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Objective@#To detect norovirus (NoV) GⅠ.1- and GⅡ.4-specific IgG, IgA and histo-blood group antigen (HBGA)-blocking antibodies in healthy populations of all age groups in China for better understanding the epidemiological features of norovirus in China from a serological point of view and providing basic data for vaccine development and clinical trial design.@*Methods@#Indirect ELISA and HBGA-blocking assay were used to detect NoV-specific IgG, IgA and HBGA-blocking antibodies in serum samples collected from healthy natural populations (n=839, aged from six months to 88 years old) in Guangzhou, Fuyang and Yantai. The results were statistically analyzed.@*Results@#The total positive rates of NoV GⅠ.1- and GⅡ.4-specific IgG antibodies were 91.9% and 93.0%. The positive rates of GⅠ.1- and GⅡ.4-specific IgA antibodies were 48.6% and 75.6%, and the titers of HBGA-blocking antibodies to GⅠ.1 and GⅡ.4 norovirus were 5.04 (95%CI: 4.63-5.49) and 18.15 (95%CI: 16.11-20.44). The positive rates of IgG and IgA antibodies generally showed an increasing trend with age. The positive rates of GⅠ.1- and GⅡ.4-specific IgG antibodies ranged from 79.2% to 100.0% and 76.7% to 100.0% in different age groups. They were 81.7% and 85.0% in the age group of 0.5-<1 year, 79.2% and 76.7% in the age group of 1-<2 years, and 98.1% and 96.3% in the age group of 12-<18 years, and maintained at 96% and 98% in the older age groups. The positive rates of GⅠ.1-specific IgA antibody ranged from 11.7% to 93.8% in different age groups and rapidly increased with age. It was 11.7% in the age group of 0.5-<1 year, and reached 93.3% in people aged 45-<60 years and 93.8% in people aged ≥60 years. The positive rates of GⅡ.4-specific IgA antibody ranged from 50.8% to 88.8% in different age groups with 50.8% in people aged 0.5-<1 year, and 86.7%-90.7% in people aged 12-<18 years and older. The titer of GⅠ.1 HBGA-blocking antibody generally increased with age. The antibody titer in populations aged 0.5-<12 years old was lower than that in those aged 18 years and above (GMT: 2.98-4.07 vs 8.21-11.62, P<0.001), and the titer in people of 12-<18 years old was lower than that in those of 45 years old and above (GMT: 5.21 vs 11.03-11.62, P<0.05). No obvious change with age was observed in the titer of GⅡ.4 HBGA-blocking antibody excepting the significant difference between populations of 2-<5 and 22-<45 years old (GMT: 26.73 vs 11.87, P<0.01).@*Conclusions@#This study revealed the characteristics of serum NoV GⅠ.1- and GⅡ.4-specific IgG, IgA and HBGA blocking antibodies in populations of different age groups in central and eastern China through analyzing their positive rates and titers and provided preliminary seroepidemiological data for the development of NoV vaccines in China.
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Objective@#In this study, phage display technology was used to construct the human anti-Zika virus(ZIKV), phage antibody library and to obtain and express the monoclonal antibody. The aim was to master the preparation and expression of human phage antibody library screening method for highly specific antibodies.@*Methods@#The whole blood samples of Zika patients were collected and the lymphocytes were isolated. The RT-PCR method was used to amplify the antibody light chain and heavy chain Fab gene from lymphocyte Ig mRNA. The pComb3H system was used to construct the gene with genetic diversity Preparation of human anti-ZIKV phage antibody library. The purified antibody library was screened by using the purified ZIKV and the obtained ZIKV E protein antigen.@*Results@#The monoclonal antibody Fab fragment gene was successfully obtained for the ZIKV E protein antigen. The gene can be efficiently expressed in Escherichia coli.@*Conclusions@#According to the sequence analysis, this study showed that the monoclonal antibody was a new human genetically engineered antibody against ZIKV, which laid the foundation for the early diagnosis of ZIKV, and obtain a specific monoclonal antibody to ZIKV for human treatment of ZIKV infection.