DNA vaccines for murine cytomegalovirus

Abstract

The murine cytomegalovirus (MCMV) immediate early gene 1 (IE1) encodes a nonstructural 89-kDa phosphoprotein (pp89) which is essential for viral replication and plays a key role in generation of protective CD8+ cytotoxic T lymphocytes (CTLs) during natural infection. Delivery of this epitope to BALB/c mice by vaccinia virus resulted in protective immunity but only partial protection was reported following immunization with a pp89 expression plasmid alone. The objective of this project is to develop a more effective DNA vaccine against MCMV using pp89 in a plasmid containing lysosome-associated membrane protein (LAMP), which has been shown to enhance both cellular and humoral immune response with a variety of antigen and vector systems. BALB/c mice were immunized with plasmid DNA encoding exons 2,3 and 4 (named 234) of the IE1 gene as a LAMP chimera and subsequently challenged with a sub-lethal dose of MCMV. Virus replication in spleens and salivary glands was monitored for 14 days post challenge. At the time of peak viral replication, virus titers in the spleens of pVAX/LAMP/234 immunized mice was a 130-fold lower than that of pVAX (vector control) immunized mice. Virus titers in the salivary gland were about 10 fold lower. Taken together, these results demonstrated that immunization with pVAX/LAMP/234 chimeras significantly reduce viral titers in target organs.