Humoral response to Type-A derived genetically modified live attenuated Francisella tularensis in rabbits

Francisella tularensis is a gram negative, non-motile, coccobacillus that is the causative agent of tularemia. There is concern that F. tularensis could be used as a biological weapon and development of vaccines is a high priority. Type A strains are highly virulent but the current live vaccine strain (LVS) is based on a type B strain which is only partially protective against aerosol challenge with SCHU S4 (S4), a type A strain. Historically mice have been the most commonly used model to study vaccines and pathogenesis of F. tularensis. However, mice are acutely sensitive to tularemia such that strains that are attenuated or avirulent in other mammals cause lethal disease in mice. Therefore, the rabbit model has been used in these studies because New Zealand White rabbits have a disease course and susceptibility similar to humans.\ud \ud The data presented here will demonstrate that the humoral immune response plays a role in the protection and survival from a F. tularensis infection. A novel ELISA assay has been used to examine antibody titers against F. tularensis in the plasma of rabbits post vaccination and analyzed to determine if there is a correlation to survival against challenge with SCHU S4. In addition, data was analyzed to compare various vaccines, vaccination routes, and vaccine doses to determine if one provided better protection and higher survival rate