Hetero-bivalent Nanobodies Provide Broad-spectrum Protection against SARS-CoV-2 Variants of Concern including Omicron

Following Delta, Omicron variant triggered a new wave of SARS-CoV-2 infection globally, adaptive evolution of the virus may not stop, the development of broad-spectrum antivirals is still urgent. We previously developed two hetero-bivalent nanobodies with potent neutralization against original WT SARS-CoV-2, termed aRBD-2-5 and aRBD-2-7, by fusing aRBD-2 with aRBD-5 or aRBD-7, respectively. Here, we resolved crystal structures of these nanobodies in complex with RBD, and found the epitope of aRBD-2 differs from that of aRBD-5, aRBD-7. aRBD-2 binds to a conserved epitope which renders its binding activity to all variants of concern (VOCs) including Omicron. Interestingly, although monovalent aRBD-5 and aRBD-7 lost binding to some variants, they effectively improved the overall affinity when transformed into the hetero-bivalent form after being fused with aRBD-2. Consistent with the high binding affinities, aRBD-2-5-Fc and aRBD-2-7-Fc exhibited ultra-potent neutralization to all five VOCs; particularly, aRBD-2-5-Fc neutralized authentic virus of Beta, Delta and Omicron with the IC50of 5.98[~]9.65 ng/mL or 54.3[~]87.6 pM. Importantly, aRBD-2-5-Fc provided in vivo prophylactic protection for mice against WT and mouse-adapted SARS-CoV-2, and provided full protection against Omicron in hamster model when administrated either prophylactically or therapeutically. Taken together, we found a conserved epitope on RBD, and hetero-bivalent nanobodies had increased affinity for VOCs over its monovalent form, and provided potent and broad-spectrum protection both in vitro and in vivo against all tested major variants, and potentially future emerging variants. Our strategy provides a new solution in the development of therapeutic antibodies for COVID-19 caused by newly emergent VOCs.

Single-dose AAV-based vaccine induces a high level of neutralizing antibodies and provides long-term protection against SARS-CoV-2 in rhesus macaques

Coronavirus disease 2019 (COVID-19), which is triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, continues to threaten global public health. Developing a vaccine that only requires single immunization but provides long-term protection for the prevention and control of COVID-19 is important. Here, we developed an adeno-associated virus (AAV)-based vaccine expressing a stable receptor-binding domain (SRBD) protein. The vaccine requires only a single shot but provides effective neutralizing antibodies (NAbs) over 598 days in rhesus macaques (Macaca mulatta). Importantly, our results showed that the NAbs were kept in high level and long lasting against authentic wild-type SARS-CoV-2, Beta, Delta and Omicron variants using plaque reduction neutralization test. Of note, although we detected pre-existing AAV2/9 antibodies before immunization, the vaccine still induced high and effective NAbs against COVID-19 in rhesus macaques. AAV-SRBD immune serum also efficiently inhibited the binding of ACE2 with RBD in the SARS-CoV-2 B.1.1.7 (Alpha), B.1.351 (Beta), P.1/P.2 (Gamma), B.1.617.2 (Delta), B.1.617.1/3(Kappa), and C.37 (Lambda) variants. Thus, these data suggest that the vaccine has great potential to prevent the spread of SARS-CoV-2.

Potent in vitro Neutralization of SARS-CoV-2 by Hetero-bivalent Alpaca Nanobodies Targeting the Spike Receptor-Binding Domain

