Pamela Dunn

Use of a Mouse Lung Challenge Model to Identify Antigens Protective against Chlamydia pneumoniae Lung Infection

Chlamydia pneumoniae is emerging as a significant human pathogen. Infection causes a range of respiratory tract diseases and is associated with atherosclerosis. A vaccine could provide a considerable public health benefit; however, antigens able to elicit a protective immune response are largely unknown. A panel of open-reading frames (ORFs) from the C. pneumoniae genome sequence was screened for ability to elicit protective responses. Balb/c mice immunized with DNA containing the ORFs were tested for their ability to limit lung infection following an intranasal challenge. Immunization with DNA encoding the major outer membrane protein or an ADP/ATP translocase (Npt1(Cp)) of C. pneumoniae resulted in a reduced bacteria load in the lung after challenge. The identification of these antigens as protective is a significant step toward development of a C. pneumoniae vaccine and demonstrates the feasibility of using a DNA immunization strategy to screen the C. pneumoniae genome for other protective ORFs.

Preclinical qualification of a new multi-antigen candidate vaccine for metastatic melanoma.

New therapies are urgently required for the treatment of patients with melanoma. Here we describe the generation and preclinical evaluation of 3 new recombinant ALVAC(2) poxviruses vCP2264, vCP2291, and vCP2292 for their ability to induce the desired cellular immune responses against the encoded melanoma-associated antigens. This was done either in HLA-A2/Kb transgenic mice or using in vitro antigen-presentation studies. These studies demonstrated that the vaccine was able to induce HLA-A*0201-restricted T-cell responses against gp100 and NY-ESO-1, detectable directly ex vivo, in HLA-A2/Kb-transgenic mice. The in vitro antigen presentation studies, in the absence of appropriate animal models, demonstrated that target cells infected with the vaccine construct were lysed by MAGE-1, MAGE-3 or MART-1 peptide-specific T cells. These data indicate that ALVAC(2)-encoded melanoma-associated antigens can be properly processed and presented to induce antigen-specific cytotoxic T-cell responses. To enhance the immunogenicity of the melanoma antigens, a TRIad of COstimulatory Molecules (TRICOM) were also cloned into all 3 vectors. Increased in vitro proliferation and IFN-γ production was observed with all ALVAC(2) poxviruses encoding TRICOM, confirming the immune-enhancing effect of the ALVAC-encoded TRICOM. These studies demonstrated that all components of the vaccine were functionally active and provide a rationale for moving this candidate vaccine to the clinic.