April 15, 2024

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New mRNA malaria vaccine effectively prevents infection and transmission

New mRNA malaria vaccine effectively prevents infection and transmission



 

New mRNA malaria vaccine effectively prevents infection and transmission. 


Malaria is caused by the continuous proliferation of Plasmodium falciparum in human red blood cells and is mainly transmitted through mosquito bites .

Malaria has long been raging in tropical developing countries such as Africa, southern Asia, and South America, causing huge casualties and economic losses.

The discovery and use of artemisinin and its derivatives saved the lives of tens of millions of people, for which Tu Youyou won the 2015 Nobel Prize in Physiology or Medicine.

 

However, malaria remains a major public health problem worldwide. Nearly 3.2 billion people in 89 countries are at risk of contracting malaria, accounting for almost half of the world’s population.

There are more than 200 million recorded cases of malaria infection and 400,000 deaths each year, most of them children .

 

In recent decades, scientists have been working on the development of anti-malaria vaccines, hoping to eradicate malaria at its root and build a malaria-free world, but these efforts have not achieved good results.

 

Limitations of previous malaria vaccines prompted scientists to develop malaria vaccines based on the new platform.

The success of mRNA vaccines in COVID-19 field highlights the huge advantages of the mRNA technology platform: highly targeted design, flexible and rapid manufacturing, and strong immune response capabilities.

Therefore, a research team began to explore malaria vaccines based on mRNA technology.

 

On July 20, 2023, the journal Nature Immunology published a research paper entitled: mRNA vaccine against malaria tailored for liver-resident memory T cells .

The study developed an mRNA malaria vaccine that effectively targets and stimulates a protective immune cell response against the malaria-causing Plasmodium parasite in preclinical animal models.

 

New mRNA malaria vaccine effectively prevents infection and transmission

 

 

Malaria is caused by plasmodium transmitted by anopheles mosquito.

After the anopheles mosquito bites the skin, the plasmodium sporozoites it carries migrate from the skin to the liver and replicate extensively in the liver (liver stage), and then appear in the form of merozoites, which can infect red blood cells and cause disease symptoms ( blood – stage ) .

 

Since liver tissue- resident memory T cells (Trm cells) were recently shown to control the liver-phase infection of malaria, the research team initiated an mRNA-based vaccine development strategy to induce liver Trm cells to prevent malaria .

 

The study found that, although mRNA vaccination could induce circulating memory CD8 T cells (Tem cells and Tcm cells) , it was relatively ineffective in inducing hepatic Trm cells and did not protect mice from Plasmodium sporozoite challenge. But this deficiency can be overcome by adding natural killer T cell ( NKT cell ) agonists.

 

The classic NKT cell agonist α-galactosylceramide ( αGC ) , also known as KRN7000, is a relatively weak hepatic Trm cell-inducing adjuvant.

However, chemical modification of the molecule produced a potent response that significantly generated hepatic Trm cells, enabling the targeting of the mRNA vaccine response to the liver, a critical site for preventing malaria parasite development and maturation in vivo .

 

New mRNA malaria vaccine effectively prevents infection and transmission

 

 

When the malaria parasite first infects, it travels to the liver, where it develops and matures, before infecting red blood cells, which is when malaria symptoms appear, the research team said .

Unlike previous mRNA COVID-19 vaccines that work by expressing neutralizing antibodies, the study’s unique approach relies on T cells that play a key role in immunity – liver tissue-resident memory T cells, which can block malaria infection in the liver, thereby preventing the spread of the infection entirely .

 

The main advantage of the vaccine is that it is not affected by previous exposure to malaria .

Many malaria vaccines in clinical trials protect well in naïve animal models or humans, but do not work as well when vaccinated in people in malaria-endemic areas.

But the malaria vaccine developed by the study was still able to generate protective liver-specific immune cells, which provided protection even after prior exposure to the malaria parasite.

This suggests that the mRNA approach developed in this study may be more effective in malaria-endemic areas, generating a broader and more promising protective immune response.

 

It is reported that the research team is currently working to advance this vaccine to human clinical trials, but it is expected to take several years.

 

 

 

Paper link

New mRNA malaria vaccine effectively prevents infection and transmission

(source:internet, reference only)


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