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A critical HA1 neutralizing domain of H5N1 influenza in an optimal conformation induces strong cross-protection.

Du L, Zhao G, Sun S, Zhang X, Zhou X, Guo Y, Li Y, Zhou Y, Jiang S - PLoS ONE (2013)

Bottom Line: Consequently, the design of an effective and safe anti-H5N1 vaccine is essential.We then constructed three additional recombinants fused with Fd plus His tag (HA-13-263-Fd-His), Fc only (HA-13-263-Fc), and His tag only (HA-13-263-His), respectively.These results suggest that the oligomeric form of the CND containing the RBD can be further developed as an effective and safe vaccine for cross-protection against divergent strains of H5N1 viruses.

View Article: PubMed Central - PubMed

Affiliation: Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America.

ABSTRACT
The highly pathogenic avian influenza (HPAI) H5N1 viruses, especially the laboratory-generated H5N1 mutants, have demonstrated the potential to cross the species barrier and infect mammals and humans. Consequently, the design of an effective and safe anti-H5N1 vaccine is essential. We previously demonstrated that the full-length hemagglutinin 1 (HA1) could induce significant neutralizing antibody response and protection. Here, we intended to identify the critical neutralizing domain (CND) in an optimal conformation that can elicit strong cross-neutralizing antibodies and protection against divergent H5N1 strains. We thus constructed six recombinant proteins covering different regions of HA1 of A/Anhui/1/2005(H5N1), each of which was fused with foldon (Fd) and Fc of human IgG. We found that the critical fragment fused with Fd/Fc (HA-13-263-Fdc, H5 numbering) that could elicit the strongest neutralizing antibody response is located in the N-terminal region of HA1 (residues 13-263), which covers the receptor-binding domain (RBD, residues 112-263). We then constructed three additional recombinants fused with Fd plus His tag (HA-13-263-Fd-His), Fc only (HA-13-263-Fc), and His tag only (HA-13-263-His), respectively. We found that the HA-13-263-Fdc, which formed an oligomeric conformation, induced the strongest neutralizing antibody response and cross-protection against challenges of two tested H5N1 virus strains covering clade 1: A/VietNam/1194/2004 (VN/1194) or clade 2.3.4: A/Shenzhen/406H/06 (SZ/406H), while HA-13-263-Fc dimer and HA-13-263-Fd-His trimer elicited higher neutralizing antibody response and protection than HA-13-263-His monomer. These results suggest that the oligomeric form of the CND containing the RBD can be further developed as an effective and safe vaccine for cross-protection against divergent strains of H5N1 viruses.

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Detection of antibody responses and evaluation of neutralizing activity for sera of mice vaccinated with truncated HA1.Sera from 10 days post-last vaccination were used for the detection. (A) Detection of sera IgG antibody responses by ELISA respectively coated with truncated HA1 protein fragments with the serum dilution at 1∶12800. The data are presented as mean A450± standard deviation (SD) of five mice per group. (B) ELISA detection of IgG binding ability to the truncated HA1 protein fragments. The data are presented as mean A450± SD of five mice per group at various dilution points. (C) Neutralizing antibody titers against HA of homologous strain A/Anhui/1/2005(H5N1) (AH-HA, clade 2.3.4) of H5N1 pseudovirus. The data are presented as mean 50% neutralizing antibody titer (NT50) ± SD from five mice per group. * indicates significant difference (P<0.05) between HA-13–263-Fdc vaccination group and other groups.
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pone-0053568-g003: Detection of antibody responses and evaluation of neutralizing activity for sera of mice vaccinated with truncated HA1.Sera from 10 days post-last vaccination were used for the detection. (A) Detection of sera IgG antibody responses by ELISA respectively coated with truncated HA1 protein fragments with the serum dilution at 1∶12800. The data are presented as mean A450± standard deviation (SD) of five mice per group. (B) ELISA detection of IgG binding ability to the truncated HA1 protein fragments. The data are presented as mean A450± SD of five mice per group at various dilution points. (C) Neutralizing antibody titers against HA of homologous strain A/Anhui/1/2005(H5N1) (AH-HA, clade 2.3.4) of H5N1 pseudovirus. The data are presented as mean 50% neutralizing antibody titer (NT50) ± SD from five mice per group. * indicates significant difference (P<0.05) between HA-13–263-Fdc vaccination group and other groups.

Mentions: All six truncated protein fragments were used to immunize mice, as described in Materials and Methods, and sera were collected 10 days post-last vaccination to detect HA1-specific antibody responses and neutralizing activity against homologous H5N1 virus. As shown in Fig. 3A, all protein fragments induced high HA1-specific IgG antibodies in the vaccinated mice, with no significant differences being detected in the sera collected from any vaccinated group. An average endpoint antibody titer of 1 : 2.1 × 108 was detected in the sera of mice vaccinated with all six proteins (Fig. 3B), suggesting that these truncated HA1 protein fragments containing suitable conformation have high immunogenicity in eliciting potent antibody responses in the vaccinated mice.


