Determinants and Mechanisms of the Low Fusogenicity and Endosomal Entry of Omicron Subvariants

The rapid spread and strong immune evasion of the SARS-CoV-2 Omicron subvariants has raised serious concerns for the global COVID-19 pandemic. These new variants exhibit reduced fusogenicity and increased endosomal entry pathway utilization compared to the ancestral D614G variant, the underlying mechanisms of which remain elusive. Here we show that the C-terminal S1 mutations of the BA.1.1 subvariant, H655Y and T547K, critically govern the low fusogenicity of Omicron. Notably, H655Y also dictates the enhanced endosome entry pathway utilization. Mechanistically, T547K and H655Y likely stabilize the spike trimer conformation, as shown by increased molecular interactions in structural modeling as well as reduced S1 shedding. Importantly, the H655Y mutation also determines the low fusogenicity and high dependence on the endosomal entry pathway of other Omicron subvariants, including BA.2, BA.2.12.1, BA.4/5 and BA.2.75. These results uncover mechanisms governing Omicron subvariant entry and provide insights into altered Omicron tissue tropism and pathogenesis.

Prime-pull immunization of mice with a BcfA-adjuvanted vaccine elicits mucosal immunity and prevents SARS CoV-2 infection and pathology

Vaccines against SARS-CoV-2 that induce mucosal immunity capable of preventing infection and disease remain urgently needed. We show that intramuscular priming of mice with an alum and BcfA-adjuvanted Spike subunit vaccine, followed by a BcfA-adjuvanted mucosal booster, generated Th17 polarized tissue resident CD4+ T cells, and mucosal and serum antibodies. The serum antibodies efficiently neutralized SARS-CoV-2 and its Delta variant, suggesting cross-protection against a recent variant of concern (VOC). Immunization with this heterologous vaccine prevented weight loss following challenge with mouse-adapted SARS-CoV-2 and reduced viral replication in the nose and lungs. Histopathology showed a strong leukocyte and polymorphonuclear (PMN) cell infiltrate without epithelial damage in mice immunized with BcfA-containing vaccines. In contrast, viral load was not reduced in the upper respiratory tract of IL-17 knockout mice immunized with the same formulation, suggesting that the Th17 polarized T cell responses are critical for protection. We show that vaccines adjuvanted with alum and BcfA, delivered through a heterologous prime-pull regimen, protect against SARS-CoV-2 infection without causing enhanced respiratory disease. SIGNIFICANCEThere remains a need for SARS CoV-2 booster vaccines that generate mucosal immunity and prevent transmission. We show that systemic priming followed by a mucosal booster with a BcfA-adjuvanted subunit vaccine generates neutralizing antibodies and Th17 polarized systemic and tissue-resident immune responses that provide sterilizing immunity against wildtype SARS CoV-2, and a variant of concern. Importantly, in contrast to alum alone, the addition of BcfA prevents respiratory pathology. These results suggest that a BcfA-adjuvanted mucosal booster may elicit mucosal immunity in individuals previously immunized systemically with approved vaccines. This foundational study in mice sets the stage for testing our vaccine regimen in larger animal models as a booster vaccine.

Suppression of de novo antibody responses against SARS-CoV2 and the Omicron variant after mRNA vaccination and booster in patients with B cell malignancies undergoing active treatment, but maintenance of pre-existing antibody levels against endemic viruses.

The impact of SARS-CoV2 vaccination in cancer patients remains incompletely understood given the heterogeneity of cancer and cancer therapies. We assessed vaccine-induced antibody response to the SARS-CoV2 Omicron (B.1.1.529) variant in 57 patients with B cell malignancies with and without active B cell-targeted therapy. Ancestral- and Omicron-reactive antibody levels were determined by ELISA and neutralization assays. In over one third of vaccinated patients at the pre-booster timepoint, there were no ELISA-detectable antibodies against either the ancestral strain or Omicron variant. The lack of vaccine-induced antibodies was predominantly in patients receiving active therapy such as anti-CD20 monoclonal antibody (mAb) or Brutons tyrosine kinase inhibitors (BTKi). While booster immunization was able to induce detectable antibodies in a small fraction of seronegative patients, the benefit was disproportionately evident in patients not on active therapy. Importantly, in patients with post-booster ELISA-detectable antibodies, there was a positive correlation of antibody levels against the ancestral strain and Omicron variant. Booster immunization increased overall antibody levels, including neutralizing antibody titers against the ancestral strain and Omicron variant; however, predominantly in patients without active therapy. Furthermore, ancestral strain neutralizing antibody titers were about 5-fold higher in comparison with those to Omicron, suggesting that even with booster administration, there may be reduced protection against the Omicron variant. Interestingly, in almost all patients regardless of active therapy, including those unable to generate detectable antibodies against SARS-CoV2 spike, we observed comparable levels of EBV, influenza, and common cold coronavirus reactive antibodies demonstrating that B cell-targeting therapies primarily impair de novo but not pre-existing antibody levels. These findings suggest that patients with B cell malignancies on active therapy may be at disproportionately higher risk to new versus endemic viral infection and suggest utility for vaccination prior to B cell-targeted therapy.

