Ultraviolet (UV-C) Light Systems for the Inactivation of Feline Calicivirus and Tulane Virus in Model Fluid Foods.

Abstract

Conventional UV-C (254nm) inactivation technologies have limitations and potential operator-safety risk. To overcome these disadvantages, novel UV-C light-emitting diodes (LED) are developed and investigated for their performance. This study aimed to determine the inactivation of human norovirus (HuNoV) surrogates, Tulane virus (TV), and feline calicivirus (FCV-F9), by UV-C (254nm) in comparison to UV-C LED (279nm) in phosphate-buffered saline (PBS) and coconut water (CW). Five-hundred microliters of FCV-F9 (~ 5 log plaque forming units (PFU)/mL) or TV (~ 6 log PFU/mL) were added to 4.5mL PBS or CW in continuously stirred glass beakers and exposed to 254nm UV-C for 0 up to 15min (maximum dosage of 33.89mJ/cm2) or 279nm UV-C LED for 0 up to 2.5min (maximum dosage of 7.03mJ/cm2). Recovered viruses were assayed in duplicate from each treatment replicated thrice. Mixed model analysis of variance was used for data analysis. Significantly lower D10 values were obtained in PBS and CW (p ≤ 0.05) for both tested viruses using UV-C LED (279nm) where FCV-F9 showed D10 values of 7.08 ± 1.75mJ/cm2 and 3.75 ± 0.11mJ/cm2, while using UV-C (254nm) showed D10 values of 13.81 ± 0.40mJ/cm2 and 6.43 ± 0.44mJ/cm2 in PBS and CW, respectively. Similarly, lower D10 values were obtained for TV of 3.91 ± 1.03mJ/cm2 and 4.26 ± 1.02mJ/cm2 with 279 nmUV-C LED and were 18.76 ± 3.16mJ/cm2 and 10.21 ± 1.48mJ/cm2 with 254nm UV-C in PBS and CW, respectively. Viral resistance to these treatments was fluid-matrix dependent. These findings indicate that use of 279nm UV-C LED is more effective in inactivating HuNoV surrogates than conventional 254nm UV-C in the tested fluids.