Molecular mechanism of de novo replication by the Ebola virus polymerase.

Non-segmented negative-strand RNA viruses, including Ebola virus (EBOV), rabies virus, human respiratory syncytial virus and pneumoviruses, can cause respiratory infections, haemorrhagic fever and encephalitis in humans and animals, and are considered a substantial health and economic burden worldwide1. Replication and transcription of the viral genome are executed by the large (L) polymerase, which is a promising target for the development of antiviral drugs. Here, using the L polymerase of EBOV as a representative, we show that de novo replication of L polymerase is controlled by the specific 3' leader sequence of the EBOV genome in an enzymatic assay, and that formation of at least three base pairs can effectively drive the elongation process of RNA synthesis independent of the specific RNA sequence. We present the high-resolution structures of the EBOV L-VP35-RNA complex and show that the 3' leader RNA binds in the template entry channel with a distinctive stable bend conformation. Using mutagenesis assays, we confirm that the bend conformation of the RNA is required for the de novo replication activity and reveal the key residues of the L protein that stabilize the RNA conformation. These findings provide a new mechanistic understanding of RNA synthesis for polymerases of non-segmented negative-strand RNA viruses, and reveal important targets for the development of antiviral drugs.

Structure of the Ebola virus polymerase complex.

Filoviruses, including Ebola virus, pose an increasing threat to the public health. Although two therapeutic monoclonal antibodies have been approved to treat the Ebola virus disease1,2, there are no approved broadly reactive drugs to control diverse filovirus infection. Filovirus has a large polymerase (L) protein and the cofactor viral protein 35 (VP35), which constitute the basic functional unit responsible for virus genome RNA synthesis3. Owing to its conservation, the L-VP35 polymerase complex is a promising target for broadly reactive antiviral drugs. Here we determined the structure of Ebola virus L protein in complex with tetrameric VP35 using cryo-electron microscopy (state 1). Structural analysis revealed that Ebola virus L possesses a filovirus-specific insertion element that is essential for RNA synthesis, and that VP35 interacts extensively with the N-terminal region of L by three protomers of the VP35 tetramer. Notably, we captured the complex structure in a second conformation with the unambiguous priming loop and supporting helix away from polymerase active site (state 2). Moreover, we demonstrated that the century-old drug suramin could inhibit the activity of the Ebola virus polymerase in an enzymatic assay. The structure of the L-VP35-suramin complex reveals that suramin can bind at the highly conserved NTP entry channel to prevent substrates from entering the active site. These findings reveal the mechanism of Ebola virus replication and may guide the development of more powerful anti-filovirus drugs.

Bioactive compounds from Huashi Baidu decoction possess both antiviral and anti-inflammatory effects against COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic is an ongoing global health concern, and effective antiviral reagents are urgently needed. Traditional Chinese medicine theory-driven natural drug research and development (TCMT-NDRD) is a feasible method to address this issue as the traditional Chinese medicine formulae have been shown effective in the treatment of COVID-19. Huashi Baidu decoction (Q-14) is a clinically approved formula for COVID-19 therapy with antiviral and anti-inflammatory effects. Here, an integrative pharmacological strategy was applied to identify the antiviral and anti-inflammatory bioactive compounds from Q-14. Overall, a total of 343 chemical compounds were initially characterized, and 60 prototype compounds in Q-14 were subsequently traced in plasma using ultrahigh-performance liquid chromatography with quadrupole time-of-flight mass spectrometry. Among the 60 compounds, six compounds (magnolol, glycyrrhisoflavone, licoisoflavone A, emodin, echinatin, and quercetin) were identified showing a dose-dependent inhibition effect on the SARS-CoV-2 infection, including two inhibitors (echinatin and quercetin) of the main protease (Mpro), as well as two inhibitors (glycyrrhisoflavone and licoisoflavone A) of the RNA-dependent RNA polymerase (RdRp). Meanwhile, three anti-inflammatory components, including licochalcone B, echinatin, and glycyrrhisoflavone, were identified in a SARS-CoV-2-infected inflammatory cell model. In addition, glycyrrhisoflavone and licoisoflavone A also displayed strong inhibitory activities against cAMP-specific 3',5'-cyclic phosphodiesterase 4 (PDE4). Crystal structures of PDE4 in complex with glycyrrhisoflavone or licoisoflavone A were determined at resolutions of 1.54 Å and 1.65 Å, respectively, and both compounds bind in the active site of PDE4 with similar interactions. These findings will greatly stimulate the study of TCMT-NDRD against COVID-19.

