A giant virus forms a specialized subcellular environment within its amoeba host for efficient translation

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Eukaryotic viruses, like mimiviruses, often exhibit codon usage differing from their hosts.
• Efficient translation relies on aligning viral codon usage with the host's cellular tRNA pool.
• The strategies viruses employ to manage tRNA supply and demand mismatches remain largely unknown.

Purpose of the Study:

• To investigate how Acanthamoeba polyphaga mimivirus (APMV) manages translation despite codon usage differences.
• To explore the role of subcellular localization in viral mRNA translation.
• To understand how APMV overcomes potential tRNA limitations.

Main Methods:

• TRNA sequencing to analyze the tRNA pool during APMV infection.
• In situ labeling to track viral mRNA and protein localization.
• Codon usage analysis comparing viral and host mRNAs.

Main Results:

• APMV infection did not significantly alter the host's tRNA pool, despite the virus encoding tRNA genes.
• Viral mRNAs and newly synthesized proteins were found localized to the periphery of viral factories.
• Viral mRNA codons showed higher tRNA accessibility compared to similar codons in host mRNAs.

Conclusions:

• APMV establishes a distinct subcellular environment, likely the viral factory periphery, to facilitate translation.
• This localized translation strategy helps the virus efficiently translate its mRNAs.
• The findings elucidate a mechanism by which viruses overcome host tRNA supply-demand imbalances.