Immunologic Analysis Induced by DNA Vaccine Encoding E Protein of Beijing-1 Strain Derived from Japanese Encephalitis Virus

Abstract

Objective: We have compared the gene expression and DNA immunization efficacy encoding prME and E proteins of a different strain (JaGAr-01) derived from Japanese encephalitis virus. This study aimed to construct a recombinant encoding E protein of the Beijing-1 strain derived from Japanese encephalitis virus and analyze the humoral, cellular and protective immunity induced by the above recombinant. Methods: The recombinant pJBE containing E (1,500 bps) gene from the Beijing-1 strain of Japanese encephalitis virus was constructed and then transfected into the HepG2 cell line by liposome fusion. The expression of E (about 53 kD) protein in transfected cells was analyzed by Western blot using a specific anti-JEV-E antibody. BALB/c mice were vaccinated with 3 µg of pJBE by the gene-gun technique. JaGAr-01 and Beijing-1 strains (10⁵ PFU/100 µl) of Japanese encephalitis virus were given to BALB/c mice by intraperitoneal injection 3 weeks after double DNA immunization with a lethal virus challenge. BALB/c mice were observed for 21 days after challenge. An 80% plaque reduction neutralization test was performed to titrate the neutralization antibody before and after viral challenge. A lactate dehydrogenase activity release test was used to examine cytotoxic T lymphocyte activity after double DNA immunization. Results: The expression of about 53 kD protein associated with pJBE was determined in transfected HepG2 cells with specific anti-JEV-E antibody. A higher level of neutralization antibodies and the cytotoxicity effect were induced with pJBE immunization using the gene-gun technique, and were similar to those induced with inactivated vaccine derive from the Beijing-1 strain of Japanese encephalitis virus. Balb/c mice immunized with pJBE survived the challenge with the different strains of Japanese encephalitis virus; however, Balb/c mice immunized with inactivated vaccine did not survive the challenge with the JaGAr-01 strain of Japanese encephalitis virus at all. Conclusions: DNA vaccine containing the E protein gene derived from Japanese encephalitis virus can provide not only better efficacy including humoral and cellular immunity, but also cross-protection against infection with homologous and heterologous Japanese encephalitis virus.

Immunogenicity of novel consensus-based DNA vaccines against Chikungunya virus

“…The sheer magnitude of the 2005-2007, Chikungunya outbreaks underscores the need for a safe and effective vaccine against CHIKV [6]. One approach that may have benefit here is DNA immunization which induce both humoral and cellular responses and or protective immunity in some animal systems against viral infections such as, HIV, Hepatitis B, Hepatitis C viruses, influenza virus and arbo viruses such as JEV [22][23][24].…”

Intramuscular Immunization with a Plasmid DNA Vaccine Encoding prM-E Protein from Japanese Encephalitis Virus: Enhanced Immunogenicity by Co-Administration of GM-CSF Gene and Genetic Fusions of prM-E Protein and GM-CSF

“…CHO cells were used for the transfection experiment and P815 cells were used as target cells. BHK cells grown at 37 ° in Eagle's medium with 1% FCS and Beijing-1 strain of JEV [22] were used for the 80% plaque reduction neutralization test (PRNT 80 ). A eukaryotic vector, pcDNA3.1(+), with the strong eukaryotic promoter derived from human cytomegalovirus and T7 bacteriophage promoter was bought from Invitrogen (Carlsbad, Calif., USA) for plasmid construction.…”

“…Cytotoxicity assays using the lactate dehydrogenase (LDH) activity released test were performed at week 8 (3 weeks after the final DNA inoculation), as described previously, with some modifications [22] . Briefly, spleen cells from 4 mice of each group were mixed and stimulated in vitro with 1/20 volume of live JEV (Beijing-1 strain, 10 3 PFU/ml) in 2 ml of RPMI 1640 containing 10% FCS and 10 U/ml rmIL-2 (R&D, Minneapolis, Minn., USA) in 24-well microplates at 37 ° for 5 days.…”

“…Neutralizing antibodies elicited in immunized mice were titrated as previously described [22] . The neutralization titer was expressed as the highest serum dilution yielding a 80% reduction in plaque number.…”

Untitled

“…In addition, the JEV EPs were also found in plasmid-based mammalian cell expression system. The recombinant plasmid was tested as a DNA vaccine candidate against JEV: it elicited immune response in mice [18,19]. Partially purified JEV EPs were used as standard antigens for serodiagnosis of JEV infection [20].…”