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Although SARS-CoV-2 is basically regarded as a homolog of SARS-CoV, with their genomic structure and the majority of their genes being highly homologous, the ORF8 genes of SARS-CoV and SARS-CoV-2 are distinct. The SARS-CoV-2 ORF8 protein also shows little homology with other viral or host proteins and is thus regarded as a novel special virulence gene of SARS-CoV-2.

Purpose To study the effects of a bandage contact lens immersed in 0.1% diclofenac on pain management for patients undergoing transepithelial photorefractive keratectomy (TPRK). Methods In a prospective, comparative, contralateral, randomized, double-masked study, we assessed a total of 51 patients. The eyes of each patient were randomly divided into two groups. After TPRK, a normal soft bandage contact lens was placed on one eye as the control group, and a bandage contact lens soaked in diclofenac was placed on the other eye as the experimental group. When the bandage contact lens was not removed, postoperative pain and other ocular discomforts were compared at 2, 18, and 24 h and 2, 3, 4, and 5 postoperative days. Patients were then examined after 1 month. Visual acuity and subepithelial haze were also evaluated. Results The mean pain score was 2.69 ± 1.96 in the control group, which was significantly higher than that in the experimental group, which received the diclofenac-soaked bandage contact lens at 2 postoperative hours. The statistical difference between the two groups’ mean foreign body sensation at 2 postoperative hours was detected (p = 0.035). No differences were detected between the two groups’ subepithelial haze scores or visual acuity. Conclusion A bandage contact lens soaked in 0.1% diclofenac solution can be used as a potential drug-delivery system to relieve early postoperative pain and foreign body sensation after TPRK.

The influenza virus, a viral respiratory pathogen, causes major morbidity and mortality worldwide. In this study, we compared and analyzed the effectiveness of the rescued two chimeric H1N1 vaccine strains rA/B-California/04/2009 and rA/B-California/07/2009, respectively, which expressed the hemagglutinin of A/California/07/2009 or A/California/04/2009 based on an influenza B virus master donor. The rA/B-California/07/2009 strain was rescued successfully. However, the rA/B-California/04/2009, which expressed the HA of A/California/07/2009 could hardly be generated. In substitution for alanine at residue 212 in the chimeric HA protein of rA/B-California/04/2009 virus, threonine was identified as a deleterious change. The free Gibbs energy change of mutating residue 212 reflected that threonine in site 212 caused a reduction in the stability of rA/B-California HAs. Additionally, with the analysis of binding free energy data and RMSD values of receptor analogs and two chimeric HAs, substitution 212T also conferred decreased receptor-binding avidity. These results suggested that the substitution A212T may enhance the stability and binding affinity of the chimeric H1N1 vaccine strains. This finding may help to design a live-attenuated influenza vaccine with more efficacy.

Influenza H3N8 viruses have been recovered frequently from wild bird species, including Anseriformes (primarily from migratory ducks) and Charadriiformes (primarily from shorebirds). However, little attention has been given to the transmission ability of H3N8 avian influenza viruses among mammals. Here, we study the potential human health threat and the molecular basis of mammalian transmissibility of H3N8 avian influenza viruses isolated from wild bird reservoirs. We classified eight H3N8 viruses into seven different genotypes based on genomic diversity. Six of eight H3N8 viruses isolated naturally from wild birds have acquired the ability to bind to the human-type receptor. However, the affinity for α-2,6-linked SAs was lower than that for α-2,3-linked SAs. Experiments on guinea pigs demonstrated that three viruses transmitted efficiently to direct-contact guinea pigs without prior adaptation. Notably, one virus transmitted efficiently via respiratory droplets in guinea pigs but not in ferrets. We further found that the PB1 S524G mutation conferred T222 virus airborne transmissibility between ferrets. We also determined that the 524G mutant increased viral pathogenicity slightly in mice compared with the WT (wild type). Based on these results, we elucidated the potential human health threat and molecular basis of mammalian transmissibility of H3N8 influenza viruses. We emphasized the need for continued surveillance of the H3N8 influenza viruses circulating in birds.

This paper focuses on the stability analysis and controller design for a family of discrete-time linear systems with quantised signals in both control input channel and measurement output channel. ...

H5N1 influenza virus is a threat to public health worldwide. The virus can cause severe morbidity and mortality in humans. We constructed an H5N1 influenza candidate virus vaccine from the A/chicken/Guizhou/1153/2016 strain that was recommended by the World Health Organization. In this study, we designed an H5N1 chimeric influenza A/B vaccine based on a cold-adapted (ca) influenza B virus B/Vienna/1/99 backbone. We modified the ectodomain of H5N1 hemagglutinin (HA) protein, while retaining the packaging signals of influenza B virus, and then rescued a chimeric cold-adapted H5N1 candidate influenza vaccine through a reverse genetic system. The chimeric H5N1 vaccine replicated well in eggs and the Madin-Darby Canine Kidney cells. It maintained a temperature-sensitive and cold-adapted phenotype. The H5N1 vaccine was attenuated in mice. Hemagglutination inhibition (HAI) antibodies, micro-neutralizing (MN) antibodies, and IgG antibodies were induced in immunized mice, and the mucosal IgA antibody responses were detected in their lung lavage fluids. The IFN-γ-secretion and IL-4-secretion by the mouse splenocytes were induced after stimulation with the specific H5N1 HA protein. The chimeric H5N1 candidate vaccine protected mice against lethal challenge with a wild-type highly pathogenic avian H5N1 influenza virus. The chimeric H5 candidate vaccine is thus a potentially safe, attenuated, and reassortment-incompetent vaccine with circulating A viruses.

Background In 2011, a new influenza virus, named Influenza D Virus (IDV), was isolated from pigs, and then cattle, presenting influenza-like symptoms. IDV is one of the causative agents of Bovine Respiratory Disease (BRD), which causes high morbidity and mortality in feedlot cattle worldwide. To date, the molecular mechanisms of IDV pathogenicity are unknown. Recent IDV outbreaks in cattle, along with serological and genetic evidence of IDV infection in humans, have raised concerns regarding the zoonotic potential of this virus. Influenza virus polymerase is a determining factor of viral pathogenicity to mammals. Methods Here we take a prospective approach to this question by creating a random mutation library about PB2 subunit of the IDV viral polymerase to test which amino acid point mutations will increase viral polymerase activity, leading to increased pathogenicity of the virus. Results Our work shows some exact sites that could affect polymerase activities in influenza D viruses. For example, two single-site mutations, PB2-D533S and PB2-G603Y, can independently increase polymerase activity. The PB2-D533S mutation alone can increase the polymerase activity by 9.92 times, while the PB2-G603Y mutation increments the activity by 8.22 times. Conclusion Taken together, our findings provide important insight into IDV replication fitness mediated by the PB2 protein, increasing our understanding of IDV replication and pathogenicity and facilitating future studies.