Coronavirus Endoribonuclease Ensures Efficient Viral Replication and Prevents Protein Kinase R Activation.

Coronavirus (CoV) nsp15 is an endoribonuclease conserved throughout the CoV family. The enzymatic activity and crystal structure of infectious bronchitis virus (IBV) nsp15 are undefined, and the protein's role in replication remains unclear. We verified the uridylate-specific endoribonuclease (EndoU) activity of IBV and found that the EndoU active sites were located in the C-terminus of nsp15 and included His223, His238, Lys278 and Tyr334. We further constructed an infectious clone of the IBV-rSD strain (rSD-wild-type [WT]) and EndoU-deficient IBVs by changing the codon for the EndoU catalytic residues to alanine. Both the rSD-WT and EndoU-deficient viruses propagated efficiently in embryonated chicken eggs. Conversely, EndoU-deficient viral propagation was severely impaired in chicken embryonic kidney cells, which was reflected in the lower viral mRNA accumulation and protein synthesis. After infecting chickens with the parental rSD-WT strain and EndoU-deficient viruses, the EndoU-deficient-virus-infected chickens presented reduced mortality, tissue injury and viral shedding.IMPORTANCE Coronaviruses can emerge from animal reservoirs into naive host species to cause pandemic respiratory and gastrointestinal diseases with significant mortality in humans and domestic animals. Infectious bronchitis virus (IBV), a γ-coronavirus, infects respiratory, renal and reproductive systems, causing millions of dollars in lost revenue worldwide annually. Mutating the viral endoribonuclease resulted in an attenuated virus and prevented protein kinase R activation. Therefore, EndoU activity is a virulence factor in IBV infections, thus providing an approach for generating live-attenuated vaccine candidates for emerging coronaviruses.

The furin-S2' site in avian coronavirus plays a key role in central nervous system damage progression.

The furin cleavage site plays an important role in virus pathogenicity. The spike protein of SARS-CoV-2 harbors a furin cleavage site insertion in contrast to SARS-CoV, which may be related to its stronger communicability. An avian coronavirus with an extra furin cleavage site upstream of the fusion peptide (S2' site) infected monocyte cells and neuron cells leading to viremia or encephalitis, respectively. Immunohistochemistry and real-time quantitative polymerase chain reaction were used to follow disease progression and demonstrated differences between the parent avian coronavirus and mutated avian coronavirus with a furin-S2' site. Magnetic resonance imaging and biological dye to evaluate the blood-brain barrier permeability showed that avian coronavirus with a furin-S2' site had increased permeability compared with parent avian coronavirus. Immunohistochemistry of brains after intracerebral injection of avian coronavirus and immunofluorescence staining of primary neuron cells demonstrated the furin-S2' site expanded the cell tropism of the mutant avian coronavirus to neuron cells. TNF-α, which has a key role in blood-brain barrier permeability, was highly induced by avian coronavirus with a furin-S2' site compared with the parent avian coronavirus. We demonstrated the process involved in mutant avian coronavirus-induced disease and that the addition of a furin-S2' site changed the virus cell tropism.IMPORTANCECoronaviruses have broken out three times in two decades. Spike (S) protein plays a key role in the process of infection. To clarify importance of furin cleavage site in spike protein for coronavirus, we investigated the pathogenesis of neurotropic avian coronavirus whose spike protein contains an extra furin cleavage site (furin-S2' site). By combining real-time quantitative polymerase chain reaction and immunohistochemistry we demonstrated that infectious bronchitis virus (IBV) infects brain instead of trachea when its S protein contains furin-S2' site. Moreover, the virus was shown to increase the permeability of blood-brain barrier, infect neuron cells and induce high expression of TNF-α. Based on these results we further show that furin cleavage site in S protein plays an important role in coronavirus pathogenicity and cell tropism. Our study extends previous publications on function of S protein of coronavirus, increasing the understanding of researchers to coronavirus.