Loss of Neutralizing Antibody Response to mRNA Vaccination against SARS-CoV-2 Variants: Differing Kinetics and Strong Boosting by Breakthrough Infection

The waning efficacy of SARS-CoV-2 vaccines combined with the continued emergence of variants resistant to vaccine-induced immunity has reignited debate over the need for booster vaccines. To address this, we examined the neutralizing antibody (nAb) response against four major SARS-CoV-2 variants--D614G, Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2)--in health care workers (HCWs) at pre-vaccination, post-first and post-second mRNA vaccine dose, and six months post-second mRNA vaccine dose. Neutralizing antibody titers against all variants, especially the Delta variant, declined dramatically from four weeks to six months post-second mRNA vaccine dose. Notably, SARS-CoV-2 infection enhanced vaccine durability, and mRNA-1273 vaccinated HCWs also exhibited ~2-fold higher nAb titers than BNT162b2 vaccinated HCWs. Together these results demonstrate possible waning of protection from infection against SARS-CoV-2 Delta variant based on decreased nAb titers, dependent on COVID-19 status and the mRNA vaccine received.

mRNA Booster Vaccines Elicit Strong Protection Against SARS-CoV-2 Omicron Variant in Cancer Patients

Following its emergence in late November of 2020, the SARS-CoV-2 Omicron (B.1.1.529) variant has caused major global public health concerns. We recently demonstrated that in healthy adults the Omicron variant exhibits strong resistance to immunity induced by two doses of the mRNA vaccines, but a booster mRNA vaccine dose can provide strong protection against Omicron. However, it is currently unknown how well these mRNA vaccine boosters protect immunocompromised groups, including cancer patients, from the Omicron variant. Here we show that (1) neutralizing antibody (nAb) titers against the Delta and Omicron variants in cancer patients after two-dose mRNA vaccines are 4.2-fold and 21.3-fold lower, respectively, compared to the ancestral D614G, and (2) nAb titers against the Delta and Omicron variants in boosted cancer patients are 3.6-fold and 5.1-fold lower, respectively, compared to D614G. Our findings highlight the effectiveness and need for booster vaccination strategies in immunocompromised groups including cancer patients to protect from the Omicron variant.

Lung-selective Cas13d-based nanotherapy inhibits lethal SARS-CoV-2 infection by targeting host protease Ctsl

The COVID-19 pandemic persists as a global health crisis for which curative treatment has been elusive. Development of effective and safe anti-SARS-CoV-2 therapies remains an urgent need. SARS-CoV-2 entry into cells requires specific host proteases including TMPRSS2 and Cathepsin L (Ctsl)1-3, but there has been no reported success in inhibiting host proteases for treatment of SARS-CoV-2 pathogenesis in vivo. Here we have developed a lung Ctsl mRNA-targeted, CRISPR/Cas13d-based nanoparticle therapy to curb fatal SARS-CoV-2 infection in a mouse model. We show that this nanotherapy can decrease lung Ctsl expression in normal mice efficiently, specifically, and safely. Importantly, this lung-selective Ctsl-targeted nanotherapy significantly extended the survival of lethally SARS-CoV-2 infected mice by decreasing lung virus burden, reducing expression of pro-inflammatory cytokines/chemokines, and diminishing the severity of pulmonary interstitial inflammation. Additional in vitro analyses demonstrated that Cas13d-mediated Ctsl knockdown inhibited infection mediated by the spike protein of SARS-CoV-1, SARS-CoV-2, and more importantly, the authentic SARS-CoV-2 B.1.617.2 Delta variant, regardless of TMPRSS2 expression status. Our results demonstrate the efficacy and safety of a lung-selective, Ctsl-targeted nanotherapy against infection by SARS-CoV-2 and likely other emerging coronaviruses, forming a basis for investigation of this approach in clinical trials.

