Recombinant Subunit Tuberculosis Vaccines
Novel Recombinant Subunit Tuberculosis Vaccines: Cellulose Microparticles as an Adjuvant for Mycobacterial Antigens Fused with Cellulose-Binding Protein Domain
Tech Area / Field
- BIO-CGM/Cytology, Genetics and Molecular Biology/Biotechnology
8 Project completed
Senior Project Manager
Melnikov V G
Gamalei Institute of Epidemiology and Microbiology, Russia, Moscow
- Institute of Immunological Engineering, Russia, Moscow reg., Lyubuchany\nCentral Tuberculosis Research Institute, Russia, Moscow
- McGill University Health Centre, Canada, QC, Montreal\nTexas A&M University System / Health Science Center, USA, TX, College Station\nCenter for Biologics Evaluation and Research/US Food and Drug Administration, USA, MD, Rockville
Project summaryAn urgent need for the development of innovative TB vaccines is defined by imperfection of BCG, the only currently available vaccine against TB. BCG failings include, almost certainly, inability of this vaccine to protect against the most prevalent form of TB - pulmonary tuberculosis in adults, interference with skin testing, variable performance in different regions of the world, low efficacy in tropical regions endemic for mycobacterial species and obstacles for administration to HIV-positive inpiduals. One of the most promising approaches to develop novel TB vaccines is an elaboration of subunit vaccines consisting of either one or a few secreted proteins/peptides from Micobacterium tuberculosis mixed with an adjuvant. Presently the main limitation to a rapid clinical application of subunit vaccines is obvious: highly reactogenic and thus hazardous adjuvants are required to reach appreciable immunogenicity and protectivity. The aim of this project is to develop a new recombinant subunit TB vaccine candidates based on the new adjuvant technology, and to test the efficacy and safety of these novel vaccines in an animal TB model.
To achieve this goal, we intend to use a biotechnological approach established in lab of Dr. Lunin during preliminary studies, which includes construction of fusion proteins, composed from two components: (i) mycobacterial antigen(s) and (ii) cellulose binding domain (CBD). The CBD, originally identified and characterized in our lab, provides an one-stage immobilization of CBD-carrying fusion proteins on the cellulose microparticles. The immobilization of mycobacterial antigens on the cellulose carrier results in stabilization and retaining of their antigenic properties for a long time – a feature important for vaccine standardization and storage. A low cost of cellulose sorbents and a unique option to use cellulose for both antigen purification and immobilization should result in an essential decrease of manufacture cost. The capacity of cellulose microparticles to serve the adjuvant component of a subunit TB vaccine will be tested with a set of recombinant proteins from M. tuberculosis with an established record of protectivity in mixtures with conventional adjuvants: Ag85A, MPT64, ESAT-6 and Cfp10. In addition, we intend to select and further test artificial antigens consisting of 2 – 3 immunodominant epitopes from the most protective vaccine candidates fused into a single product with a CBD and immobilized on cellulose microparticles. All novel vaccines developed within the frames of this proposal will be tested in a well-established mouse model in the lab of Dr. Alexander Apt (Central Institute for Tuberculosis, Moscow, Russia). Protective effect in mice vaccinated with mono- and oligo-component experimental cellulose-bounded vaccines will be compared to that in animals vaccinated with identical antigens in IFA and/or MPL/DDA adjuvants, as well as with BCG (golden standard). Sham-vaccinated (adjuvant alone) mice will serve negative controls. CFU counts in lungs and spleens, as well as mean survival time, will be compared between experimental groups. To assess whether or not cellulose-based adjuvant is less reactogenic and more safe than traditional adjuvants, gross pathology and histological changes in skin and lymph nodes draining the site of inoculum will be examined. Once particular vaccine preparation(s) is proved to be highly protective and safe, key immunological parameters (e.g., IFN- production, macrophage effector function), in response to vaccination will be evaluated in corresponding group(s) of mice and compared with control groups.