Pathogenic characteristics of a QX-like infectious bronchitis virus strain SD in chickens exposed at different ages and protective efficacy of combining live homologous and heterologous vaccination.

Continued reports of infections with infectious bronchitis virus (IBV) variants have occurred since its first isolation in the 1930s. Currently, QX-like IBVs are the predominant circulating genotype around the world. Here, the pathogenicity of QX-like IBV strain SD was characterized in chickens at different ages of exposure to the virus, and the protection efficacy of available vaccine combinations against IBV was evaluated. The results revealed that QX-like IBV strain SD was severely pathogenic in chickens, causing respiratory, urinary and reproductive infections, irrespective of age, based on clinical observations, viral distribution in tissues and a ciliostasis study. Severe respiratory signs, tracheal cilia injury, nephritis and abnormal development of the oviduct and ovarian follicles were evident throughout the experiment. A challenge experiment demonstrated that the homologous QX vaccine showed superior protection efficacy compared with other available vaccines, confirming the importance of IBV vaccine seed homology against the circulating IBV strains. Our findings aid an understanding of the pathogenicity of QX-like IBVs that may help to further control the infection.

Highly sensitive electrochemiluminescence biosensor for VEGF165 detection based on a g-C3N4/PDDA/CdSe nanocomposite.

In this work, an electrochemiluminescence (ECL) biosensor was fabricated for the selective detection of vascular endothelial growth factor (VEGF165). g-C3N4/PDDA/CdSe nanocomposites were used as the ECL substrate. Then, DNA labeled at the 5' end with amino groups (DNA1) was immobilized on the surface of g-C3N4/PDDA/CdSe nanocomposite-modified glassy carbon electrode (GCE) by amido linkage. AuNP-labeled target DNA (Au-DNA2) could hybridize with DNA1 to form a double strand. The ECL of the g-C3N4/PDDA/CdSe nanocomposite was efficiently quenched due to the resonance energy transfer between CdSe QDs and Au NPs. After VEGF165 was recognized and bound by Au-DNA2, the double helix was disrupted, and the energy transfer was broken. In this case, Au-DNA2 was released from the electrode surface, and the ECL intensity recovered to a higher level. Under optimal conditions, this ECL biosensor possesses excellent selectivity, accuracy, and stability for VEGF165 detection in a linear range of 2 pg mL-1 to 2 ng mL-1 with a detection limit of 0.68 pg mL-1. In addition, this assay has been successfully applied to the determination of VEGF165 in serum samples. Graphical abstract Schematic representation of the electrochemiluminescence sensor based on a g-C3N4/PDDA/CdSe nanocomposite, which can be determined in the concentration of vascular endothelial growth factor in serum.

Agreement Between Magnetic Resonance Imaging and Pathologic Findings in the Tumor Size Evaluation Before and After Neoadjuvant Chemotherapy Treatment: A Prospective Study.

