The Feline Immunodeficiency Virus Envelope Signal Peptide Is a Tetherin Antagonizing Protein.

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Signal peptides typically direct proteins to the endoplasmic reticulum and secretory pathway.
• Feline immunodeficiency virus (FIV) envelope glycoprotein (Env) has an unusually long signal peptide.
• Tetherin is a host restriction factor that inhibits enveloped virus release.

Purpose of the Study:

• To identify the FIV tetherin antagonist.
• To elucidate the mechanism of FIV antagonism against tetherin.
• To characterize the role of the FIV Env signal peptide (Fsp) in viral evasion.

Main Methods:

• Genetic manipulation of the FIV Env signal peptide (Fsp) via deletions.
• Assessment of viral replication and virion budding in the presence and absence of tetherin.
• Comparative analysis of Fsp's mechanism against tetherin with primate lentivirus antagonists.

Main Results:

• The FIV Env signal peptide (Fsp) was identified as the FIV tetherin antagonist.
• A deletion in Fsp impaired viral budding in the presence of tetherin, but not in its absence.
• Fsp functions autonomously and blocks tetherin incorporation into viral particles, unlike degradation or downregulation mechanisms.

Conclusions:

• Feline immunodeficiency virus (FIV) utilizes its unique, long signal peptide (Fsp) as a novel tetherin antagonist.
• Fsp's mechanism of blocking tetherin incorporation represents a new strategy for lentiviral immune evasion.
• Fsp demonstrates a dual function: mediating protein translocation and acting as a restriction factor antagonist.