Animal Testing in Malaria Research – Refine, Reduce, Replace

How the Levashina Lab at the Max Planck Institute for Infection Biology is reducing and replacing animal testing in malaria research
 

The malaria parasite has been known for over a century and is still deadly, remaining a persistent threat. Every year, over 280 million people worldwide contract malaria, with half a million fatalities. The parasite has a complex life cycle within humans and the mosquito that transmits it. For this reason, many research questions can only be answered through experiments on living organisms.

In the early years of malaria research, discoveries were often made through human experiments in colonial contexts—people were infected with malaria without their consent or knowledge. Today, humans are only infected with malaria for specific research questions, such as testing vaccines. These trials are highly controlled: participants are thoroughly informed about the trial before giving their consent and receive medical care to ensure they do not become ill.

For many other research questions, living organisms are still needed—which is why researchers use animal experiments, for example with mice. In malaria research, animal models are essential for the approval of safe drugs and vaccines. Through basic research, they have greatly advanced our understanding of the parasite’s biology. They are also used to breed mosquitoes and the parasite. However, wherever possible, we want to reduce the number of animal experiments.

On both World Day for Laboratory Animals and World Malaria Day, we are therefore sharing four methods the Levashina Lab at the Max Planck Institute for Infection Biology uses in malaria research without animal testing, as well as to reduce the number of animals and levels of suffering caused by experiments.

How we feed mosquitoes with blood

Blood provides important nutrients, such as fats, proteins, and sugars, for the development of mosquito eggs. For this reason, only female mosquitoes feed on blood. We obtain the blood from a blood bank, where volunteers, in addition to their regular blood donation, consent to provide two small tubes containing a few millilitres of blood to support our research. Each year, blood of 1,000 donors amounts to 900,000 blood meals for our mosquitoes. Depending on the type of parasite, research groups also use animals as a blood source. For example, mice are still used in experiments with the mice-specific malaria parasite.

How we infect mosquitoes with malaria parasites

High safety standards are required for the transmission of the parasite to the mosquitoes to ensure that no one is at risk of infection. At the same time, the conditions for the tropical mosquitoes must be replicated. At tropical temperatures of 28 °C and 70% humidity, mosquitoes and parasite-infected blood are handled in an infection box by specially trained personnel wearing protective clothing.

How we breed malaria parasites

Red blood cells are the major factories of malaria parasites in the human. Cell division produces 10–100 trillion new parasites within two weeks. We replicate this so-called blood stage in a cell culture dish. For this, we also use donated human blood. 

How we test the efficacy of malaria vaccine candidates

Before a vaccine is administered to humans, researchers must first establish its safety and efficacy. Animal models are indispensable for this purpose and are required by law. However, it is not possible to determine whether a malaria vaccine prevents infection in humans through animal testing alone. Further experiments involving the human malaria parasite are necessary.

We have developed a test that measures the potency of a vaccine candidate to block the malaria parasite. This enables us to compare the properties of multiple vaccine candidates. For this purpose, a blood sample collected from vaccinated laboratory animals or human subjects is sufficient for the test. Although animal vaccination and blood sample collection are considered animal testing procedures, these procedures are safer than infection with the malaria parasite. While the test does not replace animal or human trials, it improves the quality of life of the subjects.