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On August 22, 2016 at 11:00-12:00 hr.

"Viagra makes Plasmodium stiff: a new way to block malaria parasite transmission?"

On August 23rd 2016, Dr Catherine Lavazec of the Institut Cochin, Paris, gave a lunch talk titled “Viagra makes Plasmodium stiff: a new way to block malaria parasite transmission?”. Dr Lavazec is head of the Biology of Plasmodium Transmission Team at the French biomedical research institute and her part of her recent work has been demonstrating the effectiveness of Viagra in controlling gametocyte rigidity.

The talk started with a brief overview of the background information, including the life cycle of Plasmodium falciparum, the sequestration of gametocytes and the observed switch in deformability between maturation and circulation stages. Dr Lavazec explained that the observation that infected erythrocytes are ‘stiff’ before they are released but then deformable in the circulation stage, led her team to wonder if targeting this switch in deformability could be a way to prevent transmission. They proposed that increasing stiffness would decrease transmission.

Dr Lavazec’s team showed that the gametocyte deformability could be modified both genetically and chemically (for more details see the links below). They proposed a model of regulation of the erythrocyte stiffness through the introduction of a PDE inhibitor. To test this proposal they chose the two most famous PDE inhibitors – Viagra and Cialis – drugs more commonly prescribed for erectile dysfunction.

Dr Lavazac discussed the results from a 2015 paper that showed that these drugs did affect gametocyte deformability. It was shown that they significantly decreased infected gametocyte circulation. Dr Lavazac was keen to point out that her team are not suggesting everyone should take Viagra to prevent malaria! She emphasized that this work is a proof of principle that deformability of gametocytes is targetable by a drug.

The latter part of the talk focused on further testing of the concept. There is a pilot study underway in Cambodia which observes gametocyte clearance, following malaria patients for one month to ensure effects are not only short term. Additionally, there is a need to develop an in vivo model. A humanized mouse model has been developed and tested. Dr Lavazec gave a brief overview of the method of developing the model and the encouraging results of testing; the full details will be soon published in a paper by Duffier et al.

Dr Lavazec finished her talk by repeating the need for an effective way to prevent malaria transmission as a key part of the malaria elimination strategy. She hopes that her team’s work will lead to a novel multi-stage antimalarial drug with therapeutic and transmission-blocking activity.

The questions after the talk were insightful and in depth. They highlighted some of the differences of opinions in the research field and also gave Dr Lavazec an opportunity to talk about her team’s future plans and publications. We thank Dr Lavazec for her interesting talk and look forward to hearing more about her innovations in the future.

Links to articles mentioned in Dr Lavazec’s talk –

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