Cell entry by SARS-CoV-2 requires the binding between the receptor-binding domain (RBD) of the viral Spike protein and the cellular angiotensin-converting enzyme 2 (ACE2). As such, RBD has become the major target for vaccine development, while RBD-specific antibodies are pursued as therapeutics. Here, we report the development and characterization of SARS-CoV-2 RBD-specific VHH/nanobody (Nb) from immunized alpacas. Seven RBD-specific Nbs with high stability were identified using phage display. They bind to SARS-CoV-2 RBD with affinity KD ranging from 2.6 to 113 nM, and six of them can block RBD-ACE2 interaction. The fusion of the Nbs with IgG1 Fc resulted in homodimers with greatly improved RBD-binding affinities (KD ranging from 72.7 pM to 4.5 nM) and nanomolar RBD-ACE2 blocking abilities. Furthermore, fusion of two Nbs with non-overlapping epitopes resulted in hetero-bivalent Nbs, namely aRBD-2-5 and aRBD-2-7, with significantly higher RBD binding affinities (KD of 59.2 pM and 0.25 nM) and greatly enhanced SARS-CoV-2 neutralizing potency. The 50% neutralization dose (ND50) of aRBD-2-5 and aRBD-2-7 was 1.22 ng/mL ([~]0.043 nM) and 3.18 ng/mL ([~]0.111 nM), respectively. These high-affinity SARS-CoV-2 blocking Nbs could be further developed into therapeutics as well as diagnosis reagents for COVID-19. ImportanceTo date, SARS-CoV-2 has caused tremendous loss of human life and economic output worldwide. Although a few COVID-19 vaccines have been approved in several countries, the development of effective therapeutics including SARS-CoV-2 targeting antibodies remains critical. Due to their small size (13-15 kDa), highly solubility and stability, Nbs are particularly well suited for pulmonary delivery and more amenable to engineer into multi-valent formats, compared to the conventional antibody. Here, we report a serial of new anti-SARS-CoV-2 Nbs isolated from immunized alpaca and two engineered hetero-bivalent Nbs. These potent neutralizing Nbs showed promise as potential therapeutics against COVID-19.

Decline of SARS-CoV-2 specific IgG, IgM and IgA in convalescent COVID-19 patients within 100 days after hospital discharge

Monitoring the levels of SARS-CoV-2 specific antibodies such as IgG, M and A in COVID-19 patient is an alternative method for diagnosing SARS-CoV-2 infection and an simple way to monitor immune responses in convalescent patients and after vaccination. Here, we assessed the levels of SARS-CoV-2 RBD specific antibodies in twenty-seven COVID-19 convalescent patients over 28-99 days after hospital discharge. Almost all patient who had severe or moderate COVID-19 symptoms and a high-level of IgG during the hospitalization showed a significant reduction at revisit. The remaining patients who had a low-level IgG during hospitalization stayed low at revisit. As expected, IgM levels in almost all convalescent patients reduced significantly or stayed low at revisit. The RBD-specific IgA levels were also reduced significantly at revisit. We also attempted to estimate decline rates of virus-specific antibodies using a previously established exponential decay model of antibody kinetics after infection. The predicted days when convalescent patients RBD-specific IgG reaches to an undetectable level are approximately 273 days after hospital discharge, while the predicted decay times are 150 days and 108 days for IgM and IgA, respectively. This investigation and report will aid current and future studies to develope SARS-CoV-2 vaccines that are potent and long-lasting.

Analysis of the intestinal microbiota in COVID-19 patients and its correlation with the inflammatory factor IL-18 and SARS-CoV-2-specific IgA

The current global COVID-19 pandemic is caused by beta coronavirus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which already infected over 10 million and caused 500 thousand deaths by June 2020. Overproduction of cytokines triggered by COVID-19 infection, known as "cytokine storm", is a highly risk factor associated with disease severity. However, how COVID-19 infection induce cytokine storm is still largely unknown. Accumulating in vitro and in vivo evidence suggests that gut is also susceptible to COVID19 infection: Human intestinal organoids, an in vitro model which mimic the specific cell type and spatial structure of the intestine, were susceptible to SARS-CoV2 infection; A significant fraction of patients reported gut symptoms; Viral RNA may persist for more than 30 days and infectious virus could be isolated in fecal samples. The gastrointestinal tract is the primary site of interaction between the host immune system with symbiotic and pathogenic microorganisms. The bacteria resident in our gastrointestinal tract, known as gut microbiota, is important to maintain the homeostasis of our immune system. While imbalance of gut microbiota, or dysbiosis, is associated with multiple inflammation diseases5. It's possible that SARS-CoV-2 infection may lead to alternation of gut microbiota thus worsen the host symptom. IL-18 is a proinflammatory cytokine produced multiple enteric cells, including intestinal epithelial cells (IECs), immune cells as well as enteric nervous system, and was shown to increase in the serum of COVID-19 patients. Immunoglobin A (IgA) is mainly produced in the mucosal surfaces, in humans 40-60mg kg-1 day-1 than all other immunoglobulin isotypes combined, and at least 80% of all plasma cells are located in the intestinal lamina propria. Recent study showed that SARS-CoV-2 specific IgA in the serum is positively correlate with the disease severity in COVID-19 patients11. Here we investigated the alterations of microbiota in COVID-19 patients, and its correlation with inflammatory factor IL-18 and SARS-CoV2 specific IgA.

