Persistence of hepatitis A virus in a hydroponic nutrient solution at different temperatures

Controlled environment agriculture (CEA) enables year-round production of produce to meet growing consumer demands. However, prevention of microbial contamination is essential. This study assessed the persistence of hepatitis A virus (HAV) over 21 days at 4, 15, 20, and 25 °C in a hydroponic nutrient solution to understand cross-contamination risk. Two-hundred μL of HAV (∼6.5 log PFU/mL) was aseptically inoculated into 1.8 mL of a commercial hydroponic nutrient solution (pH 5.8) and stored at 4, 15, 20, or 25 °C (mimicking storage, transport, and cultivation conditions) for 21 days. Infectious viruses were recovered over time and quantified using plaque assays in duplicate. The obtained recovered virus data from triplicate experiments were statistically analyzed. Hepatitis A virus retained infectivity after 21 days with reductions ranging from 0.22 log PFU/mL to 3.34 log PFU/mL. Storage at 4 °C supported greatest viral persistence (D-value = 41.34 ± 4.06 days), compared to 15 °C (D-value = 9.23 ± 2.70 days), 20 °C (D-value = 6.31 ± 3.92 days) or 25 °C (D-value = 8.03 ± 0.22 days). These findings support the risk associated with the contamination of hydroponic nutrient solutions, as the temperature of the solution shows an impact on the persistence of HAV. Overall, this study emphasized the need for adequate precautions and implementation of control methods in CEA to reduce the risk of foodborne viral cross-contamination.