Taurolidine (TRD), a derivative of taurine, has anti-bacterial and anti-tumor effects by chemically reacting with cell-walls, endotoxins and exotoxins to inhibit the adhesion of microorganisms. However, its application in antiviral therapy is seldom reported. Here, we reported that TRD significantly inhibited the replication of influenza virus H5N1 in MDCK cells with the half-maximal inhibitory concentration (EC

Coronaviruses are commonly characterized by a unique discontinuous RNA transcriptional synthesis strategy guided by transcription-regulating sequences (TRSs). However, the details of RNA synthesis in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been fully elucidated. Here, we present a time-scaled, gene-comparable transcriptome of SARS-CoV-2, demonstrating that ACGAAC functions as a core TRS guiding the discontinuous RNA synthesis of SARS-CoV-2 from a holistic perspective. During infection, viral transcription, rather than genome replication, dominates all viral RNA synthesis activities. The most highly expressed viral gene is the nucleocapsid gene, followed by ORF7 and ORF3 genes, while the envelope gene shows the lowest expression. Host transcription dysregulation keeps exacerbating after viral RNA synthesis reaches a maximum. The most enriched host pathways are metabolism related. Two of them (cholesterol and valine metabolism) affect viral replication in reverse. Furthermore, the activation of numerous cytokines emerges before large-scale viral RNA synthesis. IMPORTANCE SARS-CoV-2 is responsible for the current severe global health emergency that began at the end of 2019. Although the universal transcriptional strategies of coronaviruses are preliminarily understood, the details of RNA synthesis, especially the time-matched transcription level of each SARS-CoV-2 gene and the principles of subgenomic mRNA synthesis, are not clear. The coterminal subgenomic mRNAs of SARS-CoV-2 present obstacles in identifying the expression of most genes by PCR-based methods, which are exacerbated by the lack of related antibodies. Moreover, SARS-CoV-2-related metabolic imbalance and cytokine storm are receiving increasing attention from both clinical and mechanistic perspectives. Our transcriptomic research provides information on both viral RNA synthesis and host responses, in which the transcription-regulating sequences and transcription levels of viral genes are demonstrated, and the metabolic dysregulation and cytokine levels identified at the host cellular level support the development of novel medical treatment strategies.

West Nile virus disease (WND) is an arthropod-borne zoonosis responsible for nonspecific fever or severe encephalitis. The pathogen is West Nile virus belonging to the genus Flavivirus, family Flaviviridae. Every year, thousands of cases were reported, which poses significant public health risk. Here, we constructed a West Nile virus chimera, ChiVax-WN01, by replacing the prMΔE gene of JEV SA14-14-2 with that of the West Nile virus NY99. The ChiVax-WN01 chimera showed clear, different characters compared with that of JEV SA14-14-2 and WNV NY99 strain. An animal study indicated that the ChiVax-WN01 chimera presented moderate safety and immunogenicity for 4-week female BALB/c mice.

Antibodies are ideal for controlling the influenza A virus, but their effect on newly emerging strains is unclear. Here, we assessed the neutralization activity of the humanized monoclonal antibodies (mAbs) F10, H98 and H40 against circulating influenza viruses (H5N1, H1N1, H3N2 and H7N7 and new subtypes viruses H5N6 and H7N9). The results showed that all the three humanized mAbs (F10, H98 and H40) displayed different degrees of virus neutralization activities when encountered with different subtypes of influenza viruses. Remarkably, the humanized monoclonal antibody F10 produced higher and broader neutralization titers (range 25–1.56 μg/ml) than those of the other two humanized mAbs (H98 (range 50–3.12 μg/ml), H40 (range 50–5.56 μg/ml)) to against the viruses H5N1, H1N1, H3N2, H7N7, H5N6 and H7N9. This mAb may represent a new class of heterosubtypic neutralizing humanized mAb that could replace vaccines and chemical drugs.

The dynamics, duration, and nature of immunity produced during SARS-CoV-2 infection are still unclear. Here, we longitudinally measured virus-neutralising antibody, specific antibodies against the spike (S) protein, receptor-binding domain (RBD), and the nucleoprotein (N) of SARS-CoV-2, as well as T cell responses, in 25 SARS-CoV-2-infected patients up to 121 days post-symptom onset (PSO). All patients seroconvert for IgG against N, S, or RBD, as well as IgM against RBD, and produce neutralising antibodies (NAb) by 14 days PSO, with the peak levels attained by 15–30 days PSO. Anti-SARS-CoV-2 IgG and NAb remain detectable and relatively stable 3–4 months PSO, whereas IgM antibody rapidly decay. Approximately 65% of patients have detectable SARS-CoV-2-specific CD4+ or CD8+ T cell responses 3–4 months PSO. Our results thus provide critical evidence that IgG, NAb, and T cell responses persist in the majority of patients for at least 3–4 months after infection., Understanding if lasting immune responses can be induced by SARS-CoV-2 infection is important for controlling the COVID-19 pandemic. Here, the authors show, in a cohort of 25 patients, that IgG and T cell responses, as well as neutralising antibody, are still detectable against various SARS-CoV-2 proteins 3 months post-symptom onset, while IgM levels largely wane at this time.

Ebolavirus (EBOV) is responsible for several EBOV disease (EVD) outbreaks in Africa, with a fatality rate of up to 90%. During 2014-2016, An epidemic of EVD spread throughout Sierra Leone, Guinea and Liberia, and killed over 11,000 people. EBOV began to circulate again in the Democratic Republic of Congo in 2018. Due to the need for a BSL-4 facility to manipulate this virus, the development and improvement of specific therapeutics has been hindered. As a result, it is imperative to perform reliable research on EBOV under lowered BSL restrictions. In this study, we developed a safe neutralization assay based on pseudotyped EBOV, which incorporates the glycoprotein of the 2014 EBOV epidemic strain into a lentivirus vector. Our results demonstrated that the tropism of pseudotyped EBOV was similar to that of authentic EBOV, but with only one infection cycle. And neutralizing activity of both authentic EBOV and pseudotyped EBOV were compared in neutralization assay using three different samples of antibody-based reagents against EBOV, similar results were obtained. In addition, an indirect ELISA was performed to show the relationship between IgG and neutralizing antibody against EBOV detected by our pseudotyped EBOV-based neutralization assay. As expected, the neutralizing antibody titers varied with the IgG titers detected by indirect ELISA, and a correlation between the results of the two assays was identified. By comparison with two different assays, the reliability of the results detected by the pseudotyped EBOV-based neutralization assay was confirmed. Collectively, in the absence of BSL-4 restrictions, pseudotyped EBOV production and neutralizing activity evaluation can be performed safely and in a manner that is neither labor- nor time-consuming, providing a simple and safe method for EBOV-neutralizing antibody detection and the assessment of immunogenicity of EBOV vaccines. All these remarkable advantages of the newly established assay highlight its potential to further application in assessment of immunogenicity of EBOV vaccine candidates.