COVID-19 diagnosis and study of serum SARS-CoV-2 specific IgA, IgM and IgG by a quantitative and sensitive immunoassay

BackgroundThe pandemic of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is causing great loss. Detecting viral RNAs is standard approach for SARS-CoV-2 diagnosis with variable success. Currently, studies describing the serological diagnostic methods are emerging, while most of them just involve the detection of SARS-CoV-2-specific IgM and IgG by ELISA or "flow immunoassay" with limited accuracy. MethodsDiagnostic approach depends on chemiluminescence immunoanalysis (CLIA) for detecting IgA, IgM and IgG specific to SARS-CoV-2 nucleocapsid protein (NP) and receptor-binding domain (RBD) was developed. The approach was tested with 216 sera from 87 COVID-19 patients and 483 sera from SARS-CoV-2 negative individuals. The diagnostic accuracy was evaluated by receiver operating characteristic (ROC) analysis. Concentration kinetics of RBD-specific serum antibodies were characterized. The relationship of serum RBD-specific antibodies and disease severity was analyzed. ResultsThe diagnostic accuracy based on RBD outperformed those based on NP. Adding IgA to a conventional serological test containing IgM and IgG improves sensitivity of SARS-CoV-2 diagnosis at early stage. CLIA for detecting RBD-specific IgA, IgM and IgG showed diagnostic sensitivities of 98.6%, 96.8% and 96.8%, and specificities of 98.1%, 92.3% and 99.8%, respectively. Median concentration of IgA and IgM peaked during 16-20 days after illness onset at 8.84 g/mL and 7.25 g/mL, respectively, while IgG peaked during 21-25 days after illness onset at 16.47 g/mL. Furthermore, the serum IgA level positively correlates with COVID-19 severity. ConclusionCLIA for detecting SARS-CoV-2 RBD-specific IgA, IgM and IgG in blood provides additional values for diagnosing and monitoring of COVID-19. SummaryChemiluminescence immunoanalysis of SARS-CoV-2 RBD-specific serum IgA as well as IgM and IgG improves accuracy of COVID-19 diagnosis. Concentration kinetics of serum RBD-specific IgA, IgM and IgG are revealed. Serum IgA levels positively correlate with COVID-19 severity.

Analysis of types and metabolic profiles of hyperphenylalaninemia / 中华实用儿科临床杂志

Objective To study the characteristics of hyperphenylalaninemia (HPA) and the differences in blood and urine metabolic index and their correlation.Methods A total of 137 patients with HPA diagnosed by the Pediatric Inherit Metabolism and Endocrine Department,Guangdong Women and Children's Hospital,Guangzhou Medical University from January 2014 to June 2017,were enrolled.Tandem mass spectrometry (MS/MS),gas chromatography/ mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) were used to analyze the concentration of blood and urine metabolites in children,and the patients were divided into different groups according to the drug load test of tetrahydrobiopterin (BH4) and dihydrobiopterindine reductase (DHPR) deficiency.The HPA metabolite analysis of horizontal concentration by statistical differences and correlation analysis were performed.Results Among the 137 cases of HPA,there were 101 cases (73.7％) of phenylalanine hydroxylase deficiency (PAH),and among them 21 cases (15.3％) were classic phenylketonuria (PKU),37 cases were mild PKU (27.0％),43 cases (31.4％) wcrc mild HPA.Thcrc were 22 cases (16.1％) with BH4 reaction,and 79 cases (57.7％) of non-reactive type.Besides,there were 36 cases (26.3％) of tetrahydrobiopterin deficiency (BH4 D),of which 6-pyruvoyl tetrahydropterin synthase deficiency (PTPS) in 34 cases (24.8％) and dihydrobiopterindine reductase deficiency (DHPR) in 2 cases (1.5％).Urinary phenylacetic acid (r =0.673,P ＜ 0.01),phenyllactic acid (r =0.736,P ＜ 0.01),phenylpyruvic acid (r =0.642,P ＜ 0.01) were significantly correlated with blood phenylalanine (Phe) concentration,and the neopterin (N) (r =0.442,P ＜ 0.01) and biopterin (B) (r =0.398,P ＜ 0.01) had low correlation.Urinary phenylacetic acid,phenyllactic acid and phenylpyruvic acid had no correlation with urinary pterin.There were significant differences among PTPS deficiency group,BH4 response type,and non-reactive type(all P ＜ 0.05),but no significant difference between the BH4 reaction type and the non-reactive group (P ＞ 0.05).Conclusions Through the analysis of the different types of HPA metabolic profiles,it can help to master the incidence and characteristics in the region,within a certain concentration range of blood Phe,the phenylacetic acid,phenyllactic acid,phenylpyruvic acid should not be tested by GC-MS alone.Uterine erythropoietin analysis of BH4D classification and identification of BH4 reaction,non-reactive PKU have a supporting role,so master the metabolic index of various types of concentration and relevance of HPA,it can provide basis for early diagnosis,accurate treatment and follow-up.

