End-organ damage from neonatal invasive fungal infection: a 14-year retrospective study from a tertiary center in China.

BACKGROUND: Invasive fungal infection (IFI) has become an increasing problem in NICU neonates, and end-organ damage (EOD) from IFI is one of the leading causes of morbidity and mortality in neonates. This study was conducted to summarize clinical data on epidemiology, risk factors, causative pathogens, and clinical outcomes of IFI-associated EOD among neonates in a center in China for the sake of providing references for prevention and treatment of fungal infections in neonates in future. METHODS: The clinical data of IFI neonates who received treatment in a tertiary NICU of China from January 2009 to December 2022 were retrospectively analyzed, including causative pathogens and the incidence of EOD. The neonates were divided into EOD group and non-EOD (NEOD) group. The general characteristics, risk factors and clinical outcomes of the two groups were compared. RESULTS: Included in this study were 223 IFI neonates (137 male and 86 female) with a median gestational age (GA) of 30.71 (29,35) weeks and a median birth weight (BW) of 1470 (1120,2150) g. Of them, 79.4% were preterm infants and 50.2% were born at a GA of ≥ 28, <32 weeks, and 37.7% with BW of 1000-1499 g. Candida albicans (C. albicans) was the most common Candida spp. in these neonates, accounting for 41.3% of all cases, followed by C. parapsilosis (30.5%) and C. glabrata (7.2%). EOD occurred in 40 (17.9%) of the 223 cases. Fungal meningitis was the most common EOD, accounting for 13.5% of the 40 EOD cases. There was no significant difference in the premature birth rate, delivery mode, GA and BW between EOD and NEOD groups, but the proportion of male infants with EOD was higher than that without. There was no significant difference in antenatal corticosteroid use, endotracheal intubation, invasive procedures, use of antibiotics, total parenteral nutrition, blood transfusion, postnatal corticosteroid use, fungal prophylaxis and the incidence of necrotizing enterocolitis between the two groups, but the proportion of C. albicans infection cases in EOD group was higher than that in NEOD group (57.5% vs. 37.7%). Compared with NEOD group, the proportion of cured or improved infants in EOD group was significantly lower (P < 0.05), and the number of infants who died or withdrew from treatment was larger (P < 0.05). CONCLUSIONS: Our retrospective study showed that preterm infants were prone to fungal infection, especially very preterm infants. C. albicans was the most common Candida spp. for IFI, and was a high-risk factor for EOD. EOD can occur in both full-term and premature infants, so the possibility of EOD should be considered in all infants with IFI.

Evaluation of the Association of Platelet Count, Mean Platelet Volume, and Platelet Transfusion With Intraventricular Hemorrhage and Death Among Preterm Infants.

Importance: Platelet transfusion is commonly performed in infants to correct severe thrombocytopenia or prevent bleeding. Exploring the associations of platelet transfusion, platelet count (PC), and mean platelet volume (MPV) with intraventricular hemorrhage (IVH) and in-hospital mortality in preterm infants can provide evidence for the establishment of future practices. Objectives: To evaluate the associations of platelet transfusion, PC, and MPV with IVH and in-hospital mortality and to explore whether platelet transfusion-associated IVH and mortality risks vary with PC and MPV levels at the time of transfusion. Design, Setting, and Participants: This retrospective cohort study included preterm infants who were transferred to the neonatal intensive care unit on their day of birth and received ventilation during their hospital stay. The study was conducted at a neonatal intensive care unit referral center in Beijing, China, between May 2016 and October 2017. Data were retrieved and analyzed from December 2020 to January 2022. Exposures: Platelet transfusion, PC, and MPV. Main Outcomes and Measures: Any grade IVH, severe IVH (grade 3 or 4), and in-hospital mortality. Results: Among the 1221 preterm infants (731 [59.9%] male; median [IQR] gestational age, 31.0 [29.0-33.0] weeks), 94 (7.7%) received 166 platelet transfusions. After adjustment for potential confounders, platelet transfusion was significantly associated with mortality (hazard ratio [HR], 1.48; 95% CI, 1.13-1.93; P = .004). A decreased PC was significantly associated with any grade IVH (HR per 50 × 103/µL, 1.13; 95% CI, 1.05-1.22; P = .001), severe IVH (HR per 50 × 103/µL, 1.16; 95% CI, 1.02-1.32; P = .02), and mortality (HR per 50 × 103/µL, 1.74; 95% CI, 1.48-2.03; P < .001). A higher MPV was associated with a lower risk of mortality (HR, 0.83; 95% CI, 0.69-0.98; P = .03). The platelet transfusion-associated risks for both IVH and mortality increased when transfusion was performed in infants with a higher PC level (eg, PC of 25 × 103/µL: HR, 1.20; 95% CI, 0.89-1.62; PC of 100 × 103/µL: HR, 1.40; 95% CI, 1.08-1.82). The platelet transfusion-associated risks of IVH and mortality varied with MPV level at the time of transfusion. Conclusions and Relevance: In preterm infants, platelet transfusion, PC, and MPV were associated with mortality, and PC was also associated with any grade IVH and severe IVH. The findings suggest that a lower platelet transfusion threshold is preferred; however, the risk of a decreased PC should not be ignored.