Background: Ebolavirus (EBOV) is responsible for several EBOV disease (EVD) outbreaks in Africa, with a fatality rate of up to 90%. During 2014-2016, An epidemic of EVD spread throughout Sierra Leone, Guinea and Liberia, and killed over 11,000 people. EBOV began to circulate again in the Democratic Republic of Congo in 2018. Due to the need for a BSL-4 facility to manipulate this virus, the development and improvement of specific therapeutics has been hindered. As a result, it is imperative to perform reliable research on EBOV under lowered BSL restrictions. Methods: Based on lentivirus vector, we developed a safe EBOV pseudotyped virus, which was used into a neutralization assay. The tropism and neutralizing activity of both authentic EBOV and EBOV pseudotyped virus were compared, using three different samples of antibody-based agents against EBOV. Findings: Our results demonstrated that the tropism of EBOV pseudotyped virus was similar to that of authentic EBOV, but with only one infection cycle. After utilizing to neutralization assay in the absence of BSL-4 restrictions, the EBOV pseudotyped virus-based assay showed similar results with the live EBOV neutralization assay and indirect ELISA. Interpretation: The remarkable simplicity and safety of EBOV pseudotyped virus-based neutralization assay highlight its potential to further application in assessment of immunogenicity of EBOV vaccine candidates. Funding: This work was supported by the National Science and Technology Major Projectof the Ministry of Science and Technology of China (grants 2015ZX09102025). Declaration of Interest: The authors have no conflicts of interest to declare. Ethical Approval: All animal studies in this work were approved bythe Animal Care and Use Committee of Chinese People’s Liberation Army (No. SYXK2009-045). All efforts were made to minimize animal suffering.

Additional file 1. Antibiotic use among adult patients with clinical features of HAI.

We previously demonstrated that intramuscular immunization with virus-like particles (VLPs) composed of the haemagglutinin (HA), neuraminidase (NA), and matrix (M1) proteins of A/meerkat/Shanghai/SH-1/2012 (clade 2.3.2.1) protected mice from lethal challenge with viruses from other H5 HPAI clades. The inclusion of additional proteins that can serve as immunological adjuvants in VLPs may enhance adaptive immune responses following vaccination, and oral vaccines may represent the safest choice. Here, we report the generation of H5N1 VLPs composed of the viral HA, NA, and M1 proteins and membrane-anchored forms of the Escherichia coli heat-labile enterotoxin B subunit protein (LTB) or the Toll-like receptor 5 ligand flagellin (Flic). Mice intramuscularly or orally immunized with VLPs containing LTB or Flic generated greater humoural and cellular immune responses than those administered H5N1 VLPs without LTB or Flic. Intramuscular immunization with VLPs protected mice from lethal challenge with homologous or heterologous H5N1 viruses irrespective of whether the VLPs additionally included LTB or Flic. In contrast, oral immunization of mice with LTB- or Flic-VLPs conferred substantial protection against lethal challenge with both homologous and heterologous H5N1 influenza viruses, whereas mice immunized orally with VLPs lacking LTB and Flic universally succumbed to infection. Mice immunized orally with LTB- or Flic-VLPs showed 10-fold higher virus-specific IgG titres than mice immunized with H5N1-VLPs lacking LTB or Flic. Collectively, these results indicate that the inclusion of immunostimulatory proteins, such as LTB and Flic, in VLP-based vaccines may represent a promising new approach for the control of current H5N1 HPAI outbreaks by eliciting higher humoural and cellular immune responses and conferring improved cross-clade protection.

The H7N9 influenza virus epidemic has been associated with a high mortality rate in China. Therefore, to prevent the H7N9 virus from causing further damage, developing a safe and effective vaccine is necessary. In this study, a vaccine candidate consisting of virus-like particles (VLPs) based on H7N9 A/Shanghai/2/2013 and containing hemagglutinin (HA), neuraminidase (NA), and matrix protein (M1) was successfully produced using a baculovirus (BV) expression system. Immunization experiments showed that strong humoral and cellular immune responses could be induced by the developed VLPs when administered via either the intramuscular (IM) or intranasal (IN) immunization routes. Notably, VLPs administered via both immunization routes provided 100% protection against lethal infection caused by the H7N9 virus. The IN immunization with 40μg of H7N9 VLPs induced strong lung IgA and lung tissue resident memory (TRM) cell-mediated local immune responses. These results provide evidence for the development of an effective preventive vaccine against the H7N9 virus based on VLPs administered through both the IM and IN immunization routes.

Avian H3N2 influenza virus follows cross-host transmission and has spread among dogs in Asia since 2005. After 2015–2016, a new H3N2 subtype canine influenza epidemic occurred in dogs in North America and Asia. The disease prevalence was assessed by virological and serological surveillance in dogs in China. Herein, five H3N2 canine influenza virus (CIV) strains were isolated from 1185 Chinese canine respiratory disease samples in 2017–2018, these strains were on the evolutionary branch of the North American CIVs after 2016 and genetically far from the classical canine H3N2 strain discovered in China before 2016. Serological surveillance showed an HI antibody positive rate of 6.68%. H3N2 was prevalent in the coastal areas and northeastern regions of China. In 2018, it became the primary epidemic strain in the country. The QK01 strain of H3N2 showed high efficiency in transmission among dogs through respiratory droplets. Nevertheless, the virus only replicated in the upper respiratory tract and exhibited low pathogenicity in mice. Furthermore, highly efficient transmission by direct contact other than respiratory droplet transmission was found in a guinea pig model. The low-level replication in avian species other than ducks could not facilitate contact and airborne transmission in chickens. The current results indicated that a novel H3N2 virus has become a predominant epidemic strain in dogs in China since 2016 and acquired highly efficient transmissibility but could not be replicated in avian species. Thus, further monitoring is required for designing optimal immunoprophylactic tools for dogs and estimating the zoonotic risk of CIV in China.