Severe anemia, malnutrition, hypotonia and aggravation of the conscious disturbance, methyl malonic acidemia or propionic acidemia? / 中华实用儿科临床杂志

The patient was a 21 days-old baby girl,admitted to Guangdong Women and Children Hospital because of "poor intake,seldom crying and no activity in 1 day".The major clinical manifestations included hypotonia,aggravation of the conscious disturbance,pancytopenia,intractable acidosis and hyperammonemia,so,inherited metabolic disorders should be considered.Screening of inherited metabolic diseases with blood and urine samples,genetic test and active treatments were carried out.After targeted next-generation sequencing,a novel homozygotic frame shift mutation in PCCB gene:c.838_839insC (L280Pfs * 11) was identified,which was validated by Sanger sequencing.This mutation had not been reported in the mutation database,and bioinformatic analysis of this mutation indicated disease-causing.So,the diagnosis of propionic acidemia was identified.The baby was in a critical condition,and despite active treatment,her conscious disturbance was aggravated,and the spontaneous breathing disappeared.Subsequently,the baby died of pneumonia.Propionic acidemia is a relatively common genetic metabolic disease in newborns.The severity and the clinical phenotypes of propionic acidemia varied,which often made the diagnosis difficult.When the baby is presented with developmental delay,hypotonia,recurrent convulsion and vomiting,etc,which can't be explained by common diseases of children,propionic acidemia may be considered.Next generation sequencing analysis of the complicated cases can easily to pinpoint a disease-causing gene,which lays a solid foundation for accurate diagnosis and treatment of the patients.

The application of non-invasive prenatal genetic sequencing for fetal chromosomal aneuploidy / 国际检验医学杂志

Objective To explore the efficiency and the clinical application value of non-invasive prenatal genetic testing for fetal chromosomal aneuploidy.Methods A total of 1 865 pregnant women treated in Guangdong Women and Children Hospital from January 201 1 to January 2013 were selected.Inclusion criteria:advanced age,prenatal screening for high risk,and fetal abnormality indicated by color ultrasonography,agreeing with non-invasive prenatal genetic testing.After non-invasive prenatal genetic testing, the pregnant women with positive result underwent cell culture and chromosomal karyotyping.Following the situations after deliv-ery were designed as the final criteria for definite diagnosis of fetal chromosomal aneuploidy.Results A total of 1 865 pregnant women underwent non-invasive prenatal genetic testing,of which 21 pregnant women were found with positive result,including 14 pregnant women with trisomy 21,5 pregnant women with trisomy 18,2 pregnant women with trisomy 13.The results of chromo-somal karyotyping after amniocentesis or umbilical cord blood puncture were designed as golden standard.Among the women with trisomy 21,one woman refused the prenatal diagnosis,self induced labor and could not be confirmed karyotype.No false positive case was found among the women with trisomy 18 and 13.No missed diagnosis was found among the pregnant women with negative result during follow-up after delivery.Through statistical analysis of non-invasive prenatal fetal genetic testing,the sensitivity for the trisomy 21 was 100%,and the accuracy was 92.9%.The sensitivity and accuracy for the trisomy 18 and 13 were 100%.Conclu-sion Non-invasive prenatal genetic testing can improve the diagnostic efficacy before delivery,reduce the birth of ill infants,and it is a quick,safe,easy-accepted and reliable prenatal diagnostic method,which is worthy to be popularized and an inexorable trend of development in the future.

