Studies On Immune Effects Of Cytomegalo Virus DNA Vaccine And Molecular Adjuvants

This article consists of three parts:(1) Overview of the cytomegalovirus (CMV) and introduction of its vaccines and adjuvants; (2) Studies on CMV M84 DNA vaccine adjuvanted with HMGB1 or IL-18 gene; (3) Studies of CMV IE1 DNA vaccine adjuvanted with IL-12 gene in normal mice and diabetic mice.The CMVs belong to the beta-herpes virus subfamily and have species specificity. They are ubiquitous pathogenic agents in nature. The human CMV (HCMV) can infect people easily and cause severe diseases in newborns and immunodeficient persons. So far, we have no effective way to cure the HCMV infection. So there is an urgent need for development of HCMV vaccine to prevent the infection. Due to the strict species specificity of the virus, the preclinical studies of CMV vaccine are all performed in animal models. Here we used mouse model infected with murine CMV (MCMV) to study CMV vaccine and adjuvants.High mobility group box protein 1 (HMGB1) is a new cytokine. It is mainly secreted by macrophages, monocytes and pituitary cells. It can mediate cell migration and cell differentiation, promote activation of dentritic cells and enhance the transcription of IL-2. All of the above suggest that HMGB1 can promote immune response. IL-18 is a cytokine found many years ago. It induces cells to produce IFN-y, GM-CSF, IL-2, TNF-α and other Th1-type cytokines, which can enhance immune response. IL-12 is a very common cytokine. It is related to cellular immune responses, and has been shown a good immune potency as an adjuvant.In this paper mice were immunized with MCMV M84 plasmids adjuvanted with plasmids encoding HMGB1 or IL-18 gene. They were challenged with a lethal dose of salivary gland virus four weeks after the immunization. The survival rates, weight loss and spleen virus titers of mice 5 days after challenge were recorded to evaluate the potency of the adjuvants. The experimental results showed that M84 DNA co-immunization with either HMGB1 or IL-18 gene significantly increased survival rate of the mice, and the adjuvant effect of IL-18 was better than that of HMGB1.Diabetes is caused by variety of factors. The immune system could be damaged by the disease, and therefore the diabetic persons would be easily attacked by many viruses. In this part the immune effect of MCMV IE1 DNA vaccine adjuvanted with IL-12 gene was explored in healthy and diabetic mice. The results showed that IL-12 as adjuvant enhanced the cellular immune responses induced by the vaccine, and that the level of cellular immune responses induced by the same doses of the vaccine in healthy mice was higher than those in diabetic mice. Two weeks after the last immunization, the mice were challenged with a lethal dose of salivary gland virus. We found that addition of adjuvant could improve the protective ability in both healthy and diabetic mice. Satisfactory protection could be achieved with much lower amount of IL-12 DNA (10 ug) in healthy mice than in diabetic mice (100 ug).