Although H1N2 avian influenza virus (AIV) only infect birds, documented cases of swine infection with H1N2 influenza viruses suggest this subtype AIV may pose a potential threat to mammals. Here, we generated mouse-adapted variants of a H1N2 AIV to identify adaptive changes that increased virulence in mammals. MLD50 of the variants were reduced >1000-fold compared to the parental virus. Variants displayed enhanced replication in vitro and in vivo, and replicate in extrapulmonary organs. These data show that enhanced replication capacity and expanded tissue tropism may increase the virulence of H1N2 AIV in mice. Sequence analysis revealed multiple amino acid substitutions in the PB2 (L134H, I647L, and D701N), HA (G228S), and M1 (D231N) proteins. These results indicate that H1N2 AIV can rapidly acquire adaptive amino acid substitutions in mammalian hosts, and these amino acid substitutions collaboratively enhance the ability of H1N2 AIV to replicate and cause severe disease in mammals.

// Kun Zhang 1, 2 , Wei wei Xu 1 , Zhaowei Zhang 1 , Jing liu 1 , Jing Li 3 , Lijuan Sun 4 , Weiyang Sun 1 , Peirong Jiao 5 , Xiaoyu Sang 1 , Zhiguang Ren 1 , Zhijun Yu 1 , Yuanguo Li 1 , Na Feng 1 , Tiecheng Wang 1 , Hualei Wang 1 , Songtao Yang 1 , Yongkun Zhao 1 , Xuemei Zhang 4 , Peter R. Wilker 6 , WenJun Liu 3 , Ming Liao 5 , Hualan Chen 7 , Yuwei Gao 1 , Xianzhu Xia 1 1 Key Laboratory of Jilin Province for Zoonosis Prevention and Control, The Military Veterinary Institute, Academy of Military Medical Science of PLA, Changchun, 130122, PR China 2 Philips Institute for Oral Health Research, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, 23298, USA 3 CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, PR China 4 Department of Influenza Vaccine, Changchun Institute of Biological Product, Changchun, 130062, PR China 5 College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China 6 Department of Microbiology, University of Wisconsin La Crosse, La Crosse, Wisconsin, 54601, USA 7 State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150001, PR China Correspondence to: Yuwei Gao, email: gaoyuwei@gmail.com Xianzhu Xia, email: xiaxzh@cae.cn Keywords: innate immunity, guinea pig, highly pathogenic avian influenza virus, GBP-1, RIG-I Received: August 26, 2016 Accepted: February 27, 2017 Published: March 23, 2017 ABSTRACT H5N1 avian influenza viruses are a major pandemic concern. In contrast to the highly virulent phenotype of H5N1 in humans and many animal models, guinea pigs do not typically display signs of severe disease in response to H5N1 virus infection. Here, proteomic and transcriptional profiling were applied to identify host factors that account for the observed attenuation of A/Tiger/Harbin/01/2002 (H5N1) virulence in guinea pigs. RIG-I and numerous interferon stimulated genes were among host proteins with altered expression in guinea pig lungs during H5N1 infection. Overexpression of RIG-I or the RIG-I adaptor protein MAVS in guinea pig cell lines inhibited H5N1 replication. Endogenous GBP-1 expression was required for RIG-I mediated inhibition of viral replication upstream of the activity of MAVS. Furthermore, we show that guinea pig complement is involved in viral clearance, the regulation of inflammation, and cellular apoptosis during influenza virus infection of guinea pigs. This work uncovers features of the guinea pig innate immune response to influenza that may render guinea pigs resistant to highly pathogenic influenza viruses.

// Ling Li 1, 2 , Hongli Jin 1, 2 , Hualei Wang 2, 4 , Zengguo Cao 2 , Na Feng 2, 4 , Jianzhong Wang 3 , Yongkun Zhao 2 , Xuexing Zheng 2, 5 , Pengfei Hou 1, 2 , Nan Li 2 , Hang Chi 2 , Pei Huang 2, 3 , Cuicui Jiao 2 , Qian Li 2 , Lina Wang 2, 3 , Tiecheng Wang 2 , Weiyang Sun 2 , Yuwei Gao 2, 4 , Changchun Tu 2 , Guixue Hu 3 , Songtao Yang 2, 4 , Xianzhu Xia 2, 4 1 Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, China 2 Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China 3 Department of Preventive Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun, China 4 Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou, China 5 School of Public Health, Shandong University, Jinan, China Correspondence to: Hualei Wang email: whl831125@163.com Songtao Yang email: yst62041@163.com Guixue Hu email: huguixue901103@163.com Keywords: rabies virus, proteome, proteomics analysis, autophagy, differential virulence Received: May 23, 2016 Accepted: January 16, 2017 Published: February 08, 2017 ABSTRACT Rabies virus (RABV) is a neurotropic virus that causes serious disease in humans and animals worldwide. It has been reported that different RABV strains can result in divergent prognoses in animal model. To identify host factors that affect different infection processes, a kinetic analysis of host proteome alterations in mouse brains infected with different virulent RABV strains was performed using isobaric tags for a relative and absolute quantification (iTRAQ)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach, and this analysis identified 147 differentially expressed proteins (DEPs) between the pathogenic challenge virus standard (CVS)-11 strain and the attenuated SRV9 strain. Bioinformatics analyses of these DEPs revealed that autophagy and several pathways associated with autophagy, such as mammalian target of rapamycin (mTOR) signaling, p70S6K signaling, nuclear factor erythroid 2-related factor 2 (NRF2)-mediated oxidative stress and superoxide radical degradation, were dysregulated. Validation of the proteomic data showed that attenuated SRV9 induced more autophagosome accumulation than CVS-11 in an in vitro model. Our findings provide new insights into the pathogenesis of RABV and encourage further studies on this topic.

Middle East Respiratory Syndrome (MERS) is a highly lethal pulmonary infection caused by a coronavirus (CoV), MERS-CoV. With the continuing spread of MERS-CoV, prophylactic and therapeutic treatments are urgently needed. In this study, we prepared purified equine F(ab’)2 from horses immunized with MERS-CoV virus-like particles (VLPs) expressing MERS-CoV S, M and E proteins. Both IgG and F(ab’)2 efficiently neutralized MERS-CoV replication in tissue culture. Passive transfer of equine immune antibodies significantly reduced virus titers and accelerated virus clearance from the lungs of MERS-CoV infected mice. Our data show that horses immunized with MERS-CoV VLPs can serve as a primary source of protective F(ab’)2 for potential use in the prophylactic or therapeutic treatment of exposed or infected patients., Highlights • Healthy horses immunized with MERS-CoV virus-like particles rapidly generate high titers of virus neutralizing antibodies. • Passive transfer of equine immune antibodies significantly reduced virus titers from the lungs of MERS-CoV infected mice. • F(ab’)2 fragments prepared by digestion of antibody with pepsin to reduce possible allergic responses. • Equine immune antibodies are polyclonal and recognize more antigen determinants in MERS-CoV spike protein.

