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Isolation of a Reassortant H1N2 Swine Flu Strain of Type "Swine-Human-Avian" and Its Genetic Variability Analysis.

Thu, 07/19/2018 - 01:00
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Isolation of a Reassortant H1N2 Swine Flu Strain of Type "Swine-Human-Avian" and Its Genetic Variability Analysis.

Biomed Res Int. 2018;2018:1096079

Authors: Wang LB, Chen QY, Wu XM, Che YL, Wang CY, Chen RJ, Zhou LJ

Abstract
We isolated an influenza strain named A/Swine/Fujian/F1/2010 (H1N2) from a pig suspected to be infected with swine flu. The results of electron microscopy, hemagglutination (HA) assay, hemagglutination inhibition (HI) assay, and whole genome sequencing analysis suggest that it was a reassortant virus of swine (H1N1 subtype), human (H3N2 subtype), and avian influenza viruses. To further study the genetic evolution of A/Swine/Fujian/F1/2010 (H1N2), we cloned its whole genome fragments using RT-PCR and performed phylogenetic analysis on the eight genes. As a result, the nucleotide sequences of HA, NA, PB1, PA, PB2, NP, M, and NS gene are similar to those of A/Swine/Shanghai/1/2007(H1N2) with identity of 98.9%, 98.9%, 99.0%, 98.6%, 99.0%, 98.9%, 99.3%, and 99.3%, respectively. Similar to A/Swine/Shanghai/1/2007(H1N2), we inferred that the HA, NP, M, and NS gene fragments of A/Swine/Fujian/F1/2010 (H1N2) strain were derived from classical swine influenza H3N2 subtype, NA and PB1 were derived from human swine influenza H3N2 subtype, and PB2 and PA genes were derived from avian influenza virus. This further validates the role of swine as a "mixer" for influenza viruses.

PMID: 30003086 [PubMed - in process]

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Analysis of the affinity of influenza A virus protein epitopes for swine MHC I by a modified in vitro refolding method indicated cross-reactivity between swine and human MHC I specificities.

Thu, 07/19/2018 - 01:00
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Analysis of the affinity of influenza A virus protein epitopes for swine MHC I by a modified in vitro refolding method indicated cross-reactivity between swine and human MHC I specificities.

Immunogenetics. 2018 Jul 10;:

Authors: Fan S, Wang Y, Wang X, Huang L, Zhang Y, Liu X, Zhu W

Abstract
In vitro refolding assays can be used to investigate the affinity and stability of the binding of epitope peptides to major histocompatibility complex (MHC) class I molecules, which are key factors in the presentation of peptides to cytotoxic T lymphocytes (CTLs). The recognition of peptide epitopes by CTLs is crucial for protection against influenza A virus (IAV) infection. The peptide-binding motif of the swine SLA-3*hs0202 molecule has been previously reported and partly overlaps with the binding motif of the most abundant human MHC allele, HLA-A*0201. In this study, we screened all the protein sequences of the swine-origin epidemic IAV strain A/Beijing/01/2009 (H1N1), and a total of 73 9-mer epitope peptides were predicted to fit the consensus motif of the swine SLA-3*hs0202 or HLA-A*0201 molecule. Then, 14 peptides were selected, and their affinities to SLA-3*hs0202 were tested by a modified in vitro refolding assay. Our results show that ten epitopes could tolerate gel filtration, indicating that these epitopes formed stable or partly stable complexes with SLA-3*hs0202. Eight out of the ten epitopes have been previously reported as HLA-A2-restricted epitopes, which implied cross-reactivity between swine and human MHC I specificities. Furthermore, the modified mini-system refolding method could be applied for the screening of peptides because the refolding efficiency remained almost unchanged with the positive peptide (HA-KMN9) subjected to size-exclusion chromatography and Resource Q anion-exchange chromatography. The results presented here provide new insight into the development of epitope-based vaccines to control IAV and increase our understanding of swine molecular immunology.

PMID: 29992375 [PubMed - as supplied by publisher]

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A multifunctional human monoclonal neutralizing antibody that targets a unique conserved epitope on influenza HA.

Thu, 07/19/2018 - 01:00
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A multifunctional human monoclonal neutralizing antibody that targets a unique conserved epitope on influenza HA.

Nat Commun. 2018 Jul 10;9(1):2669

Authors: Bangaru S, Zhang H, Gilchuk IM, Voss TG, Irving RP, Gilchuk P, Matta P, Zhu X, Lang S, Nieusma T, Richt JA, Albrecht RA, Vanderven HA, Bombardi R, Kent SJ, Ward AB, Wilson IA, Crowe JE

Abstract
The high rate of antigenic drift in seasonal influenza viruses necessitates frequent changes in vaccine composition. Recent seasonal H3 vaccines do not protect against swine-origin H3N2 variant (H3N2v) strains that recently have caused severe human infections. Here, we report a human VH1-69 gene-encoded monoclonal antibody (mAb) designated H3v-47 that exhibits potent cross-reactive neutralization activity against human and swine H3N2 viruses that circulated since 1989. The crystal structure and electron microscopy reconstruction of H3v-47 Fab with the H3N2v hemagglutinin (HA) identify a unique epitope spanning the vestigial esterase and receptor-binding subdomains that is distinct from that of any known neutralizing antibody for influenza A H3 viruses. MAb H3v-47 functions largely by blocking viral egress from infected cells. Interestingly, H3v-47 also engages Fcγ receptor and mediates antibody dependent cellular cytotoxicity (ADCC). This newly identified conserved epitope can be used in design of novel immunogens for development of broadly protective H3 vaccines.

PMID: 29991715 [PubMed - in process]

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