The Incidence and Characteristics of Perinatal Stroke in Beijing: A Multicenter Study.

Objective: To assess the incidence, risk factors, and clinical characteristics of perinatal stroke in Beijing. Methods: This multicenter prospective study included all the live births from 17 representative maternal delivery hospitals in Beijing from March 1, 2019 to February 29, 2020. Neonates with a stroke were assigned to the study group. Clinical data, including general information, clinical manifestations, and risk factors, were collected. Up until 18 months after birth, neonates were routinely assessed according to the Ages and Stages Questionnaire (ASQ) and/or the Bayley scale. Statistical analysis was done using the chi-squared, t-tests, and logistic regression analysis using SPSS version 26.0. Outcomes: In total, 27 cases were identified and the incidence of perinatal stroke in Beijing was 1/2,660 live births, including 1/5,985 for ischemic stroke and 1/4,788 for hemorrhagic stroke. Seventeen cases (62.96%) of acute symptomatic stroke and convulsions within 72 h (10 cases, 37.04%) were the most common presentations. Ten patients showed no neurological symptoms and were found to have had a stroke through routine cranial ultrasonography after being hospitalized for non-neurological diseases. The risk factors include primiparity, placental or uterine abruption/acute chorioamnionitis, intrauterine distress, asphyxia, and severe infection. In the study group, 11.1% (3/27) of patients had adverse neurodevelopmental outcomes. The patients in the study group had lower scores for the ASQ than those in the control group in the communication, gross, and fine motor dimensions. Conclusion: The incidence of perinatal stroke in Beijing was consistent with that in other countries. Routine neuroimaging of infants with risk factors may enable identification of asymptomatic strokes in more patients. Patients who have suffered from a stroke may have neurological sequelae; therefore, early detection, treatment, and regular follow-ups are beneficial for improving their recovery outcomes.

Pathogenesis of bronchopulmonary dysplasia in preterm neonates revealed by an RNA sequencing interaction network analysis.