An improved chaotic laser system, which has a slave semiconductor laser (SL) injected by a master SL with double optical feedback (DOF), is proposed, so that the time delay (TD) signature can be successfully concealed from both intensity and phase chaos via choosing appropriate parameters. The TD signature is investigated by employing autocorrelation function (ACF) and mutual information (MI) function. Through analyzing the influence on TD signature in the region of injection current and injection strength for the slave SL, we find that, for both intensity chaos and phase chaos, the TD signature can be easily concealed under weak injection strength. When the injection strength is strong, we can not only successfully conceal TD signature, but also improve the bandwidth of chaotic laser output by choosing the optimal detuning frequency.

Rift Valley fever virus (RVFV), which causes Rift Valley fever (RVF), is a mosquito-borne zoonotic pathogen that causes serious morbidity and mortality in livestock and humans. RVF is a World Health Organization (WHO) priority disease and, together with rabies, is a major health burden in Africa. Here, we present the development and characterization of an inactivated recombinant RVFV and rabies virus (RABV) vaccine candidate (rSRV9-eGn). Immunization with rSRV9-eGn stimulated the production of RVFV-specific IgG antibodies and induced humoral and cellular immunity in mice but did not induce the production of neutralizing antibodies. IgG1 and IgG2a were the main isotypes observed by IgG subtype detection, and IgG3 antibodies were not detected. The ratios of IgG1/IgG2a &gt, 1 indicated a Type 2 humoral immune response. An effective vaccine is intended to establish a long-lived population of memory T cells, and mice generated memory cells among the proliferating T cell population after immunization with rSRV9-eGn, with effector memory T cells (TEM) as the major population. Due to the lack of prophylactic treatment experiments, it is impossible to predict whether this vaccine can protect animals from RVFV infection with only high titres of anti-RVFV IgG antibodies and no neutralizing antibodies induced, and thus, protection confirmation needs further verification. However, this RVFV vaccine designed with RABV as the vector provides ideas for the development of vaccines that prevent RVFV and RABV infections.

Middle East respiratory syndrome coronavirus (MERS-CoV), a new coronavirus that has been causing severe and fatal acute respiratory illnesses in humans since its outbreak in 2012, has raised public fear worldwide. The development of prophylactics and therapeutics is urgently needed to prevent and control MERS-CoV infections. In this study, a bacterium (Lactococcus lactis)-like particle (BLP) vaccine displaying the MERS-CoV receptor-binding domain (RBD) was developed, and gram-positive enhancer matrix (GEM) particles were used as substrates to externally bind to the MERS-CoV RBD through a protein anchor (PA). The designs included different numbers of lysin motif (LysM) repeats in the PAs linked by linkers (RBD-linker-PA2 (RLP2), RBD-linker-PA3 (RLP3) and RBD-PA3 (RP3)), and three LysM repeats and a linker in the fusion proteins increased the binding activity to the RBD. The specific immune responses were tested by intranasally immunizing mice with RLP3-GEM with or without the adjuvant GEL01. The results showed that GEL01-adjuvanted RLP3-GEM increased the systemic humoral, cellular and local mucosal immune responses in the mouse model, especially in the intestinal tract. The above results indicate that the MERS-CoV BLP product has the potential to be developed into a promising mucosal candidate vaccine to protect against MERS-CoV infections.

Background Available data on antibiotic resistance in sub-Saharan Africa is limited despite its increasing threat to global public health. As there is no previous study on antibiotic resistance in patients with clinical features of healthcare-associated infections (HAIs) in Sierra Leone, research is needed to inform public health policies. Our study aimed to assess antibiotic resistance rates from isolates in the urine and sputum samples of patients with clinical features of HAIs. Methodology We conducted a cross-sectional study of adult inpatients aged ≥18 years at Connaught Hospital, an urban tertiary care hospital in Freetown between February and June 2018. Results Over the course of the study, we enrolled 164 patients. Risk factors for HAIs were previous antibiotic use (93.3%), comorbidities (58.5%) and age (≥65 years) (23.9%). Of the 164 samples, 89.6% were urine. Bacterial growth was recorded in 58.8% of cultured specimens; the type of specimen was an independent predictor of bacterial growth (p Escherichia coli and Klebsiella pneumoniae; 29.2% and 19.0% in urine samples and 18.8% and 31.3% in sputum samples, respectively. The overall resistance rates were 58% for all extended-spectrum beta-lactamase (ESBL)-producing organisms, 13.4% for carbapenem-resistant non-lactose fermenting gram-negative bacilli, 8.7% for carbapenem-resistant Acinetobacter baumannii (CRAB) and 1.3% for carbapenem-resistant Enterobacteriaceae (CRE). There were no carbapenem-resistant P. aeruginosa (CRPA) isolates but all Staphylococcus aureus isolates were methicillin-resistant S. aureus. Conclusion We demonstrated a high prevalence rate of ESBL-producing organisms which are a significant burden at the main tertiary hospital in Sierra Leone. Urgent action is needed to strengthen microbiological diagnostic infrastructure, initiate surveillance on antibiotic resistance and develop and implement policy framework on antibiotic stewardship.

We previously obtained mouse-adapted variants of H1N2 avian influenza virus that contained PB2-L134H, PB2-I647L, PB2-D701N, HA-G228S, and M1-D231N mutations. Here, we analyzed the effects of these mutations on viral pathogenicity in a mammalian model. By evaluating the virulence of mouse-adapted H1N2 variants at different generations, we found that the PB2-D701N and HA-G228S mutations both contribute to the virulence of this virus in mammals. Furthermore, we found that the PB2-D701N and HA-G228S mutations both enhance the ability of the virus to replicate in vivo and in vitro and that the PB2-D701N substitution results in an expansion of viral tissue tropism. These results suggest that the PB2-D701N mutation and the HA-G228S mutation are the major mammalian determinants of H1N2 virus. These results help us to understand more about the mechanisms by which influenza viruses adapt to mammals, and monitoring of these mutations can be used in continuous influenza surveillance to assess the pandemic potential of avian influenza virus variants.

