Translational control in murine hepatitis virus infection

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Mouse hepatitis virus (MHV) is a significant pathogen affecting various cell types.
• Understanding viral mechanisms that disrupt host cell functions is crucial for developing antiviral strategies.

Purpose of the Study:

• To investigate the impact of MHV infection on host protein synthesis and translation machinery.
• To determine the stage at which MHV inhibits protein synthesis and the role of viral mRNA accumulation.

Main Methods:

• Infection of mouse fibroblast L-2 cells with MHV.
• Measurement of total protein synthesis and translatable RNA levels.
• Superinfection experiments with vesicular stomatitis virus.
• Comparative polysome analysis.
• In vitro translation assays.
• Detection of specific cellular mRNA (actin) using cDNA probes.

Main Results:

• MHV infection rapidly reduced host protein synthesis to 7% within 6 hours.
• Intracellular translatable RNA increased threefold due to viral mRNA accumulation.
• MHV-infected cells supported superinfection, indicating translational machinery was not irreversibly damaged.
• Polysome analysis revealed an increase in 80S ribosomes and a shift towards shorter polysomes.
• In vitro translation and actin mRNA detection confirmed a decrease in cellular mRNA levels post-infection.

Conclusions:

• MHV infection inhibits host protein synthesis at an early stage, evidenced by increased 80S ribosomes.
• Accumulated viral mRNAs compete with cellular mRNAs for ribosomes, leading to reduced host protein production.
• MHV infection causes a significant decrease in cellular mRNA levels, including actin mRNA.