Persistent infection of human intestinal Caco-2 cell line by Coxsackieviruses B

Inhibition of Type III Interferon Expression in Intestinal Epithelial Cells-A Strategy Used by Coxsackie B Virus to Evade the Host's Innate Immune Response at the Primary Site of Infection?

Increasing evidence highlights the importance of the antiviral activities of the type III interferons (IFNλs; IL-28A, IL-28B, IL29, and IFNλ4) in the intestine. However, many viruses have developed strategies to counteract these defense mechanisms by preventing the production of IFNs. Here we use infection models, a clinical virus isolate, and several molecular biology techniques to demonstrate that both type I and III IFNs induce an antiviral state and attenuate Coxsackievirus group B (CVB) replication in human intestinal epithelial cells (IECs). While treatment of IECs with a viral mimic (poly (I:C)) induced a robust expression of both type I and III IFNs, no such up-regulation was observed after CVB infection. The blunted IFN response was paralleled by a reduction in the abundance of proteins involved in the induction of interferon gene transcription, including TIR-domain-containing adapter-inducing interferon-β (TRIF), mitochondrial antiviral-signaling protein (MAVS), and the global protein translation initiator eukaryotic translation initiation factor 4G (eIF4G). Taken together, this study highlights a potent anti-Coxsackieviral effect of both type I and III IFNs in cells located at the primary site of infection. Furthermore, we show for the first time that the production of type I and III IFNs in IECs is blocked by CVBs. These findings suggest that CVBs evade the host immune response in order to successfully infect the intestine.

Antiviral activity of Bifidobacterium adolescentis SPM1605 against Coxsackievirus B3

Bifidobacteria are considered one of the most beneficial probiotics and have been widely studied for their effects against specific pathogens. The present study investigated the antiviral activity of probiotics isolated from Koreans against Coxsackievirus B3 (CVB3). The effect of probiotic isolates against CVB3 was measured by the plaque assay and cellular toxicity of bifidobacteria in HeLa cells was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among 13 probiotic isolates, 3 Bifidobacterium adolescentis, 2 Bifidobacterium longum and 1 Bifidobacterium pseudocatenulatum had an antiviral effect against CVB3, while the others did not show such effect. B. adolescentis SPM1605 showed the greatest inhibitory properties against CVB3. When the threshold cycle (CT) values for the treated B. adolescentis SPM1605 samples were compared to the results for the non-treated samples, it was shown that the amplified viral sequences from the CVB3 had their copy number lowered by B. adolescentis SPM1605. Moreover, the gene expression in infected HeLa cells was also inhibited by 50%. The results suggest that B. adolescentis SPM1605 suppresses CVB3 and could be used as an alternative therapy against infectious diseases caused by coxsackieviruses.