Incomplete dsRNA genomes in purified infectious pancreatic necrosis virus

Area of Science:

• Virology
• Molecular Biology
• RNA Replication

Background:

• Infectious pancreatic necrosis virus (IPNV) is a double-stranded RNA (dsRNA) virus.
• IPNV possesses a virion-associated RNA-dependent RNA polymerase crucial for RNA synthesis.
• Previous studies indicated this polymerase acts as both primer and polymerase in vitro.

Purpose of the Study:

• To investigate the nature of radiolabeled RNA synthesized in vitro by IPNV.
• To characterize the composition and structure of viral RNA products.
• To elucidate implications for dsRNA virus replication mechanisms.

Main Methods:

• In vitro radiolabeling of virion RNA using [alpha 32P]GTP.
• Deproteinization followed by agarose gel electrophoresis (AGE) of labeled RNA.
• Northern blot hybridization with strand- and end-specific oligonucleotides.
• Denaturation of RNA prior to AGE.
• Reverse transcription-polymerase chain reaction (RT-PCR) with specific primers.

Main Results:

• Radiolabeled RNA products migrated with dsRNA genome or as a faster-migrating heterogeneous smear.
• The dsRNA-migrating fraction contained small (100-500 nucleotides), 5' end plus RNA molecules.
• The smear represented incomplete dsRNAs with full-length minus strands and 3' truncated plus strands (95% of cases).
• RT-PCR confirmed the presence of full-length minus strands and truncated plus strands in incomplete dsRNAs.

Conclusions:

• IPNV produces significant amounts of incomplete dsRNA during in vitro RNA synthesis.
• These incomplete dsRNAs consist primarily of full-length minus strands and 3' truncated plus strands.
• Findings provide insights into the RNA replication strategy of dsRNA viruses.