Infectious bronchitis virus nucleocapsid protein suppressed type I interferon production by interfering with the binding of MDA5-dsRNA and interacting with LGP2.

The type I interferon (IFN-I) is a critical component of the innate immune responses, and Coronaviruses (CoVs) from both the Alphacoronavirus and Betacoronavirus genera interfere with the IFN-I signaling pathway in various ways. Of the gammacoronaviruses that mainly infect birds, little is known about how infectious bronchitis virus (IBV), evades or interferes with the innate immune responses in avian hosts since few IBV strains have been adapted to grow in avian passage cells. Previously, we reported that a highly pathogenic IBV strain GD17/04 has adaptability in an avian cell line, providing a material basis for further study on the interaction mechanism. In the present work, we describe the suppression of IBV to IFN-I and the potential role of IBV-encoded nucleocapsid (N) protein. We show that IBV significantly inhibits the poly I: C-induced IFN-I production, accordingly the nuclear translocation of STAT1, and the expression of IFN-stimulated genes (ISGs). A detailed analysis revealed that N protein, acting as an IFN-I antagonist, significantly impedes the activation of the IFN-ß promoter stimulated by MDA5 and LGP2 but does not counteract its activation by MAVS, TBK1, and IRF7. Further results showed that IBV N protein, verified to be an RNA-binding protein, interferes with MDA5 recognizing double-stranded RNA (dsRNA). Moreover, we found that the N protein targets LGP2, which is required in the chicken IFN-I signaling pathway. Taken together, this study provides a comprehensive analysis of the mechanism by which IBV evades avian innate immune responses.

Sublethal Effects of Beauveria bassiana Strain BEdy1 on the Development and Reproduction of the White-Backed Planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae).

Rice (Oryza sativa) is the most important food crop all over the world, while white-backed planthopper (WBPH), Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) is an important pest causing rice yield reduction. The purpose of this study is to evaluate the sublethal effects of strain BEdy1 Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) on S. furcifera using the two-sex life table analytical method, compare the life tables of the F0 and F1 generations of WBPHs which were treated with sublethal concentrations (LC10, LC25) of B. bassiana BEdy1 with a control group. The results showed that the duration of the egg, 4th-instar and 5th-instar nymph, pre-adult, total pre-oviposition (TPOP) and mean generation time (T) for the LC25 treatment were significantly longer than those of the control and LC10 treatment. However, the duration of the adult, the longevity of male and female adults and the oviposition days of female adults for the LC25 treatment were significantly shortened. The fecundity of female adults, intrinsic rate of increase (r), net reproductive rate (R0) and finite rate of increase (λ) for the LC25 treatment were significantly decreased compared with those of other treatments. The duration of the egg and pre-adult stage for the LC10 treatment were longer than those of the control group, but the population parameters showed no significant difference. Therefore, the LC25 of B. bassiana BEdy1 can inhibit the population growth of S. furcifera.

Emodin from Aloe inhibits Swine acute diarrhea syndrome coronavirus in cell culture.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an emerging swine enteropathogenic coronavirus that causes severe diarrhea in neonatal piglets, leading to serious economic losses to the pig industries. At present, there are no effective control measures for SADS, making an urgent need to exploit effective antiviral therapies. Here, we confirmed that Aloe extract (Ae) can strongly inhibit SADS-CoV in Vero and IPI-FX cells in vitro. Furthermore, we detected that Emodin from Ae had anti-SADS-CoV activity in cells but did not impair SADS-CoV infectivity directly. The time-of-addition assay showed that Emodin inhibits SADS-CoV infection at the whole stages of the viral replication cycle. Notably, we found that Emodin can significantly reduce virus particles attaching to the cell surface and induce TLR3 (p < 0.001), IFN-λ3 (p < 0.01), and ISG15 (p < 0.01) expressions in IPI-FX cells, indicating that the anti-SADS-CoV activity of Emodin might be due to blocking viral attachment and the activation of TLR3-IFN-λ3-ISG15 signaling axis. These results suggest that Emodin has the potential value for the development of anti-SADS-CoV drugs.

Genome-wide transcriptome analysis of porcine epidemic diarrhea virus virulent or avirulent strain-infected porcine small intestinal epithelial cells.

Porcine epidemic diarrhea virus (PEDV) is the main cause of diarrhea, vomiting, and mortality in pigs, which results in devastating economic loss to the pig industry around the globe. In recent years, the advent of RNA-sequencing technologies has led to delineate host responses at late stages of PEDV infection; however, the comparative analysis of host responses to early-stage infection of virulent and avirulent PEDV strains is currently unknown. Here, using the BGI DNBSEQ RNA-sequencing, we performed global gene expression profiles of pig intestinal epithelial cells infected with virulent (GDS01) or avirulent (HX) PEDV strains for 3, 6, and 12 â€‹h. It was observed that over half of all significantly dysregulated genes in both infection groups exhibited a down-regulated expression pattern. Functional enrichment analyses indicated that the differentially expressed genes (DEGs) in the GDS01 group were predominantly related to autophagy and apoptosis, whereas the genes showing the differential expression in the HX group were strongly enriched in immune responses/inflammation. Among the DEGs, the functional association of TLR3 and IFIT2 genes with the HX and GDS01 strains replication was experimentally validated by TLR3 inhibition and IFIT2 overexpression systems in cultured cells. TLR3 expression was found to inhibit HX strain, but not GDS01 strain, replication by enhancing the IFIT2 expression in infected cells. In conclusion, our study highlights similarities and differences in gene expression patterns and cellular processes/pathways altered at the early-stage infection of PEDV virulent and avirulent strains. These findings may provide a foundation for establishing novel therapies to control PEDV infection.

Emodin from Aloe Inhibits Porcine Reproductive and Respiratory Syndrome Virus via Toll-Like Receptor 3 Activation.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes severe reproductive failure in sows and respiratory diseases in growing and finishing pigs and results in great economic losses to the swine industry. Although vaccines are available, PRRSV remains a major threat to the pig farms. Thus, there is an urgent need to develop antiviral drugs to compensate for vaccines. In this study, we report that Aloe extract (Ae) can strongly inhibit PRRSV in Marc-145 cells and porcine alveolar macrophages lines (iPAMs) in vitro. Furthermore, we identified a novel anti-PRRSV molecule, Emodin, from Ae by high-performance liquid chromatography (HPLC). Emodin exerted its inhibitory effect through targeting the whole stages of PRRSV infectious cycle. Moreover, we also found that Emodin can inactivate PRRSV particles directly. Notably, we confirmed that Emodin was able to significantly induce Toll-like receptor 3 (TLR3) (p < 0.01), IFN-α (p < 0.05) and IFN-ß expression in iPAMs, indicating that induction of antiviral agents via TLR3 activation by Emodin might contribute to its anti-PRRSV effect. These findings imply that the Emodin from Aloe could hamper the proliferation of PRRSV in vitro and might constitute a new approach for treating PRRSV infection.