Canine distemper virus (CDV) is the causative agent of canine distemper (CD), which is one of the most important infectious diseases affecting wild and domestic carnivores. Vaccination represents an effective approach to prevent CDV infection among domestic carnivores. Canarypox-vectored recombinant CD vaccines (such as Recombitek CDV, PureVax Ferret Distemper, and Merial) with the CDV hemagglutinin (H) and fusion (F) genes can induce a potent immune response in dogs and ferrets. However, the vaccine's effectiveness varies with the species. In the current study, we developed a highly efficient recombinant canarypox virus termed as "ALVAC-CDV-M-F-H/C5-" that contained CDV virus-like particles (VLPs) by using the CRISPR/Cas9 gene editing method, which enabled concurrent expression of the matrix (M), H, and F genes. The recombinant strain provided faster seroconversion than the parent strain among minks as well as provided higher rates of antibody positivity than the parent strain among foxes and minks even before the administration of a second booster vaccination. We demonstrated, for the first time, that the CRISPR/Cas9 system can be applied for the rapid and efficient modification of the ALVAC-CDV-F-H genome and also that a high-dose new recombinant strain that produces CDV VLPs may present good outcomes in the prevention of CD among foxes and minks.

To identify molecular features that confer enhanced H7N9 virulence in mammals, we independently generated three mouse-adapted variants of A/Shanghai/2/2013 (H7N9) by serial passage in mice. The mouse lethal doses (MLD 50 ) of the mouse-adapted variants were reduced >1000–100000-fold when compared to the parental virus. Adapted variants displayed enhanced replication kinetics in vivo , and were capable of replicating in multiple organs. Analysis of adapted viral genomes revealed a total of 14 amino acid changes among the three variant viruses in the PA (T97I, K328R, P332T, and Q556R), HA (H3 numbering; A107T, R220I, L226Q, and R354K), NP (A284T and M352I), NA (M26I, N142S, and G389D), and M1 (M128R) proteins. Notably, many of these adaptive amino acid changes have been identified in naturally occurring H7 isolates. Our results identify amino acid substitutions that collectively enhance the ability of a human H7N9 virus to replicate and cause severe disease in mice.

The fast development of image encryption requires performance evaluation metrics. Traditional metrics like entropy do not consider the correlation between local pixel and its neighborhood. These metrics cannot estimate encryption based on image pixel coordinate permutation. A novel effectiveness evaluation metric is proposed in this paper to address the issue. The cipher text image is transformed to bit stream. Then, Poker Test is implemented. The proposed metric considers the neighbor correlations of image by neighborhood selection and clip scan. The randomness of the cipher text image is tested by calculating the chi-square test value. Experiment results verify the efficiency of the proposed metrics.

The paper is concerned with the H∞ filtering problems for a family of discrete-time systems. The measurement signals of the system are transmitted via a network, in which multiple communication channels coexist. It is considered that only one of these channels is active for the data communication at one time instant, and the switching of activated channel is governed by a Markov chain. In each channel, the practical phenomenon of packet dropouts is taken into account, and the packet dropout rates of different channels are different. With the construction of a Lyapunov function that depends on the index of the activated channel, stochastic stability and H∞ performance criteria are established, based on which a set of H∞ filters depending on the index of the activated channel are designed. In order to show the effectiveness of the designed H∞ filter, we apply the developed theoretical results to a numerical example.

This paper is concerned with the problems of stability analysis and Hoo control for a class of systems with quantized signals in both control input channel and measurement output channel. The quantization density of each quantizer is considered to be variable, and the variations of the quantizers are governed by a Markov chain. With the aid of quantization-error-dependent Lyapunov function approach, a set of Hoo controllers depending on the mode of quantization density are carried out to achieve the stochastic stability and the prescribed Hoo performance of the closed-loop system. Finally, a numerical example is provided to illustrate the effectiveness of the proposed control method and the benefits of the variability of quantization density.

Influenza viruses cause significant morbidity and mortality and pose a substantial threat to public health. Vaccination represents the principle means of preventing influenza virus infection. Current vaccine approaches are hindered by the need to routinely reformulate vaccine compositions in an effort to account for the progressive antigenic changes that occur as influenza viruses circulate in the human population. In this study, we evaluated chimeric virus-like particle (cVLP) vaccines containing conserved elements of influenza proteins (HL5M2e (HA stem gene with 5M2e gene inserted) and NP), with or without glycosylphosphatidylinositol-anchored CCL28 (GPI-CCL28) and/or GM-CSF (GPI-GM-CSF) fusion proteins as molecular adjuvants. cVLPs elicited strong humoral and cellular immune responses against homologous and heterologous viruses, and improved survival following lethal challenge with both homologous and heterologous viruses. Inclusion of GPI-anchored adjuvants in cVLP vaccines augmented the generation of influenza-specific humoral and cellular immune responses in mice in comparison to the non-adjuvanted cVLP vaccines. VLPs containing GPI-anchored adjuvants reduced morbidity and improved survival to lethal challenge with homologous and heterologous influenza viruses. This work suggests that VLP vaccines incorporating conserved influenza virus proteins and GPI-anchored molecular adjuvants may serve as a platform for a broadly protective “universal” influenza vaccine.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a novel human coronavirus that can cause human respiratory disease. The development of a detection method for this virus that can lead to rapid and accurate diagnosis would be significant. In this study, we established a nucleic acid visualization technique that combines the reverse transcription loop-mediated isothermal amplification technique and a vertical flow visualization strip (RT-LAMP-VF) to detect the N gene of MERS-CoV. The RT-LAMP-VF assay was performed in a constant temperature water bath for 30 min, and the result was visible by the naked eye within 5 min. The RT-LAMP-VF assay was capable of detecting 2 × 101 copies/μl of synthesized RNA transcript and 1 × 101 copies/μl of MERS-CoV RNA. The method exhibits no cross-reactivities with multiple CoVs including SARS-related (SARSr)-CoV, HKU4, HKU1, OC43 and 229E, and thus exhibits high specificity. Compared to the real-time RT-PCR (rRT-PCR) method recommended by the World Health Organization (WHO), the RT-LAMP-VF assay is easy to handle, does not require expensive equipment and can rapidly complete detection within 35 min.

