Malaria

The malaria group chiefly carries out research and is also involved in standardisation. NIBSC stocks a range of reference materials for malaria and other parasitology products.

Malaria is caused by parasites of the genus Plasmodium transmitted by the bite of infected mosquitos. In humans, malaria is caused by 5 species, of which P. falciparum and P. vivax are the most common.

There were about 207 million cases of malaria in 2012 worldwide and around 627,000 deaths – mostly children under the age of 5 in sub-Saharan Africa.

Vaccination and treatment

The furthest developed candidate vaccine for malaria is RTS,S/AS01.

There is a range of medicines to treat the disease, the most widespread being artemisinin combination therapy (ACT). But, in common with most malaria medications, there are signs that the parasite is developing resistance, putting this element of control programmes at risk.

At NIBSC, as well as producing standards for diagnostics and serology analysis, we are harmonising parasite growth assays and performing research into how the parasite adapts and continues to thrive in the presence of multiple different control strategies

Research 

Our aim is to understand the consequences of red cell heterogeneity, both in terms of age and genotype for the growth of P. falciparum in culture. We are investigating how this relates to growth inhibition and invasion assays, and how the parasite adapts to changing environments.

Characterisation of invasion assays

Plasmodium falciparum invasion assays commonly involve quantifying the effect that enzyme treatment of red blood cells has on the ability of the parasite to invade them. Our work will define more closely the effects of enzyme treatments on the surface of red blood cells. We will investigate if there is an order in which receptors are removed and how partial removal then affects parasite invasion.

Adaptability of the malaria parasite

Changes in the host erythrocyte population are features that parasites encounter both in vitro – as blood batches change – and in vivo, as parasites go from host to host.

In vitro, parasites can adapt to artificial changes in the erythrocyte population with variation at the genetic transcript and protein level. Parasites that are at least partially resistant to enzyme treatment of erythrocytes can be selected.

In vivo, sexual recombination happens as the parasite moves from human to human – providing one source of adaptability – but the parasite may still need to adapt to immune pressure once an asexual stage infection is established.

We will explore how the malaria parasite can adapt to a changing environment, and how rapidly that happens.

European Research Infrastructures for Poverty Related Diseases (EURIPRED)
 

EURIPRED is a collaborative infrastructure programme which aims to reinforce the knowledge infrastructure across diseases.

Alongside EURIPRED we are harmonising malaria in vitro growth inhibition assays and serology assays. We are also planning production of antigens, proteins, antibodies, and peptide arrays for dissemination to the research community.

Development of biological reference reagents

NIBSC produces a range of reference reagents for malaria research. We are supporting available materials with further evaluation across a wider range of antigens representing pre-erythrocytic stages as well as sexual and asexual blood stages. These include:

• pooled serum from Kenyan adults with strong cross-reactivity for the malarial apical membrane antigen 1 (AMA-1) which is in the final stages of preparation
• research reagents (non-catalogue items): new and existing sera samples are being characterised with the aim of identifying species-specific reagents as well as potency evaluation relative to the reference reagent