Characterization of a hospital-based gastroenteritis outbreak caused by GII.6 norovirus in Jinshan, China

Figures

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  Fig. 1.. The epidemic curve of the studied acute gastroenteritis outbreak by date of onset in a hospital of Jinshan in November 2018. Column chart indicating the numbers of acute gastroenteritis cases (Y-axis) in the two care units. X-axis shows dates.

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  Fig. 2.. Phylogenetic tree analyses based on nucleotide sequences encoding capsid NS terminus (387 bp fragment) (a) and P domain (b) (978 bp fragment, corresponding to the nucleotide 661–1638 of the VP1 encoding gene) of GII.6 noroviruses. The sequences isolated were marked with a triangle and the tree made with reference strains using the neighbour-joining method. The bootstrap values generated from 1000 replicates are shown at each node. GII.6 strains were classified into three distinct clusters a–c.

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  Fig. 3.. Comparisons of P domain sequences that built the HBGA binding interfaces of GII.6 noroviruses and the neighbour regions. The representative sequences of GII.6 noroviruses are selected from different major phylogenetic clusters. The outbreak strain is shown with bold fonts. The sequences are aligned using MegAlign program (DNAstar 7.1). Amino acids in green are associated with HBGA binding, while those in light blue are related to the binding specificity based on previous studies [24, 25].

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  Fig. 4.. Recombinant P protein of the studied GII.6/Jinshan 06 strain binding to well-characterised saliva samples representing various blood types. The binding signals are shown in optical density (Y-axis), while the well-characterised saliva (V as abbreviation for volunteers) [22] samples are shown in X-axis. A, B, O and N stands for blood type A, B, O and non-secretor, respectively.

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  Fig. 5.. (a) and (b): GII.6-specific IgG titres (a) and blockade titres (b) against NoV GII.6 P domain binding to HBGAs of the pared human sera collected from the outbreak. Blue (acute phase sera) and red (convalescent sera) columns show the IgG titres (a) or blockade titres (b), while different sera in indicating codes are shown in X-axis. The seroconversion between acute- and convalescent-phase sera were determined and shown. Green columns show the increased folds in GII.6 specific IgG titres or blocking titres by comparing their corresponding titres in the acute and convalescent sera.