Prediction and identification of linear B-cell epitopes in the hemagglutinin of H7N9 avian influenza virus in human / 中华临床感染病杂志

Objective To predict and identify liner B-cell epitopes in the hemagglutinin ( HA) of human-infected avian-origin H7N9 influenza virus and analyze the specificity of H7 subtype.Methods Three serum samples collected at different times from the same patient who was confirmed to be infected with H7N9 influenza virus were provided by Shaoxing People’s Hospital, and one serum sample from healthy person was collected as the control.The extracellular region of HA protein was predicted by TMHMM Sever v.2.0.The potential B-cell epitopes were predicted by DNAStar Lasergene’ s Protean, BcePred and ABCpred tools, and the immunogenicity of the predicted B cell antigen epitopes was assessed by indirect enzyme-linked immunosordent assay ( ELISA ) .H7 subtype specificity was analyzed by comparing HA protein amino acid sequence with H7N9 and H1-H16 subtype influenza virus from Genbank using Clustal X 2.1 software, and Cn3D 4.3.1 software was used to detect the distribution and 3D structure of predicted epitopes on the HA protein of H7N9.Results The potential B-cell epitopes may be located in 172-183, 363-380, 452-472 and 491-506 of extracellular N-terminus of HA protein.ELISA showed that four predicted eptiopes specifically reacted with positive serums from patient.Multi-sequence alignment demonstrated that peptide 172-183 and 363-380 had higher H7 subtype specificity compared with amino acid sequences of other subtypes.Moreover, the predicted linear B-cell epitopes all located on the surface of HA protein according to the 3D structure analysis.Conclusion Four potential B-cell epitopes were identified, in which peptide 172-183 and 363-380 have higher H7 subtype specificity, and may be used in the design of epitope-based vaccines and diagnostics tests.

Clinical features of sporadic cases with H7N9 avian influenza in Taizhou city of Zhejiang province and characteristics of viral gene / 中华临床感染病杂志

Objective To examine the clinical features of sporadic patients with H7N9 avian influenzain Taizhou city of Zhejiang province and to characterize its viral genes.Methods Fifteen patients with H7N9 influenza infection confirmed by Zhejiang Provincial Centre for Disease Control and Prevention during January 201 4 and January 201 5 were included in the study.The basic diseases,poultry exposure history,clinical manifestation,laboratory examination,imaging features,treatment and outcome and viral gene sequencing were analyzed retrospectively.Results The first clinical symptoms were fever and cough in all patients,acuterespiratory distress syndrome(ARDS)occurred in 1 3 patients,the average time from onset to antiviral therapy was (7 ±2)d.Among 1 5 patients,9 survived and 6 died,including 2 died of multiple organ failure (MOF).The phylogenetic tree showed that there was highly homologous in hemagglutinin (HA)and neuraminidase(NA)genes between human H7N9 virus strains and poultry reference strains.The result of genetic sequencing indicated that human H7N9 virus strains had mutations at 226 (Q226L)sites in HA protein.Conclusions ARDS is likely to occur in patients with H7N9 viral infection,and early antiviral treatment usually leads to a good prognosis.With the occurrence of adaptive mutation in avian influenza virus H7N9,spread from poultry to the human beings may take place.

Molecular and phylogenetic analysis of human avian influenza A (H7N9) virus infection in Zhejiang province during 2013 and 2015 / 中华临床感染病杂志

Objective To analyze the molecular characteristics of human pathogenic avian influenza A H7N9 virus.Methods The gene sequences of avian influenza A H7N9 virus (30 human-originated and 15 avian-originated) isolated in Zhejiang province from 2013 to 2015 were downloaded from Global Initiative on Sharing Avian Influenza Data ( GISAID), and then the evolution characteristics, the sites related to receptor binding, virulence and drug resistance of H7N9 virus were analyzed by MEGA 6.0 software. Results There were minor differences in HA and NA genes between human H7N9 virus strains and poultry reference strains in Zhejiang province with the homology of 98.0%-100.0% and 97.4%-100.0%, respectively.Viral amino acid variation showed that 30 representative strains had mutations at 226 (Q226L/I) and 186(G186V) sites in HA protein, and all strains isolated from 2015 had A134V mutation;one strain had R294K mutation in NA gene;19 strains had E627K mutation in PB2 and 2 strains had D701N mutation;mutation S31N was found in M2 gene in all isolates; and all HA cleavage sites were PEIPKGR↓GLF, indicating low pathogenic strain.Conclusions The homology of HA and NA genes is high between poultry reference strains and human H7N9 virus strains in Zhejiang province during 2013 and 2015.Strains have some significant mutations of amino acid in HA and NA protein.All isolates show ion channel inhibitors ( Amantadine) resistance, and some isolates show resistance mutations with neuraminidase inhibitors.

