Channel catfish virus gene expression in experimentally infected channel catfish, Ictalurus punctatus (Rafinesque)

Area of Science:

• Aquatic animal health
• Virology
• Molecular biology

Background:

• Channel catfish virus (CCV) causes significant disease in channel catfish.
• CCV establishes latent infections in survivors of acute disease.
• Understanding CCV gene expression is crucial for disease management.

Purpose of the Study:

• To investigate CCV gene expression in various tissues of experimentally infected channel catfish.
• To detect viral transcripts during acute and latent infection stages.
• To lay the groundwork for studying CCV pathogenesis and latency.

Main Methods:

• Development of reverse transcriptase polymerase chain reaction (RT-PCR) assays for CCV direct repeat region genes.
• Analysis of CCV gene expression in CCV-infected channel catfish ovary cells.
• Detection of viral transcripts in blood, brain, kidney, and liver tissues of infected fish.

Main Results:

• Immediate-early, early, and late CCV gene transcripts were detected in multiple tissues during acute infection, indicating active viral replication.
• No evidence of viral replication was found in surviving fish by 24 days post-infection.
• Viral latency-associated transcripts were not detected in latently infected catfish.

Conclusions:

• CCV actively replicates in multiple host tissues during the acute phase of infection.
• Evidence suggests that CCV does not maintain active replication or latency-associated transcription in surviving fish.
• Further research is needed to elucidate the molecular mechanisms underlying CCV pathogenesis and latency.