Genetic vaccines to elicit T-cell immune responses

All existing vaccines work by generating an antibody response. It is now clear, however, that an antibody response is insufficient for protecting against many diseases, for which a T cell-based immune response is also needed.

The most relevant T-cell population for the clearance of intracellular pathogens and the elimination of tumour cells are cytotoxic CD8 T-cells. Evidence of a major role of CD8 T-cells in the protection or treatment from infection has been obtained for a number of infectious diseases, including HIV, hepatitis C, malaria, influenza, respiratory syncytial virus and cytomegalovirus, as well as for the regression of some tumours.

The best way to elicit a CD8 T-cell response against an antigen is to deliver the gene coding for the antigen. This forms the basis of a genetic vaccine, containing a segment of DNA encoding a specific antigen, delivered to the body either as naked DNA or encapsidated in a viral particle. The body’s cells, usually muscle, then make the corresponding protein antigen.

At Okairos, we have shown that our proprietary adenovirus vector technology is capable of stimulating a highly potent CD8 T-cell response, both preclinically and now in the clinic. This potent property of our vectors, combined with their ability to also stimulate a robust humoral response, creates a robust and balanced immune response that holds the potential to address disease where historical vaccine technologies have failed.

Our corporate presentation (pdf) provides further information on the strength and quality of the immune response elicited by our vectors.