Although H7N7 AIVs primarily circulate in wild waterfowl, documented cases of human infection with H7N7 viruses suggest they may pose a pandemic threat. Here, we generated mouse-adapted variants of a wild waterfowl-origin H7N7 virus to identify adaptive changes that confer enhanced virulence in mammals. The mouse lethal doses (MLD50) of the adapted variants were reduced >5000-fold compared to the parental virus. Mouse-adapted variants viruses displayed enhanced replication in vitro and in vivo, and acquired the ability to replicate in extrapulmonary tissues. These observations suggest that enhanced growth characteristics and modified cell tropism may increase the virulence of H7N7 AIVs in mice. Genomic analysis of the adapted variant viruses revealed amino acid changes in the PB2 (E627K), PB1 (R118I), PA (L550M), HA (G214R), and NA (S372N) proteins. Our results suggest that these amino acid substitutions collaboratively enhance the ability of H7N7 virus to replicate and cause severe disease in mammals.

H7 avian influenza viruses (AIVs) have caused a number of human infections, highlighting the pandemic potential of them. However, the factors that promote their replication in mammals remain poorly understood. Here, we generated mouse-adapted variants of a reassortant H7N1 virus to identify adaptive changes that confer enhanced virulence in mammals. The mouse lethal doses (MLD50) of the variants were reduced >10,000-fold compared to the parental virus. Adapted variants displayed enhanced replication kinetics in vitro and vivo, and were capable of replicating in multiple organs. Analysis of the variant virus genomes revealed amino acid changes in the PB2 (E627K), HA (H3 numbering; E114K, G205E, and G218E), and NA (S350N) proteins. Notably, some amino acid changes have been identified in natural H7 isolates. Our results implicate a number of amino acid substitutions that collectively enhance the ability of a wild bird-origin H7N1 AIV to replicate and cause severe disease in mice.

H6N1 avian influenza viruses (AIVs) are one of the most abundantly detected avian influenza virus subtype, and a human H6N1 infection case has been reported in 2013. H6N1 AIVs may pose a potential human risk, however, the factors that promote the replication of H6N1 viruses in mammals remain poorly understood. Here, we generated mouse-adapted variants of a H6N1 virus (A/Mallard/SanJiang/275/2007) to identify adaptive changes that confer enhanced virulence to H6N1 viruses in mammals. After eight sequential passages in mice, the mouse lethal doses (MLD50) of the variants were reduced >1000-fold compared to the parental virus. We found that the variants displayed the greatest enhancement of replication in vitro and in vivo, and also were capable of replicating in the brains of infected mice. These observations suggest that enhanced growth characteristics and modified cell tropism may contribute to increased virulence of H6N1 AIVs in mice. Sequencing of the variants revealed amino acid changes in the PB2 (E627K), PA (T97I), and HA (N394T) proteins. Our results suggest that these mutations involved in the enhancement of the ability of H6N1 virus to efficient replicate and cause severe disease in mammals.

H5 clade 2.3.4.4 influenza A viruses pose a potential threat to public health and are a cause of public concern. Here, we generated mouse-adapted viruses of a waterfowl-origin H5N5 virus (H5 clade 2.3.4.4) to identify adaptive changes that confer increased virulence in mammals. After two passages, we obtained a mouse-adapted H5N5 virus that contained single amino acid substitutions in the PB2 (E627K) and hemagglutinin (HA) (F430L) proteins. We then analyzed the impact of these individual amino acid substitutions on viral pathogenicity to mammals. The 50% mouse lethal dose (MLD50) of the H5N5 virus containing the PB2-E627K substitution or the HA-F430L substitution was reduced 1000-fold or 3.16-fold, respectively. Furthermore, we found that PB2-E627K enhanced viral replication kinetics in vitro and in vivo. These results suggest that the PB2-E627K and HA-F430L substitutions are important for adaptation of H5N5 AIVs to mammals. These findings emphasize the importance of continued surveillance of poultry for H5N5 AIVs with these amino acid substitutions.

Frequent emergence of low pathogenic avian influenza H3N2 viruses in the wild birds has caused concern for human health. Here, we generated mouse-adapted strains of a wild waterfowl-origin low pathogenic avian influenza H3N2 virus to identify adaptive mutations that confer enhanced virulence in mammals. The mouse lethal doses (MLD50) of the adapted strains were reduced >562-fold compared to the parental virus. Mouse-adapted strains displayed enhanced replication in vitro and in vivo, and acquired the ability to replicate in extrapulmonary tissues. These observations suggest that enhanced growth characteristics and modified cell tropism may increase the virulence of H3N2 AIVs in mice. Genomic analysis revealed mutations in the PB2 (E192K and D701N), PB1 (F269S, I475V, and L598P), HA (V242E), NA (G170R), and M1 (M192V) proteins. Our results suggest that these amino acid substitutions collaboratively enhance the ability of H3N2 avian influenza A virus to replicate and cause severe disease in mammals.

Avian influenza viruses (AIVs) are globally important contagions. Several domestic mammals can be infected with AIVs and may play important roles in the adaptation and transmission of these viruses in mammals, although the roles of wild mammals in the natural ecology of AIVs are not yet clear. Here, we performed a serological survey of apparently healthy Plateau pikas at Qinghai Lake in China to assess the prevalence of exposure to AIVs. Ninety-two of 293 (31%) of wild Plateau pikas possessed serum antibodies against a lowly pathogenic avian influenza (LPAI) H9N2 virus. Experimental inoculation of Plateau pikas with a LPAI H9N2 virus resulted in productive viral replication in respiratory tissues without prior adaptation. Our findings suggest that Plateau pikas represent a natural mammalian host to H9N2 AIVs and may play a role in the ongoing circulation of H9N2 viruses at Qinghai Lake in China. Surveillance for AIV infection in Plateau pika populations and other mammals that have close contact with the Plateau pikas should be considered.

Natural small-molecule products are promising lead compounds for developing a generation of novel antimicrobials agents to meet the challenge of antibiotic-resistant pathogens. To facilitate the search for novel anti-virulence agents, we chose a virulence factor of Type Three Secretion System (T3SS) as a drug target to screen candidates from a small-molecule library in our laboratory. This study demonstrated fusaric acid had dramatically inhibitory effects on secretion of Salmonella island 1 (SPI-1) effector proteins and invasion of Salmonella into HeLa cells. Moreover, fusaric acid had no inhibitory effects on bacterial growth and viability of host cells. Protein HilA is a key regulator of SPI-1 in Salmonella, which affects transcription of SPI-1 effectors and SPI-1 apparatus genes. In this study, fusaric acid (FA) did not affect secretion of SPI-1 effectors in HilA over-expressed strain, suggesting it did not affect the transcription of SPI-1. In addition, fusaric acid did not affect the protein level of apparatus protein PrgH in SPI-1 needle complex. As a result, we proposed fusaric acid had an inhibitory effect on SPI-1 probably depending on its influence on SicA/InvF. In summary, fusaric acid is a novel inhibitor of T3SS with potential for further developing novel anti-virulence agents.

