Gain-of-function experiments with bacteriophage lambda uncover residues under diversifying selection in nature

Area of Science:

• Virology
• Evolutionary Biology
• Molecular Biology

Background:

• Viral gain-of-function mutations are common in lab studies.
• It remains unknown if lab-evolved mutations occur naturally and have similar evolutionary impacts.

Purpose of the Study:

• To investigate if laboratory-evolved viral mutations also occur in nature.
• To determine if these mutations drive similar evolutionary outcomes in natural settings.
• To identify the specific genetic changes responsible for viral host-shifts.

Main Methods:

• Studied bacteriophage lambda (λ) evolution under laboratory conditions.
• Analyzed natural lambda variants for mutations in the J protein.
• Correlated amino acid site diversity and evolutionary rates with phylogenetic data.

Main Results:

• Two specific residues in the lambda J protein are essential for exploiting a new host receptor.
• These amino acid sites exhibit high diversity and rapid evolution in natural lambda populations.
• Insertions and deletions at these sites correlate with ecological diversification patterns.

Conclusions:

• Laboratory viral evolution accurately reflects natural evolutionary trajectories.
• Combining lab experiments with sequence analysis can reveal real-world viral evolution drivers.
• Evidence suggests extensive host-shift evolution occurs in lambdoid viruses.