Fifty-two species-associated amino acid residues were found between human and avian influenza viruses.
The human glioblastoma SF268 cell line was used to investigate the induction of apoptosis by the 3C protease of enterovirus 71 (EV71). Transient expression in these cells of the wild-type 3C protein encoded by EV71 induced morphological alterations typical of apoptosis, including generation of apoptotic bodies. Degradation of cellular DNA in nucleosomes was also observed. When two of the amino acids in the catalytic motif of 3C were changed by mutagenesis, the 3C protein not only lost its proteolytic activity, but also its ability to induce apoptosis in the SF268 cells. Twenty-four hours after 3C transfection, poly(ADP-ribose) polymerase, a DNA repair enzyme, was cleaved, indicating that caspases were activated by the expression of EV71 3C. The 3C-induced apoptosis was blocked by the caspase inhibitors DEVD-fmk and VAD-fmk. Our findings suggest that the proteolytic activity of 3C triggers apoptosis in the SF268 cells through a mechanism involving caspase activation and that this apoptotic pathway may play an important role in the pathogenesis of EV71 infection.
Human enterovirus (EV) belongs to the picornavirus family, which consists of over 200 medically relevant viruses. A peptidomimetic inhibitor AG7088 was developed to inhibit the 3C protease of rhinovirus (a member of the family), a chymotrypsin-like protease required for viral replication, by forming a covalent bond with the active site Cys residue. In this study, we have prepared the recombinant 3C protease from EV71 (TW/2231/98), a particular strain which causes severe outbreaks in Asia, and developed inhibitors against the protease and the viral replication. For inhibitor design, the P3 group of AG7088, which is not interacting with the rhinovirus protease, was replaced with a series of cinnamoyl derivatives directly linked to P2 group through an amide bond to simplify the synthesis. While the replacement caused decreased potency, the activity can be largely improved by substituting the alpha,beta-unsaturated ester with an aldehyde at the P1' position. The best inhibitor 10b showed EC(50) of 18 nM without apparent toxicity (CC(50)>25 microM). Our study provides potent inhibitors of the EV71 3C protease as anti-EV71 agents and facilitates the combinatorial synthesis of derivatives for further improving the inhibitory activity.
The intestinal microbiome has been shown to influence animal nutrient metabolism and immune homeostasis. The present study aimed to examine the effect of heat stress on the intestinal microbiome of broilers using pyrosequencing technologies. Ninety-six Arbor Acres broiler chicks were allocated to thermoneutral control (TC; 21 ± 1°C) and high ambient temperature (HT; 31 ± 1°C) groups (6 cages of 8 birds per group), respectively, and raised in 2 controlled climate chambers from 28 to 42 d old. Genomic DNA was extracted from ileal contents isolated from 6 male broiler chicks of each group at 42 d old, and then amplified based on the V3-4 hyper-variable region of 16S rRNA. High temperature had no significant effects, but tended to influence the relative abundance of major phyla and orders in the broilers' ileal microbiota. Analysis of linear effect size feature selection identified 9 discriminative features (genus level, linear discriminant analysis score > 3). Clostridium XIVb, Streptophyta, Faecalibacterium, Rothia, Alistipes, Azospirillum, and Oscillibacter were enriched, while Coprococcus and Streptococcus were reduced in heat-stressed broilers. High temperature significantly influenced the alpha diversity, with higher observed species (P = 0.004), whole-tree phylogenetic diversity (P = 0.002), and Chao 1 (P = 0.002), but the Pielou, Shannon, and Simpson indices were unaltered (P > 0.05), indicating that high temperature increased the ileal microbiota species richness. Based on unweighted UniFrac distance metric matrices, principal component analysis showed that the HT group formed a distinct cluster clearly set apart from the TC group. Analysis of similarity also indicated that samples within groups were more similar to each other than to any samples from other groups (R = 0.626; P = 0.004). In conclusion, high temperature influenced the bacterial composition and community structure of the ileal microbiota of broilers, specifically by increasing the species richness.
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