ABSTRACT
Purpose: To investigate the antibacterial activity of pimaradienoic acid, a natural product isolated from Eleutherococcus trifoliatus. Methods: Pimaradienoic acid was purified from E. trifoliatus and tested against three Gram-positive bacteria. Minimum inhibitory concentrations (MICs) were determined, and bacterial growth curves were measured. Scanning electron microscopy (SEM) was used to observe morphological changes in bacteria after drug treatment. Results: Pimaradienoic acid exhibited concentration-dependent inhibition of the growth of the three bacteria tested. The MIC and bacterial growth dynamics results indicated that pimaradienoic acid had potent antibacterial activity. SEM revealed that pimaradienoic acid disrupted the bacterial membrane, leading to cell death. Conclusions: Pimaradienoic acid has significant antibacterial activity against Gram-positive bacteria, suggesting its potential as a novel antimicrobial agent.
ABSTRACT
The newly emerged Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains more than 30 mutations on the spike protein, 15 of which are located within the receptor binding domain (RBD). Consequently, Omicron is able to extensively escape existing neutralizing antibodies and may therefore compromise the efficacy of current vaccines based on the original strain, highlighting the importance and urgency of developing effective vaccines against Omicron. Here we report the rapid generation and evaluation of an mRNA vaccine candidate specific to Omicron. This mRNA vaccine encodes the RBD of Omicron (designated RBD-O) and is formulated with lipid nanoparticle. Two doses of the RBD-O mRNA vaccine efficiently induce neutralizing antibodies in mice; however, the antisera are effective only on the Omicron variant but not on the wildtype and Delta strains, indicating a narrow neutralization spectrum. It is noted that the neutralization profile of the RBD-O mRNA vaccine is opposite to that observed for the mRNA vaccine expressing the wildtype RBD (RBD-WT). Our work demonstrates the feasibility and potency of an RBD-based mRNA vaccine specific to Omicron, providing important information for further development of bivalent or multivalent SARS-CoV-2 vaccines with broad-spectrum efficacy.
ABSTRACT
The SARS-CoV-2 Omicron variant exhibits striking immune evasion and is spreading globally at an unprecedented speed. Understanding the underlying structural basis of the high transmissibility and greatly enhanced immune evasion of Omicron is of high importance. Here through cryo-EM analysis, we present both the closed and open states of the Omicron spike, which appear more compact than the counterparts of the G614 strain, potentially related to the Omicron substitution induced enhanced protomer-protomer and S1-S2 interactions. The closed state showing dominant population may indicate a conformational masking mechanism of immune evasion for Omicron spike. Moreover, we capture two states for the Omicron S/ACE2 complex with S binding one or two ACE2s, revealing that the substitutions on the Omicron RBM result in new salt bridges/H-bonds and more favorable electrostatic surface properties, together strengthened interaction with ACE2, in line with the higher ACE2 affinity of the Omicron relative to the G614 strain. Furthermore, we determine cryo-EM structures of the Omicron S/S3H3 Fab, an antibody able to cross-neutralize major variants of concern including Omicron, elucidating the structural basis for S3H3-mediated broad-spectrum neutralization. Our findings shed new lights on the high transmissibility and immune evasion of the Omicron variant and may also inform design of broadly effective vaccines against emerging variants.
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A wide variety of diseases are commonly diagnosed via the visual examination of cell morphology within a peripheral blood smear. For certain diseases, such as COVID-19, morphological impact across the multitude of blood cell types is still poorly understood. In this paper, we present a multiple instance learning-based approach to aggregate high-resolution morphological information across many blood cells and cell types to automatically diagnose disease at a per-patient level. We integrated image and diagnostic information from across 236 patients to demonstrate not only that there is a significant link between blood and a patients COVID-19 infection status, but also that novel machine learning approaches offer a powerful and scalable means to analyze peripheral blood smears. Our results both backup and enhance hematological findings relating blood cell morphology to COVID-19, and offer a high diagnostic efficacy; with a 79% accuracy and a ROC-AUC of 0.90.
