only more effective but also safer by preventing an enhanced respiratory disease response. Kang will test a second vaccine, a split RSV vaccine administered with TLR agonist adjuvants, in cotton rats.

“It is essential that we develop an RSV vaccine that can effectively and safely protect vulnerable populations,” said Kang. “We have established rigorous models for evaluating these two vaccines, and we are hopeful that the results put us closer to that goal.”