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Complement evasion by apicomplexans: Convergent strategies across diverse parasites
Sofía Espinosa-Hernández1, Carlos J Ramírez-Flores1
1Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico.
Plos Pathogens
|July 17, 2026
Summary
Apicomplexan parasites evade the host complement system by modulating its activity, not inhibiting it. Four key strategies, including C3 regulation, ensure parasite survival during infection.
Area of Science:
- Parasitology
- Immunology
- Molecular Biology
Background:
- Apicomplexan parasites face the host complement system during extracellular infection stages.
- Complement activation leads to pathogen elimination via opsonization, inflammation, and membrane attack complex (MAC) formation.
Purpose of the Study:
- To define a unifying framework for apicomplexan complement evasion strategies.
- To understand how apicomplexans modulate complement activity for survival.
Main Methods:
- Analysis of apicomplexan strategies for modulating complement.
- Identification of mechanisms regulating complement activation and C3 deposition.
Main Results:
- Apicomplexans employ distinct but convergent strategies to modulate complement, rather than fully inhibiting it.
- Key strategies include rapid invasion, recruitment of host regulatory proteins, surface shielding, and direct interference with complement activation.
- Regulation of C3 deposition and processing is central to these evasion mechanisms.
Conclusions:
- A unifying framework for apicomplexan complement evasion is proposed, based on four core mechanisms.
- These strategies allow apicomplexans to persist despite the host complement system's barrier.
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