Stepwise prediction and statistical screening: B-cell epitopes on neuraminidase of human avian H5N1 virus

Patched bimetallic surfaces are active catalysts for ammonia decomposition

Ammonia decomposition is often used as an archetypical reaction for predicting new catalytic materials and understanding the very reason of why some reactions are sensitive on material's structure. Core-shell or surface-segregated bimetallic nanoparticles expose outstanding activity for many heterogeneously catalysed reactions but the reasons remain elusive owing to the difficulties in experimentally characterizing active sites. Here by performing multiscale simulations in ammonia decomposition on various nickel loadings on platinum (111), we show that the very high activity of core-shell structures requires patches of the guest metal to create and sustain dual active sites: nickel terraces catalyse N-H bond breaking and nickel edge sites drive atomic nitrogen association. The structure sensitivity on these active catalysts depends profoundly on reaction conditions due to kinetically competing relevant elementary reaction steps. We expose a remarkable difference in active sites between transient and steady-state studies and provide insights into optimal material design.

Epitope peptides of influenza H3N2 virus neuraminidase gene designed by immunoinformatics

The virus surface protein neuraminidase (NA) is a main subtype-specific antigen in influenza type A viruses. Neuraminidase functions as an enzyme to break the bonds between hemagglutinin (HA) and sialic acid to release newly formed viruses from infected cells. In this study, NA genes from the H3N2 subtype virus were sequenced and NA proteins were screened for B-cell epitopes and assessed based on immunoinformatics. Based on this information, three peptides ES8, RR9, and WK7 (covering amino acid residues 221-228, 292-300, and 383-389, respectively) of the NA protein were selected and synthesized artificially. These peptides were used to immunize New Zealand rabbits subcutaneously to raise antisera. Results showed that these three peptides were capable of eliciting antibodies against H3N2 viruses in a specific and sensitive manner, detected in vitro by enzyme-linked immunosorbent assay. Furthermore, hemadsorption anti-releasing effects occurred in three antisera mixtures at a dilution of 1:40. Alignment using database software showed that amino acid residues in these three epitope peptides were substituted at specific sites in all the NAs sequenced in this study. We suggest that these NA epitope peptides might be used in conjunction with HA proteins as vaccine antigens.

Linear B-cell epitope mapping of neuraminidases of the 2009 A H1N1 viruses based on immunoinformatics

The 2009 A H1N1 viruses have spread throughout the world, as the viral neuraminidase (NA) is a receptor-destroying enzyme, removing sialic acid from carbohydrate chains attached to NA, and releasing the viruses from infected cells. In this study, the NA genes of Guangdong viruses were sequenced, then their B-cell epitopes were predicted, screened and assessed based on immunoinformatics. The antisera were raised in rabbits against five linear synthetic peptides spanning the NA protein of 2009 A H1N1. Five peptides, LR17, SS12, DP9, DS11 and DI14, respectively, are capable of eliciting neutralizing antibodies against 2009 A H1N1 in the in vitro microneutralization assay. DI14 was identified to be particularly potent in eliciting a neutralizing antibody titer comparable to that obtained with a whole virion-immunized serum. Immunization of rabbit with either five peptides triggered a 2009 A H1N1-specific antibody response as high as that obtained with the whole virion as immunogen. Alignment with databases showed that the amino acid residues of five epitope peptides are highly conserved among the NA sequences of 2009 A H1N1 strains isolated from the world. Altogether, these data indicate that LR17, SS12, DP9, DS11 and DI14 represent a promising candidate for an effective synthetic peptide-based vaccine against 2009 A H1N1 viruses.