tetano
Editor, Senior Moderator
Vet Microbiol
. 2026 Apr 24:318:111040.
doi: 10.1016/j.vetmic.2026.111040. Online ahead of print.
Construction and immunogenicity evaluation of avian Escherichia coli-derived bacterial biomimetic vesicles displaying H9 subtype avian influenza virus HA1 protein
Yue Li[SUP] 1 [/SUP], Yuji Quan[SUP] 1 [/SUP], Keji Quan[SUP] 1 [/SUP], Mengqi Lin[SUP] 1 [/SUP], Peng Chen[SUP] 1 [/SUP], Xiangkai Zhuge[SUP] 2 [/SUP], Tao Qin[SUP] 3 [/SUP], Sujuan Chen[SUP] 3 [/SUP], Yuncong Yin[SUP] 4 [/SUP], Daxin Peng[SUP] 5 [/SUP]
Affiliations
Co-infection with H9N2 subtype avian influenza virus (AIV) and avian pathogenic Escherichia coli (APEC) is common in poultry, yet no vaccine is currently available that simultaneously prevents both infections. Biomimetic bacterial vesicles (BBVs) derived from avian E. coli are a platform for delivering heterologous subunit antigens. In this study, an antigen display strategy was adopted, which involved the genetic fusion of the H9 hemagglutinin subunit HA1 to the outer membrane-anchored protein cytolysin A (ClyA), followed by high-pressure homogenization to prepare BBV-HA1. Intranasal immunization of specific-pathogen-free chickens with BBV-HA1 induced strong mucosal and systemic immunity. Compared with the PBS control, BBV-HA1 vaccination significantly increased the levels of serum IgY directed against outer-membrane proteins of APEC and the HA antigen of H9N2 AIV. It also enhanced the secretory IgA levels in nasal and tracheal lavages. Specifically, hemagglutination inhibition titers of 5.2 ± 0.84 log2 against H9N2 AIV were detected in the immunized sera of the BBV-HA1 group, along with improved in vitro bactericidal activity against APEC. Ex vivo re-stimulation of peripheral blood lymphocytes resulted in higher proliferation indices, and flow cytometry revealed an elevated CD4[SUP]+[/SUP] /CD8[SUP]+[/SUP] ratio in the BBV-HA1-immunized chickens. After the challenge, BBV-HA1 reduced the APEC O78 bacterial loads, alleviated air-sac and cardiac lesions, and accelerated body-weight recovery. Following the H9N2 challenge, oropharyngeal viral loading at day 7 was detected in 2/8 BBV-HA1-immunized chickens versus 6/8 PBS-inoculated chickens. These results demonstrate that ClyA-anchored HA1 displayed on BBVs induces coordinated mucosal and systemic responses and confers dual protection against H9N2 avian influenza virus and APEC O78.
Keywords: APEC; Bacterial biomimetic vesicle; Co-infections; H9N2 subtype avian influenza virus; Subunit vaccine.
. 2026 Apr 24:318:111040.
doi: 10.1016/j.vetmic.2026.111040. Online ahead of print.
Construction and immunogenicity evaluation of avian Escherichia coli-derived bacterial biomimetic vesicles displaying H9 subtype avian influenza virus HA1 protein
Yue Li[SUP] 1 [/SUP], Yuji Quan[SUP] 1 [/SUP], Keji Quan[SUP] 1 [/SUP], Mengqi Lin[SUP] 1 [/SUP], Peng Chen[SUP] 1 [/SUP], Xiangkai Zhuge[SUP] 2 [/SUP], Tao Qin[SUP] 3 [/SUP], Sujuan Chen[SUP] 3 [/SUP], Yuncong Yin[SUP] 4 [/SUP], Daxin Peng[SUP] 5 [/SUP]
Affiliations
- PMID: 42061219
- DOI: 10.1016/j.vetmic.2026.111040
Co-infection with H9N2 subtype avian influenza virus (AIV) and avian pathogenic Escherichia coli (APEC) is common in poultry, yet no vaccine is currently available that simultaneously prevents both infections. Biomimetic bacterial vesicles (BBVs) derived from avian E. coli are a platform for delivering heterologous subunit antigens. In this study, an antigen display strategy was adopted, which involved the genetic fusion of the H9 hemagglutinin subunit HA1 to the outer membrane-anchored protein cytolysin A (ClyA), followed by high-pressure homogenization to prepare BBV-HA1. Intranasal immunization of specific-pathogen-free chickens with BBV-HA1 induced strong mucosal and systemic immunity. Compared with the PBS control, BBV-HA1 vaccination significantly increased the levels of serum IgY directed against outer-membrane proteins of APEC and the HA antigen of H9N2 AIV. It also enhanced the secretory IgA levels in nasal and tracheal lavages. Specifically, hemagglutination inhibition titers of 5.2 ± 0.84 log2 against H9N2 AIV were detected in the immunized sera of the BBV-HA1 group, along with improved in vitro bactericidal activity against APEC. Ex vivo re-stimulation of peripheral blood lymphocytes resulted in higher proliferation indices, and flow cytometry revealed an elevated CD4[SUP]+[/SUP] /CD8[SUP]+[/SUP] ratio in the BBV-HA1-immunized chickens. After the challenge, BBV-HA1 reduced the APEC O78 bacterial loads, alleviated air-sac and cardiac lesions, and accelerated body-weight recovery. Following the H9N2 challenge, oropharyngeal viral loading at day 7 was detected in 2/8 BBV-HA1-immunized chickens versus 6/8 PBS-inoculated chickens. These results demonstrate that ClyA-anchored HA1 displayed on BBVs induces coordinated mucosal and systemic responses and confers dual protection against H9N2 avian influenza virus and APEC O78.
Keywords: APEC; Bacterial biomimetic vesicle; Co-infections; H9N2 subtype avian influenza virus; Subunit vaccine.