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Hinged multi-body systems are gaining popularity in the field of ocean engineering. Their performance is commonly evaluated using numerical simulations, but comparisons with experimental data are required to ensure the accuracy of the computational tools. However, there is a dearth of experimental studies on the motion performance of hinged multi-body systems, particularly those involving more than two hinged floating bodies. This study aims to fill this gap in experimental data for hinged multi-body systems beyond two bodies. The rectangular box was chosen as the test model due to its stable hydrodynamic properties and ease of numerical modelling. Five identical boxes were prefabricated and subsequently tested in the pool in a sequence ranging from one to five boxes to capture the motion performance. Additionally, a numerical programme based on potential flow theory was developed for mutual validation with the experimental data. Firstly, the physical properties of each box were determined through equations calculation and a free decay test, enabling the acquisition of all parameters for conducting numerical simulations. Then, the response amplitude operator (RAO) curves for the heave and pitch motion of a single box were depicted, and the results indicated that the resonant frequency in pitch direction obtained from the regular wave test was consistent with that obtained from the free decay test. Finally, the motion RAO curves of hinged multi-body systems were presented and analysed. The agreement between the measured and computed results confirms the suitability of the experimental data presented in this study as benchmark data for validating numerical simulations.

Ebola virus (EBOV) is classified as a category A pathogen as it causes viral hemorrhagic fever, one of the most-deadly virus-related diseases. Since its discovery in 1976, EBOV has caused a number of global public health incidents, which have posed a serious threat to both humans and non-human primates. Thus, numerous preventive vaccine studies are underway, including research on inactivated vaccines, DNA vaccines, subunit vaccines, virus-like particles, Venezuelan equine encephalitis virus replicon particles, and several viral vector vaccines. The vesicular stomatitis virus-based vaccine Ervebo was recently approved by the Food and Drug Administration and the European Union, and several other vaccines have also been proven to confer potent protection in non-human primates against EBOV lethal challenge. This review provides a brief background of EBOV, with a focus on the epidemiology, available animal models, and advances in preventive approaches for EBOV infection.

Abstract The genus Flavivirus comprises numerous emerging and re‐emerging arboviruses causing human illness. Vaccines are the best approach to prevent flavivirus diseases. But pathogen diversities are always one of the major hindrances for timely development of new vaccines when confronting unpredicted flavivirus outbreaks. We used West Nile virus (WNV) as a model to develop a new live‐attenuated vaccine (LAV), WNV‐poly(A), by replacing 5ʹ portion (corresponding to SL and DB domains in WNV) of 3ʹ‐UTR with internal poly(A) tract. WNV‐poly(A) not only propagated efficiently in Vero cells, but also was highly attenuated in mouse model. A single‐dose vaccination elicited robust and long‐lasting immune responses, conferring full protection against WNV challenge. Such “poly(A)” vaccine strategy may be promising for wide application in the development of flavivirus LAVs because of its general target regions in flaviviruses.

Floating structures have become a major part of offshore structure communities as offshore engineering moves from shallow waters to deeper ones. Floating installation ships or platforms are widely used in these engineering operations. Unexpected wave-induced motions affect floating structures, especially in harsh sea conditions. Horizontal motions on the sea surface can be offset by a dynamic positioning system, and heave motions can be controlled by a heave compensation system. Active heave compensation (AHC) systems are applied to control vertical heave motions and improve safety and efficiency. Predictive control based on machine learning prediction algorithms further improves the performance of active heave compensation control systems. This study proposes a predictive control strategy for an active heave compensation system with a machine learning prediction algorithm to minimise the heave motion of crane payload. A predictive active compensation model is presented to verify the proposed predictive control strategy, and proportion–integration–differentiation control with predictive control is adopted. The reliability of back propagation neural network (BPNN) and long short-term memory recurrent neural network (LSTM RNN) prediction algorithms is proven. The influence of the predictive error on compensation performance is analysed by comparing predictive feedforward cases with actual-data feedforward cases. Predictive feedforward control with regular and irregular wave conditions is discussed, and the possible strategies are examined. After implementing the proposed predictive control strategy based on a machine learning algorithm in an active heave compensation system, the heave motion of the payload is reduced considerably. This investigation is expected to contribute to the motion control strategy of floating structures.