OBJECTIVES: To compare the agreement between magnetic resonance imaging (MRI) results and postsurgical pathologic findings for tumor size evaluation in cervical cancer patients before and after neoadjuvant chemotherapy (NACT) treatment. METHODS: The study analyzed the agreement between pretreatment MRI results and postsurgical pathologic findings about the tumor size in 100 cervical cancer patients without NACT and 397 cervical cancer patients with NACT, respectively. RESULTS: In general, the agreement between pretreatment MRI results and postsurgical pathologic findings of tumor size was 0.855 (95% confidence interval [CI], 0.763-0.909) in cervical cancer patients without NACT, whereas the agreement between posttreatment MRI results and postsurgical pathologic findings was 0.503 (95% CI, 0.421-0.576). Only 62.72% (249/397) of patients who underwent NACT treatment have the same chemotherapy response evaluation results; the κ coefficient was 0.384(95% CI, 0.310-0.457) between posttreatment MRI and postsurgical pathologic findings. We still found International Federation of Gynecology and Obstetrics stage is associated with the chemotherapy response evaluation. CONCLUSIONS: Our data suggest that pretreatment MRI can be a surrogate indicator for postsurgical pathologic findings. However, posttreatment MRI could not be a surrogate indicator for postsurgical pathologic findings. The chemotherapy response evaluation based on only MRI is not so reliable. More indicators should be developed for chemotherapy response evaluation.

Large radius of curvature measurement based on virtual quadratic Newton rings phase-shifting moiré-fringes measurement method in a nonnull interferometer.

We have proposed a virtual quadratic Newton rings phase-shifting moiré-fringes measurement method in a nonnull interferometer to measure the large radius of curvature for a spherical surface. In a quadratic polar coordinate system, linear carrier testing Newton rings interferogram and virtual Newton rings interferogram form the moiré fringes. It is possible to retrieve the wavefront difference data between the testing and standard spherical surface from the moiré fringes after low-pass filtering. Based on the wavefront difference data, we deduced a precise formula to calculate the radius of curvature in the quadratic polar coordinate system. We calculated the retrace error in the nonnull interferometer using the multi-configuration model of the nonnull interferometric system in ZEMAX. Our experimental results indicate that the measurement accuracy is better than 0.18% for a spherical mirror with a radius of curvature of 41,400 mm.

Carrier squeezing interferometry with π/4 phase shift: phase extraction in the presence of multi-beam interference.

Multi-beam interference exists in testing high-reflectivity surfaces with a Fizeau interferometer. In this paper, the multi-beam interference intensity was estimated as the sum of the first six order harmonics using the Fourier series expansion. Then, by adopting carrier squeezing interferometry with a π/4 phase shift, an algorithm was proposed to extract the phase from multi-beam interferograms. To ensure the separation of the lobes of phase-shift errors and the phase in the frequency domain, conditions of the necessary linear carrier in the proposed algorithm were derived. Simulation results indicated that the phase retrieving precision is better than PV 0.008λ and RMS 0.001λ, even when the reflection coefficient of the test surface is as high as 0.9 and the phase shift varies within π/4±π/20. Compared with the other algorithms, the proposed algorithm for multi-beam interference was validated by its good performance in the experiments, especially when the phase-shift error exists.

Small intestinal injury in mice infected with respiratory influenza A virus: evidence for virus induced gastroenteritis.

OBJECTIVES: Influenza in humans is often accompanied by gastroenteritis-like symptoms such as diarrhea and abdominal pain nausea, but the underlying mechanism remains unclear. RESULTS: Mice infected with three subtypes of respiratory influenza A virus (IAV), particularly H5N1 and H7N2, developed intestinal injury. The avian H5N1 and H7N2 IAV were detected in the small intestine, whereas the human H1N1 was not detected. Section staining with the sialic acid (SA) receptor demonstrated that the small intestine mainly expressed SA α2, 3 Gal instead of SA α2, 6 Gal which preferentially binds to avian IAV. The number of goblet and sIgA cells in the small intestine increased, whereas CD4(+) and CD8(+) T cells decreased in all infected mice except for CD8(+) T cells increased in H7N2 infected mice. CONCLUSIONS: Respiratory IAV infection, particularly infected by avian IAV, can cause small intestine structural damage and modify the local immune response, thereby resulting in gastroenteritis-like symptoms.

Generation by reverse genetics of an effective attenuated Newcastle disease virus vaccine based on a prevalent highly virulent Chinese strain.

