A third of the world's population is infected with the tuberculosis bacterium (TB) and new infections are continuously ongoing. All the people do not develop the disease and latent and asymptomatic infections are common but although this, about one in ten infected subjects will develop the disease that, if not cured, kills half of the victims. According to the World Health Organisation, TB kills approximately 2 million people every year, mainly in the developing countries, but, also in the developed countries there are a higher number of persons who contract tuberculosis as consequence of an increased immigration and/or because the immune system are compromised by immunosuppressive drugs, substance abuse or AIDS. Therefore it become more obvious the needs to develop new vaccines/adjuvants to ameliorate the response to BCG which has been demonstrated to be really efficacious in children to prevent tuberculosis meningitis and systemic forms but for unknown reasons, has limited efficacy in prevent a adult pulmonary disease in highly endemic areas and even worth in halt the transmission of the infection. The ideal would be therefore to arrive to an effective vaccination for the all population, to all the ages, also for already sensitized subjects and against all the stages of the tuberculosis (latent, pulmonary, extra pulmonary). In particular it seems to be promising to employ genetic vaccination using plasmid DNA and/or modified viruses where genes encoding protective antigens and/or cytokines have been inserted. The most common antigens that have been used are ESAT-6, Ag85A, Ag85B, and Mpt. In this respect, a new generation of viral vectors based on Herpes simplex type 1 (HSV-1) virus seems to have all the characteristics to carry vaccine antigens alone or in combination. Our proposal is to ameliorate and to increase the efficacy of the Herpes simplex type 1 (HSV-1) vectors expressing mycobacterium antigens to combine with rBCG vaccine to fight tuberculosis (TB). More precisely, we have constructed recombinants that express a fusion protein in order to induce a more complete pattern of immune responses, that include several mycobacterium antigens (TB5Ag.: Ag85B, ESAT-6, Mpt 64/63/83), a TPA (tissue plasminogen activator signal sequence), which ensure the release of the fusion protein and a sequence codifying for hemoagglutinin epitope that allows the identification of the protein with the specific antibody. Our goals in this project are: a) to test, together with U.O.UCSC, these viruses in prime-boost experiments in combination with rBCG vaccine and with the vaccines that have been developed from the other units; b) to associate, in these recombinants expressing the fusion protein (TB5Ag), one cytokine (e.g.: GM-CSF, IL-12) in order to induce an immune response that would be optimally adapted to organisms infected with TB, this work actually is already ongoing; also another goal not less important is c) to explore and develop a more efficacious HSV-1 based vaccine expressing fusion proteins from the multiantigens Ag85B-ESAT-6 and/or Mpt64-63-83 together with Tat as an adjuvant. We have seen in preliminary experiments that Tat can function as a potent adjuvant not only for an HIV vaccine, but also for other o infections. The Tat protein modulates the CTL epitope hierarchy and broadens the epitope-specific T cell responses of heterologous antigens in vitro by modifying the catalytic subunit composition of the immunoproteasome. For these reasons, it will be interesting to see if by increasing the size and broadening the diversity of T cell responses to a given antigen would increase the efficacy of BCG vaccine and also reduce epitope mutation and CTL escape. The use of HIV-Tat adjuvant in the design of new Herpes-based vectors expressing Mycobacterial antigens makes these vectors specifically useful for the implementation of immunization strategies, and for the possibility to design vaccines that specifically recognize and target antigens directly involved in the pathogenesis of TB. The results that will be obtained will generate knowledge in new immune epitopes and technologies to design new vaccines to increase the efficacy of BCG and consequently the response against TB. These last vectors will be tested in vivo in collaboration of U.O.UCSC.
Vettori erpetici ricombinanti in strategie di vaccinazione prime-boosting per aumentare l'immunogenicità e l'efficacia protettiva di BCG Recombinant Herpes simplex-based vectors in prime-boosting vaccination strategies in order to increase the immunogenicity and the protecting effectiveness of BCG
MARCONI, Peggy Carla Raffaella
2011
Abstract
A third of the world's population is infected with the tuberculosis bacterium (TB) and new infections are continuously ongoing. All the people do not develop the disease and latent and asymptomatic infections are common but although this, about one in ten infected subjects will develop the disease that, if not cured, kills half of the victims. According to the World Health Organisation, TB kills approximately 2 million people every year, mainly in the developing countries, but, also in the developed countries there are a higher number of persons who contract tuberculosis as consequence of an increased immigration and/or because the immune system are compromised by immunosuppressive drugs, substance abuse or AIDS. Therefore it become more obvious the needs to develop new vaccines/adjuvants to ameliorate the response to BCG which has been demonstrated to be really efficacious in children to prevent tuberculosis meningitis and systemic forms but for unknown reasons, has limited efficacy in prevent a adult pulmonary disease in highly endemic areas and even worth in halt the transmission of the infection. The ideal would be therefore to arrive to an effective vaccination for the all population, to all the ages, also for already sensitized subjects and against all the stages of the tuberculosis (latent, pulmonary, extra pulmonary). In particular it seems to be promising to employ genetic vaccination using plasmid DNA and/or modified viruses where genes encoding protective antigens and/or cytokines have been inserted. The most common antigens that have been used are ESAT-6, Ag85A, Ag85B, and Mpt. In this respect, a new generation of viral vectors based on Herpes simplex type 1 (HSV-1) virus seems to have all the characteristics to carry vaccine antigens alone or in combination. Our proposal is to ameliorate and to increase the efficacy of the Herpes simplex type 1 (HSV-1) vectors expressing mycobacterium antigens to combine with rBCG vaccine to fight tuberculosis (TB). More precisely, we have constructed recombinants that express a fusion protein in order to induce a more complete pattern of immune responses, that include several mycobacterium antigens (TB5Ag.: Ag85B, ESAT-6, Mpt 64/63/83), a TPA (tissue plasminogen activator signal sequence), which ensure the release of the fusion protein and a sequence codifying for hemoagglutinin epitope that allows the identification of the protein with the specific antibody. Our goals in this project are: a) to test, together with U.O.UCSC, these viruses in prime-boost experiments in combination with rBCG vaccine and with the vaccines that have been developed from the other units; b) to associate, in these recombinants expressing the fusion protein (TB5Ag), one cytokine (e.g.: GM-CSF, IL-12) in order to induce an immune response that would be optimally adapted to organisms infected with TB, this work actually is already ongoing; also another goal not less important is c) to explore and develop a more efficacious HSV-1 based vaccine expressing fusion proteins from the multiantigens Ag85B-ESAT-6 and/or Mpt64-63-83 together with Tat as an adjuvant. We have seen in preliminary experiments that Tat can function as a potent adjuvant not only for an HIV vaccine, but also for other o infections. The Tat protein modulates the CTL epitope hierarchy and broadens the epitope-specific T cell responses of heterologous antigens in vitro by modifying the catalytic subunit composition of the immunoproteasome. For these reasons, it will be interesting to see if by increasing the size and broadening the diversity of T cell responses to a given antigen would increase the efficacy of BCG vaccine and also reduce epitope mutation and CTL escape. The use of HIV-Tat adjuvant in the design of new Herpes-based vectors expressing Mycobacterial antigens makes these vectors specifically useful for the implementation of immunization strategies, and for the possibility to design vaccines that specifically recognize and target antigens directly involved in the pathogenesis of TB. The results that will be obtained will generate knowledge in new immune epitopes and technologies to design new vaccines to increase the efficacy of BCG and consequently the response against TB. These last vectors will be tested in vivo in collaboration of U.O.UCSC.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
