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Vet Sci
. 2026 Jan 28;13(2):127.
doi: 10.3390/vetsci13020127.
Antigenic Matching of rHVT-H5 via CRISPR/Cas9 Confers Complete Protection Against Novel H5N1 Clade 2.3.4.4b in Chicken
Sang-Won Kim 1 , Jong-Yeol Park 1 , Ji-Eun Son 1 , Cheng-Dong Yu 1 , Ki-Woong Kim 1 , Won-Bin Jeon 1 , Yu-Ri Choi 1 , Hyung-Kwan Jang 1 2 , Bai Wei 1 , Min Kang 1 2
Affiliations
The widespread panzootic of clade 2.3.4.4b highly pathogenic avian influenza (HPAI) H5N1 necessitates the development of vaccine platforms capable of rapid adaptation to emerging antigenic variants. Although commercial recombinant turkey herpesvirus (rHVT) vaccines are available, they often utilize heterologous inserts that may fail to optimally limit viral shedding of novel field strains. Here, we report the rapid construction of a homologous rHVT-H5 vaccine expressing the hemagglutinin (HA) gene of a representative clade 2.3.4.4b isolate via CRISPR/Cas9-mediated non-homologous end joining (NHEJ). In vitro characterization confirmed stable HA surface expression and growth kinetics comparable to the parental virus. In specific-pathogen-free (SPF) chickens, rHVT-H5 elicited robust hemagglutination inhibition (HI) antibody titers. Following lethal challenge with a homologous clade 2.3.4.4b H5N1 virus, the vaccine conferred 100% protection against mortality and clinical signs while significantly reduced oropharyngeal sheddings and completely inhibited viral shedding in cloacal samples. These findings demonstrate that an antigenically matched rHVT-H5 constitutes a promising strategy for mitigating the ongoing global threat posed by clade 2.3.4.4b HPAI H5N1.
Keywords: CRISPR/Cas9; clade 2.3.4.4b; herpesvirus of turkeys; highly pathogenic avian influenza virus; recombinant viral vector vaccine.
. 2026 Jan 28;13(2):127.
doi: 10.3390/vetsci13020127.
Antigenic Matching of rHVT-H5 via CRISPR/Cas9 Confers Complete Protection Against Novel H5N1 Clade 2.3.4.4b in Chicken
Sang-Won Kim 1 , Jong-Yeol Park 1 , Ji-Eun Son 1 , Cheng-Dong Yu 1 , Ki-Woong Kim 1 , Won-Bin Jeon 1 , Yu-Ri Choi 1 , Hyung-Kwan Jang 1 2 , Bai Wei 1 , Min Kang 1 2
Affiliations
- PMID: 41745921
- PMCID: PMC12944848
- DOI: 10.3390/vetsci13020127
The widespread panzootic of clade 2.3.4.4b highly pathogenic avian influenza (HPAI) H5N1 necessitates the development of vaccine platforms capable of rapid adaptation to emerging antigenic variants. Although commercial recombinant turkey herpesvirus (rHVT) vaccines are available, they often utilize heterologous inserts that may fail to optimally limit viral shedding of novel field strains. Here, we report the rapid construction of a homologous rHVT-H5 vaccine expressing the hemagglutinin (HA) gene of a representative clade 2.3.4.4b isolate via CRISPR/Cas9-mediated non-homologous end joining (NHEJ). In vitro characterization confirmed stable HA surface expression and growth kinetics comparable to the parental virus. In specific-pathogen-free (SPF) chickens, rHVT-H5 elicited robust hemagglutination inhibition (HI) antibody titers. Following lethal challenge with a homologous clade 2.3.4.4b H5N1 virus, the vaccine conferred 100% protection against mortality and clinical signs while significantly reduced oropharyngeal sheddings and completely inhibited viral shedding in cloacal samples. These findings demonstrate that an antigenically matched rHVT-H5 constitutes a promising strategy for mitigating the ongoing global threat posed by clade 2.3.4.4b HPAI H5N1.
Keywords: CRISPR/Cas9; clade 2.3.4.4b; herpesvirus of turkeys; highly pathogenic avian influenza virus; recombinant viral vector vaccine.