Superiority of intramuscular route and full length glycoprotein D for DNA vaccination against herpes simplex 2. Enhancement of protection by the co-delivery of the GM-CSF gene

Immunization with naked DNA has been analyzed in two critical variables: th e site of injection and the cellular compartment to which the coded protein is directed. The gene for the full length of the glycoprotein D (gD) of HS V-2 under the control of the citomegalovirus (CMV) promoter was injected vi a the intradermal (i.d.) or the intramuscular (i.m.) routes in mice. Immuni zation in the quadricep muscle was superior to the intradermal immunization in the footpads. A stronger activation of IFN-gamma-secreting cells in the spleen and draining lymph nodes (DLN) was induced, resulting in a more eff icient protection against an intravaginal challenge. In order to analyze th e effect of the cellular localizations of the coded protein, the DNA for th e truncated form of the gD (Delta gD) was injected via the i.m. route. Immu nization with a vector encoding for Delta gD resulted in higher antibody le vels in serum and vaginal washes than immunization with the gene for the fu ll length gD. However, immunization with the Delta gD DNA elicited a much w eaker cell-mediated immune response and was inferior to go DNA in providing protection against a lethal intravaginal challenge with HSV. Co-injection of an expression cassette for the granulocyte macrophage colony-stimulating factor (GM-CSF) increased both the humoral and cell-mediated immune respon se with both gD and Delta gD. A strong activation of IL-4-secreting cells w as observed in the spleen and DLN together with an increase in the number o f IFN-gamma-secreting cells. In addition, a reduction in the vaginal virus titers after an intravaginal challenge was observed in mice co-injected wit h the GM-CSF gene as compared to those immunized with pCDNAgD only. (C) 200 0 Elsevier Science Ltd. All rights reserved.