Enhancement of VP6 immunogenicity and protective efficacy against rotavirus by VP2 in a genetic immunization.

VP2/VP6 virus like particles (VLPs) are very effective in inducing protection against the rotavirus infection in animal models. Individually, VP6 can also induce protection. However, there is no information about the immunogenicity of VP2. The aim of this work was to evaluate the efficacy of DNA vaccines codifying for VP2 or VP6, alone or combined, to induce protection against the rotavirus infection. Murine rotavirus VP2 and VP6 genes were cloned into the pcDNA3 vector. Adult BALB/c mice were inoculated three times by intramuscular (i.m.) injections with 100 or 200µg of pcDNA3-VP2 or pcDNA3-VP6 alone or co-administered with 100µg of pcDNA3-VP2/100µg of pcDNA3-VP6. Two weeks after the last inoculation, mice were challenged with the wild type murine rotavirus strain epizootic diarrhea of infant mice (EDIMwt). We found that both plasmids, pcDNA3-VP2 and pcDNA3-VP6, were able to induce rotavirus-specific serum antibodies, but not intestinal rotavirus-specific IgA; only 200µg of pcDNA3-VP6 induced 35% protection against the infection. A similar level of protection was found when mice were co-administered with 100µg of pcDNA3-VP2/100µg of pcDNA3-VP6 (1:1 ratio). However, the best protection (up to 58%) occurred when mice were inoculated with 10µg of pcDNA3-VP2/100µg of pcDNA3-VP6 (1:10 ratio). These results indicate that the DNA plasmid expressing VP6 is a better vaccine candidate that the one expressing VP2. However, when co-expressed, VP2 potentiates the immunogenicity and protective efficacy of VP6.

CD43 signals prepare human T cells to receive cytokine differentiation signals.

T cells are increasingly used for passive immunotherapy and bone marrow transplantation. Proper ex-vivo management of the cells is important for the desired therapeutic effects. For differentiation into effector cells of the Th1 and Th2 phenotypes, T-cells require signals from IFNγ and IL-4, respectively. Naïve cells have an extremely low expression of the specific receptors that recognize these cytokines, indicating that in order to differentiate, cells need to perceive other signals that will enable them to sense the cytokine milieu. CD43 has been proposed as one of the molecules that make the initial contacts with antigen presenting cells. We report here that in cord blood, adult naïve and total human T cells, CD43 signals induced the expression of both IFNγ and IL-4 receptors, mediate their capping, increased their signaling and augmented differentiation mediated by these receptors. CD43 signals also stimulated the expression of IFNγ and in neonatal cells that of IL-4 as well. These data demonstrate an important role for CD43 signals in T-cell preparedness for differentiation into effector cells.