The Concept of Developing a Plasmodium vivax Malarial Vaccine with a Focus on its Pre-erythrocytic Stage

Abstract

Plasmodium vivax, one of the most prevalent human malarial parasites, continues to cause significant morbidity for hundreds of millions worldwide. Due to increasing drug resistance and vivax specific relapses, immunoprophylaxis signifies a key control strategy in efforts to eradicate malaria worldwide. By far, the circumsporozoite protein (CSP) based vaccines are being developed since the 1980’s. However, they have produced major limitations in eliciting partial immune responses towards the parasite. Nevertheless, the Long Synthetic Peptides (LSP’s) and Vivax Malarial Protein 001 (VMP001) have produced considerable amount of immune responses and are currently undergoing phase 1 clinical trials according to several studies. Recent developments of a Virus-like particle (VLP) was found to be an efficacious vaccine candidate against a human sporozoite challenge model. The VLP’s elicited high antibody titers that remained consistent for a number of days but eventually decreased. In addition, vaccine candidates such as the VLP’s are currently being used to target CSP based–antigens such as the Cell-Traversal Proteins to obstruct hepatocyte invasion by sporozoites. However, substantial humoral and cellular immune responses were not produced to alleviate this process. Further research of these vaccine candidates as well as to analyze its effects towards specific CSP based antigens would immensely contribute to move clinical development forward and to further identify mechanism of immunity.