Epidemiology of norovirus gastroenteritis in hospitalized children under five years old in western China, 2015-2019.

OBJECTIVES: Norovirus is associated with one-fifth of all gastroenteritis cases, but basic epidemiological data is lacking, especially in developing countries. As long-term surveillance on norovirus gastroenteritis is scarce in western China, this study aims to update the epidemiological knowledge of norovirus gastroenteritis and to characterize the genotypes of norovirus strains. METHODS: Stool samples were collected from hospitalized children under 5 years old with gastroenteritis in Chengdu, China. All samples were tested for norovirus as well as rotavirus, sapovirus, enteric adenovirus, and astrovirus by real-time RT-PCR. RdRp and VP1 genes were sequenced in norovirus-positive samples to investigate viral phylogenies. RESULTS: Of the 1181 samples collected from 2015 to 2019, 242 (20.5%) were positive for norovirus. Among norovirus-positive cases, 65 cases had co-infection with another virus; norovirus/enteric adenovirus was most frequently detected (50.8%, 33/65). The highest positive rate was observed in children aged 13-18 months (23.7%, 68/287). Norovirus infection peaked in autumn (36.6%, 91/249), followed by summer (20.3%, 70/345). Pearson correlation analysis showed significant correlation between the norovirus-positive rate and humidity (r = 0.773, P < 0.05). GII.4 Sydney 2012 [P31] (48.5%, 79/163) and GII.3 [P12] (35.6%, 58/163) were the dominant norovirus strains. CONCLUSIONS: Norovirus has become one of the most common causes of viral gastroenteritis in children under 5 years old in western China. Continuous monitoring is imperative for predicting the emergence of new epidemic strains and for current vaccine development.

[The New Bacteria Expressing Recombinant Multi-epitope Vaccine against Helicobacter pylori and Its Microbiological Characteristics].

OJECTIVE: To construct the engineering bacteria with recombinant plasmid expressing the multi-epitope vaccine which composed of Helicobacter pylori urea membrane channel protein (UreI), Helicobacter pylori urease B subunit (UreB) and cholera toxin B subunit (CTB), and then to study it's microbiological characteristics. METHODS: The sequence contains some dominant epitopes of Helicobacter pylori UreI and UreB was designed, and ctB was added at the N-terminal, all the sequence were linked by flexible linkers. Codon optimization was done according to Escherichia coli (E. coli) BL21 (DE3) bias, the optimized sequence was designated BIB. BIB sequence was synthesized and cloned into plasmid pET28a(+). The recombinant plasmid was confirmed by restriction enzyme digestion and DNA sequencing. The recombinant protein BIB was expressed in E. coli BL21 (DE3) and analyzed by Western blot. RESULTS: The plasmid of pET28a(+)/BIB was constructed successfully, confirmed by restriction enzyme digestion and DNA sequencing. The recombinant protein BIB with relative molecular mass about 33 x 10(3) could be produced by E. coli BL21 (DE3) and was detected by Western blot. The relative molecular mass and N-terminal amino acid sequence of BIB were 100% identity with the design. CONCLUTION: The engineering bacteria with recombinant plasmid expressing the multi-epitope vaccine against Helicobacter pylori was constructed successfully. The recombinant protein BIB can be identified by anti-Sydney strain 1 of Helicobacter pylori (H. pylori SS1) polyclonal antibody and anti-CTB monoclonal antibody, which demonstrated that BIB has the expected antigenicity.

[Construction and expression characteristics in vitro of human papillomavirus type 16 E7 suicidal DNA vaccine].

OBJECTIVE: To construct the suicidal DNA vaccine of human papillomavirus type 16 E7 gene (HPV16), and explore the DNA vaccine expression characteristics in vitro and capacity of inducing the transfected cells into apoptosis. METHODS: HPV16 E7 gene cloned by PCR from pET32/E7 was inserted into the plasmid pSCA1 to construct the recombinant plasmid pSCA/E7, followed by identification with PCR, BamH I and Sma I digestion and sequencing. pSCA/E7 was then used to transfect BHK-21 cell line. The transient expression of HPV16 E7 gene was confirmed by immuno-fluorescent staining, and the apoptosis induced by pSCA/E7 was checked with TDT-mediated dUTP nick end-labeling (TUNEL). RESULTS: The cloned E7 gene fragment was about 400 bp in length. PCR, restriction endonuclease digestion and sequence analysis revealed that the HPV16 E7 gene was cloned into the eukaryotic expression plasmid pSCA1 successfully. Immunofluorescent staining confirmed that the E7 gene could express in BHK-21 cell line. The BHK-21 cells transfected with pSCA/E7 could be induced into apoptosis which was confirmed by TUNEL. CONCLUSION: The results show that HPV16 E7 suicidal DNA vaccine can express in BHK-21 cell line, and induce the pSCA/E7 transfected cells into apoptosis. These findings may provide the foundation for exploring the therapeutic vaccine against HPV16-associated cervical cancer.