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Open Access Highly Accessed Research

Comparison of multiple DNA vaccines for protection against cytomegalovirus infection in BALB/c mice

Chaoyang Huang1, Huadong Wang3, Shuting Wu1, Haiyan Chang1, Lalan Liu1, Bo Peng1, Fang Fang1* and Ze Chen12*

Author Affiliations

1 College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China

2 Shanghai Institute of Biological Products, Shanghai 200052, China

3 State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, Hubei, China

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Virology Journal 2014, 11:104  doi:10.1186/1743-422X-11-104

Published: 5 June 2014

Abstract

Background

Human cytomegalovirus (HCMV) causes serious HCMV-related diseases in immunocompromised people. Vaccination is the most effective measure to control infection with the pathogen, yet no vaccine has been licensed till now. We performed a head-to-head comparison of the protective abilities of multiple DNA vaccines in murine model of murine cytomegalovirus (MCMV) infection.

Methods

Five DNA vaccines were constructed. Four encoding MCMV proteins gp34 (m04), p65 (M84), DNA helicase (M105), and immediate-early 1 protein pp89 (IE-1) , respectively, which were reported to induce CD8+ T cell responses, were compared with the one expressing gB (M55), the neutralizing antibody target antigen, for immune protection in BALB/c mice. Mice were immunized with these DNA vaccines 1 to 4 times via intramuscular injection followed by electroporation, and were subsequently infected with a lethal dose (3 × LD50) of highly virulent SG-MCMV. Specific antibodies and IFN-γ secreting splenocytes were detected by immunoblotting and ELISPOT, respectively. Protective abilities in mice provided by the vaccines were evaluated by residual virus titers in organs, survival rate and weight loss.

Results

These DNA vaccines, especially m04, M84 and IE-1, could effectively reduce the virus loads in salivary glands and spleens of mice, but they couldn’t completely clear the residual virus. Survival rates of 100% in mice after a lethal dose of MCMV infection could be reached by more than one dose of M84 vaccine or two doses of m04 or IE-1 vaccine. Immunization with M55 or M105 DNA at four doses offered mice only 62.5% survival rate after the lethal challenge.

Conclusions

The study demonstrated that DNA vaccines could effectively afford mice protection against infection with a highly virulent MCMV and that the protection offered by induced CD8+ T cell immunity might be superior to that by gB-specific antibodies. These results are valuable references for development and application of HCMV vaccines.

Keywords:
Cytomegalovirus; DNA vaccine; M04 (gp34); M84 (p65); M105 (DNA helicase); IE-1 (pp89); M55 (glycoprotein B)