A critical HA1 neutralizing domain of H5N1 influenza in an optimal conformation induces strong cross-protection.

Du L, Zhao G, Sun S, Zhang X, Zhou X, Guo Y, Li Y, Zhou Y, Jiang S - PLoS ONE (2013)

Detection of antibody responses and evaluation of neutralizing activity for sera of mice vaccinated with truncated HA1.Sera from 10 days post-last vaccination were used for the detection. (A) Detection of sera IgG antibody responses by ELISA respectively coated with truncated HA1 protein fragments with the serum dilution at 1∶12800. The data are presented as mean A450± standard deviation (SD) of five mice per group. (B) ELISA detection of IgG binding ability to the truncated HA1 protein fragments. The data are presented as mean A450± SD of five mice per group at various dilution points. (C) Neutralizing antibody titers against HA of homologous strain A/Anhui/1/2005(H5N1) (AH-HA, clade 2.3.4) of H5N1 pseudovirus. The data are presented as mean 50% neutralizing antibody titer (NT50) ± SD from five mice per group. * indicates significant difference (P<0.05) between HA-13–263-Fdc vaccination group and other groups.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539987&req=5

pone-0053568-g003: Detection of antibody responses and evaluation of neutralizing activity for sera of mice vaccinated with truncated HA1.Sera from 10 days post-last vaccination were used for the detection. (A) Detection of sera IgG antibody responses by ELISA respectively coated with truncated HA1 protein fragments with the serum dilution at 1∶12800. The data are presented as mean A450± standard deviation (SD) of five mice per group. (B) ELISA detection of IgG binding ability to the truncated HA1 protein fragments. The data are presented as mean A450± SD of five mice per group at various dilution points. (C) Neutralizing antibody titers against HA of homologous strain A/Anhui/1/2005(H5N1) (AH-HA, clade 2.3.4) of H5N1 pseudovirus. The data are presented as mean 50% neutralizing antibody titer (NT50) ± SD from five mice per group. * indicates significant difference (P<0.05) between HA-13–263-Fdc vaccination group and other groups.
Mentions: All six truncated protein fragments were used to immunize mice, as described in Materials and Methods, and sera were collected 10 days post-last vaccination to detect HA1-specific antibody responses and neutralizing activity against homologous H5N1 virus. As shown in Fig. 3A, all protein fragments induced high HA1-specific IgG antibodies in the vaccinated mice, with no significant differences being detected in the sera collected from any vaccinated group. An average endpoint antibody titer of 1 : 2.1 × 108 was detected in the sera of mice vaccinated with all six proteins (Fig. 3B), suggesting that these truncated HA1 protein fragments containing suitable conformation have high immunogenicity in eliciting potent antibody responses in the vaccinated mice.

Bottom Line: Consequently, the design of an effective and safe anti-H5N1 vaccine is essential.We then constructed three additional recombinants fused with Fd plus His tag (HA-13-263-Fd-His), Fc only (HA-13-263-Fc), and His tag only (HA-13-263-His), respectively.These results suggest that the oligomeric form of the CND containing the RBD can be further developed as an effective and safe vaccine for cross-protection against divergent strains of H5N1 viruses.

View Article: PubMed Central - PubMed

Affiliation: Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America.

ABSTRACT
The highly pathogenic avian influenza (HPAI) H5N1 viruses, especially the laboratory-generated H5N1 mutants, have demonstrated the potential to cross the species barrier and infect mammals and humans. Consequently, the design of an effective and safe anti-H5N1 vaccine is essential. We previously demonstrated that the full-length hemagglutinin 1 (HA1) could induce significant neutralizing antibody response and protection. Here, we intended to identify the critical neutralizing domain (CND) in an optimal conformation that can elicit strong cross-neutralizing antibodies and protection against divergent H5N1 strains. We thus constructed six recombinant proteins covering different regions of HA1 of A/Anhui/1/2005(H5N1), each of which was fused with foldon (Fd) and Fc of human IgG. We found that the critical fragment fused with Fd/Fc (HA-13-263-Fdc, H5 numbering) that could elicit the strongest neutralizing antibody response is located in the N-terminal region of HA1 (residues 13-263), which covers the receptor-binding domain (RBD, residues 112-263). We then constructed three additional recombinants fused with Fd plus His tag (HA-13-263-Fd-His), Fc only (HA-13-263-Fc), and His tag only (HA-13-263-His), respectively. We found that the HA-13-263-Fdc, which formed an oligomeric conformation, induced the strongest neutralizing antibody response and cross-protection against challenges of two tested H5N1 virus strains covering clade 1: A/VietNam/1194/2004 (VN/1194) or clade 2.3.4: A/Shenzhen/406H/06 (SZ/406H), while HA-13-263-Fc dimer and HA-13-263-Fd-His trimer elicited higher neutralizing antibody response and protection than HA-13-263-His monomer. These results suggest that the oligomeric form of the CND containing the RBD can be further developed as an effective and safe vaccine for cross-protection against divergent strains of H5N1 viruses.

Show MeSH
Related in: MedlinePlus