Background: The chronic lung condition known as bronchopulmonary dysplasia (BPD), which primarily affects newborns, especially preterm neonates, is brought on by prolonged oxygen consumption and mechanical ventilation. This case-control study sought to investigate the pathogenesis of BPD in preterm neonates by RNA sequencing (RNA-seq). Methods: First, RNA-seq samples were collected from 3 BPD and 3 healthy preterm neonates. Based on the sequencing data and microarray data sets, MERGE.57185.1, the key long non-coding RNA (lncRNA), was identified from the differentially expressed lncRNAs and the key module by a weighted gene co-expression network analysis (WGCNA), a Venn diagram, and an expression analysis. Next, the differentially expressed messenger RNAs (mRNAs) and microRNAs (miRNAs) that were strongly correlated to MERGE.57185.1 were identified in the protein-protein interaction networks and underwent a functional enrichment analysis and Spearman correlation analysis. Finally, the mRNA [i.e., eukaryotic translation initiation factor 5A (EIF5A)] and miRNA (i.e., hsa-miR-6833-5p) with the strongest correlations to MERGE.57185.1 were identified as the downstream targets. Results: Among the 32 genes in the dark-red module and the 158 differentially expressed lncRNAs, 21 overlapping genes were identified. In the gene expression analysis, MERGE.57185.1 (an oncogene) was identified as the key lncRNA in BPD. The results of the multiple bioinformatics analysis showed that the mRNA and the miRNA with the strongest correlations to MERGE.57185.1 were hsa-miR-6833-5p (a suppressor gene) and EIF5A (an oncogene), respectively. Hsa-miR-6833-5p was lowly expressed in the BPD group, while EIF5A was highly expressed in the BPD group. Conclusions: This study identified 1 key upregulated lncRNA (i.e., MERGE.57185.1) in preterm neonatal BPD, and revealed the MERGE.57185.1/hsa-miR-6833-5p/EIF5A mechanism in preterm neonatal BPD from the lncRNA-miRNA-mRNA network. This key lncRNA gene could serve as a promising diagnostic biomarker for prenatal examinations.

[Effect of breastfeeding on the development of infection-related diseases during hospitalization in late preterm infants in 25 hospitals in Beijing, China].

OBJECTIVE: To investigate the incidence rate of infectious diseases during hospitalization in late preterm infants in Beijing, China, as well as the risk factors for infectious diseases and the effect of breastfeeding on the development of infectious diseases. METHODS: Related data were collected from the late preterm infants who were hospitalized in the neonatal wards of 25 hospitals in Beijing, China, from October 23, 2015 to October 30, 2017. According to the feeding pattern, they were divided into a breastfeeding group and a formula feeding group. The two groups were compared in terms of general status and incidence rate of infectious diseases. A multivariate logistic regression analysis was used to investigate the risk factors for infectious diseases. RESULTS: A total of 1 576 late preterm infants were enrolled, with 153 infants in the breastfeeding group and 1 423 in the formula feeding group. Of all infants, 484 (30.71%) experienced infectious diseases. The breastfeeding group had a significantly lower incidence rate of infectious diseases than the formula feeding group (22.88% vs 31.55%, P=0.033). The multivariate logistic regression analysis showed that breastfeeding was an independent protective factor against infectious diseases (OR=0.534, P=0.004), while male sex, premature rupture of membranes, gestational diabetes mellitus, and asphyxia were risk factors for infectious diseases (OR=1.328, 5.386, 1.535, and 2.353 respectively, P < 0.05). CONCLUSIONS: Breastfeeding can significantly reduce the incidence of infectious diseases and is a protective factor against infectious diseases in late preterm infants. Breastfeeding should therefore be actively promoted for late preterm infants during hospitalization.

A 7-Year Report of Spectrum of Inborn Errors of Metabolism on Full-Term and Premature Infants in a Chinese Neonatal Intensive Care Unit.

Inborn errors of metabolism (IEMs) have great repercussions in neonatal intensive care units (NICUs). However, the integrative analysis of the incidence for full-term and premature neonates of IEMs in NICUs have not been reported. In this study, we aimed to estimate the incidence of IEMs in the NICU population so as to better evaluate the impact of IEMs on Chinese NICUs. A total of 42,257 newborns (proportion of premature as 36.7%) enrolled to the largest Chinese NICU center for a sequential 7 years screen, and 66 were diagnosed with IEMs. The prevalence of IEMs in total, full-term, and premature infants was 1:640, 1:446, and 1:2,584, respectively. In spectrum of our NICU, diseases that cause endogenous intoxication like methylmalonic acidemia accounted for 93.9% (62/66), and this ratio was higher in full-term infants with 98.3% (59/60), while the most prevalent disease in premature newborn was hyperphenylalaninemia (50%, 3/6), respectively. The genetic analysis of 49 cases revealed 62 potentially pathogenic mutations in 10 well-documented pathogenic genes of IEMs, among which 21 were novel. In conclusion, differences in incidence and spectrum of full-term and premature births we obtained in NICU will provide diagnostic guidelines and therapeutic clues of neonatal IEMs for pediatricians.

miR-5582-5p inhibits cell proliferation of non-small cell lung cancer through targeting FGF-10.

