Variability of virus attachment patterns to butterhead lettuce

Area of Science:

• Food safety
• Virology
• Surface chemistry

Background:

• Enteric viruses are a leading cause of foodborne illness in the U.S.
• Understanding virus-lettuce interactions is crucial for food safety.
• Existing models for virus adsorption may not apply to produce.

Purpose of the Study:

• To investigate the effect of virus isoelectric point (pI) on attachment to butterhead lettuce.
• To evaluate the applicability of the Derjaguin-Landau-Verway-Overbeek model to virus-lettuce adsorption.
• To assess potential biases in virus recovery methods from lettuce.

Main Methods:

• Studied attachment of feline calicivirus (FCV), echovirus 11, and bacteriophages phiX174 and MS2 to lettuce.
• Varied pH conditions to assess the influence of isoelectric point (pI) on adsorption.
• Compared experimental results with the Derjaguin-Landau-Verway-Overbeek model.

Main Results:

• Virus adsorption to lettuce was highly variable.
• Bacteriophage MS2 was the only virus fitting the DLVO model.
• Echovirus 11 showed highest affinity, with reversible attachment above its pI and strong adsorption below.
• FCV adsorption peaked above its pI.
• Bacteriophage phiX174 exhibited complex adsorption at pH extremes.

Conclusions:

• The standard virus-sediment adsorption model is insufficient for lettuce.
• Isoelectric point significantly influences virus attachment to lettuce.
• Current virus recovery methods may lead to differential detection of specific virus types on lettuce.