Radix Isatidis polysaccharide (RIP) resists the infection of QX-type infectious bronchitis virus via the MDA5/TLR3/IRF7 signaling pathway.

Although vaccines play a major role in the prevention of infectious bronchitis (IB), Anti-IB drugs still have great potential in poultry production. Radix Isatidis polysaccharide (RIP) is a crude extract of Banlangen with antioxidant, antibacterial, antiviral, and multiple immunomodulatory functions. The aim of this study was to explore the innate immune mechanisms responsible for RIP-mediated alleviation of infectious bronchitis virus (IBV)-induced kidney lesions in chickens. Specific-pathogen-free (SPF) chicken and chicken embryo kidney (CEK) cells cultures were pretreated with RIP and then infected with the QX-type IBV strain, Sczy3. Morbidity, mortality, and tissue mean lesion scores were calculated for IBV-infected chickens, and the viral loads, inflammatory factor gene mRNA expression levels, and innate immune pathway gene mRNA expression levels in infected chickens and CEK cell cultures were determined. The results show that RIP could alleviate IBV-induced kidney damage, decrease CEK cells susceptibility to IBV infection, and reduce viral loads. Additionally, RIP reduced the mRNA expression levels of the inflammatory factors IL-6, IL-8, and IL-1ß by decreasing the mRNA expression level of NF-κB. Conversely, the expression levels of MDA5, TLR3, STING, Myd88, IRF7, and IFN-ß were increased, indicating that RIP conferred resistance to QX-type IBV infection via the MDA5, TLR3, IRF7 signaling pathway. These results provide a reference for both further research into the antiviral mechanisms of RIP and the development of preventative and therapeutic drugs for IB.

The conserved L1089 in the S2 subunit of avian infectious bronchitis virus determines viral kidney tropism by disrupting virus-cell fusion.

The virulence of avian gamma-coronavirus infectious bronchitis viruses (IBV) for the kidney has led to high mortality in dominant-genotype isolations, but the key sites of viral protein that determine kidney tropism are still not fully clear. In this study, the amino acid sequences of the S2 subunit of IBVs with opposing adaptivity to chicken embryonic kidney cells (CEKs) were aligned to identify putative sites associated with differences in viral adaptability. The S2 gene and the putative sites of the non-adapted CN strain were introduced into the CEKs-adapted SczyC30 strain to rescue seven mutants. Analysis of growth characteristics showed that the replacement of the entire S2 subunit and the L1089I substitution in the S2 subunit entirely abolished the proliferation of recombinant IBV in CEKs as well as in primary chicken oviduct epithelial cells. Pathogenicity assays also support the decisive role of this L1089 for viral nephrotropism, and this non-nephrotropic L1089I substitution significantly attenuates pathogenicity. Analysis of the putative cause of proliferation inhibition in CEKs suggests that the L1089I substitution affects neither virus attachment nor endocytosis, but instead fails to form double-membrane vesicles to initiate the viral replication and translation. Position 1089 of the IBV S2 subunit is conservative and predicted to lie in heptad repeat 2 domains. It is therefore reasonable to conclude that the L1089I substitution alters the nephrotropism of parent strain by affecting virus-cell fusion. These findings provide crucial insights into the adaptive mechanisms of IBV and have applications in the development of vaccines and drugs against IB.

The N1038S Substitution and 1153EQTRPKKSV1162 Deletion of the S2 Subunit of QX-Type Avian Infectious Bronchitis Virus Can Synergistically Enhance Viral Proliferation.