Accumulating evidence has suggested that microRNAs (miRNAs) play important roles in regulating the progression of cancerby acting as tumor suppressors or oncogenes. Here, our results demonstrated that miR-5582-5p was significantly down-regulated in non-small cell lung cancer (NSCLC) tissues and cell lines compared with normal controls. Overexpression of miR-5582-5p markedly inhibited the proliferation and migration of NSCLC cells. Consistently, the apoptosis of NSCLC cells was also significantly promoted by overexpressed miR-5582-5p. Functional study uncovered that miR-5582-5p bound the 3'-untranslated region (UTR) of fibroblastic growth factor-10 (FGF-10) and decreased the expression of FGF-10 in NSCLC cells. FGF-10 was up-regulated in NSCLC tissues and inversely correlated with the level of miR-5582-5p in NSCLC tissues. Overexpression of FGF-10 significantly reversed the inhibitory effect of miR-5582-5p on the proliferation of NSCLC cells. Taken together, our results demonstrated the functional mechanism of miR-5582-5p in suppressing malignant behaviors of NSCLC cells by targeting FGF-10. These findings demonstrated that miR-5582-5p might be a novel therapeutic target in the treatment of NSCLC.

Treatment of Hyperoxia-Induced Lung Injury with Lung Mesenchymal Stem Cells in Mice.

OBJECTIVE: Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in preterm neonates and has no effective treatment. This study aimed to investigate the therapeutic effects of neonatal mouse lung resident mesenchymal stem cells (L-MSCs) on the hyperoxia-induced lung injury. METHODS: L-MSCs were separated and identified according to the MSC criterions. Hyperoxia-Induced Lung Injury (HILI) of neonatal KM mice was induced with hyperoxia (FiO2 = 60%) and investigated with pathological methods. Neonatal KM mice were divided into 3 groups (hyperoxia + L-MSC group, hyperoxia + PBS group, and air control group). Mice in the hyperoxia + L-MSC group were treated with L-MSCs at 3, 7, and 14 days after birth. After hyperoxia exposure for 21 days, the lung pathology, Radial Alveolar Count (RAC), CD31 expression, and vascular endothelial growth factor (VEGF) expression were investigated. RESULTS: After hyperoxia exposure, the body weight, RAC, CD31 expression, and VEGF expression in the hyperoxia + L-MSC group were significantly better than those in the hyperoxia + PBS group but inferior to those in the air control group significantly. These indicate L-MSCs are partially protective on the lung injury of mice with hyperoxia-induced BPD. CONCLUSION: L-MSCs are helpful for the prevention and treatment of BPD, and endogenous L-MSCs may play a role in the postinjury repair of the lung.

[A review on neonatal acute respiratory distress syndrome].

Acute respiratory distress syndrome (ARDS) is a common clinical critical disease and is one of the main causes of death and disability in neonates. The etiology and pathogenesis of neonatal ARDS are complicated. It is an acute pulmonary inflammatory disease caused by the lack of pulmonary surfactant (PS) related to various pathological factors. It is difficult to distinguish neonatal ARDS from other diseases. At present, there is no specific treatment method for this disease. Respiratory support, PS replacement, extracorporeal membrane oxygenation, nutrition support and liquid management are main treatment strategies. This paper reviews the research advance in etiology, clinical characteristics, diagnosis and treatment strategies of neonatal ARDS.

Therapeutic effects of fibroblast growth factor-10 on hyperoxia-induced bronchopulmonary dysplasia in neonatal mice.

