[Persistence of Newcastle disease virus in mouse cells]

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Newcastle disease virus (NDV) can establish persistent infections in host cells.
• Understanding the mechanisms of persistent viral infections is crucial for developing therapeutic strategies.

Purpose of the Study:

• To analyze the characteristics of persistent Newcastle disease virus (NDV) infection in mouse L cells (LNDV).
• To investigate the state of viral genetic material and infectious virus production during persistent infection.

Main Methods:

• Infection of mouse L cells with NDV to establish persistent infection (LNDV).
• Quantification of infectious intra- and extracellular virus production.
• Analysis of viral antigen production using immunofluorescence.
• Detection and characterization of viral RNA synthesis.
• Extraction of DNA using Hirt's method to identify virus-specific sequences.

Main Results:

• Markedly reduced production of infectious NDV (less than 10(1) PFU/ml) in LNDV-infected cells.
• Approximately 30% of cells produced virus-specific antigen.
• Predominance of low molecular weight RNAs during NDV replication.
• Virus-specific DNA sequences were detected in Hirt's DNA fraction.
• Infectious viral material was exclusively found in the 'supernatant' Hirt's fraction.

Conclusions:

• Persistent NDV infection is characterized by significantly impaired infectious virus release.
• The presence of virus-specific sequences in the supernatant Hirt's fraction suggests the potential for free, unintegrated viral DNA.
• Further investigation is warranted to elucidate the role of unintegrated viral sequences in persistent NDV infections.