Back to the future for antiparasite vaccines?

Abstract

[Extract] In a recent review on forward and reverse gazing in vaccinology, Stanley and Susan Plotkin noted that, As the development of vaccines continues in the 21st century … it is useful to contemplate the past. This is all the more true because there is a great deal of forward gazing, with an explosion of new potential strategies for vaccine development based on genetic engineering, and the hope that systems biology and structural biology will tell us which genes must be upregulated or downregulated and what antigenic constructions are needed to achieve a protective immune response … However, as the future unfolds, the past is sometimes deprecated… [1]. While their article went on to focus primarily on vaccines for viruses and bacteria, the same philosophies hold true (and perhaps are even accentuated) for parasites. It is generally accepted that it is easier to develop a vaccine against a disease where protective immunity develops naturally and rapidly after early exposure(s). This is the case for many of the bacterial and viral diseases for which vaccines exist. The eukaryotic parasites of humans, however, are a formidable opponent, and effective immunity, if it develops at all, is slow to progress and is by no means sterilizing in many individuals. For the purposes of this editorial, we will focus on some of the most important blood-feeding parasites of humans – the single-celled apicomplexan parasite Plasmodium (the cause of malaria) and the multicellular helminths (hookworms and schistosomes). Together, these parasites cause more than 1 million deaths per year and while drugs are available, they need to be administered frequently to prevent reinfection, and development of drug resistance is a major concern that has fuelled research efforts into vaccine development.