Two coordination polymers involving Cd(II), i.e., [Cd2(IDPA)2(bpe) (H2O)2]n·2n(H2O) (1) (H2IDPA is 5-(1-oxoisoindolin-2-yl)isophthalic acid, bpe is 1,2-bis(4-pyridyl)ethane, 4-bpmh is N, N-bis-pyridin-4-ylmethylene-hydrazine), and [Cd(IDPA)(4-bpmh)0.5(H2O)2]n·n(H2O) (2) are prepared under solvothermal conditions via tuning the auxiliary ligand from bpe to 4-bpmh. Moreover, the as-prepared complexes 1–2 reveal much stronger luminescence in contrast to that of the free organic ligands. Their preventive effect and mechanism on scar formation after cosmetic surgery was explored. First, the two complexes’ suppression of the viability of the human immortal keratinocyte line (HaCaT) cell line was examined via exploiting cell counting kit-8 (CCK-8) detection. The vascular endothelial growth factor (VEGF) signal pathway activation in HaCaT cells was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR) assay.

ABSTRACTThe ongoing COVID-19 pandemic is causing huge impact on health, life, and global economy, which is characterized by rapid spreading of SARS-CoV-2, high number of confirmed cases and a fatality/case rate worldwide reported by WHO. The most effective intervention measure will be to develop safe and effective vaccines to protect the population from the disease and limit the spread of the virus. An inactivated, whole virus vaccine candidate of SARS-CoV-2 has been developed by Wuhan Institute of Biological Products and Wuhan Institute of Virology. The low toxicity, immunogenicity, and immune persistence were investigated in preclinical studies using seven different species of animals. The results showed that the vaccine candidate was well tolerated and stimulated high levels of specific IgG and neutralizing antibodies. Low or no toxicity in three species of animals was also demonstrated in preclinical study of the vaccine candidate. Biochemical analysis of structural proteins and purity analysis were performed. The inactivated, whole virion vaccine was characterized with safe double-inactivation, no use of DNases and high purity. Dosages, boosting times, adjuvants, and immunization schedules were shown to be important for stimulating a strong humoral immune response in animals tested. Preliminary observation in ongoing phase I and II clinical trials of the vaccine candidate in Wuzhi County, Henan Province, showed that the vaccine is well tolerant. The results were characterized by very low proportion and low degree of side effects, high levels of neutralizing antibodies, and seroconversion. These results consistent with the results obtained from preclinical data on the safety.

ABSTRACTIn the face of COVID-19 pandemic caused by the newly emerged SARS-CoV-2, an inactivated, Vero cell-based, whole virion vaccine candidate has been developed and entered into phase III clinical trials within six months. Biochemical and immunogenic characterization of structural proteins and their post-translational modifications in virions, the end-products of the vaccine candidate, would be essential for the quality control and process development of vaccine products and for studying the immunogenicity and pathogenesis of SARS-CoV-2. By using a panel of rabbit antisera against virions and five structural proteins together with a convalescent serum, the spike (S) glycoprotein was shown to be N-linked glycosylated, PNGase F-sensitive, endoglycosidase H-resistant and cleaved by Furin-like proteases into S1 and S2 subunits. The full-length S and S1/S2 subunits could form homodimers/trimers. The membrane (M) protein was partially N-linked glycosylated; the accessory protein 3a existed in three different forms, indicative of cleavage and dimerization. Furthermore, analysis of the antigenicity of these proteins and their post-translationally modified forms demonstrated that S protein induced the strongest antibody response in both convalescent and immunized animal sera. Interestingly, immunization with the inactivated vaccine did not elicit antibody response against the S2 subunit, whereas strong antibody response against both S1 and S2 subunits was detected in the convalescent serum. Moreover, vaccination stimulated stronger antibody response against S multimers than did the natural infection. This study revealed that the native S glycoprotein stimulated neutralizing antibodies, while bacterially-expressed S fragments did not. The study on S modifications would facilitate design of S-based anti-SARS-CoV-2 vaccines.

ABSTRACTThe emerging SARS-CoV-2 infection associated with the outbreak of viral pneumonia in China is ongoing worldwide. There are no approved antiviral therapies to treat this viral disease. Here we examined the antiviral abilities of three broad-spectrum antiviral compounds gemcitabine, lycorine and oxysophoridine against SARS-CoV-2 in cell culture. We found that all three tested compounds inhibited viral replication in Vero-E6 cells at noncytotoxic concentrations. The antiviral effect of gemcitabine was suppressed efficiently by the cytidine nucleosides. Additionally, combination of gemcitabine with oxysophoridine had an additive antiviral effect against SARS-CoV-2. Our results demonstrate that broad-spectrum antiviral compounds may have a priority for the screening of antiviral compounds against newly emerging viruses to control viral infection.