Furanocoumarin imperatorin is the major active component of Angelica dahurica root extracts, widely used in traditional medicine to treat headache, toothache, and orbital eye pain. In this study, we investigated the mechanisms that may underlie the pain-relieving effects of the compound. We found that imperatorin significantly inhibited formalin- and capsaicin-induced nocifensive responses but did not alter baseline thermal withdrawal thresholds in the rat. We established that imperatorin is a weak agonist of TRPV1, a channel implicated in detecting several noxious stimuli, exhibiting a 50% effective concentration (EC50) of 12.6 ± 3.2 μM. A specific TRPV1 antagonist, JNJ-17203212 (0.5 μM), potently inhibited imperatorin-induced TRPV1 activation. Site-directed mutagenesis studies revealed that imperatorin most likely acted via a site adjacent to or overlapping with the TRPV1 capsaicin-binding site. TRPV1 recovery from desensitization was delayed in the presence of imperatorin. Conversely, imperatorin sensitized TRPV1 to acid activation but did not affect the current amplitude and/or the activation-inactivation properties of Na(v)1.7, a channel important for transmission of nociceptive information. Thus, our data indicate that furanocoumarins represent a novel group of TRPV1 modulators that may become important lead compounds in the drug discovery process aimed at developing new treatments for pain management.

West Nile virus (WNV) is prevalent in Africa, Europe, the Middle East, West Asia, and North America, and causes epidemic encephalitis. To date, no effective therapy for WNV infection has been developed; therefore, there is urgent need to find an efficient method to prevent WNV disease. In this study, we prepared and evaluated the protective efficacy of immune serum IgG and pepsin-digested F(ab′)2 fragments from horses immunized with the WNV virus-like particles (VLP) expressing the WNV M and E proteins. Immune equine F(ab′)2 fragments and immune horse sera efficiently neutralized WNV infection in tissue culture. The passive transfer of equine immune antibodies significantly accelerated the virus clearance in the spleens and brains of WNV infected mice, and reduced mortality. Thus, equine immunoglobulin or equine neutralizing F(ab′)2 passive immunotherapy is a potential strategy for the prophylactic or therapeutic treatment of patients infected with WNV.

We first report avipoxvirus (APV) infection and an isolate named APV/03/2016 from a red-flanked blue robin (Tarsiger cyanurus) captured at Songhua Lake Scenic Area in Jilin City (Jilin Province, China) on March 24, 2016. The partial sequence of the 4b core protein gene and DNA polymerase gene of APV/03/2016 suggests that the virus belongs to the subclade B1 cluster of clade B (canarypox virus). The BLAST results showed the highest similarity of the two genes with the Pacific shearwater-isolated strain SWPV-2 (KX857215), canarypox virus strain D98-11133 (GQ487567), canarypox virus strain ATCC VR-111 (AY318871), avipoxvirus Mississippi isolate P89 (KC018048), and avipoxvirus Wisconsin isolate P92 (KC018051). The results indicate that APV/03/2016 is a canarypox-like virus. These findings demonstrate the continuous emergence of new APV hosts such as red-flanked blue robins and suggest that monitoring of APV circulation and evolution should be strengthened for T. cyanurus conservation.

In this paper, two novel non-reference objective image fusion quality evaluation metrics are presented. The novel metrics are based on the correlation between human visual perception and quantized discrete cosine transform coefficients. Hamming distance is adopted to calculate similarity, and then the novel metrics are deduced. The influence of quantization table selection is analyzed. Experiments verify the effectiveness and efficiency of the novel metrics.

To analyze the molecular basis of the variation of the pathogenicity of the influenza B virus, we rescued a recombinant virus with a deletion in the carboxyl terminal of the NS1 protein using reverse genetics based on the parental virus B-S9 of B/Yamagata/16/88. A mutant strain with a deletion of 171 amino acids in the carboxyl terminal of the NS1 protein was named "B-L5". BALB/c mice were inoculated with 3 X 105 EID50 of B-L5 and the parental virus B-S9, respectively. Then, weight changes, survival, and viral titers were documented. During 3 days post-inoculation (dpi) to 7 dpi, the weight of mice infected with B-S9 decreased. However, the weight of mice infected with B-L5 showed weight decreases only at 2 dpi, and quickly recovered at 3 dpi. B-S9 and B-L5 could replicate in the lungs of BALB/c mice. However, viral titers in the lungs of mice infected with B-L5 were 7900-times lower than those of mice infected with B-S9 at 3 dpi. Viral titers in the lungs of mice infected with B-L5 were not detected at 6 dpi. These results showed that, compared with the parent virus B-S9, the mutant virus B-L5 showed lower pathogenicity in BALB/c mice. Our study suggests that deletion of the carboxyl terminal of the NS1 protein decreases the pathogenicity of the influenza B virus. Establishment of a reverse-genetics system for the B influenza virus will provide a platform for studying its pathogenesis, and mechanism of transmission, and for developing live-attenuated influenza B virus vaccines.

Bacterial virulence factors have been increasingly regarded as attractive targets for development of novel antibacterial agents. Virulence inhibitors are less likely to generate bacterial resistance, which makes them superior to traditional antibiotics that target bacterial viability. Salmonella enterica serovar Typhimurium, an important food-borne human pathogen, has type III secretion system (T3SS) as its major virulence factor. T3SS secretes effector proteins to facilitate invasion into host cells. In this study, we identified several analogs of cytosporone B (Csn-B) that strongly block the secretion of Salmonella pathogenicity island 1 (SPI-1)-associated effector proteins, without affecting the secretion of flagellar protein FliC in vitro . Csn-B and two other derivatives exhibited a strong inhibitory effect on SPI-1-mediated invasion to HeLa cells, while no significant toxicity to bacteria was observed. Nucleoid proteins Hha and H-NS bind to the promoters of SPI-1 regulator genes hilD , hilC , and rtsA to repress their expression and consequently regulate the expression of SPI-1 apparatus and effector genes. We found that Csn-B upregulated the transcription of hha and hns , implying that Csn-B probably affected the secretion of effectors through the Hha–H-NS regulatory pathway. In summary, this study presented an effective SPI-1 inhibitor, Csn-B, which may have potential in drug development against antibiotic-resistant Salmonella .