ABSTRACT
The ongoing coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current SARS-CoV-2 vaccines are based on spike (S) protein, S1 subunit, or receptor-binding domain (RBD) of prototype strain. Emergence of several novel SARS-CoV-2 variants has raised concern about potential immune escape. In this study, we performed an immunogenicity comparison of ancestral RBD, S1, and S ectodomain trimer (S-trimer) antigens and tested the efficacy of these prototype vaccines against the circulating variants, especially B.1.617 that has been linked to Indias current COVID-19 surge. We found that RBD and S-trimer proteins could induce significantly higher neutralizing antibody titers than S1 protein. For the three vaccines, the neutralizing titers decreased over time, but still remained high for at least five months after immunization. Importantly, the three prototype vaccines were still effective in neutralizing the variants of concern, although B.1.351 and B.1.617.1 lineages showed varying degrees of reduction in neutralization by the immune sera. The vaccines-induced sera were shown to block receptor binding and inhibit S protein-mediated membrane fusion. In addition, the immune sera did not promote antibody-dependent enhancement (ADE) in vitro. Our work provides valuable information for development of SARS-CoV-2 subunit vaccines and also supports the continued use of ancestral RBD or S-based vaccines to fight the COVID-19 epidemic.
ABSTRACT
Recently emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the ongoing coronavirus disease 2019 (COVID-19) pandemic. Currently, there is no vaccine available for preventing SARS-CoV-2 infection. Like closely related severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2 also uses its receptor-binding domain (RBD) on the spike (S) protein to engage the host receptor, human angiotensin-converting enzyme 2 (ACE2), facilitating subsequent viral entry. Here we report the immunogenicity and vaccine potential of SARS-CoV-2 RBD (SARS2-RBD)-based recombinant proteins. Immunization with SARS2-RBD recombinant proteins potently induced a multi-functional antibody response in mice. The resulting antisera could efficiently block the interaction between SARS2-RBD and ACE2, inhibit S-mediated cell-cell fusion, and neutralize both SARS-CoV-2 pseudovirus entry and authentic SARS-CoV-2 infection. In addition, the anti-RBD sera also exhibited cross binding, ACE2-blockade, and neutralization effects towards SARS-CoV. More importantly, we found that the anti-RBD sera did not promote antibody-dependent enhancement of either SARS-CoV-2 pseudovirus entry or authentic virus infection of Fc receptor-bearing cells. These findings provide a solid foundation for developing RBD-based subunit vaccines for SARS-CoV2.
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Objective To launch systematic research on long-term asymptomatic hyperuricemia (HUA) from hemorheological viewpoint,so as to provide references for clinical treatment of asymptomatic HUA.Methods Twenty rats were randomly and evenly divided into normal control group and model group.The rats were intraperitoneally injected with 250 mg/(kg · d) oxonate for 8 weeks to induce the model of asymptomatic HUA.The blood samples were obtained to measure the serum uric acid,hemorheological parameters,oxidative and anti-oxidative indices.Results The aggregation index,haemolysis rate,serum xanthine oxidase (XOD),plasma fibrinogen and blood viscosity significantly increased,while the orientation index,electrophoresis rate,serum superoxide dismutase (SOD),activated partial thromboplastin time (APTT) and prothrombin time (PT) significantly induced.Conclusions The asymptomatic HUA can lead to more serious oxidative stress,deteriorate the hemorheological parameters of red blood cells in rats,and induce higher blood viscosity and coagulation status.The research findings indicate that asymptomatic HUA should be correctly understood and timely intervened in clinical diagnosis.
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Objective To explore the relationship among aggression of patients,doctor-patient trust and perceived social support,and to provide a new prospective of improving doctor-patient relationship.Methods Data of Chinese buss-perry aggression scale,wake forest physician trust scale and perceived social support were collected from a sample of 338 patients in Guangzhou and analyzed with structural equation modeling.Results ①Median (interquartile range) of aggression,doctor-patient trust and perceived social support were 54(18),32(8) and 62(15) respectively.②Total score of aggression(Z=-2.37,P=0.02) and the dimension score of physical-aggression(Z=-4.07,P＜0.01) between different gender were statistically significant,and the scores of male were higher than female.③According to relevant result,aggression of patients was significantly negatively correlated with both doctor-patient trust (r=-0.13,P＜0.05)and perceived social support(r=-0.14,P＜0.01).Doctor-patient trust was significantly positively correlated with perceived social support(r=0.36,P＜0.01) ④Perceived social support fully mediate the relationship between aggression of patients and doctor-patient trust(GFI =0.989,NFI =0.989,IFI =0.998,CFI =0.998,RMSEA =0.026,x2/df=1.229).Conclusion Perceived social support is a protective factor of aggression of patients.Improving the perceived social support of patients can promote the doctor-patient trust.