ABSTRACTChikungunya virus (CHIKV), a mosquito-borne alphavirus, has become an important re-emerging pathogen with its rapid spread to many non-endemic areas. The lack of effective vaccines and antiviral agents is largely attributed to the elusive infection and dissemination dynamics in vivo. In this study, we designed and developed a novel, replication-competent, CHIKV reporter virus (CHIKV-iRFP) encoding a near infrared fluorescent protein (iRFP). In vitro and in vivo characterization demonstrated that CHIKV-iRFP retained similar replication and virulence phenotypes to its parental virus. Neonatal BABL/c mice and IFNAR−/− A129 mice were highly susceptible to CHIKV-iRFP infection. Following intracranial (i.c.) inoculation, CHIKV-iRFP efficiently replicated and disseminated into whole body, resulting in rapid death in an age-dependent manner. Remarkably, upon footpad injection, CHIKV-iRFP readily disseminated from footpad to head and whole skeleton, with a specific tropism for bone marrow. Taken together, this novel reporter virus provides a powerful tool to track real time CHIKV replication and to test the in vivo efficacy of vaccines and antiviral therapeutics.

The flavivirus NS5 harbors both a methyltransferase (MTase) and an RNA-dependent RNA polymerase (RdRP). Both enzyme activities of NS5 are critical for viral replication. Recently, the full-length NS5 crystal structure of Japanese encephalitis virus reveals a conserved MTase-RdRP interface that features two conserved components: a six-residue hydrophobic network and a GTR sequence. Here we showed for the first time that these key interface components are essential for flavivirus replication by various reverse genetics approaches. Interestingly, some replication-impaired variants generated a common compensatory NS5 mutation outside the interface (L322F), providing novel routes to further explore the crosstalk between MTase and RdRP.

Chikungunya virus (CHIKV), a member of the Alphavirus genus, is an important human emerging/re-emerging pathogen. Currently, there are no effective antiviral drugs or vaccines against CHIKV infection. Herein, we construct an infectious clone of CHIKV and an eGFP reporter CHIKV (eGFP-CHIKV) with an isolated strain (assigned to Asian lineage) from CHIKV-infected patients. The eGFP-CHIKV reporter virus allows for direct visualization of viral replication through the levels of eGFP expression. Using a known CHIKV inhibitor, ribavirin, we confirmed that the eGFP-CHIKV reporter virus could be used to identify inhibitors against CHIKV. Importantly, we developed a novel and reliable eGFP-CHIKV reporter virus-based neutralization assay that could be used for rapid screening neutralizing antibodies against CHIKV.

The article discusses research which found a surrogate Ebola virus (EBOV) lethal mice model of recombinant vesicular stomatitis viruses (VSV) that could be used as a platform for EBOV glycoprotein-targeting prophylactic vaccines evaluation in biosafety level-2 (BSL-2) laboratories. The study determined the susceptibility of immunodeficient mice to VSV-EBOV. It determined tissue tropism and organ virus load in infected mice and observed outcomes in mice following VSV-EBOV infection.

Ships often have to pass each other in proximity in harbor areas and waterways in dense shipping-traffic environment. Hydrodynamic interaction occurs when a ship is overtaking (or being overtaken) or encountering other ships. Such an interactive effect could bemagnified in confined waterways, e.g., shallowand narrow rivers. Since Yeung published his initial work on ship interaction in shallow water, progress on unsteady interaction among multiple ships has been slow, though steady, over the following decades. With some exceptions, nearly all the published studies on ship-to-ship problem neglected free-surface effects, and a rigid-wall condition has often been applied on the water surface as the boundary condition.When the speed of the ships is low, this assumption is reasonably accurate as the hydrodynamic interaction is mainly induced by near-field disturbances. However, in many maneuvering operations, the encountering or overtaking speeds are actually moderately high (Froude number Fn > 0.2,where Fn ≡ U √gL p,Uis ship speed, g is the gravitational acceleration, and L is the ship length), especiallywhen the lateral separation between ships is the order of ship length. Here, the far-field effects arising from ship waves can be important. The hydrodynamic interaction model must take into account the surface-wave effects. Classical potential-flowformulation is only able to dealwith the boundary value problem when there is only one speed involved in the free-surface boundary condition. For multiple ships traveling with different speeds, it is not possible to express the freesurface boundary condition by a single velocity potential. Instead, a superposition method can be applied to account for the velocity field induced by each vessel with its own and unique speed. The main objective of the present article is to propose a rational superposition method to handle the unsteady free-surface boundary condition containing two or more speed terms, and validate its feasibility in predicting the hydrodynamic behavior in ship encountering. Themethodology used in the present article is a three-dimensional boundary-elementmethod based on a Rankine-type (infinite-space) source function, initially introduced by Bai and Yeung. The numerical simulations are conducted by using an in-house--developed multibody hydrodynamic interaction program "MHydro." Waves generated and forces (or moments) are calculated when ships are encountering or passing each other. Published model-test results are used to validate our calculations, and very good agreement has been observed. The numerical results show that free-surface effects need to be taken into account for Fn > 0.2. [ABSTRACT FROM AUTHOR]