Impaired Neutralizing Antibody Response to COVID-19 mRNA Vaccines in Cancer Patients

There is currently a critical need to determine the efficacy of SARS-CoV-2 vaccination for immunocompromised patients. In this study, we determined the neutralizing antibody response in 160 cancer patients diagnosed with chronic lymphocytic leukemia (CLL), lung cancer, breast cancer, and various non-Hodgkins lymphomas (NHL), after they received two doses of mRNA vaccines. Serum from 46 mRNA vaccinated health care workers (HCWs) served as healthy controls. We discovered that (1) cancer patients exhibited reduced neutralizing antibody titer (NT50) compared to HCWs; (2) CLL and NHL patients exhibited the lowest NT50 levels, with 50-60% of them below the detection limit; (3) mean NT50 levels in patients with CLL and NHL was [~]2.6 fold lower than those with solid tumors; and (4) cancer patients who received anti-B cell therapy exhibited significantly reduced NT50 levels. Our results demonstrate an urgent need for novel immunization strategies for cancer patients against SARS-CoV-2, particularly those with hematological cancers and those on anti-B cell therapies.

Immunological Insights Into the Therapeutic Roles of CD24Fc Against Severe COVID-19

BACKGROUNDSARS-CoV-2 causes COVID-19 through direct lysis of infected lung epithelial cells, which releases damage-associated molecular patterns (DAMPs) and induces a pro-inflammatory cytokine milieu causing systemic inflammation. Anti-viral and anti-inflammatory agents have shown limited therapeutic efficacy. Soluble CD24 (CD24Fc) is able to blunt the broad inflammatory response induced by DAMPs in multiple models. A recent randomized phase III trial evaluating the impact of CD24Fc in patients with severe COVID-19 demonstrated encouraging clinical efficacy. METHODSWe studied peripheral blood samples obtained from patients enrolled at a single institution in the SAC-COVID trial (NCT04317040) collected before and after treatment with CD24Fc or placebo. We performed high dimensional spectral flow cytometry analysis of peripheral blood mononuclear cells and measured the levels of a broad array of cytokines and chemokines. A systems analytical approach was used to discern the impact of CD24Fc treatment on immune homeostasis in patients with COVID-19. FINDINGSTwenty-two patients were enrolled, and the clinical characteristics from the CD24Fc vs. placebo groups were matched. Using high-content spectral flow cytometry and network-level analysis, we found systemic hyper-activation of multiple cellular compartments in the placebo group, including CD8+ T cells, CD4+ T cells, and CD56+ NK cells. By contrast, CD24Fc-treated patients demonstrated blunted systemic inflammation, with a return to homeostasis in both NK and T cells within days without compromising the ability of patients to mount an effective anti-Spike protein antibody response. A single dose of CD24Fc significantly attenuated induction of the systemic cytokine response, including expression of IL-10 and IL-15, and diminished the coexpression and network connectivity among extensive circulating inflammatory cytokines, the parameters associated with COVID-19 disease severity. INTERPRETATIONOur data demonstrates that CD24Fc treatment rapidly down-modulates systemic inflammation and restores immune homeostasis in SARS-CoV-2-infected individuals, supporting further development of CD24Fc as a novel therapeutic against severe COVID-19. FUNDINGNIH

SARS-CoV-2 Spreads through Cell-to-Cell Transmission

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible coronavirus responsible for the global COVID-19 pandemic. Herein we provide evidence that SARS-CoV-2 spreads through cell-cell contact in cultures, mediated by the spike glycoprotein. SARS-CoV-2 spike is more efficient in facilitating cell-to-cell transmission than SARS-CoV spike, which reflects, in part, their differential cell-cell fusion activity. Interestingly, treatment of cocultured cells with endosomal entry inhibitors impairs cell-to-cell transmission, implicating endosomal membrane fusion as an underlying mechanism. Compared with cell-free infection, cell-to-cell transmission of SARS-CoV-2 is refractory to inhibition by neutralizing antibody or convalescent sera of COVID-19 patients. While ACE2 enhances cell-to-cell transmission, we find that it is not absolutely required. Notably, despite differences in cell-free infectivity, the variants of concern (VOC) B.1.1.7 and B.1.351 have similar cell-to-cell transmission capability. Moreover, B.1.351 is more resistant to neutralization by vaccinee sera in cell-free infection, whereas B.1.1.7 is more resistant to inhibition by vaccine sera in cell-to-cell transmission. Overall, our study reveals critical features of SARS-CoV-2 spike-mediated cell-to-cell transmission, with important implications for a better understanding of SARS-CoV-2 spread and pathogenesis.

