Enhanced Immunogenicity to Mycobacterium tuberculosis by Vaccination with an Alphavirus Plasmid Replicon Expressing Antigen 85A
Cellular Immunology Section, Vaccine Research Center,1 Laboratory of Immunogenetics,2 National Institute of Allergy and Infectious Diseases, National Institutes of Health, and Food and Drug Administration, Bethesda, Maryland,3 Vaccines Research, Chiron Corporation, Emeryville, California,4 Microbiology Department, Colorado State University, Fort Collins, Colorado5p|@r*, 百拇医药
Received 24 July 2002/ Returned for modification 29 August 2002/ Accepted 10 September 2002p|@r*, 百拇医药
ABSTRACTp|@r*, 百拇医药
The immunogenicity of a plasmid DNA vaccine incorporating Sindbis virus RNA replicase functions (pSINCP) and expressing antigen 85A (Ag85A) from Mycobacterium tuberculosis was compared with a conventional plasmid DNA vector encoding Ag85A. pSINCP-85A was highly immunogenic in mice and gave enhanced long-term protection against M. tuberculosis compared with the conventional vector.p|@r*, 百拇医药
TEXTp|@r*, 百拇医药
Tuberculosis (TB) remains a significant worldwide public health problem. Despite the staggering global impact of this disease, the effectiveness of the present vaccine, Mycobacterium bovis BCG, remains uncertain; in various studies, its efficacy has varied from 0 to 80%. Clearly, there remains an urgent need for a new and more reliable TB vaccine.
Recently, there has been increasing interest in using plasmid DNA vaccination to prevent infectious diseases that require cell-mediated protective responses, including TB. While DNA vaccination has been shown to induce broad humoral and cellular immune responses in mice, it is far less immunogenic in primates and humans. Reasons for this inconsistency may include qualitative and quantitative differences in the host response and the amount of DNA injected in mice and humans.k3z1g, 百拇医药
We sought to improve upon the efficacy of conventional DNA vaccines against TB by using a DNA vaccine based on the Sindbis virus RNA replicase and encoding antigen 85A (Ag85A) from Mycobacterium tuberculosis. Incorporation of alphavirus replicons into plasmid DNA vectors to direct the amplification of RNA expressing the gene of interest has been an exciting approach toward improving DNA vaccination (8).k3z1g, 百拇医药
Vectors encoding the alphavirus-derived RNA replicase have been shown to be immunogenic in murine models at doses up to 1,000-fold lower than those used for conventional plasmid vectors (11, 16) and are effective when used as vaccines against cancer (7, 12, 15, 16) or viral infections (3, 5, 11, 14). The first product of a plasmid DNA replicon is the RNA replicase, which uses the primary positive-strand RNA transcript as a template to make negative-strand RNA and then makes more copies of full-length positive-strand RNA (encoding both replicase and antigen) as well as a shorter subgenome-length mRNA encoding only the antigen (17).k3z1g, 百拇医药
The enhanced immunogenicity of plasmid DNA replicons cannot be accounted for based only on levels of antigen production but rather through other mechanisms. In addition to producing antigen, cells transfected with the plasmid DNA replicon produce double-stranded RNA (dsRNA), which may provide immunostimulatory adjuvant effects (18). dsRNA is recognized by Toll-like receptor 3 on antigen-presenting cells and induces production of alpha interferon (IFN-), IFN-ß, IFN-(Joanna R. Kirman Tara Turon Hua Su Amy Li Carl Kraus John M. Polo John Belisle Sheldon Morris and Ro)
Received 24 July 2002/ Returned for modification 29 August 2002/ Accepted 10 September 2002p|@r*, 百拇医药
ABSTRACTp|@r*, 百拇医药
The immunogenicity of a plasmid DNA vaccine incorporating Sindbis virus RNA replicase functions (pSINCP) and expressing antigen 85A (Ag85A) from Mycobacterium tuberculosis was compared with a conventional plasmid DNA vector encoding Ag85A. pSINCP-85A was highly immunogenic in mice and gave enhanced long-term protection against M. tuberculosis compared with the conventional vector.p|@r*, 百拇医药
TEXTp|@r*, 百拇医药
Tuberculosis (TB) remains a significant worldwide public health problem. Despite the staggering global impact of this disease, the effectiveness of the present vaccine, Mycobacterium bovis BCG, remains uncertain; in various studies, its efficacy has varied from 0 to 80%. Clearly, there remains an urgent need for a new and more reliable TB vaccine.
Recently, there has been increasing interest in using plasmid DNA vaccination to prevent infectious diseases that require cell-mediated protective responses, including TB. While DNA vaccination has been shown to induce broad humoral and cellular immune responses in mice, it is far less immunogenic in primates and humans. Reasons for this inconsistency may include qualitative and quantitative differences in the host response and the amount of DNA injected in mice and humans.k3z1g, 百拇医药
We sought to improve upon the efficacy of conventional DNA vaccines against TB by using a DNA vaccine based on the Sindbis virus RNA replicase and encoding antigen 85A (Ag85A) from Mycobacterium tuberculosis. Incorporation of alphavirus replicons into plasmid DNA vectors to direct the amplification of RNA expressing the gene of interest has been an exciting approach toward improving DNA vaccination (8).k3z1g, 百拇医药
Vectors encoding the alphavirus-derived RNA replicase have been shown to be immunogenic in murine models at doses up to 1,000-fold lower than those used for conventional plasmid vectors (11, 16) and are effective when used as vaccines against cancer (7, 12, 15, 16) or viral infections (3, 5, 11, 14). The first product of a plasmid DNA replicon is the RNA replicase, which uses the primary positive-strand RNA transcript as a template to make negative-strand RNA and then makes more copies of full-length positive-strand RNA (encoding both replicase and antigen) as well as a shorter subgenome-length mRNA encoding only the antigen (17).k3z1g, 百拇医药
The enhanced immunogenicity of plasmid DNA replicons cannot be accounted for based only on levels of antigen production but rather through other mechanisms. In addition to producing antigen, cells transfected with the plasmid DNA replicon produce double-stranded RNA (dsRNA), which may provide immunostimulatory adjuvant effects (18). dsRNA is recognized by Toll-like receptor 3 on antigen-presenting cells and induces production of alpha interferon (IFN-), IFN-ß, IFN-(Joanna R. Kirman Tara Turon Hua Su Amy Li Carl Kraus John M. Polo John Belisle Sheldon Morris and Ro)