Emerging SARS-CoV-2 variants reduce neutralization sensitivity to convalescent sera and monoclonal antibodies

Coronaviruses are enveloped,positive-stranded RNA viruses that contain the largest known RNA genomes to date.As severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)continues to circulate in the human population,multiple mutations have accumulated over time,which may affect its transmission,virulence and antigenicity.

Changes in the humoral immunity response in SARS-CoV-2 convalescent patients over 8 months

Many countries around the world have seen a sharp rise in COVID-19 cases since the beginning of October due to the second wave of the pandemic.A decline in the antibody response to severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which was reported exclusively in the early month,increases the risk of reinfection for convalescent individuals.There is a current need to follow the maintenance of specific antibodies against SARS-CoV-2.

The clinical and immunological features of pediatric COVID-19 patients in China

In December 2019,the corona virus disease 2019(COVID-19)caused by novel coronavirus(SARS-CoV-2)emerged in Wuhan,China and rapidly spread worldwide.Few information on clinical features and immunological profile of COVID-19 in paediatrics.The clinical features and treatment outcomes of twelve paediatric patients confirmed as COVID-19 were analyzed.The immunological features of children patients was investigated and compared with twenty adult patients.The median age was 14.5-years(range from 0.64 to 17),and six of the patients were male.The average incubation period was 8 days.Clinically,cough(9/12,75%)and fever(7/12,58.3%)were the most common symptoms.Four patients(33.3%)had diarrhea during the disease.As to the immune profile,children had higher amount of total T cell,CD8t T cell and B cell but lower CRP levels than adults(P<0.05).Ground-glass opacity(GGO)and local patchy shadowing were the typical radiological findings on chest CT scan.All patients received antiviral and symptomatic treatment and the symptom relieved in 3e4 days after admitted to hospital.The paediatric patients showed mild symptom but with longer incubation period.Children infected with SARS-CoV-2 had different immune profile with higher T cell amount and low inflammatory factors level,which might ascribed to the mild clinical symptom.We advise that nucleic acid test or examination of serum IgM/IgG antibodies against SARS-CoV-2 should be taken for children with exposure history regardless of clinical symptom.

Kinetic analysis of γ-glutamyltransferase reaction process for measuring activity via an integration strategy at low concentrations of γ-glutamyl p-nitroaniline

At 0.12 mmol/L γ-glutamyl p-nitroaniline(GGPNA),an improved integrated method was developed for kinetic analysis of γ-glutamyltransferase(GGT) reaction process and the integration with the classical initial rate method to measure serum GGT.For the improved integrated method,an integrated rate equation,which used the predictor variable of reaction time and considered inhibitions by both GGPNA and products,was nonlinearly fit to GGT reaction processes.For the integration strategy,classical initial rates were estimated when GGPNA consumption percentages were below 50%;otherwise,maximal reaction rates of GGT were estimated by the improved integrated method and converted into initial rates according to the differential rate equation at 0.11 mmol/L GGPNA.The inte-gration strategy was validated using optimized GGT kinetic parameters and 10-s intervals to record reaction curves within 8.0 min.By the integration strategy,there was a linear response from 0.9 to 32.0 U/L GGT,coefficients of variation were below 3.5%for GGT from 8.0 to 32.0 U/L(n=5) ,and GGT activities in clinical sera responded linearly to their classical initial rates at 2.00 mmol/L GGPNA with an expected slope.Therefore,the integration strategy was successful in measuring GGT at 0.12 mmol/L GGPNA.

Reduced neutralization of SARS-CoV-2 B.1.617 variant by convalescent and vaccinated sera

Coronavirus disease 2019(COVID-19)is caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).The Spike protein that mediates coronavirus entry into host cells is a major target for COVID-19 vaccines and antibody therapeutics.However,multiple variants of SARS-CoV-2 have emerged,which may potentially compromise vaccine effectiveness.Using a pseudovirus-based assay,we evaluated SARS-CoV-2 cell entry mediated by the viral Spike B.1.617 and B.1.1.7 variants.We also compared the neutralization ability of monoclonal antibodies from convalescent sera and neutralizing antibodies(NAbs)elicited by CoronaVac(inactivated vaccine)and ZF2001(RBD-subunit vaccine)against B.1.617 and B.1.1.7 variants.Our results showed that,compared to D614G and B.1.1.7 variants,B.1.617 shows enhanced viral entry and membrane fusion,as well as more resistant to antibody neutralization.These findings have important implications for understanding viral infectivity and for immunization policy against SARS-CoV-2 variants.

Correction: Changes in the humoral immunity response in SARS-CoV-2 convalescent patients over 8 months

Correction to:Cellular&Molecular Immunology https:/doi.org/10.1038/s41423-020-00605-4,published online 08 January 2021 The licence information was missing from this article and should havebeen CC-BY.The original article has been corrected.