The survival rate of preterm neonates increases significantly with the development of neonatal care and comprehensive treatment, but more and more high-risk preterm neonates suffer from bronchopulmonary dysplasia (BPD). Currently, there is no effective treatment for BPD, thus it is still a major cause of disability and mortality in neonates. Thus, it is imperative to investigate the pathogenesis and treatment of BPD in depth. Fibroblast growth factor-10 (FGF-10) is a paracrine growth factor binding its receptors (FGFR1 and FGFR2) to regulate a lot of biological processes. FGF-10, with mitotic and chemotactic activities, plays an important role in histogenesis during embryonic stage. It can prevent and attenuate mechanical or infection induced inflammation in lung. Results showed lung FGF-10 expression reduced significantly in neonatal mice with BPD, and exogenous FGF-10 was able to promote the growth of pulmonary mesenchymal stem cells and alveolar epithelial cells type II and reduce the expression of pro-inflammatory cytokines. We preliminarily explored the relationship between FGF-10 and NF-κB in this animal model and found FGF-10 could inhibit NF-κB p65 expression as a feedback. Thus, to investigate the protective effects of FGF-10 on hyperoxia induced BPD in neonatal mice will provide a new strategy for the treatment of BPD.

Neonatal outcomes of very preterm infants from a neonatal intensive care center.

BACKGROUND: Information about clinical outcomes of very preterm (VPT) infants in tertiary neonatal intensive care unit (NICU) setting is scant in China. This study aimed to investigate the mortality and morbidity of VPT infants admitted to BaYi Children's Hospital, which serves as a NICU referral center for the city of Beijing, China. METHODS: Retrospectively collected perinatal/neonatal data on all admissions of infants born at <32 weeks of gestational age and subsequently admitted to the VPTNICU from clinical records between October 2010 and September 2011. RESULTS: Totally 729 infants were identified. 90% of VPT infants were outborn. The overall survival of the infants to discharge was 92%, which increased with increasing gestational age (range from 69% at <28 weeks to 99% at 31 weeks). The incidence of bronchopulmonary dysplasia was 4%, retinopathy of prematurity requiring treatment 2%, intraventricular hemorrhage III-IV 6%, and periventricular leukomalacia 2%. 10% of the VPT infants had a major morbidity at discharge. CONCLUSIONS: The outcomes of the VTP infants at this referral NICU were comparable to those in tertiary centers in developed countries. The most common complications were lower than those in other cohorts. Accordingly, high-volume NICU may minimize the adverse effects of VPT infants' transport.

Lipopolysaccharides shapes the human Wharton's jelly-derived mesenchymal stem cells in vitro.

BACKGROUND: Although the expression of toll-like receptors (TLRs) on different types of human mesenchymal stem cells (hMSCs) has recently been reported, controversy remains regarding the presence of TLR4 as well as its engagement and impact on human Wharton's jelly-derived MSCs (hWJ-MSCs). METHODS: In the present study, the expression and role of TLR4 in hWJ-MSCs was investigated using a model of lipopolysaccharide (LPS). Proliferation, apoptosis, and the expression of paracrine factors in hWJ-MSCs primed with LPS were analysed. RESULTS: The expression of TLR4 was high at the RNA level but very low at the protein level. hWJ-MSCs responded to LPS stimulation and initiated a marked up-regulation of inflammatory cytokine (IL-1α, IL-1ß, IL-6, and IL-8) production. Moreover, hWJ-MSCs LPS stimulation resulted in the up-regulation of indoleamine 2,3-dioxygenase [IDO]-1, Cox2, interferon [IFN]-ß, and matrix metalloproteinase (MMP)-2 but a down-regulation of MMP-9, which affect the immunosuppressive potential of hWJ-MSCs. CONCLUSIONS: These data suggest that LPS engagement shapes hWJ-MSCs and results in the production of pro-inflammatory cytokines and inhibitory immune mediators, showing TLR4 agonist induces the hWJ-MSCs polarization to a pro-inflammatory and immunosuppressive state, which may be beneficial for the exploration of the clinical potential of hWJ-MSCs.

Role of bone marrow-derived mesenchymal stem cells in the prevention of hyperoxia-induced lung injury in newborn mice.

BPD (bronchopulmonary dysplasia) is predominantly characterized by persistent abnormalities in lung structure and arrested lung development, but therapy can be palliative. While promising, the use of BMSC (bone marrow-derived mesenchymal stem cell) in the treatment of lung diseases remains controversial. We have assessed the therapeutic effects of BMSC in vitro and in vivo. In vitro co-culturing with injured lung tissue increased the migration-potential of BMSC; and SP-C (surfactant protein-C), a specific marker of AEC2 (type II alveolar epithelial cells), was expressed. Following intraperitoneal injection of BMSC into experimental BPD mice on post-natal day 7, it was found that BMSC can home to the injured lung, express SP-C, improve pulmonary architecture, attenuate pulmonary fibrosis and increase the survival rate of BPD mice. This work supports the notion that BMSC are of therapeutic benefit through the production of soluble factors at bioactive levels that regulate the pathogenesis of inflammation and fibrosis following hyperoxia.

