Serological Investigation into the Infected Genotypes of Patients with Japanese Encephalitis in the Coastal Provinces of China

Objective Genotypes(G)1,3,and 5 of the Japanese encephalitis virus(JEV)have been isolated in China,but the dominant genotype circulating in Chinese coastal areas remains unknown.We searched for G5 JEV-infected cases and attempted to elucidate which JEV genotype was most closely related to human Japanese encephalitis(JE)in the coastal provinces of China.Methods In this study,we collected serum specimens from patients with JE in three coastal provinces of China(Guangdong,Zhejiang,and Shandong)from 2018 to 2020 and conducted JEV cross-neutralization tests against G1,G3,and G5.Results Acute serum specimens from clinically reported JE cases were obtained for laboratory confirmation from hospitals in Shandong(92 patients),Zhejiang(192 patients),and Guangdong(77 patients),China,from 2018 to 2020.Seventy of the 361 serum specimens were laboratory-confirmed to be infected with JEV.Two cases were confirmed to be infected with G1 JEV,32 with G3 JEV,and two with G5 JEV.Conclusion G3 was the primary infection genotype among JE cases with a definite infection genotype,and the infection caused by G5 JEV was confirmed serologically in China.

Recent Developments in SARS-CoV-2 Neutralizing Antibody Detection Methods

The ongoing Coronavirus disease 19 pandemic has likely changed the world in ways not seen in the past.Neutralizing antibody(NAb)assays play an important role in the management of the severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)outbreak.Using these tools,we can assess the presence and duration of antibody-mediated protection in naturally infected individuals,screen convalescent plasma preparations for donation,test the efficacy of immunotherapy,and analyze NAb titers and persistence after vaccination to predict vaccine-induced protective effects.This review briefly summarizes the various methods used for the detection of SARS-CoV-2 NAbs and compares their advantages and disadvantages to facilitate their development and clinical application.

Establishment of animal model for potency evaluationof inactivated SARS virus experimental vaccine

The purpose of this study was to test the effectiveness of source virus strain for the manufacture of the inactivated SARS virus vaccine, and establish an experimental method and preliminary standard for potency evaluation. Mice were divided into groups for being immunized with corresponding serially diluted experimental SARS virus inactivated vaccine. And the rabbits were immunized with undiluted vaccine. Challenge assay was conducted with a heterologous SARS virus. And the neutralization antibody was determined with plaque reduction neutralization test (PRNT), to which the neutralization antibody in the convalescent serum of SARS patients was compared. The experimental vaccine viral strains were proved to be suitable for manufacturing the vaccine. Mice immunized by vaccines of serial dilutions were able to elicit neutralizing antibody. The antibody titer from mice immunized with the undiluted vaccine could reach up to 1∶495.2, while those of rabbits immunized with the undiluted vaccine could reach a GMT of 55.0-79.9. The capability of the antibody to neutralize the virus from Guangdong is more efficient than that from Beijing. The GMT of neutralizing antibody in SARS convalescents living in south and north China ranged from 50.12 to 54.95, and the titers of convalescents from north China were higher than those from south China. Mice and rabbits used as the model for evaluation of potency are of sensitivity, and the test is of reproducibility. The candidate challenge viral strains showed a relatively consistent effect on evaluating antibodies produced by various batches and different vaccine-source strains, hence they can be used to evaluate potency of the vaccine. The method for testing the vaccine potency and the evaluation standard was established preliminarily.