Survey Of Neutralization Antibodies Against JEV Among Japanese Encephalitis Patients In Three Costal Provinces Of China From 2018 To 2019

Background: Japanese encephalitis(JE)is a zoonotic disease caused by Japanese encephalitis virus(JEV).JE is the main cause of viral encephalitis in Asia-Pacific area.JE is a great damage to human health because of its high fatality and high incidence of sequalae.JEV can be divided into 5 genotypes.All the JE vaccines used at present can’t provide robust protection against G5 JEV.In recent years,G5 JEV was found in Asia several times and was reported caused human disease in South Korea.Both the costal area of China(including Guangdong Province,Zhejiang Province and Shandong Province)and South Korea are in East Asia JEV endemic cycle.Thus,these 3 provinces are under the risk of G5 JEV transmission.It is unpractical to determine the genotype of causative JEV by molecular biological method.However,because the E protein associated with the induction of neutralization antibody,varies in different genotypes,the genotype of the causative JEV can be determined by comparing the neutralization antibody levels of different genotype of JEV in the same patient.At present,there is no report of human infection of Genotype 5 JEV in China.We conducted a retrospective serum-epidemic survey among JE patients in three costal provinces in China.The aim of the survey was to understand which genotype of JEV is more connective to human JE and whether there was G5 JEV infected patient or not.This study provided a scientific basis for the prevention and control of JE.Methods: This was a cross-sectional study and convenience sampling method was used.We collected serum samples and epidemic information of JE patients from Guangdong Province,Zhejiang Province and Shandong Province.The serum samples were subjected to anti-JEV Ig M detection,JEV RNA detection and neutralization antibodies detection against G1,G3 and G5 JEV.Compared the neutralization antibody titers of G1,G3 and G5 JEV of each patient,if one titer of the neutralization antibody was 4-fold or higher than the two others,we determined this genotype of JEV is the causative virus of JE.Results: 49 JE patients were admitted to this study.11,20 and 18 patients were from Guangdong,Zhejiang and Shandong Province respectively.All the serum were positive for JEV Ig M detection and negative for JEV RNA detection.In total,the geometric mean titers of G1,G3 and G5 JEV were 1:19.17、1:51.00 and 1:8.56 respectively.The positive rate of neutralization antibodies of G1,G3 and G5 JEV were 77.55%,93.88%and 38.78%.The cross-neutralization test suggested there were 1 G1 JEV-infected patient,15 G3 JEV-infected patients and 1 G5 JEV-infected patient.In addition,we could not determine the causative genotype of JEV of the other 32 samples according to the cross-neutralization test.Conclusions: In 2018-2019,most JE patients in Guangdong Province,Zhejiang Province and Shandong Province were male.The younger age group 0-14 years and the older age group >40 years may be the high incidence population of JE.July and August are the peak seasons of JE incidence in these 3 provinces.There might be G5 JEVinfected patient in Zhejiang Province in 2019.G1,G3 and G5 JEV co-circulated in Guangdong Province,Zhejiang Province and Shandong Province from 2018 to 2019.G3 JEV might be the main cause of JE in these 3 provinces.