Study: Effective vaccine for tularemia should target type A strain

Developing an effective vaccine for tularemia, a high-risk infectious disease considered to be a potential bioterrorism agent, may require focusing on the higher-risk type A strain, according to a recent study.

A Korean research team looked into the progress made by scientists attempting to develop an effective live attenuated vaccine strain for tularemia. Tularemia is caused by the gram-negative bacterium Francisella tularensis, which has a high fatality rate at low colony-forming units. Most vaccine research has used the subunit F. holarctica, also known as type B, to provide better laboratory safety.

The vaccine development process for tularemia has yet to yield an LVS candidate with approved levels of efficacy and safety.

The researchers found that subunit or recombinant vaccine candidates did not show more effective prevention efficacy than the LVS candidates that used the higher-risk F. tularensis. Other research trials have focused on using mutant strains or nonpathogenic F. novicida, but none of the trials led to effective candidates.

The authors of the study suggested that given the low level of protection of many recombinant and subunit vaccine candidates, scientists should consider developing a live vaccine using the type A strain to combat the deadly tularemia.

The study was conducted by researchers from Korea's National Institute of Health, specifically the Division of High-Risk Pathogen Research and the Division of Zoonoses.