Rules governing genetic exchanges among viral types from different Enterovirus A clusters

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Enterovirus A (EV-A) comprises conventional and unconventional types.
• Previous sequence analysis indicated no recombination between these clusters.
• The genetic factors preventing recombination were previously unknown.

Purpose of the Study:

• To investigate the genetic barriers to recombination between conventional and unconventional EV-A types.
• To identify specific viral genome components responsible for the observed genetic isolation.

Main Methods:

• Utilized viral reverse genetics tools for systematic genome dissection.
• Assessed capsid expression and trans-encapsidation efficiency across EV-A types.
• Constructed and evaluated replication-competent replicons with exchanged genomic regions.
• Generated a recombinant virus (EVA71) with a modified P3 region.

Main Results:

• Unconventional EV-A types exhibited poor capsid expression in human cells.
• Trans-encapsidation between conventional and unconventional EV-A types showed low efficiency.
• Replicons with exchanged 5'-untranslated regions (UTR) or non-structural regions from unconventional types were replication-competent.
• A viable recombinant EVA71 with an unconventional P3 region was successfully created.

Conclusions:

• Demonstrated the potential for genetic exchange between conventional and unconventional EV-A types.
• Identified uncoordinated capsid expression and particle assembly as potential recombination barriers.
• Opened new avenues for studying EV-A evolution and generating novel viral strains.