Prevalence of Porcine teschovirus genotypes in Hunan, China: identification of novel viral species and genotypes.

Porcine teschovirus (PTV) comprises at least 13 genotypes (PTV 1-13). Here, the genotypes of field strains prevalent among pig populations in Hunan Province, China, were identified. Multiple PTV genotypes, including all genotypes except PTV 7 and 8, were found co-circulating in the pig populations, reflecting a high genetic diversity. Moreover, we identified nine novel PTV genotypes, provisionally designated as PTV 14-22. PTV 21-HuN41 and PTV 21-HuN42 were successfully isolated, and their nearly complete genomes were sequenced. Homology comparison of the polyprotein genes of PTV 21-HuN41-42 to those of other known PTVs revealed low identities, ranging from 70.1 to 71.9 % (nucleotide identity) and 75.4 to 77.6 % (amino acid identity). Moreover, PTV 21-HuN41-42 were identified as a novel teschovirus species (tentatively Teschovirus B), based on the analyses of phylogenetics and evolutionary divergence. The findings of this study are expected to greatly enrich our knowledge of PTV genotypes.

Identification of Bacterial Surface Antigens by Screening Peptide Phage Libraries Using Whole Bacteria Cell-Purified Antisera.

Bacterial surface proteins can be good vaccine candidates. In the present study, we used polyclonal antibodies purified with intact Erysipelothrix rhusiopthiae to screen phage-displayed random dodecapeptide and loop-constrained heptapeptide libraries, which led to the identification of mimotopes. Homology search of the mimotope sequences against E. rhusiopthiae-encoded ORF sequences revealed 14 new antigens that may localize on the surface of E. rhusiopthiae. When these putative surface proteins were used to immunize mice, 9/11 antigens induced protective immunity. Thus, we have demonstrated that a combination of using the whole bacterial cells to purify antibodies and using the phage-displayed peptide libraries to determine the antigen specificities of the antibodies can lead to the discovery of novel bacterial surface antigens. This can be a general approach for identifying surface antigens for other bacterial species.