The hydrodynamic performance of a vessel is highly dependent on its maneuvering waterways. The existence of the banks and bottom, as well as the presence of the other vessels, could have a significant influence on a ship's hydrodynamic behavior. In confined waterways, many researchers suspect the applicability of the classical potential flow method because of its nonviscous and irrotational assumption. The main objective of the present article is to improve and develop the boundary value problem (BVP) of a potential flow method and validate its feasibility in predicting the hydrodynamic behavior of ships advancing in confined waterways. The methodology used in the present study is a 3D boundary element method based on a Rankine-type Green function. The numerical simulations are performed by using the in-house developed multibody hydrodynamic interaction program MHydro. The waves and forces (or moments) are calculated when ships are maneuvering in shallow and narrow channels, when ships are entering locks, or when two ships are encountering or passing each other. These calculations are compared with the benchmark test data published in MASHCON, and the published computational fluid dynamics results. It has been found that the free-surface elevation, lateral force, and roll moment can be well predicted in ship-bank and ship-bottom problems. However, the potential flow solver fails to predict the sign of the yaw moment because of the cross-flow effect. When a ship is entering a lock, the return-flow effect has to be considered. By adding a proper return-flow velocity to the BVP, the modified potential flow solver could predict the resistance and lateral forces very well. However, it fails to predict the yaw moment because of the flow separation at the lock entrance. The potential flow method is very reliable in predicting the ship-ship problem. The resistance and lateral force, as well as the yaw moment, can be predicted well by using the potential flow method. [ABSTRACT FROM AUTHOR]

Bacillus sphaericus LP1-G, belonging to flagellar serotype H3, has been found to have moderate toxicity against two resistant Culex quinquefasciatus colonies (RLCq1 and RLCq2) and the susceptible contrast (SLCq). With an aim of screening mosquitocidal acting factor, a partial genome library was prepared from a partial HindIII digest of the total DNA from Bacillus sphaericus LP1-G. Two thousand twenty Escherichia coli clones were screened for toxicity against susceptible SLCq, and a toxic clone, designated E-UL68, was chosen for further study. The recombinant E-UL68 performed toxicity against both susceptible and two resistant colonies, having the same level of toxicity as that of wide-type strain LP1-G. Sequence analysis revealed that the inserted fragment was composed of 3876 nucleotides and contained a complete gene, whose sequence was identical to that of the mtx gene from B. sphaericus SSII-1. Because the binary toxin produced during sporulation of strain LP1-G has no activity against the target mosquitoes, this indicates that the Mtx toxin or other active factors might perhaps be responsible for the toxicity of LP1-G against different colonies of mosquito larvae. [ABSTRACT FROM AUTHOR]

Mosquito-borne flaviviruses, which include many important human pathogens such as West Nile virus (WNV), Dengue virus (DENV) and Zika virus (ZIKV), had caused numerous emerging epidemics in recent years. Knowledge on the viral genome functions necessary for effective viral replication in mosquito and vertebrate hosts remained obscure. Here, using ZIKV as a model, we found that the conserved downstream of AUG region (DAR), which is known as an essential element for the genome cyclization, involved in viral replication in a host specific manner. Mutational analysis of the DAR element showed that a single-nucleotide mismatch between 5'DAR-3'DAR had little effect on ZIKV replication in mammalian cells, but dramatically impaired viral propagation in mosquito cells. The revertant viruses passaged in mosquito cells generated compensatory mutations restoring the base pairing of DAR, further confirming the importance of the complementarity of DAR in mosquito cells. We demonstrated that a single nucleotide mutation in DAR is sufficient to destroy long-range RNA interaction of ZIKV genome, and affects de novo RNA synthesis at 28 °C instead of 37 °C, resulting in the different replication efficiencies of the mutant viruses in mosquito and mammalian cells. Our results reveal a novel function of the circular form of flavivirus genome in host-specific viral replication, providing new ideas to further explore the functions of viral genome during host adaptation. [ABSTRACT FROM AUTHOR]