Neutralizing antibody against SARS-CoV-2 spike in COVID-19 patients, health care workers and convalescent plasma donors: a cohort study using a rapid and sensitive high-throughput neutralization assay

Rapid and specific antibody testing is crucial for improved understanding, control, and treatment of COVID-19 pathogenesis. Herein, we describe and apply a rapid, sensitive, and accurate virus neutralization assay for SARS-CoV-2 antibodies. The new assay is based on an HIV-1 lentiviral vector that contains a secreted intron Gaussia luciferase or secreted Nano-luciferase reporter cassette, pseudotyped with the SARS-CoV-2 spike (S) glycoprotein, and is validated with a plaque reduction assay using an authentic, infectious SARS-CoV-2 strain. The new assay was used to evaluate SARS-CoV-2 antibodies in serum from individuals with a broad range of COVID-19 symptoms, including intensive care unit (ICU) patients, health care workers (HCWs), and convalescent plasma donors. The highest neutralizing antibody titers were observed among ICU patients, followed by general hospitalized patients, HCWs and convalescent plasma donors. Our study highlights a wide phenotypic variation in human antibody responses against SARS-CoV-2, and demonstrates the efficacy of a novel lentivirus pseudotype assay for high-throughput serological surveys of neutralizing antibody titers in large cohorts.

Risk factors and survival analysis for central nervous system complications after allogeneic hematopoietic stem cell transplantation / 中南大学学报(医学版)

OBJECTIVES@#To investigate the risk factors as well as their impact on patients' survival of central nervous system (CNS) complications following allogeneic hematopoietic stem cell transplantation (HSCT).@*METHODS@#All relevant clinical data from a total of 323 patients, who underwent allogeneic HSCT in Xiangya Hospital of Central South University from September 2016 to September 2019, were retrospectively reviewed in this study. The complications' occurrence time, common symptoms and some other clinical data of the patients who developed CNS complications were analyzed descriptively. The risk factors for CNS complications following allogeneic HSCT were analyzed through univariate and multivariate analysis. And the survival analysis was conducted as well.@*RESULTS@#Among the 323 patients who underwent allogeneic HSCT, 32 patients developed CNS complications. These complications occurred in these patients at a median of 32 (range from -1 to 584) d after transplantation. Common symptoms were disturbance of consciousness (78.1%), convulsion (59.4%), and headache (12.5%). Univariate analysis showed that there were significant differences in neutrophil engraftment, platelet (PLT) engraftment, serum cytomegalovirus (CMV) DNA positive, combined with acute graft-versus-host disease (aGVHD), donor selection (@*CONCLUSIONS@#The delay or the failure of PLT engraftment and combined with aGVHD are the risk factors for CNS complications. The facts indicate that we should prevent CNS complications when patients who underwent allogeneic HSCT with the delay or the failure of PLT engraftment or aGVHD. Compared with non-CNS complication group, patients who developed CNS complications usually have poor prognosis.

Prescription Law of New Coronavirus Pneumonia in Different Stages / 中国实验方剂学杂志

Objective:To study the clinical medication regulation for the prevention and treatment of new coronavirus pneumonia with traditional Chinese medicine（TCM），especially prescriptions，on the basis of "treatment in accordance with seasonal conditions". Method:The guidelines and suggestions on novel coronavirus pneumonia formulated and published by national，provincial and municipal governments and experts before February 17，2020, were retrieved and summarized. Data was recorded in stages according to "prevention period，clinical observation period，pre-clinical period，middle clinical period，late clinical period and recovery period". The frequency analysis of TCM and its efficacy，prescription and proprietary Chinese medicine was carried out，and then the factor analysis and cluster analysis of TCM were carried out to obtain rational drug combinations. Result:Totally 172 suggestions on combined structure of drugs，50 suggestions on prescriptions and 31 suggestions on proprietary Chinese medicine were involved in the study，and provided by 24 official agencies and 24 medical experts， 147 kinds of herbs，44 prescriptions and 16 proprietary Chinese medicines were collected. No matter for the drug category or for the specific drug selection，the law of drug use in different stages was not the same. Huoxiang Zhengqi capsule，Shufeng Jiedu capsule，Lianhua Qingwen capsule and Jinhua Qinggan capsule can be used in the observation period. Xuanbai Chengqitang can be used in the middle of the disease. Angong Niuhuangwan，Suhexiangwan or Zixuedan, and Angong Niuhuangwan can be selected in the middle of the disease. And Qingfei Paidu decoction can be used in all stages of the disease. Conclusion:Doctors need to adjust their prescriptions along with the progress of the disease，because the law of medication in each stage of the new coronavirus pneumonia is different.