Application of nomogram model in predicting mortality of patients infected with avian influenza A (H7 N9) / 中华临床感染病杂志

Objective To develop and validate a mortality risk prediction model for patients infected with avian influenza A H 7N9 virus.Methods A stratified and random sampling method was adopted for selection of subjects .A total of 102 patients infected with avian influenza A H7N9 virus, who were admitted to the designated hospitals in Zhejiang Province during March 2013 and March 2015, were enrolled.Standard questionnaires were used to collect data about demographic , epidemiologic and clinical characteristics , and the data were retrospectively reviewed . Univariate analysis and stepwise logistic regression analysis were used to identify the mortality risk factors of patients infected with avian influenza A H7N9 virus, and nomogram was applied to develop the risk prediction model .The accuracy of the prediction model was assessed using Concordance index (C-index) and receiver operating characteristic (ROC) curve. Results Stepwise multiple logistic regression analysis showed that age ≥60 years (χ2 =3.98, OR=2.99, 95%CI:1.05-9.21, P<0.05), increased initial neutrophil count (χ2 =6.66,OR=5.06, 95%CI:1.56-18.83, P<0.05), C-reactive protein≥120mg/L (χ2 =8.63, OR=5.15, 95%CI:1.79-16.31, P<0. 01), poor hand hygiene (χ2 =6.83, OR =10.29, 95%CI:2.18-81.49, P <0.01) and 5 days of incubation period or shorter (χ2 =7.23, OR=4.75, 95%CI:1.59-15.80, P<0.01) were independent risk factors for mortality of patients .Based on the above study , a risk prediction model of nomogram was developed.Poor hand hygiene (grade A, 100.0 points) ranked on the top of all risk factors, followed by C-reactive protein≥120 mg/L (grade B, 76.5 points), increased initial neutrophil count (grade C, 70.5 points), 5 days of incubation period or shorter (grade D, 62.0 points) and age ≥60 years (grade E, 51.0 points).The C-index and the area under the curve were 0.833 and 0.817 for the nomogram model , respectively;and the nomogram model fitted well .Conclusion Nomogram model can effectively predict and estimate the risk of death for patients infected with avian influenza A H 7N9 virus.

Characteristics of avian influenza A (H7N9) virus and its pathogenicity in human beings / 中华临床感染病杂志

The origin,diversity,hemagglutinin protein and mutations of avian influenza A (H7N9) virus are widely studied recently.Although this virus is low-pathogenic in domestic poultry,it becomes highly pathogenic in human when gene mutations occur.The available evidence has revealed that the novel avian influenza A (H7N9) virus is a multiple gene reassortment,and virus shedding in quail and chickens is much higher than in other species.When human infected with H7N9 virus,immune responses will be activated,and massive cytokines and chemokine are produced,which may result in secondary hemophagocytic syndrome and multiple organ dysfunction.The prognosis of H7N9 viral infection may be associated with high level of angiotensin Ⅱ in plasma and the genetic trait of individuals (carrying rs12252-C/C genotype IFITM3).This paper reviews the recent progress on H7N9 virus infection,to provide reference for the control of human infection with H7N9 avian influenza virus and the management of severe cases.

Retrospective study of risk factors of mortality in human avian influenza A(H7N9)cases in Hangzhou / 中华传染病杂志

Objective To investigate the risk factors related to mortality in human avian influenza A (H7N9)cases in Hangzhou.Methods The clinical and epidemiological data of 61 H7N9 patients whose diagnoses were confirmed by laboratory tests between 1st March,2013 and 2nd March,2014 in Hangzhou were collected.Descriptive analysis and univariate analysis were used to analyze the demographic,clinical and epidemiological characteristics and treatment outcomes.Patients were classified into improvement group and death group according to treatment outcomes,and risk factors for death were explored.Chi square test and t test were used for statistical analysis.Results A total of 61 patients were included in this study,among which 20(32.8%)patients died.The ratio of men to women for death attributed to H7N9 infection was three to one.The mean age of patients in death group was (63.6 ±3.8)years,which was older than that in improvement group ([55 .4±2.2]years,t =1 .97,P =0.05 ).The univariate analysis showed that the risk factors of mortality included over 60 years (χ2 =5 .16,P =0.02;OR =3.65 ,95 %CI :1 .19-11 .13 ),low education level (χ2 = 5 .42,P =0.02;OR =4.20,95 %CI :1 .24 - 14.00 ), chronic diseases (χ2 =4.67,P =0.03;OR=3.81 ,95 %CI :1 .12-12.69),bad hand hygiene (χ2 =4.05 , P =0.04;OR=4.67,95 %CI :1 .04 -11 .56 ),C-reactive protein (CRP)≥120 mg/L (χ2 =4.04,P =0.04;OR=6.00,95 %CI :1 .04-35 .33),increased initial neutrophil count (χ2 =3.90,P =0.05 ;OR=4.58,95 %CI :1 .01 -34.22)and decreased initial lymphocyte count (χ2 =7.12,P =0.01 ;OR =7.53, 95 %CI :1 .63 - 24.51 ).Conclusion Over 60 years,low education level,chronic diseases,bad hand hygiene,CRP≥ 120 mg/L,increased initial neutrophil count and decreased initial lymphocyte count are identified as risk factors for death in H7N9 cases in Hangzhou.