Studies on dicistronic polioviruses implicate viral proteinase 2Apro in RNA replication

Area of Science:

• Virology
• Molecular Biology
• Biochemistry

Background:

• Poliovirus replication relies on polyprotein processing by viral proteinases.
• The proteinase 2Apro's role in viral replication beyond proteolytic processing was unclear.
• Internal ribosomal entry site (IRES) elements can disrupt normal polyprotein processing.

Purpose of the Study:

• To investigate the non-proteolytic functions of poliovirus proteinase 2Apro in viral replication.
• To determine the necessity of 2Apro for poliovirus RNA synthesis.
• To analyze the impact of altering 2Apro's function on viral replication and phenotype.

Main Methods:

• Construction and transfection of dicistronic poliovirus constructs with modified 2Apro.
• Assessing viral RNA replication using reverse transcription/PCR.
• Observing viral replication, cytopathic effects, and virus recovery.

Main Results:

• Deletion of 2Apro abolished viral RNA replication.
• Partial deletion or catalytic site mutation of 2Apro reduced RNA replication.
• A novel dicistronic virus with an EMCV IRES showed a small plaque phenotype, indicating P2 polypeptide and 2AB are not essential.

Conclusions:

• Poliovirus proteinase 2Apro is essential for viral RNA replication.
• The catalytic activity of 2Apro is crucial for RNA synthesis.
• Viral proliferation does not require the intact P2 polypeptide or the 2AB cleavage fragment.