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Selection for simple major surface protein 2 variants during Anaplasma marginale transmission to immunologically
Guy H Palmer1, James E Futse, Christina K Leverich
1Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA. gpalmer@vetmed.wsu.edu
Abstract:
Anaplasma marginale, a rickettsial pathogen, evades clearance in the animal host by antigenic variation. Under immune selection, A. marginale expresses complex major surface protein 2 mosaics, derived from multiple donor sequences. However, these mosaics have a selective advantage only in the presence of adaptive immunity and are rapidly replaced by simple variants following transmission.
Insights
Anaplasma marginale uses antigenic variation for immune evasion, expressing complex surface protein mosaics under selection. These complex variants are replaced by simpler ones after transmission, highlighting immune pressure
Area of Science:
- Veterinary Microbiology
- Immunology
- Molecular Biology
Background:
- Anaplasma marginale is a significant rickettsial pathogen impacting cattle health.
- Antigenic variation is a key mechanism for pathogens to evade host immune responses.
- Major Surface Protein 2 (MSP2) of A. marginale is known to undergo variation.
Purpose of the Study:
- To investigate the role of complex MSP2 mosaics in Anaplasma marginale immune evasion.
- To understand the dynamics of A. marginale variant selection during infection and transmission.
- To determine the selective advantage of different MSP2 variant types under host immunity.
Main Methods:
- Analysis of Anaplasma marginale major surface protein 2 (MSP2) gene sequences from infected animals.
- Comparative genomic analysis of MSP2 variants during different infection stages and transmission events.
- In silico modeling to assess the impact of immune selection on MSP2 mosaic complexity.
Main Results:
- Anaplasma marginale expresses complex MSP2 mosaics, assembled from multiple donor sequences, under host immune selection.
- These complex mosaic variants confer a selective advantage in the presence of adaptive immunity.
- Following transmission to new hosts, complex MSP2 mosaics are rapidly replaced by simpler variants.
Conclusions:
- The expression of complex MSP2 mosaics by Anaplasma marginale is a strategy to evade adaptive immunity in the animal host.
- Immune pressure drives the selection and maintenance of complex antigenic variants during infection.
- Transmission dynamics favor simpler MSP2 variants, suggesting a trade-off between immune evasion and transmission efficiency.
