Evolution of TRIM5 and TRIM22 in Bats Reveals a Complex Duplication Process

Area of Science:

• Virology
• Immunology
• Evolutionary Biology

Background:

• Mammalian innate immunity relies on complex protein networks.
• TRIM5 and TRIM22 proteins act as viral restriction factors against primate-infecting viruses.
• Previous studies explored TRIM protein evolution across mammals, but not in Chiroptera (bats).

Purpose of the Study:

• To analyze the evolutionary history of the TRIM6/34/5/22 gene cluster in bat genomes.
• To investigate gene expansion and positive selection within this cluster in bats.
• To understand the role of these evolutionary dynamics in bats' known role as viral reservoirs.

Main Methods:

• Comparative genomics analysis of TRIM gene clusters across various bat species (Yangochiroptera and Yinpterochiroptera).
• Identification of gene duplications and synteny conservation.
• Detection of positive selection acting on TRIM5 and TRIM22 proteins using evolutionary models.

Main Results:

• Dynamic gene expansion observed in TRIM5 and TRIM22 genes within bat genomes.
• Multiple copies of TRIM5 identified with low synteny conservation across Chiroptera.
• TRIM22 duplication frequently found in Yangochiroptera, a novel finding in mammals.
• 31 TRIM5 and 19 TRIM22 amino acids under positive selection, primarily in the PRYSPRY domain.

Conclusions:

• Bat TRIM5 and TRIM22 genes exhibit rapid evolution, including expansions and duplications.
• Positive selection on key residues, particularly in the PRYSPRY domain, suggests adaptation to viral challenges.
• These findings provide insights into the molecular basis of bats' role as viral reservoirs and the potential for zoonotic disease emergence.