Evaluation of different plasmid DNA delivery system for immunization against HER2/neu in a transgenic murine model of mammary carcinoma

Studies of DNA vaccination against HER2/neu showed the effectiveness of immunization protocols in models of transplantable or spontaneous tumors; scarce information, however, has been provided to identify the procedure of DNA administration that more effectively contributes to the activation of immune system against spontaneously arising HER2/neu-positive tumors. We compared the effectiveness of different procedures of DNA vaccine delivery (intradermic injection (ID), gene gun (GG) delivery and intramuscular injection (IM) alone or with electroporation) in a murine transgenic model of mammary carcinoma overexpressing HER2/neu. We highlighted the role of DNA delivery system in the success of DNA vaccination showing that, among the analysed methods, intramuscular injection of the vaccine, particularly when associated to electroporation, elicits a better protection against HER2/neu spontaneous tumor development inducing antibody and cell-mediated immune responsiveness against HER2/neu and a ThI polarization of the immune response

DNA Vaccination Against Rat Her-2/Neu p185 More Effectively Inhibits Carcinogenesis Than Transplantable Carcinomas in Transgenic BALB/c Mice

The ability of vaccination with plasmids coding for the extracellular and the transmembrane domain of the product of transforming rat Her-2/ neu oncogene (r-p185) to protect against r-p185 + transplantable carcinoma (TUBO) cells and mammary carcinogenesis was evaluated. In normal BALB/c mice, DNA vaccination elicits anti-r-p185 Ab, but only a marginal CTL reactivity, and protects against a TUBO cell challenge. Massive reactive infiltration is associated with TUBO cell rejection. In BALB/c mice transgenic for the rat Her-2/ neu gene (BALB-neuT), DNA vaccination elicits a lower anti-r-p185 Ab response, no CTL activity and only incompletely protects against TUBO cells, but markedly hampers the progression of carcinogenesis. At 33 wk of age, when control BALB-neuT mice display palpable tumors in all mammary glands, about 60% of immunized mice are tumor free, and tumor multiplicity is markedly reduced. Tumor-free mammary glands still display the atypical hyperplasia of the early stages of carcinogenesis, and a marked down-modulation of r-p185, along with a massive reactive infiltrate. However, BALB-neuT mice protected against mammary carcinogenesis fail to efficiently reject a TUBO cell challenge. This suggests that the mechanisms required for the rejection of transplantable tumors may not coincide with those that inhibit the slow progression of carcinogenesis

Low effectiveness of DNA vaccination against HER-2/neu in ageing

We evaluated the effectiveness of vaccination with a HER-2/neu DNA plasmid to induce protective immunity against HER-2/neu overexpressing syngeneic TUBO tumour cells in old ages. Young and old Balb/c mice received three immunizations with a pCMVneuNT DNA plasmid and, successively, were challenged with TUBO cells. Young mice were completely protected whereas less than 60% protection was observed in old mice. Anti-p185neu antibodies were found in the sera from both young and old immunized mice, even if antibody production was significantly higher in young in comparison with old mice. Similarly, higher anti-p185neu lymphocyte proliferation was induced in young than in old mice. No anti-p185neu cytotoxicity was found in lymphocytes from old animals. We conclude that anticancer DNA vaccination has a lower effectiveness in old than in young ages

Binding of feline immunodeficency viral gag-p24 polypepdide to non immune Igs

Available data on the existence of lentivirus proteins with properties of unconventional Ag for B cells, have been so far restricted to human immunodeficiency virus (i.e. gp-120 of HIV-I). By using biotinylated-MAbs-anti-biotin IgG as readout system, we now report that gag-p24 antigen, either assembled in feline immunodeficiency virus (FIV) particles or expressed as recombinant polypeptide (rec.p24) may bind to nonimmune IgGs purified from mouse or cat sera. Moreover, FACS scanning experiments are consistent with the possibility that rec.p24 interacts with surface-Ig in a sub-population (5-6%) of rodent B cells. We hypothesize that gag-p24 peptide encoded regions may bind to unconventional Ig sites or, alternatively, that they may represent 'public' epitopes for natural polyreactive antibody