Human adenovirus (HAdV) infection in children with acute respiratory tract infections in Guangzhou, China, 2010-2021: a molecular epidemiology study.

BACKGROUND: Human adenovirus (HAdV) infection can cause a variety of diseases. It is a major pathogen of pediatric acute respiratory tract infections (ARIs) and can be life-threatening in younger children. We described the epidemiology and subtypes shifting of HAdV among children with ARI in Guangzhou, China. METHODS: We conducted a retrospective study of 161,079 children diagnosed with acute respiratory illness at the Guangzhou Women and Children's Medical Center between 2010 and 2021. HAdV specimens were detected by real-time PCR and the hexon gene was used for phylogenetic analysis. RESULTS: Before the COVID-19 outbreak in Guangzhou, the annual frequency of adenovirus infection detected during this period ranged from 3.92% to 13.58%, with an epidemic peak every four to five years. HAdV demonstrated a clear seasonal distribution, with the lowest positivity in March and peaking during summer (July or August) every year. A significant increase in HAdV cases was recorded for 2018 and 2019, which coincided with a shift in the dominant HAdV subtype from HAdV-3 to HAdV-7. The latter was associated with a more severe disease compared to HAdV-3. The average mortality proportion for children infected with HAdV from 2016 to 2019 was 0.38% but increased to 20% in severe cases. After COVID-19 emerged, HAdV cases dropped to 2.68%, suggesting that non-pharmaceutical interventions probably reduced the transmission of HAdV in the community. CONCLUSION: Our study provides the foundation for the understanding of the epidemiology of HAdV and its associated risks in children in Southern China.

[Preparation, characterization and preliminary application of monoclonal antibodies against the expressed Norovirus capsid protein].

AIM: To prepare the monoclonal antibodies (mAbs) against Norovirus capsid protein for the development of a rapid assay of Norovirus and to investigate the pathogenesis of this virus. METHODS: Sp2/0-Ag-14 myeloma cells were fused with spleen cells of BALB/c mice immunized with the recombinant protein of Norovirus NVgz01 (DQ369797), which was overexpressed in E.coli. The monoclonal antibodies against Norovirus capsid protein were screened by selective culture medium. The obtained Ig subtypes, titer and specificity of the mAbs were examined by ELISA and Western blot respectively. RESULTS: After cell fusion and subcloning, four hybridoma cell lines which secreted monoclonal antibodies specifically against Norovirus capsid protein were obtained and named as N2C3, N7C2, N4B1 and N8A9. Indirect ELISA and Western blot assay showed that the four mAbs specifically recognized the Norovirus capsid protein expressed in E.coli. The native Norovirus capsid protein in the stool samples were also recognized by them. The Sandwich ELISA, a rapid detection assay of the expressed and native Norovirus capsid protein, demonstrated that N2C3 and N7C2 were matched successfully. CONCLUSION: The mAbs against GII Norovirus capsid protein have been developed, which can be used for the development of detection assay and the basic research of Norovirus.

[Preparation and characterization of specific monoclonal antibodies against hexon of HAdV 3].

OBJECTIVE: To obtain the monoclonal antibody against hexon protein of human adenovirus. METHODS: BALB/c mice were immunized with purified recombinant hexon protein, and the spleen cells of the mice were isolated and fused with myloma cells. Four hybridoma cell strains were screened by indirect ELISA and cultured, and the sensitivity, specificity and virus neutralizing activity were analyzed with ELISA, Western blotting and neutralizing test. RESULTS: The mouse ascites produced by these hybridoma cells contained specific monoclonal antibodies against hexon protein of human adenovirus as identified by ELISA and Western blot, and the antibody generated by 4C6 strain showed human adenovirus type 3-neutralizing activity. CONCLUSION: The monoclonal antibodies against hexon protein with high specificity have been successfully obtained, and these antibodies can be useful in developing assays for early diagnosis of HAdV3 infection and also in study of therapeutic drugs of the infection.

[Cloning, expression and immunocharacterization of the capsid protein of human Norwalk virus Guangzhou strain NVgz01].

OBJECTIVE: To clone, express and characterize the capsid protein of human Norwalk virus Guangzhou strain NVgz01. METHODS: On the basis of successful construction of full-genome clones and sequence analysis of human norovirus Guangzhou strain NVgz01, the full capsid gene was ligated into pET28a (+) for expression. After IPTG induction, the recombinant protein was purified through metal (Ni(2+)) chelating affinity chromatography. Western blotting and enzyme-linked immunosorbent assay (ELISA) were used to determine the antigenicity of the recombinant protein. RESULTS: The recombinant capsid gene was overexpressed in E.coli, yielding the recombinant protein with relative molecular mass of 62x10(3) that was highly purified through metal (Ni(2+)) chelating affinity chromatography. IDEIA Norovirus Kit and immunoassay showed that the recombinant protein had good antigenicity. CONCLUSION: The capsid gene of norovirus Guangzhou strain has been cloned and expressed, which can be useful for developing diagnostic reagents or vaccine of norovirus.