Langerhans cell histiocytosis, a new clinical phenotype of x-linked lymphoproliferative disease?

Langerhans' cell histiocytosis (LCH) is a rare disease of unkown cause and is characterized by clonal proliferation of Langerhans cells. Here, we describe the case of a 22-month-old boy with LCH associated with X-linked lymphoproliferative disease (XLP). Sequence analysis of SH2D1A for mutations that cause T-cell dysfunction revealed a CT substitution at nucleotide 462. This is the first case that hints at an association between XLP and LCH.

[Cloning, purification, and antigenic characterization of three recombinant fragments derived from SARS-CoV S1 domain].

OBJECTIVE: The present study aimed to clone and express three fragments of genomic RNA derived from SARS associated coronavirus (SARS-CoV) S1 domain and to study its immunogenicity. METHODS: The S1 domain gene was amplified by PCR with specific primers and was inserted into the prokaryotic expression vector pQE-30. Three fragments (40-751, 746-1344 and 746-2001 bp) derived from S1 domain produced after the recombinant plasmid (pQE-30/S1) was digested by restriction endonucleases. The three fragments were cloned into pQE-30 and expressed in M15 strains of Escherichia coli. The expression products, designated S1a, S1b and S1c respectively, were purified by Ni affinity chromatography. The immunogenicity was analyzed by Western Blot and ELISA using serologically confirmed sera from SARS patients and the sera from healthy donors was used as control at the same assay. RESULTS: Three recombinant plasmids (pQE-30/S1a, pQE-30/S1b, pQE-30/S1c) were constructed.Fusion proteins with relative molecular mass of 26,700, 22,500 and 46,000 dalton were successfully expressed with amounts of 35%, 35% and 30% of total cell protein and purified by Ni affinity chromatography, respectively. Western Blot and ELISA analysis showed that the S1c protein could be specifically recognized by the sera from SARS patients. CONCLUSION: The recombinant S1c protein was a good immunogen and has the potential to be used as a vaccine against SARS-CoV infection.

[Specific antibodies against the nucleocapsid protein and S1 domain of spike glycoprotein in patients with severe acute respiratory syndrome].

OBJECTIVE: To explore the laws of the appearance of the specific serum antibodies against the nucleocapsid (N) protein and the S1 domain of spike (S) glycoprotein in patients with severe acute respiratory syndrome (SARS) and to evaluate the value of these two proteins to be used as diagnostic makers for SARS. METHODS: The serum samples of 86 patients with SARS confirmed clinically and serologically, 31 males and 55 females, aged 9 approximately 86, with the course of disease of 1 approximately 81 days, and 745 healthy persons were collected during the course. The specific immunoglobulin G (IgG) against N protein, IgG against S1 domain of S protein, and the SARS-CoV IgG in these sera were detected by ELISA. RESULTS: The positive rates of anti-N-IgG, anti S1-IgG, and anti-SARS-CoV IgG were 14% (6/44), 5% (2/44), and 14% (6/44) respectively in the first week of the course of disease, 56% (10/18), 39% (7/18), and 56% (10/18) respectively in the second week, and 100% (24/24), S1-IgG 83% (20/24), and 100% (24/24) respectively in the third week. The agreement rates of the results of anti-N-IgG and anti-s1-IgG with that of the anti-SARS-CoV IgG were 88% (76/86) and 83% (71/86) respectively. The anti-SARS-CoV IgG positive rate in the healthy persons was 1.88% (14.745). CONCLUSION: The N protein and S1 protein may be used as antigens in the development of serological assay for detection of SARS-CoV infection.

Antigenic cross-reactivity between severe acute respiratory syndrome-associated coronavirus and human coronaviruses 229E and OC43.

