The construction and characterization of recombinant sindbis virus vectors as a platform for anthrax vaccine development

The intentional release of anthrax spores in the U. S. mail system and the subsequent fatalities have renewed interest in developing therapeutics to protect against B. anthracis. Anthrax Vaccine Adsorbed (AVA) is the only licensed vaccine preparation currently used however, immunogenicity is variable and the boosting regimen is long-term and must be maintained to ensure continued protection. Protective antigen (PA), the chief component of AVA, is an 83kDa protein responsible for binding host cell receptors and promoting toxin entry into susceptible cells. Analysis of the PA molecule has identified a specific region, termed domain four, that contains epitopes responsible for antibody binding. Sindbis virus, the prototypical member of the genus alphavirus, has been extensively used as a vector of foreign gene expression. Several characteristics, including ease of manipulation, high levels of transgenic expression, and lack of pathogenicity in humans make Sindbis virus an attractive candidate as a vaccine vector. The purpose of this proposal is to construct and characterize replication-competent Sindbis virus vaccine vectors that express PA using in vivo and in vitro analysis in order to generate a recombinant viral vaccine capable of providing protection from virulent anthrax spore challenge.