Effect of stress-induced hyperglycemia on myocardial perfusion and prognosis in elderly patients with acute myocardial infarction undergoing primary percutaneous coronary intervention / 中华老年医学杂志

Objective To investigate the effect of stress-induced hyperglycemia (SHG) on myocardial perfusion and clinical prognosis in elderly patients with acute myocardial infarction (AMI) who underwent primary percutaneous coronary intervention (PCI).Methods 348 elderly patients with first-time occurrence of acute ST-elevation myocardial infarction (STEMI) who underwent primary PCI within 12 hours from June 2008 to June 2010 were enrolled and followed up.All patients were divided into three groups according to serum glucose (SG) on admission:normal group (SG＜ 7.0 mmol/L,n=112);SG elevation group (7.0 mmol/L≤SG≤11.1 mmol/L,n=128) and (steady high blood glucose) SHG group (SG＞11.1 mmol/L,n=108).Myocardial perfusion indexes,including ST segment resolution (STR),TIMI myocardial perfusion grade (TMPG),peak value of creatine kinase CK-MB,left ventricular ejection (LVEF),and major adverse cardiac events (MACE) of patients in three groups,were measured and compared after emergency PCI.Results The blood glucose levels were increased,ST-elevation 2 h after PCI were well declined,the percentages of patients with TMPG 2-3 were decreased and peak values of CK-MB were increased in the three groups (all P＜0.01).After 12 months of follow-up,Kaplan-Meier survival analysis showed that patients of three groups had significantly different cumulative non-events survival rates [89.3％ (100/112) vs.85.9％ (110/128),76.3％ (83/108),P＜0.05].Multivariate Cox regression analysis showed that steady high blood glucose were the independent predictor for the occurrence of MACE in patients undergoing PCI after adjusting for age and gender,and the risk of MACE was increased by 5.811 folds in SHG group as compared with normal group (P＜0.01).Conclusions Stress induced hyperglycemia in elderly patients with STEMI can decrease myocardial perfusion level after primary PCI,which will lead to high incidence of MACE.

Protective effect of curcumin derivative B06 on kidney of type 2 diabetic rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To observe the effect and mechanism of curcumin derivative B06 on kidney from rats with hyperlipidemia and type 2 diabetes.</p><p><b>METHODS</b>Thirty five male SD rats were randomly divided into five groups(n = 7): the normal control group, high-fat group, high-fat + B06-treatd group, diabetic group, diabetic + B06-treated group. After fed with high-fat diet for 4 weeks, the later two groups were in- jected with streptozotocin intraperitoneally to induce type 2 diabetes mellitus. B06-treated groups were given B06 by gavage at a dosage of 0.2 mg/kg . d for 8 weeks. After the treatment, the serum creatinine, blood urea nitrogen and uric acid were detected biochemically, the morphology of kidney was observed with light and transmission electron microscopy, the expression of collagen fibers was observed with Masson staining, the protein expression of collogen IV and fibronectin in kidney were determined by Immunohistochemistry.</p><p><b>RESULTS</b>It was showed that the levels of the serum creatinine and blood urea nitrogen elevated significantly in diabetic group. In high-fat and diabetic groups, increased glomerular mesangial matrix and collagen fiber and thicken glomerular basal membrane were observed under light microscopy, swelling and fusion of foot process were found under electron microscope; increased green matrix within glomeruli was observed under Masson staining. collogen IV and fibronectin protein expression were significantly enhanced in high-fat group and diabetic group. After B06's intervention, the levels of serum creatinine and blood urea nitrogen were decreased in diabetic groups, the morphological change of kidney was obviously relieved, Collogen IV and fibronectin protein expression reduced.</p><p><b>CONCLUSION</b>Curcumin derivative B06 exerts a protective effect on kidney in type 2 diabetic rats, reduced expressions of collogen IV and fibronectin, inhibition of the accumulation of extracellular matrix and glomerular mesangial proliferation, and then prevention of renal fibrosis may be the mechanism.</p>