Development of an extraction method to detect enteric viruses in dressed vegetables

Area of Science:

• Food safety microbiology
• Molecular detection of foodborne viruses

Background:

• Food-borne viral infections, primarily from noroviruses (NoV) and hepatitis A virus (HAV), pose significant public health risks.
• Standard methods (NF EN ISO 15216-1:2017) for detecting NoV and HAV in foods like vegetables are inadequate for complex matrices such as dressed salads.
• Oily, fatty, or emulsified salad dressings interfere with existing viral quantification techniques, necessitating improved detection methods.

Purpose of the Study:

• To develop and validate a sensitive and reliable RT-qPCR based method for detecting and quantifying NoV and HAV in vegetables with various dressings.
• To address the limitations of current standard methods for analyzing composite food products like dressed salads.

Main Methods:

• Evaluation of three distinct methods for recovering NoV and HAV from artificially contaminated dressed vegetables.
• Selection and optimization of a recovery method based on Trizol reagent for enhanced viral extraction.
• Application of RT-qPCR for the sensitive detection and quantification of NoV and HAV in prepared vegetable samples.

Main Results:

• The Trizol reagent-based method demonstrated effective recovery of both NoV and HAV from dressed vegetables.
• The limit of detection varied by dressing type, ranging from 10^4 to 10^6 genome copies/g for NoV.
• The limit of detection for HAV ranged from 10^2 to 10^3 PFU/g, indicating high sensitivity for both viruses.

Conclusions:

• A novel RT-qPCR method utilizing Trizol reagent has been successfully developed for detecting NoV and HAV in dressed vegetables.
• This method overcomes the limitations of existing protocols for analyzing complex food matrices containing salad dressings.
• The validated technique is suitable for routine diagnosis and ensuring the safety of food products potentially contaminated with these viruses.