Our malaria-fuelled nightmares could soon be a horror of the past, as a key breakthrough has been made into developing a human vaccine. Malaria currently has the second highest mortality rate of any infectious disease, killing over 500,000 people in 2013 alone. It’s spread throughout the tropics by the female Anopheles mosquito which is a vector for the Plasmodium parasites that causes the disease.
Dr Richard Bucala identified the macrophage migration inhibitory factor (PMIF), an essential protein unique to Plasmodium which gives malaria its potency by suppressing memory T cells. These T cells are a key component of the immune system that acts as immunological memory; after a first infection, these cells remain in the circulation of the body to respond to any subsequent reinvasions by the same disease. They are essential to our immune system as any future invasions by the same infection will be dealt with much more swiftly than the first time. This could help to explain why infected individuals only develop partial immunity against malaria.
Malaria currently has the second highest mortality rate of any infectious disease, killing over 500,000 people in 2013 alone
Dr Bucala, working alongside with Novartis Vaccines Inc., has published results of a potential vaccine to target the aforementioned PMIF protein. To begin, the PMIF gene that synthesises the protein was deleted, and already infected mice were re-infected with Plasmodium. Results showed a stronger immune response to the infection thus demonstrating the proof of the PMIF concept. Developing on these promising results, they created two models, one with an early-stage liver infection from mosquito parasites and another with a late-stage blood infected, and successfully vaccinated both against reinfection. Finally, the team transferred the memory T cells the immunised mice developed to mice that hadn’t been infected, who didn’t develop malaria when they were infected. This study highlights the effectiveness of the anti-PMIF vaccine, and Bucala hopes it’ll be used as a malaria vaccine for uninfected children.
As malaria is spread by the mosquito, its geographical distribution is defined by the mosquitoes’ habitat. There is great concern amongst epidemiologists as the overall increase in global temperature will see the transmission rates of mosquito-borne diseases like malaria increase. There is direct evidence of this phenomenon already as nine years ago, a team from the Kenyan Medical Research Institute concluded that a seven-fold increase of outbreaks in the Central Highlands of Kenya could only be attributed to temperature rises. If that is a harbinger of what is to follow, then a malaria vaccine is just what’s needed.