ABSTRACT
Objective:To study the protective effects of bicistronic DNA vaccines carrying herpes simplex virus type 2 glycoprotein D (HSV-2 gD) and adjuvant CCL28 sequences that were connected by internal ribosome entry site (IRES) sequence in mouse model.Methods:The recombinant DNA vaccines, pgD-IRES-CCL28 and pCCL28-IRES-gD, encoding HSV-2 gD and adjuvant CCL28 were constructed with IRES sequence. After verified by sequencing, they were intramuscularly injected twice into BALB/c mice. Serum samples and vaginal lavage fluids were collected regularly. Splenocytes, mesenteric lymph node cells and rectal mucosa tissues were separated and collected. The titers of antigen-specific antibodies in immunized mice were analyzed with end-point ELISA. In vitro neutralization assay was used to measure neutralizing antibody titers in serum and vaginal lavage fluid after vaccination and virus challenge. CCL28-responsive immune cells in splenocytes, mesenteric lymph node cells and rectal tissues were detected by chemotaxis experiment and immunohistochemical staining. The protective effects of the bicistronic DNA vaccines were evaluated by fluorescent quantitative PCR, weighing and disease severity assessment. Humoral and cellular immune responses induced by the bicistronic DNA vaccines and their efficacy in immunoprotection were analyzed by comparing with pgD+ pCCL28 group. Results:IgG titers in serum samples and IgA antibody titers in vaginal lavage fluids of mice immunized with pCCL28-IRES-gD were similar to those in pgD+ pCCL28 group. The neutralizing ability of antibodies, the number of rectal mucosal IgA+ plasma cells and CCL28-responsive immune cells in mucosal tissues were increased in pCCL28-IRES-gD group. Serum neutralizing antibodies were not produced immediately in the mice challenged with HSV-2, but no weight loss, disease symptoms or death was observed. However, pgD+ pcDNA3.1 and pgD-IRES-CCL28 were ineffective against HSV-2 infection in mice.Conclusions:The recombinant bicistronic DNA vaccine of pCCL28-IRES-gD could induce stronger mucosal immune response in mice and provide better protective effects.
ABSTRACT
Objective:To compare the immune responses to simply mixed and fused recombinant DNA vaccines of herpes simplex virus type 2 glycoprotein D (HSV-2 gD) and molecular adjuvant CCL19 in mice and to evaluate the protective effects.Methods:Gene recombination technology was used to construct recombinant DNA vaccines expressing HSV-2 gD and CCL19 alone or fused together. After verification by sequencing, Western blot and ELISA, BALB/c mice were immunized twice by intramuscular injection. Serum samples and vaginal lavage fluids were collected regularly after immunization. Splenocytes, mesenteric lymph node cells and rectal tissues were collected after immunization. Differences in humoral and cellular immune responses to the two forms of vaccines and their protective effects in mice were analyzed using end-point ELISA, in vitro neutralization assay, immunohistochemical staining, chemotaxis assay, vaginal virus challenge, fluorescence quantitative PCR, weighing and disease severity assessment. Results:The fused recombinant pgD-IZ-CCL19 plasmid could express gD protein and CCL19 protein in vitro, but the level of expressed CCL19 protein by pCCL19-IZ-gD plasmid was less than that by pgD-IZ-CCL19. The mice immunized with pgD-IZ-CCL19 showed higher levels of IgG in sera and IgA in vaginal lavage fluids ( P<0.01) and stronger neutralization ability than the mice vaccinated with pgD+ pCCL19. Compared with other groups, more lymphocytes were recruited in the rectal mucosa, the spleen and mesenteric lymph nodes of mice immunized with pgD-IZ-CCL19. Weight loss or disease symptoms were not observed in the pgD-IZ-CCL19 group after virus challenge. In addition, the positive rate of HSV-2 in vaginal mucosa and the mortality rate in the pgD-IZ-CCL19 group were the lowest. However, pCCL19-IZ-gD turned out ineffective in preventing HSV-2 infection. Conclusions:The fused recombinant DNA vaccine pgD-IZ-CCL19 could induce stronger immune responses in mice and provide better protective effects, which was superior to the simply mixed DNA vaccine.
ABSTRACT
Studies of the mechanism of HIV entry and transmission have identified multiple new targets for drug development. A range of inhibitors have demonstrated potent antiretroviral activity by interfering with CD4-gp120 interaction, coreceptor binding or viral-cell fusion in preclinical and clinical studies. One of these agents, fusion inhibitor enfuvirtide, is already in clinical use. Here we review the progress in the development of specific entry inhibitors as novel therapeutics. The potential of entry inhibitors as topical microbicides to block HIV transmission is also discussed.