Mosquito-borne flaviviruses consist of a positive-sense genome RNA flanked by the untranslated regions (UTRs). There is a panel of highly complex RNA structures in the UTRs with critical functions. For instance, Xrn1-resistant RNAs (xrRNAs) halt Xrn1 digestion, leading to the production of subgenomic flaviviral RNA (sfRNA). Conserved short direct repeats (DRs), also known as conserved sequences (CS) and repeated conserved sequences (RCS), have been identified as being among the RNA elements locating downstream of xrRNAs, but their biological function remains unknown. In this study, we revealed that the specific DRs are involved in the production of specific sfRNAs in both mammalian and mosquito cells. Biochemical assays and structural remodeling demonstrate that the base pairings in the stem of these DRs control sfRNA formation by maintaining the binding affinity of the corresponding xrRNAs to Xrn1. On the basis of these findings, we propose that DRs functions like a bracket holding the Xrn1-xrRNA complex for sfRNA formation. [ABSTRACT FROM AUTHOR]

We previously produced a replication-defective West Nile virus lacking NS1 WNV-ΔNS1) that could propagate at low levels (105 IU/ml) in a 293T cell line expressing wild-type (WT) NS1. This finding indicates the potential of developing WNV-ΔNS1 as a non-infectious vaccine. To explore this idea, we developed an NS1-expressing Vero cell line (VeroNS1) that significantly improved the yield of WNV-ΔNS1 (108 IU/ml). We evaluated the safety and efficacy of WNV-ΔNS1 in mice. WNV-ΔNS1 appeared to be safe as no replicative virus on naïve Vero cells after continuously culturing of WNV-ΔNS1 on VeroNS1 cells for fifteen rounds. WNV-ΔNS1 was non-infectious in mice, even when IFNAR-/- mice were administrated with a high dose of WNV-ΔNS1. A single dose of WNV-ΔNS1 vaccination protected mice from a highly lethal challenge of WT WNV. The antibody response against WNV correlated well with the protection of vaccinated mice. Our study demonstrates the potential of the NS1 trans complementation system as a new platform for flavivirus vaccine development. [ABSTRACT FROM AUTHOR]

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes epidemics of debilitating disease worldwide. Currently, there are no licensed vaccines or antivirals available against CHIKV infection. In this study, we generated a novel live attenuated vaccine (LAV) candidate of CHIKV with a complete deficiency of capsid (ΔC-CHIKV). It could propagate in BHK-21 cells, and had similar antigenic properties as native CHIKV. Vaccination of either immunocompromised IFNAR-/- mice or immunocompetent C57BL/6 mice with a single dose of ΔC-CHIKV conferred complete protection upon challenge with wild type (WT) CHIKV. Taken together, this vaccine candidate appeared to be safe and efficacious, representing a novel strategy for CHIKV vaccine design. [ABSTRACT FROM AUTHOR]

Flavivirus nonstructural protein 2B (NS2B) is a transmembrane protein that functions as a cofactor for viral NS3 protease. The cytoplasmic region (amino acids 51 to 95) alone of NS2B is sufficient for NS3 protease activity, whereas the role of transmembrane domains (TMDs) remains obscure. Here, we demonstrate for the first time that flavivirus NS2B plays a critical role in virion assembly. Using Japanese encephalitis virus (JEV) as a model, we performed a systematic mutagenesis at the flavivirus conserved residues within the TMDs of NS2B. As expected, some mutations severely attenuated (L38A and R101A) or completely destroyed (G12L) viral RNA synthesis. Interestingly, two mutations (G37L and P112A) reduced viral RNA synthesis and blocked virion assembly. None of the mutations affected NS2B-NS3 protease activity. Because mutations G37L and P112A affected virion assembly, we selected revertant viruses for these two mutants. For mutant G37L, replacement with G37F, G37H, G37T, or G37S restored virion assembly. For mutant P112A, insertion ofKat position K127 (leading to K127KK) of NS2B rescued virion assembly. A biomolecular fluorescent complementation (BiFC) analysis demonstrated that (i) mutation P112A selectively weakened NS2B-NS2A interaction and (ii) the adaptive mutation K127KK restored NS2B-NS2A interaction. Collectively, our results demonstrate that, in addition to being a cofactor for NS3 protease, flavivirus NS2B also functions in viralRNAreplication, as well as virion assembly. [ABSTRACT FROM AUTHOR]