Immunofluorescence-assisted investigation of Human Astrovirus-1 in oyster processing and production.

Abstract

This study evaluated the antiviral efficacy of chlorine dioxide (ClO2) and peracetic acid (PAA) as chemical disinfectants, and UV-C irradiation as a physical treatment, against HAstV-1, applied individually or sequentially on three relevant matrices: oysters, stainless steel (SS; food-contact surface), and low-density polyethylene (LDPE; packaging surface). Infectious viral titers were quantified using a modified immunofluorescence (IF) assay, which was optimized for oyster matrices in this study by adjusting virus adsorption time, antibody conditions, and buffer composition to enhance reproducibility and signal clarity. Treatment with ClO2 (200 ppm, 5 min) and PAA (200 ppm, 1 min) resulted in greater reductions (>2 log10 FFU/mL) on oyster tissues compared to UV-C irradiation (1800 mJ/cm2; 1.8 log10 FFU/mL). HAstV-1 levels dropped below the detection limit when treated with ≥700 ppm ClO2 and ≥1500 ppm PAA on SS and ≥300 ppm ClO2 and ≥900 ppm PAA on LDPE, respectively. UV-C treatment at 3600 mJ/cm2 achieved reductions of 1.37 and 1.63 log10 FFU/mL on SS and LDPE, respectively. Sequential treatments combining ClO2 (50 ppm) or PAA (150 ppm) with subsequent UV-C irradiation (600 mJ/cm2) significantly enhanced HAstV-1 inactivation on oyster surfaces, yielding additional reductions of 0.96 and 0.57 log10 FFU/mL, respectively. Texture and color analyses indicated slight decreases in hardness and chewiness (p < 0.05); however, no significant differences were observed in elasticity or color parameters (p > 0.05). The modified IF assay demonstrated improved reproducibility and signal clarity and was successfully applied for detecting infectious HAstV-1 in oyster matrices.