A block in full-length transcript maturation in cells nonpermissive for B19 parvovirus

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Vertebrate parvoviruses exhibit conserved genomic organization with distinct left-side nonstructural and right-side structural genes.
• Gene expression regulation in parvoviruses involves temporal and cell-specific mechanisms, differing between species like rodent parvoviruses and human B19 parvovirus.

Purpose of the Study:

• To investigate the regulatory mechanisms governing the alternative processing of human B19 parvovirus transcripts.
• To elucidate the role of postinitiation events and 3' processing signals in determining viral RNA abundance.

Main Methods:

• Sensitive RNA analyses were performed on wild-type and mutant human B19 parvovirus templates.
• Experiments involved assessing RNA transcript levels in both permissive and nonpermissive cell types.
• Mutations were introduced to disrupt 3' processing signals and polyadenylation sites within the viral genome.

Main Results:

• Human B19 parvovirus utilizes a single promoter for both left- and right-side transcripts, requiring extensive processing.
• In permissive cells, structural gene transcripts (right-side) are more abundant than nonstructural gene transcripts (left-side).
• In nonpermissive cells, nonstructural gene transcripts predominate, and disruption of 3' processing signals or polyadenylation sites alters transcript ratios and readthrough.

Conclusions:

• The abundance of human B19 parvovirus RNAs is actively controlled by 3' processing events.
• RNA processing is coupled to DNA template replication, influencing viral gene expression.
• These findings highlight unique postinitiation regulatory mechanisms in human B19 parvovirus RNA metabolism.