Cross-reactivity between antibodies to different human coronaviruses (HCoVs) has not been systematically studied. By use of Western blot analysis, indirect immunofluorescence assay (IFA), and enzyme-linked immunosorbent assay (ELISA), antigenic cross-reactivity between severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) and 2 HCoVs (229E and OC43) was demonstrated in immunized animals and human serum. In 5 of 11 and 10 of 11 patients with SARS, paired serum samples showed a > or =4-fold increase in antibody titers against HCoV-229E and HCoV-OC43, respectively, by IFA. Overall, serum samples from convalescent patients who had SARS had a 1-way cross-reactivity with the 2 known HCoVs. Antigens of SARS-CoV and HCoV-OC43 were more cross-reactive than were those of SARS-CoV and HCoV-229E.

Monoclonal antibody-based antigen capture enzyme-linked immunosorbent assay reveals high sensitivity of the nucleocapsid protein in acute-phase sera of severe acute respiratory syndrome patients.

Accurate and timely diagnosis of severe acute respiratory syndrome coronavirus (SARS-CoV) infection is a critical step in preventing another global outbreak. In this study, 829 serum specimens were collected from 643 patients initially reported to be infected with SARS-CoV. The sera were tested for the N protein of SARS-CoV by using an antigen capture enzyme-linked immunosorbent assay (ELISA) based on monoclonal antibodies against the N protein of SARS-CoV and compared to 197 control serum samples from healthy donors and non-SARS febrile patients. The results of the N protein detection analysis were directly related to the serological analysis data. From 27 SARS patients who tested positive with the neutralization test, 100% of the 24 sera collected from 1 to 10 days after the onset of symptoms were positive for the N protein. N protein was not detected beyond day 11 in this group. The positive rates of N protein for sera collected at 1 to 5, 6 to 10, 11 to 15, and 16 to 20 days after the onset of symptoms for 414 samples from 298 serologically confirmed patients were 92.9, 69.8, 36.4, and 21.1%, respectively. For 294 sera from 248 serological test-negative patients, the rates were 25.6, 16.7, 9.3, and 0%, respectively. The N protein was not detected in 66 patients with cases of what was initially suspected to be SARS but serologically proven to be negative for SARS and in 197 serum samples from healthy donors and non-SARS febrile patients. The specificity of the assay was 100%. Furthermore, of 16 sera collected from four patients during the SARS recurrence in Guangzhou, 5 sera collected from 7 to 9 days after the onset of symptoms were positive for the N protein. N protein detection exhibited a high positive rate, 96 to 100%, between day 3 and day 5 after the onset of symptoms for 27 neutralization test-positive SARS patients and 298 serologically confirmed patients. The N protein detection rate continually decreased beginning with day 10, and N protein was not detected beyond day 19 after the onset of symptoms. In conclusion, an antigen capture ELISA reveals a high N protein detection rate in acute-phase sera of patients with SARS, which makes it useful for early diagnosis of SARS.

Preparation and characterization of monoclonal antibodies against S1 domain at N-terminal residues 249 to 667 of SARS-associated coronavirus S1 protein.

OBJECTIVE: To prepare and characterize monoclonal antibodies (mAbs) against S1 protein of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV). METHODS: 6-His-tagged recombinant fragment at N-terminal residues 249 to 667 of SARS-CoV S1 protein including S-protein receptor-binding domain was expressed in E.coli. The immunogenicity of this S1 domain was identified and used to immunize BALB/c mice for the production of hybridomas. The identification of the mAbs against this S1 domain was performed using indirect enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay (IFA) and Western blotting, respectively. RESULTS: Three hybridomas producing mAbs specific to the S1 domain was obtained, with a relative molecular mass of 48,500. None of the 3 mAbs were reactive with human coronaviruses 229E and OC43. Two of the mAbs were IgG2a isotype, and the other was IgG1. CONCLUSIONS: This is the first report of mAbs produced against S-protein receptor-binding domain of SARS-CoV. The 3 S1-specific mAbs may be useful for further study of the function of the S protein and for diagnosis of SARS-CoV infection.