Human noroviruses (huNoVs) recognize histo-blood group antigens (HBGAs) as attachment factors, in which genogroup (G) I and GII huNoVs use distinct binding interfaces. The genetic and evolutionary relationships of GII huNoVs under selection by the host HBGAs have been well elucidated via a number of structural studies; however, such relationships among GI NoVs remain less clear due to the fact that the structures of HBGA-binding interfaces of only three GI NoVs with similar binding profiles are known. In this study the crystal structures of the P dimers of a Lewis-binding strain, the GI.8 Boxer virus (BV) that does not bind the A and H antigens, in complex with the Lewis b (Le(b)) and Le(y) antigens, respectively, were determined and compared with those of the three previously known GI huNoVs, i.e. GI.1 Norwalk virus (NV), GI.2 FUV258 (FUV) and GI.7 TCH060 (TCH) that bind the A/H/Le antigens. The HBGA binding interface of BV is composed of a conserved central binding pocket (CBP) that interacts with the β-galactose of the precursor, and a well-developed Le epitope-binding site formed by five amino acids, including three consecutive residues from the long P-loop and one from the S-loop of the P1 subdomain, a feature that was not seen in the other GI NoVs. On the other hand, the H epitope/acetamido binding site observed in the other GI NoVs is greatly degenerated in BV. These data explain the evolutionary path of GI NoVs selected by the polymorphic human HBGAs. While the CBP is conserved, the regions surrounding the CBP are flexible, providing freedom for changes. The loss or degeneration of the H epitope/acetamido binding site and the reinforcement of the Le binding site of the GI.8 BV is a typical example of such change selected by the host Lewis epitope.
Binding Sites ; Blood Group Antigens ; chemistry ; immunology ; Caliciviridae Infections ; immunology ; virology ; Crystallography, X-Ray ; Epitopes ; chemistry ; immunology ; Evolution, Molecular ; Humans ; Lewis Blood-Group System ; chemistry ; immunology ; Norovirus ; chemistry ; immunology ; pathogenicity ; Protein Binding ; Viral Proteins ; chemistry ; immunology

In order to investigate peptide mimics of carbohydrate blood group A antigen, a phage display 12-mer peptide library was screened with a monoclonal antibody against blood group A antigen, NaM87-1F6. The antibody-binding properties of the selected phage peptides were evaluated by phage ELISA and phage capture assay. The peptides were co-expressed as glutathione S-transferase (GST) fusion proteins. RBC agglutination inhibition assay was performed to assess the natural blood group A antigen-mimicking ability of the fusion proteins. The results showed that seven phage clones selected bound to NaM87-1F6 specifically, among which, 6 clones bore the same peptide sequence, EYWYCGMNRTGC and another harbored a different one QIWYERTLPFTF. The two peptides were successfully expressed at the N terminal of GST protein. Both of the fusion proteins inhibited the RBC agglutination mediated by anti-A serum in a concentration-dependent manner. These results suggested that the fusion proteins based on the selected peptides could mimic the blood group A antigen and might be used as anti-A antibody-adsorbing materials when immunoabsorption was applied in ABO incompatible transplantation.
Adsorption ; Bacteriophages ; Blood Group Antigens/*chemistry ; Enzyme-Linked Immunosorbent Assay ; Epitopes/chemistry ; Glutathione Transferase/metabolism ; Peptide Library ; Peptides/*chemistry ; Protein Structure, Tertiary ; Recombinant Fusion Proteins/chemistry

OBJECTIVETo investigate the expression of aquaporin-1 (AQP1) in the human peritoneum and to evaluate the effect of peritoneal dialysis (PD) on its expression.

METHODSPeritoneal biopsies were obtained from normal subjects (n = 10), uremic nondialysis patients (n = 12) at catheter insertion and PD patients (n = 10) at the time of catheter removal, reinsertion or renal transplantation. Western blot, immuno-histochemical staining and reverse transcript-polymerase chain reaction (RT-PCR) techniques were used to investigate AQP1 expression.

RESULTSAll peritoneal samples expressed AQP1 at both mRNA and protein levels. Western blot revealed a major band at 28 kD as well as more diffuse bands between 35 and 50 kD. The 28 kD band represents the nonglycosylated form of the protein while the 35 - 50 kD bands correspond to glycosylated AQP1. Immunohistochemical staining found the positive deposits were distributed in the mesothelial cells, endothelial cells of capillaries, venules and small veins, whereas no signal was detected in the arterioles. Semi-quantitative analysis showed that AQP1 expression was remarkably stable in all samples, whatever their origin (P > 0.05).

CONCLUSIONSOur findings suggested that AQP1 is the molecular counterpart of an ultra small pore during PD. Secondly, the peritoneal mesothelial cell might also be involved in peritoneal transcellular water transport. As regards whether or not the structural or distributional alterations of AQP1 in the peritoneum may be more obviously expressed during PD, further study is needed.

Adult ; Aquaporin 1 ; Aquaporins ; analysis ; Blood Group Antigens ; Female ; Humans ; Male ; Middle Aged ; Peritoneal Dialysis ; Peritoneum ; chemistry ; physiology ; Uremia ; physiopathology

OBJECTIVETo study the binding profile of NV strain SZ9711 (GII-4) with human histo-blood group antigens (HBGAs).

METHODSThe P domain-encoding fragment was amplified by RT-PCR from the stain SZ9711 and cloned into the pGEX-4T-1 vector. The recombinant fusion protein was expressed in E. coli and purified using the column Sepharose 4B. The P protein was released by thrombin cleavage. The binding of P particles of SZ9711 and VA387 with the HBGAs were measured by saliva-based EIA method.

RESULTSThe expression of the recombinant fusion protein was shown by the SDS-PAGE, in which a 38 x 10(3)-P protein was obtained. Saliva-based EIA revealed that the P particle of SZ9711 bound to HBGAs in saliva similar to that of the strain VA387 reported previously. It bound strongly to saliva of type A, B and O(secretor) but did not interact with saliva of type O(non-secretor). Noteworthy, binding ability of SZ9711 P particle to type A saliva was lower than that of the VA387 P particle.

CONCLUSIONThis is the first time that a P particle was prepared from a norovirus strain isolated in China and the binding ability of the P particle with HBGAs was analyzed. The result indicated the binding profile of the SZ9711 P particle was similar to that of VA387 reported previously. These data may be valuable in studying the relationship between noroviruses and their bindings to HGBA receptors.

Blood Group Antigens ; metabolism ; Caliciviridae Infections ; metabolism ; virology ; China ; Humans ; Norovirus ; chemistry ; genetics ; metabolism ; Protein Binding ; Saliva ; chemistry ; metabolism ; Viral Proteins ; genetics ; isolation & purification ; metabolism

To develop a real-time FQ-PCR method for quantifying human ermap, a set of primers and a fluorescent probe were designed by primer express 2.0. pBluescriptSK(+) plasmid contained ermap cDNA was transcribed to generate calibration standards for quantification. A real time FQ-PCR method was established. The results showed that when the concentrations of DNA to be amplified were ranged from 1.725 x 10(7) to 1.725 x 10(10) cps/ml, there was a good correlation between template concentration and cycle threshold, and the correlation coefficient reached to -0.999376. In conclusion, real time FQ-PCR which is specific, sensitive and accurate can be used to further research on human ermap.
Blood Group Antigens ; genetics ; Butyrophilins ; DNA, Complementary ; chemistry ; genetics ; Fluorescent Dyes ; chemistry ; Fluorometry ; methods ; Humans ; Polymerase Chain Reaction ; methods ; Reproducibility of Results