| Background:Seasonal or pandemic influenza caused by the H1N1 influenza virus has posed a continuing threat to human health and public health nearly a century.Severe infections and deaths have occurred worldwide almost every year since the H1N1 outbreak in 2009 and remain a global public health concern.Despite significant advances in influenza A(H1N1)virus and vaccine research,influenza viruses are highly variable and uncertain,leading to the prevention and control of influenza A(H1N1)still faces enormous challenges.Public health surveillance and clinical treatment were still important means for influenza prevention and control before the advent of the"universal"influenza vaccine.It was particularly important to comprehensively understand its epidemic characteristics and features from the perspective of public health,identify key areas for prevention and control,and optimize the allocation of influenza prevention and control resources.From a clinical perspective,rapid and accurate early diagnosis is essential for timely initiation of antiviral therapy to reduce influenza-related morbidity and mortality during seasonal and pandemic influenza,and to reduce inappropriate clinical use of antibiotics.Objectives:The epidemic characteristics and spatial distribution of A(H1N1)in Jiangsu province from 2009 to 2019 were analyzed to provide scientific basis for the prevention and control of A(H1N1).In the other hand,in order to providing a rapid and accurate methods for the diagnosis of influenza,the double antibody sandwich ELISA(DAS-ELISA)was established by using the monoclonal antibody which produced using influenza neuraminidase as the target.Methods:1.Statistical analysis:The positive case data of A(H1N1)were obtained through the influenza surveillance network of Jiangsu province,and the number of resident population in each county was sorted out from the statistical yearbook of each city as the denominator to calculate the incidence of A(H1N1).The chi-square test was performed using SPSS22.0 to compare the positive rates of A(H1N1)among different populations.Arc GIS 10.2 software was used for spatial autocorrelation analysis and visualization of the research results.Moran’s I index and Getis-ord General G index reflect the Global autocorrelation of A(H1N1)incidence in Jiangsu province.Local Moran’s I index and getis-ord Gi*index were used to analyze the Local autocorrelation of incidence.2.Experimental study:The purified influenza virus was used to immunize mice as immunogenicity,then the monoclonal antibodies against influenza neuraminidase was screened.Based on the affinity to influenza viruses of H9N2,the best matching monoclonal antibodies were screened by exchanging different detection and capture monoclonal antibodies.The optimum working condition of the detection system was determined by square matrix titration.The specificity of the detection system was determined by detecting influenza viruses of different subtypes,and the sensitivity of the detection system was determined by different concentrations of recombinant proteins and different titers of influenza viruses.Results:1.The number of positive cases of A(H1N1)in Jiangsu province from 2009 to 2019accounted for 1/3 of the total positive cases of influenza,with an average annual positive rate of 4.0%.The epidemic peak mainly occurs in winter when it’s circulating as seasonal influenza,and the distribution is unimodal.2.The demographic distribution of A(H1N1)in Jiangsu province from 2009 to 2019showed that there was no statistically significant difference between gender in the annual positive rate of A(H1N1)(χ~2=1.273,P=0.259).However,There was a significant difference among different age group,(χ~2=13.570,P<0.05),the highest was 7.2%in the age group of15～25 years old,and the lowest was 2.6%in the age group of over 60 years old.In addition,the difference in the annual positive rate of different occupational groups was also statistically significant(χ~2=1489.892,P<0.001),student has the highest rate which was 6.3%,and the retired/domestic and unemployed has the the lowest rate which was 2.9%.In addition,the annual positive rate in northern jiangsu was higher than that in central and southern jiangsu(3.9%vs 3.9%vs 4.2%).3.Further demographic analysis by years showed that except the positive rate of females was slightly higher than that of males in 2010(χ~2=5.854,P=0.016),there was no statistical difference in the gender distribution of A(H1N1)in Jiangsu province in each year.In terms of age distribution,the differences in age distribution of A(H1N1)in all years except 2015 were statistically significant,and in 2009,2014,2016,2018 and 2019,the age group of 25～60 years replaced the age group under 25 years old as the age group with the highest detection rate gradually.In addition,there was no specific occupational distribution of A(H1N1)in Jiangsu province among 2009 to 2019.However,the positive rate of A(H1N1)was higher among occupational groups with closed working conditions and close contact with the public.4.The incidence of A(H1N1)in Jiangsu province from 2009 to 2018 showed an upward trend of fluctuation.The total incidence of influenza in Jiangsu province was randomly distributed in space.According to the analysis of local spatial autocorrelation,Guangling district of Yangzhou city may be a high incidence area and a concentration area of A(H1N1).Getis-Ord general Gi*index in different years showed that the hot spots distributed irregularly,but further observation can be found that the hot spots are mainly distributed in Zhenjiang,Yangzhou,Taizhou,Xuzhou and Suqian and mainly in district,and there is an expansion trend in hot fields.5.The double-antibody sandwich ELISA system,developed with monoclonal antibodies targeting avian influenza H9N2 neuraminidase,can detect only avian H9N2influenza viruses,including opportunistic H9N2 influenza viruses isolated from humans,but not other subtypes or other N2 subtypes of influenza viruses combined with HA.The detection system also has a good sensitivity,the detection limit of H9N2 influenza virus was0.25 HAU/50μl and for rec N2 was 10ng/ml.Conclution:1.The incidence of A(H1N1)in Jiangsu province showed a fluctuating uprising tendency,the peak of the seasonal epidemic occurs in winter.Compared with the period of the pandemic,the positive rate was higher in the 25-60 age group.It is suggested to further strengthen the influenza A(H1N1)surveillance,such as expanding the surveillance population during the high incidence season,and strengthening the surveillance for the 25～60 age group and the occupational exposed population.2.The incidence of A(H1N1)in Jiangsu province showed a certain high value clustering distribution,and there was an expanding trend of hot spots.Suggesting that the implementation of influenza prevention and control measures should not only focus on hot spots,but also be included in the surrounding areas.3.The double antibody sandwich ELISA,which was established with influenza neuraminidase as the target,had good specificity and sensitivity to detect H9N2 influenza virus. |
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