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

Developing a Live Probiotic Vaccine Based on the Enterococcus faecium L3 Strain Expressing Influenza Neuraminidase

Probiotic microorganisms are currently considered as a promising platform for the development of recombinant vaccines expressing foreign antigens. In this study, we generated and evaluated the live mucosal recombinant vaccine by integrating genes encoding influenza virus neuraminidase (NA) of the N2 subtype into the DNA of the probiotic strain Enterococcus faecium L3 (L3). We confirmed NA expression in the pili of L3 using immune electron microscopy. Mice were fed with a probiotic vaccine containing the NA gene (L3-NA) or pure L3. Oral administration of L3-NA caused detectable increase in virus-specific serum IgG and local IgA after the third feeding. Immunization with L3-NA increased the survival rate by 34% when the mice were infected using A(H1N1)pdm09 influenza virus after the third feeding. After S. pneumoniae post-influenza infection, the L3-NA-immunized mice were 50% more protected from lethality in comparison with L3-fed mice. Thus, a live probiotic vaccine candidate based on L3 induced the formation of systemic and local immunity and provide partial protection against complicated influenza.

A Highly Conserved Epitope (RNNQIPQDF) of Porcine teschovirus Induced a Group-Specific Antiserum: A Bioinformatics-Predicted Model with Pan-PTV Potential

Porcine teschovirus (PTV) is an OIE-listed pathogen with 13 known PTV serotypes. Heterologous PTV serotypes frequently co-circulate and co-infect with another swine pathogen, causing various symptoms in all age groups, thus highlighting the need for a pan-PTV diagnostic tool. Here, a recombinant protein composed of a highly conserved “RNNQIPQDF” epitope on the GH loop of VP1, predicted in silico, and a tandem repeat of this epitope carrying the pan DR (PADRE) and Toxin B epitopes was constructed to serve as a PTV detection tool. This recombinant GST-PADRE-(RNNQIPQDF)ⁿ-Toxin B protein was used as an immunogen, which effectively raised non-neutralizing or undetectable neutralizing antibodies against PTV in mice. The raised antiserum was reactive against all the PTV serotypes (PTV–1–7) tested, but not against members of the closely related genera Sapelovirus and Cardiovirus, and the unrelated virus controls. This potential pan-PTV diagnostic reagent may be used to differentiate naturally infected animals from vaccinated animals that have antibodies against a subunit vaccine that does not contain this epitope or to screen for PTV before further subtyping. To our knowledge, this is the first report that utilized in silico PTV epitope prediction to find a reagent broadly reactive to various PTV serotypes.

Immunosignatures can predict vaccine efficacy

The development of new vaccines would be greatly facilitated by having effective methods to predict vaccine performance. Such methods could also be helpful in monitoring individual vaccine responses to existing vaccines. We have developed "immunosignaturing" as a simple, comprehensive, chip-based method to display the antibody diversity in an individual on peptide arrays. Here we examined whether this technology could be used to develop correlates for predicting vaccine effectiveness. By using a mouse influenza infection, we show that the immunosignaturing of a natural infection can be used to discriminate a protective from nonprotective vaccine. Further, we demonstrate that an immunosignature can determine which mice receiving the same vaccine will survive. Finally, we show that the peptides comprising the correlate signatures of protection can be used to identify possible epitopes in the influenza virus proteome that are correlates of protection.

Potential T cell epitopes within swine-origin triple reassortant influenza A (H3N2) variant virus which emerged in 2011: an immunoinformatics study

An immuno-informatics study was conducted to determine possible pre-existing T cellular immunity to the recently emerged swine-origin triple reassortant H3N2 variant (S-OtrH3N2v-2011) which acquired the matrix gene of influenza A (H1N1)pdm09. Given the genetic origin of S-OtrH3N2v-2011, our study focused on the hemagglutinin (HA) and matrix1 (M1) proteins to identify common and conserved T cell epitopes. We compared HA CD4+ T cell epitopes of S-OtrH3N2v-2011 with seasonal H3N2 (1968-2011)-HA proteins. M1 CD4+ and CD8+ T cell epitopes of S-OtrH3N2v-2011 were compared with the M1 proteins of seasonal H1N1 (1977-2009) and A (H1N1)pdm09 (2009-2011) subtypes. The results revealed a high conservancy of epitopes localized particularly on HA2 and the entire M1 protein. The overall cross reactivity of predicted CD4+ T cell epitopes with previously experimentally defined (Immuno Epitope Database) CD4+ T epitopes of HA and M1 proteins was ∼51%. CD8+ T cell cross-reactivity of ∼74% was documented for M1 protein. Analysis suggests possible pre-existing CD4+ T cell immunity to S-OtrH3N2v-2011 in the human population.

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.