RESUMEN
Blueberry polyphenols are known for their high antioxidant and antimicrobial potential. Aichi virus (AiV) is an emerging human enteric virus that causes gastroenteritis outbreaks worldwide. This study aimed to (1) determine the time- and dose-dependent effects of blueberry proanthocyanidins (B-PAC) against AiV over 24â¯hâ¯at 37⯰C; (2) gain insights on their mode of action using pre- and post-treatment of host cells and Transmission Electron Microscopy; and (3) determine their anti-AiV effects in model foods and under simulated gastric conditions. AiV at â¼5 log PFU/ml was incubated with equal volumes of commercial blueberry juice (BJ, pH 2.8), neutralized BJ (pH 7.0), B-PAC (2, 4, and 10 mg/ml) prepared either in 10% ethanol, apple juice (AJ), 2% milk, simulated gastric fluid (SGF, pH 1.5) or simulated intestinal fluid (SIF, pH 7.5), and controls (malic acid (pH 3.0), phosphate buffered saline (pH 7.2), apple juice (pH 3.6) and 2% milk) over 24â¯hâ¯at 37⯰C, followed by standard plaque assays. Each experiment was replicated thrice and data were statistically analyzed. Differences in AiV titers with 1â¯mg/ml B-PAC were 2.13⯱â¯0.06 log PFU/ml lower after 24â¯h and ≥3 log PFU/ml (undetectable levels) lower with 2 and 5 mg/ml B-PAC compared to AiV titers in PBS after 24 h and 3â¯h, respectively. BJ at 37⯰C resulted in titer differences (lower titers compared to PBS) of 0.17⯱â¯0.06, 1.27⯱â¯0.01, and 1.73⯱â¯0.23 log PFU/ml after 1, 3, and 6â¯h and ≥3 log PFU/ml after 24â¯h. Pre- and post-treatment of host cells with 0.5 mg/ml B-PAC caused titer decreases of 0.62⯱â¯0.33 and 0.30⯱â¯0.06 log PFU/ml, respectively suggesting a moderate effect on viral-host cell binding. B-PAC at 2 mg/ml in AJ caused titer differences of ≥3 log PFU/ml after 0.5â¯h, while differences of 0.84⯱â¯0.03 log PFU/ml with 5 mg/ml B-PAC in milk, and ≥3 log PFU/ml with B-PAC at 5 mg/ml in SIF after 30 min were obtained. This study shows the ability of BJ and B-PAC to decrease AiV titers to potentially prevent AiV-related illness and outbreaks.
Asunto(s)
Antivirales/farmacología , Arándanos Azules (Planta)/química , Microbiología de Alimentos , Kobuvirus/efectos de los fármacos , Proantocianidinas/farmacología , Animales , Chlorocebus aethiops , Enfermedades Transmitidas por los Alimentos/prevención & control , Jugos de Frutas y Vegetales/análisis , Jugos de Frutas y Vegetales/virología , Gastroenteritis/prevención & control , Leche/virología , Extractos Vegetales/química , Extractos Vegetales/farmacología , Temperatura , Células Vero , Acoplamiento Viral/efectos de los fármacos , Replicación Viral/efectos de los fármacosRESUMEN
Blueberry juice and blueberry polyphenols reportedly have antimicrobial properties against foodborne pathogens, without much currently known on their effects against Cronobacter sakazakii. This study evaluated the antimicrobial effects of blueberry proanthocyanidins (PAC) and commercial blueberry juice (BJ) against two strains of C. sakazakii, ATCC 29004 and 29544. BJ (pH 2.8), blueberry PAC (5 mg/ml) and controls (phosphate buffered saline (PBS), pH 7.2, and malic acid pH 3.0) were mixed with equal volumes of washed overnight cultures of C. sakazakii and incubated for 30 min, 1 h, 3 h and 6 h at 37°C. Reductions of â¼1 and 1.50 log CFU/ml were obtained for strains 29004 and 29544, respectively after 30 min with BJ or blueberry PAC. Both C. sakazakii strains 29004 and 29544 were reduced to undetectable levels from 8.25 ± 0.12 log CFU/ml and 8.48 ± 0.03 log CFU/ml, respectively with BJ (pH 2.8) or blueberry PAC after 1 h, while malic acid (pH 3.0) showed â¼1.3 log CFU/ml reduction for both strains. Scanning electron microscopy studies showed differences in cell membrane morphology with clumping and formation of blebs of the treated strains compared to untreated controls. These results warrant further in vivo studies with blueberry bioactives to determine potential for preventing and treating C. sakazakii infections.