A primate model of severe malarial anaemia: a comparative pathogenesis study

Area of Science:

• Immunology
• Parasitology
• Hematology

Background:

• Severe malarial anaemia (SMA) is a major cause of mortality in African children infected with Plasmodium falciparum.
• SMA pathogenesis involves haemolysis, impaired red blood cell production, inflammation, and reduced complement regulatory proteins like CD35.
• Improved animal models are needed to understand SMA mechanisms.

Purpose of the Study:

• To compare the pathogenesis of Plasmodium coatneyi infection in rhesus macaques and cynomolgus macaques to identify factors associated with severe malarial anaemia (SMA).

Main Methods:

• Comparative study of two macaque species (rhesus and cynomolgus) infected with blood-stage Plasmodium coatneyi.
• Monitoring of haematological parameters, including haematocrit and reticulocyte production.
• Assessment of haemolysis via haptoglobin consumption.
• Quantification of inflammatory responses.
• Measurement of CD35 levels on red blood cells (RBCs) at baseline and during infection.

Main Results:

• Rhesus macaques developed SMA within 2 weeks, characterized by a sharp drop in haematocrit, haptoglobin consumption, and poor reticulocyte production.
• Cynomolgus macaques exhibited only mild to moderate anaemia.
• Rhesus macaques showed a greater inflammatory response compared to cynomolgus macaques.
• Rhesus macaques had lower baseline CD35 levels on RBCs, with a significant reduction during infection.

Conclusions:

• Rhesus macaques infected with P. coatneyi serve as a relevant model for studying severe malarial anaemia (SMA) in children.
• Low baseline CD35 levels on RBCs and early inflammatory responses are associated with SMA pathogenesis.