Targeting T Cell-Mediated Immune Response in Malaria Vaccination

Vaccination is an effective way of preventing infectious disease. It introduces an antigen, derived from a disease-causing organism, which stimulates the immune system to develop protective immunity against that pathogen. Plasmodium falciparum malaria claimed about 0.8 million deaths, and more than 200 million cases are reported each year. Previous vaccine strategies aimed at high-titer functional antibodies to protect against malaria infection gave only discouraging results despite sustained efforts over many years.

Recently, T cell responses are found to be protective against blood-stage parasites independent of antibodies in human, non-human primate and mouse models. However, no malaria vaccine trial reported to date was designed to induce T cell responses against blood-stage malaria pathogen, until the present research article published in Molecular Therapy.

In this article, the authors tested a chimpanzee adenovirus 63 vector carrying Plasmodium falciparum blood stage antigen MSP1, with or without later boosting by a modified vaccinia virus Ankara (replication deficient) vector carrying MSP1. The study was conducted in 16 health volunteers. Quite encouragingly, researchers found that the vaccine was safe and generally well tolerated in both low and high dose, with only few adverse events. Importantly, the vaccine induced extraordinary strong T cell responses as well as substantial serum immunoglobulin G antibody.

This study paves the way for a novel vaccine strategy for malaria. This same strategy may be applicable for vaccine development against HIV-1 or cancer. Future studies will be designed to demonstrate actual protection against malaria infection.