The present invention provides viral adjuvants for enhancing an immune response to an immunogen. In particular embodiments, the viral adjuvant is an alphavirus adjuvant or a Venezuelan Equine Encephalitis viral adjuvant. Also provided are compositions comprising the viral adjuvant and an immunogen, and pharmaceutical formulations comprising the viral adjuvant or compositions of the invention in a pharmaceutically acceptable carrier. Further provided are methods of producing an immune response against an immunogen in a subject comprising administering the immunogen and a viral adjuvant of the invention to the subject.