OBJECTIVES: To investigate whether the differences between the circulating Newcastle disease virus (NDV) isolates and the used vaccine might account for the current ND outbreaks in vaccinated poultry flocks. RESULTS: A reverse genetics system using prevalent genotype VIId isolate SG10 was constructed and a mutant virus, named aSG10, was developed by changing the virulent F protein cleavage site motif "(112)RRQKR↓F(117)" into an avirulent motif "(112)GRQGR↓L(117)". The attenuated pathogenicity of aSG10 was confirmed from the mean death time and intracerebral pathogenicity index. aSG10 and LaSota both protected vaccinated birds from death after challenge with highly virulent genotype VII NDV, strain SG10. However, aSG10 significantly reduced the challenge virus shedding from the vaccinated birds compared to LaSota vaccine. We also generated a recombinant virus, aSG10-enhanced green fluorescent protein (EGFP), which expresses EGFP. aSG10-EGFP stably expressed EGFP for at least 10 passages. CONCLUSIONS: The mutant, aSG10, can be safely used as a vaccine vector and is a potential vaccine candidate in increasing the protective efficacy for the control of current ND epidemic in China.

Molecular characterization of an infectious bronchitis virus strain isolated from northern China in 2012.

This study reports the complete genome sequence of an infectious bronchitis virus (CK/CH/SD/121220, KJ128295) isolated in 2012 from Shandong Province in northern China. The genome is 27,666 nt long, comprising six genes and 5' and 3' untranslated regions. The full-length genome of the CK/CH/SD/121220 isolate had the highest nucleotide sequence identity (96.7 %) to the YX10 strain. Sites of recombination were identified in the genes 1ab, S, 5a, 5b and N, with their putative parental strains belonging to the QX- and YN-type subgroups, which are already circulating in China. Our findings suggest an important role played by recombination in IBV evolution.

Comparative assessment of orthogonal polynomials for wavefront reconstruction over the square aperture.

Four orthogonal polynomials for reconstructing a wavefront over a square aperture based on the modal method are currently available, namely, the 2D Chebyshev polynomials, 2D Legendre polynomials, Zernike square polynomials and Numerical polynomials. They are all orthogonal over the full unit square domain. 2D Chebyshev polynomials are defined by the product of Chebyshev polynomials in x and y variables, as are 2D Legendre polynomials. Zernike square polynomials are derived by the Gram-Schmidt orthogonalization process, where the integration region across the full unit square is circumscribed outside the unit circle. Numerical polynomials are obtained by numerical calculation. The presented study is to compare these four orthogonal polynomials by theoretical analysis and numerical experiments from the aspects of reconstruction accuracy, remaining errors, and robustness. Results show that the Numerical orthogonal polynomial is superior to the other three polynomials because of its high accuracy and robustness even in the case of a wavefront with incomplete data.

Coupling and interaction mechanism between green urbanization and tourism competitiveness based an empirical study in the Yellow River Basin of China.

Exploring the spatial coupling relationship and interaction mechanism between green urbanization (GU) and tourism competitiveness (TC) is of great significance for promoting urban sustainable development. However, the lack of research on the interaction mechanism between GU and TC limits the formulation of effective environmental management policy and urban planning. Taking 734 counties in the Yellow River Basin (YRB) as the study area, this paper analyzes the spatial coupling relationship between GU and TC on the basis of comprehensive evaluation of GU and TC. Then, the interactive mechanism between GU and TC is systematically discussed, and the synergistic development strategy of the two is proposed. The results show that the GU level presents a multicore circle structure, with provincial capitals, prefecture-level urban districts and economically developed counties in east-central regions as high-value centers. The TC at county scale presents a multi-center spatial structure. Additionally, there is a significant positive spatial coupling between GU and TC in the YRB. The analysis further reveals that green urbanization level, social progress, population development, infrastructure construction, economic development quality, and eco-environmental protection has a observably influence on TC. Tourism competitiveness, service competitiveness, location competitiveness, resource competitiveness, market competitiveness, environmental influence, and talent competitiveness has a observably influence on GU. TC can promote GU, and the improvement of green urbanization level can support the development of tourism competitiveness. According to the spatial zoning method, 734 counties are divided into 6 categories, and the coordinated development strategy of GU and TC for each type of district is proposed.

