Enhancement of protective humoral (Th2) and cell-mediated (Th1) immune responses against herpes simplex virus-2 through co-delivery of granulocyte-macrophage colony-stimulating factor expression cassettes.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) could in theory attract antigen-presenting cells in muscle following intramuscular DNA immunization, resulting in enhanced antigen-specific immune responses. Thus, such adjuvants could constitute an important addition to a herpes vaccine by amplifying specific immune responses. Here we investigate the utility of GM-CSF cDNA as a vaccine adjuvant for herpes simplex virus (HSV)-2 in a mouse challenge model. GM-CSF cDNA co-injection enhanced levels of specific IgG, IgE and IgA against HSV-2 gD protein significantly higher than gD plasmid vaccination alone. Moreover, GM-CSF co-injection induced a dramatic increase in IgG1 levels, as compared to IgG2a levels, suggesting a Th2 bias in the response. T helper cell proliferation and secretion of cytokines (IL-2 and IFN-gamma) were significantly increased by GM-CSF cDNA co-injection. When challenged with a lethal dose of HSV-2, GM-CSF co-injection increased survival rates to 90%, an improvement as compared to gD vaccination alone (60-63%). Furthermore, GM-CSF cDNA co-injection reduced herpetic lesions and resulted in a faster recovery from lesions. These data indicate that GM-CSF cDNA enhances both humoral and cellular immune responses and enhances vaccine efficacy, resulting in reduced HSV-2-derived morbidity as well as mortality.