Activation state of and expressions of surface co-stimulatory molecules on peripheral CD4 + T cells from patients with pemphigus / 中华皮肤科杂志

Objective To investigate the activation state of and expressions of surface co-stimulatory molecules on peripheral CD4+ T cells from patients with pemphigus and healthy human controls.Methods Ninety patients with pemphigus including 24 patients with first-onset pemphigus,51 with quiescent pemphigus and 15 with recurrent pemphigus,as well as 30 healthy human controls were enrolled in this study.Peripheral blood samples were obtained from these subjects followed by lymphocyte isolation.Flow cytometry was performed to detect the expressions of CD69,intercellular adhesion molecule-1 (ICAM-1),inducible co-stimulatory molecule (ICOS),CD40 ligand (CD40L) and OX40 on CD4+ T cells.Statistical analysis was done by Mann-Whitney test using Graphpad 5.0 software.Results The expression rate of CD69 on peripheral CD4+ T cells from the healthy human controls was significantly lower than that from patients with pemphigus,patients with first-onset pemphigus,patients with quiescent pemphigus,and patients with recurrent pemphigus ((1.26 ± 0.19)％ vs.(2.46 ± 0.19)％,(2.77 ± 0.40)％,(2.15 ± 0.25)％ and (2.36 ± 0.35)％,all P ＜ 0.05).The patients with pemphigus also showed a significant increase in the expression rates of ICAM-1,CD40L and OX40 compared with the healthy human controls ((55.88 ± 1.67)％ vs.(47.75 ± 2.52)％,P＜ 0.05; (2.23 ± 0.22)％ vs.(0.73 ± 0.07)％,P＜ 0.01; (2.55 ± 0.29)％vs.(0.62 ± 0.17)％,P ＜ 0.01).No significant differences were observed between patients with different stages of pemphigus in the expression rates of CD69,ICAM-1,CD40L or OX40 (all P ＞ 0.05).The percentage of ICOS-expressing CD4+ T cells was significantly up-regulated in only patients with first-onset pemphigus as compared to the healthy controls ((3.73 ± 0.60)％ vs.(2.39 ± 0.16)％,P ＜ 0.05).Conclusions The peripheral blood CD4+ T cells from patients with pemphigus are in a relatively active state with up-regulated surface expressions of many costimulatory molecules,suggesting that CD4+ T cells are involved in the initiation and progression of pemphigus by interacting with B cells through co-stimulatory molecules.

Study on serum cancer antigens 125 expression in different types of ovarian endometriosis and related factors / 中国医师进修杂志

Objective To investigate serum cancer antigens (CA) 125 expression in different types of ovarian endometriosis and related factors.Methods A total of 182 patients with ovarian endometriosis was collected,then they were divided into two groups:ovarian endometriosis combined with other parts of lesions (A group,88 cases),simple ovarian endometriosis group (B group,94 cases).And selected 100 healthy physical check-up women from the hospital outpatient department were as control group.The serum level of CA125 was detected.The patients' information including body shape,menstrual factors,reproductive activities and disease staging were collected.Chi-square criterion and multivariate binary Logistic regression analysis were completed.Results The serum levels of CA125 in A group,B group and control group were (48.64 ± 33.18),(41.35 ± 23.46),(22.16 ± 13.73) kU/L,respectively,and the positive expression rate of three groups were 64.77％ (57/88),52.13％ (49/94),2.00％ (2/100),respectively,there were significant differences (P ＜ 0.05).The multivariate binary Logistic regression analysis result showed that age of 35-49years,reforming American fertility society of Ⅲ-Ⅳ stage,pelvic adhesion and menorrhalgia were the important factors of positive expression of CA125.Conclusion The serum level of CA125 can be used as the evaluation of the diagnosis and treatment of ovarian endometriosis.