Tensile Strength Statistics and Fracture Mechanism of Ultrahigh Molecular Weight Polyethylene Fibers: On the Weibull Distribution.

To study the distribution of ultrahigh molecular weight polyethylene fiber (UHMWPE) strength, three groups of UHMWPE fibers were spun by the gel spinning method, which was undrafted raw fibers (with high strain at break) and fibers with different prespinning and postspinning draw ratios. It is found that even when the strain at break (εb) > 46%, the tensile strength of the fiber still obeys the Weibull distribution. The draw ratio has a great influence on the distribution of fiber strength, especially the draw ratios of the spinneret in the prespinning process. It may be that different drafting processes affect the fracture mechanism of the fibers. This paper analyzes and discusses that and proves it by differential scanning calorimetry and the taut tie molecules (TTMs) fractions. The parameters of the Weibull distribution suggest the quality of the fiber. The Weibull modulus is closely related to the dispersion of the fiber properties and processing parameters. The characteristic strength is similar to the test average strength, which is more suitable for the judgment of fiber reliability in actual use. At the same time, the normality of the samples was tested by Kolmogorov-Smirnov, Shapiro-Wilk, Jarque-Bera test, and quantile-quantile (Q-Q) plots, and the strength distribution was visually displayed by the bell curve. The results show that the Gaussian distribution is not so suitable to describe the strength distribution of the stretched fiber compared to the Weibull distribution.

Attenuated Viral Replication of Avian Infectious Bronchitis Virus with a Novel 82-Nucleotide Deletion in the 5a Gene Indicates a Critical Role for 5a in Virus-Host Interactions.

We previously found that a deletion in γ-coronavirus Infectious bronchitis virus (IBV) accessory gene 5a is critical for decreased viral pathogenicity in chickens. Here, we systematically analyzed IBV virus infection: invasion, genome replication, subgenomic mRNA (sgmRNA) synthesis, protein synthesis, and virion release. The ability of the mutant IBV strain rYN-Δ5a to invade susceptible cells was not significantly different from that of parental rYN. However, compared with rYN, the level of sgmRNA synthesis and genome replication after cell entry by rYN-Δ5a was significantly lower in the early stage, resulting in a significantly lower level of nucleoprotein (N) synthesis and a consequent significantly lower number of offspring viruses released into the supernatant. The detected 5a protein was diffusely distributed in the cytoplasm and perinuclear area. We identified 16 differentially expressed host proteins, 8 of which were found to be host nuclear and cytoplasmic transport-related proteins. Coimmunoprecipitation revealed an interaction between hemagglutinin (HA)-tagged TNPO1, TNPO3, XPO1, XPOT, RanBP1, and EIF2B4 proteins and Flag-tagged 5a protein, and laser confocal microscopy confirmed 5a protein colocalization with these proteins, indicating that 5a protein can cause changes in the host protein localization. These host proteins promote the nuclear localization of N proteins, so we believe that 5a protein can hijack host nucleoplasmic transport-related proteins to help N enter the nucleus. This may involve regulating the cell cycle to promote the optimal intracellular conditions for virus assembly or by participating in the regulation of nucleolar function as a strategy to optimize virus replication. IMPORTANCE Coronaviruses (CoVs) have a huge impact on humans and animals. It is important for the prevention and control of the viruses to assess the molecular mechanisms related to virulence attenuation. Here, we systematically analyzed a single cycle of virus infection by γ-CoV IBV lacking accessory protein 5a. We observed that a 5a deletion in the IBV genome affected virus replication and sgmRNA synthesis early in the virus life cycle, leading to decreases in protein synthesis, offspring virus assembly, and virion release in chicken embryonic kidney cells. IBV 5a protein was found to interact with multiple host nuclear and cytoplasmic transport- and translation-related proteins, which can also interact with IBV N and relocate it into the cell nucleus. These findings provide a comprehensive view regarding the importance of IBV accessory protein 5a and an important theoretical basis for studying the interaction between coronavirus and host cell proteins.

