Abstract
Although two investigational vaccines are used to immunize humans against Venezuelan equine encephalomyelitis virus, neither had previously been tested for protective efficacy against aerosol exposure. Live attenuated vaccine (TC-83) protected all hamsters challenged by either aerosol or subcutaneous routes with 4.7 to 5.2 log10 PFU of virulent Venezuelan equine encephalomyelitis virus. Formaldehyde-inactivated vaccine (C-84) failed to protect against aerosol challenge but did protect against subcutaneous challenge. Protection elicited by TC-83 vaccine did not depend solely on serum-neutralizing antibody. These studies suggest that TC-83 vaccine is preferable to C-84 vaccine for protecting laboratory workers at risk to aerosol exposure.