The S2 subunit of infectious bronchitis virus (IBV) plays a critical role in the process of IBV infection. A comparison between the S2 subunit sequence of chicken embryo kidney cell (CEK) adapted virulent QX-like IBV strain SczyC30 (hereafter referred to as zy30) and its CEK-attenuated strain, SczyC100, revealed an N1038S substitution in S2 subunit and a 1154EQTRPKKSV1162 residue deletion in the C-terminus of the S2 subunit. In order to explore whether these two mutations are related to changes in the biological characteristics of IBV, we firstly constructed an infectious clone of zy30 using a bacterial artificial chromosome (BAC), which combines the transcription of infectious IBV genomic RNA in non-susceptible BHK-21 cells with the amplification of rescued virus rzy30 in CEK cells. Then, three recombinant viruses, including an rzy30S2-N1038S strain that contained the N1038S substitution, an rzy30S2-CT9△ strain that contained the 1154EQTRPKKSV1162 deletion, and an rzy30S2-N1038S-CT9△ strain that contained both mutations, were constructed using rescued virus rzy30 as the backbone. The results showed that each mutation did not significantly affect the replication titer in CEK cells but reduced pathogenicity in chickens, while in combination, the N1038S substitution and 1154EQTRPKKSV1162 deletion improved the proliferation efficiency in CEK cells and reduced pathogenicity, compared to rzy30 strain. The contribution made by the 1154EQTRPKKSV1162 deletion in reducing pathogenicity was higher than that of N1038S substitution. Our results revealed that the N1038S substitution and 1154EQTRPKKSV1162 deletion in S2 subunit were deeply involved in the replication efficiency of IBV and contributed to reduction of viral pathogenicity.

Major Impact of Coping Styles on Anxiety and Depression Symptoms in Healthcare Workers During the Outbreak of COVID-19

Background In the early days of COVID-19 outbreak, the normally orderly health system was severely challenged by large numbers of feverish patients and shortage of healthcare workers. The outbreak played a harmful role in the mental health of these healthcare workers. Objective We aim to assess the prevalence of moderate or severe anxiety and depression symptoms (ADSs) of healthcare workers in different regions during COVID-19 disaster and identify the potential risk factors. Methods We did a cross-sectional study on ADS of healthcare workers in epicenter-Hubei province and regions in lower epidemic-other provinces by questionnaire online. The data of ADS, the demographic characteristics, occupational exposure, physical condition, family situation, and coping styles were collected and analyzed. Results A total of 24.68% of the respondents had experienced moderate or severe ADS. Moderate or severe ADSs were in a higher prevalence in Hubei (32.39%) than other provinces (18.22%). Suspicious symptoms on their own and in family members were independent risk factors of moderate or severe ADS of all health workers. Working on the frontline was the independent risk factor for participants in Hubei province, whereas quarantine was the independent risk factor for those in other provinces. Moreover, among all participants, those with negative coping style were more than four times more likely to have moderate or severe ADS than those with positive coping style. Conclusion Moderate or severe ADSs were in a higher prevalence in healthcare workers of Hubei province during COVID-19 outbreak. The coping style may have major impact on ADS in such situation.

Risk factors for depression and anxiety in healthcare workers deployed during the COVID-19 outbreak in China.

PURPOSE: This study was conducted to evaluate the status of depression and anxiety of healthcare workers and to explore the risk factors during the outbreak of COVID-19 in China. METHODS: A cross-sectional study was designed using convenience sampling to obtain a sample of healthcare workers. A structured questionnaire was designed to collect the information of the basic characteristics, workload, and the health condition. Burnout, coping style, anxiety, and depression were measured by specific scales. Multiple logistic regression model was performed to explore the risk factors of anxiety or depression. RESULTS: There were 902 questionnaires received between February 9, 2020 and February 11, 2020. The proportion of healthcare workers with symptoms of moderate/severe anxiety and moderate/severe depression were 16.63% and 18.29%, respectively. There were 24.50% healthcare workers experiencing moderate/severe anxiety and depression at the same time. The increased workload, respiratory symptoms, digestive symptoms, having done specific test(s) related to COVID-19, having family member needs to be taken care of, negative coping style, and job burnout were the independent risk factors of anxiety. Furthermore, the increased workload, respiratory symptoms, digestive symptoms, having done specific test(s) related to COVID-19, negative coping style, and job burnout were the independent risk factors of depression. CONCLUSION: More attention should be paid to the mental health of frontline healthcare workers at the outbreak of COVID-19 in China. Taking steps to reduce the intensity of the work and burnout will be effective to stabilize the mental state of them.