A rational approach for predicting the minimum composition of anti-parasite sub-unit vaccines: a multiple target vaccine hypothesis

Abstract

The present article introduces a new concept, termed a multiple vaccine target hypothesis (MVTH) for determining the minimum number of vaccine targets (epitopes/antigens) necessary to construct a highly efficacious (greater than 90%) anti-parasite vaccine. Drawing inspiration from the Metabolic Control Analysis (MCA) and immunological reasoning it is proposed that for a multi-stage parasite an effective anti-parasite vaccine will necessarily act on more than one stage of the parasite in the definitive host. It is argued that the minimum number of sub-unit targets for a highly efficacious anti-parasite vaccine will vary from one parasite to the other and will be equal to twice the number of major parasite stages occurring in the human host. Quantitatively stated, C_v=2n where C_v the number of required targets is, and n represents the number of major parasite stages in the definitive host. Conditions when the value of C_v may deviate from what is predicted by the formula given above are discussed. Extensive literature search on malaria, onchocerciasis and schistosomiasis sub-unit vaccine development suggests that subunit vaccines constructed from single components and directed to just one parasite stage are less efficacious that multivariate sub-unit vaccines, and obviously whole parasite vaccines. MVTH therefore provides a rational framework for constituting a sub-unit anti-parasite vaccine.

Keywords: Vaccine, malaria, Onchocerca volvulus, schistosomiasis, parasite, equation