Genomics Analysis to Identify Multiple Genetic Determinants That Drive the Global Transmission of the Pandemic ST95 Lineage of Extraintestinal Pathogenic Escherichia coli (ExPEC).

Extraintestinal pathogenic Escherichia coli (ExPEC) is a pathogen that causes host extraintestinal diseases. The ST95 E. coli lineage is one of the dominant ExPEC lineages in humans and poultry. In this study, we took advantage of extensive E. coli genomes available through public open-access databases to construct a detailed understanding of the phylogeny and evolution of ST95. We used a high variability of accessory genomes to highlight the diversity and dynamic traits of ST95. Isolates from diverse hosts and geographic sources were randomly located on the phylogenetic tree, which suggested that there is no host specificity for ST95. The time-scaled phylogeny showed that ST95 is an ancient and long-lasting lineage. The virulence genes, resistance genes, and pathogenicity islands (PAIs) were characterized in ST95 pan-genomes to provide novel insights into the pathogenicity and multidrug resistance (MDR) genotypes. We found that a pool of large plasmids drives virulence and MDR. Based on the unique genes in the ST95 pan-genome, we designed a novel multiplex PCR reaction to rapidly detect ST95. Overall, our study addressed a gap in the current understanding of ST95 ExPEC genomes, with significant implications for recognizing the success and spread of ST95.

An attenuated TW-like infectious bronchitis virus strain has potential to become a candidate vaccine and S gene is responsible for its attenuation.

TW-like infectious bronchitis virus (IBV) with high pathogenicity is becoming the predominant IBV type circulating in China. To develop vaccines against TW-like IBV strains and investigate the critical genes associated with their virulence, GD strain was attenuated by 140 serial passages in specific-pathogen-free embryonated eggs and the safety and efficacy of the attenuated GD strain (aGD) were examined. The genome sequences of GD and aGD were also compared and the effects of mutations in the S gene were observed. The results revealed that aGD strain showed no obvious pathogenicity with superior protective efficacy against TW-like and QX-like virulent IBV strains. The genomes of strains aGD and GD shared high similarity (99.87 %) and most of the mutations occurred in S gene. Recombinant IBV strain rGDaGD-S, in which the S gene was replaced with the corresponding regions from aGD, showed decreased pathogenicity compared with its parental strain. In conclusion, attenuated TW-like IBV strain aGD is a potential vaccine candidate and the S gene is responsible for its attenuation. Our research has laid the foundation for future exploration of the attenuating molecular mechanism of IBV.

Fermented Soybean Meal Affects the Reproductive Performance and Oxidative Status of Sows, and the Growth of Piglets.

This study aimed to investigate the effect of the fermented soybean meal on the reproductive performance, oxidative stress and colostrum composition of sows, and the growth performance of their progeny. A total of 44 sows were allotted to four dietary groups (n = 11/group). The dietary groups included the basal diet group (control) and the treatment groups in which soybean meal in the basal diet was replaced with 2%, 4%, and 6% fermented soybean meal, respectively. The experimental diets were fed to the sows from the 78th day of gestation to the 21st day of lactation. Replacing soybean meal in the basal maternal diet with the fermented soybean meal decreased the levels of malondialdehyde, cortisol, and 8-iso-prostaglandinF2α in the serum of sows and increased the average weight of piglets on the 14th day and the 21st day after birth. The activity of superoxide dismutase in the serum of sows was increased in the group with 4% fermented soybean meal on the 17th day of lactation. The levels of estrogen and growth factors in the serum of sows were enhanced in the group with 6% fermented soybean meal. In the colostrum, the levels of the protein and the immunoglobulin G were enhanced in the group with 4% fermented soybean meal. In conclusion, replacing the soybean meal in the basal maternal diet with the fermented soybean meal attenuates the oxidative stress status of the gestational and lactational sows, and enhances the average weight of their offspring.