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Small variant STEVOR antigen is uniquely located within Maurer's clefts in Plasmodium falciparum-infected red blood
M Kaviratne1, S M Khan, W Jarra
1Division of Parasitology, National Institute for Medical Research, London, United Kingdom.
Abstract:
Malaria parasite antigens encoded by multigene families are important factors in virulence and in disease pathology. In Plasmodium falciparum, the virulence factor PfEMP-1 is encoded by the var multigene family and is exposed at the infected erythrocyte surface. PfEMP-1 is clonally variant, allowing the parasite to evade host immunity. The recently identified P. falciparum stevor multigene family and its products also have the potential to be involved in similar important aspects of host-parasite interactions. Here, we show tightly regulated stage-specific transcription of stevor occurring over just a few hours of the asexual parasite life cycle. Only a subset of stevor genes are transcribed in parasite populations maintained in cultures and in single micromanipulated parasites. Antibodies against STEVOR recognize proteins of the expected size (approximately 37 kDa) and localize STEVOR in Maurer's clefts, unique membranous structures located in the cytoplasm of infected erythrocytes. The fact that the timing of stevor expression and the location of STEVOR are clearly distinct from those of other parasite variant antigens suggests that this gene family may have a novel role in P. falciparum biology.
Insights
The Plasmodium falciparum stevor gene family shows tightly regulated, stage-specific transcription during the asexual parasite life cycle. STEVOR proteins are located in Maurer's clefts, suggesting a novel role distinct from other variant antigens.
Area of Science:
- Malariology
- Molecular Parasitology
- Immunology
Background:
- Malaria parasite antigens, like PfEMP-1 from the var gene family, are crucial for Plasmodium falciparum virulence and immune evasion.
- The recently identified stevor multigene family in P. falciparum also holds potential significance in host-parasite interactions.
Purpose of the Study:
- To investigate the transcriptional regulation and protein localization of the P. falciparum stevor gene family.
- To determine if stevor family members play a role in parasite virulence and host immune evasion.
Main Methods:
- Analysis of stevor gene transcription during the asexual parasite life cycle.
- Detection and localization of STEVOR proteins using antibodies in infected erythrocytes.
- Characterization of STEVOR protein size and cellular location.
Main Results:
- Stevor exhibits tightly regulated, stage-specific transcription within a narrow window of the asexual parasite life cycle.
- Only a subset of stevor genes are transcribed in cultured parasites and single cells.
- Antibodies recognize STEVOR proteins of approximately 37 kDa, localizing them to Maurer's clefts within infected erythrocytes.
Conclusions:
- The distinct temporal expression and cellular localization of STEVOR differentiate it from other P. falciparum variant antigens.
- The stevor gene family likely possesses a novel function in P. falciparum biology, potentially distinct from established virulence mechanisms.
- Further research is warranted to elucidate the precise role of STEVOR in malaria pathogenesis.