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Literature detail

Evaluation of Cross-Immunogenicity of Ferret Antisera Following Immunization with H5N1 Vaccine Strains.

Seungyeon Kim1,2 Eun Young Jang1 Seo Young Moon1,2 Eun Bee Choi1,2 Hye Won Lee1 Min-Suk Song3 Beom Kyu Kim3 YooKyoung Lee1 In-Ohk Ouh1
Affiliations 3 institutions
  1. Division of Vaccine Development Coordination, Center for Vaccine Research, National Institute of Infectious Diseases, National Institute of Health, Korea Disease Control and Prevention Agency, Cheongju 28160, Republic of Korea.
  2. College of Veterinary Medicine, Institute for Veterinary Biomedical Science, Kyungpook National University, Daegu 41566, Republic of Korea.
  3. Department of Microbiology, Chungbuk National University Medical School, Cheongju 28160, Republic of Korea.
PMID 42042777 2026 Vaccines (Basel) eng epublish
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Article

Publication summary

Highly pathogenic avian influenza H5N1 viruses of clade 2.3.4.4b have spread globally since 2021, causing extensive outbreaks in avian populations and repeated spillovers into diverse mammalian hosts, including humans. These cross-species transmission events highlight ongoing pandemic risks and underscore the need for vaccine strategies that reflect viral evolution at the human-animal interface. Despite the availability of licensed H5 vaccines and newly recommended World Health Organization (WHO) candidate vaccine viruses (CVVs), the extent to which these vaccines elicit cross-reactive antibody responses against contemporary clade 2.3.4.4b viruses, including mammalian spillover isolates of avian origin, remains incompletely characterized. In this study, ferret antisera were generated using four WHO-recommended H5 CVVs, including a clade 1 strain (A/Vietnam/1194/2004) and three clade 2.3.4.4b strains (A/Astrakhan/3212/2020, A/American wigeon/South Carolina/22-000345-001/2021, and A/Ezo red fox/Hokkaido/1/2022), formulated with alum adjuvant to reflect licensed vaccine formulation used in national preparedness programs. Antibody responses and cross-reactive activity were evaluated using hemagglutination inhibition (HI) and microneutralization (MN) assays against homologous vaccine strains and a feline-origin clade 2.3.4.4b H5N1 field isolate from Korea, A/Feline/Korea/SNU-01/2023. Antisera induced by clade 2.3.4.4b CVVs showed cross-reactive antibody responses against homologous and heterologous clade 2.3.4.4b viruses and demonstrated measurable HI and MN responses against the feline-origin field isolate. In contrast, antisera raised against the clade 1 Vietnam CVV exhibited limited cross-reactivity against clade 2.3.4.4b viruses. Overall, clade 2.3.4.4b CVVs generally showed higher antibody responses than the clade 1 vaccine strain across multiple panels. These findings provide descriptive insights into antigenic differences between clade 1 and clade 2.3.4.4b viruses and support the antigenic relevance of clade 2.3.4.4b CVVs for contemporary H5N1 strains. This study highlights the importance of ongoing antigenic evaluation to inform vaccine strain selection within a One Health framework.

avian influenza candidate vaccine virus cross-neutralization One Health

Structured evidence records

Evidence records

3 total
Cross Species Transmission 1 records
Cross Species Transmission Extraction confidence 0.85
Key finding

H5N1 clade 2.3.4.4b viruses have spilled over from avian populations into diverse mammalian hosts, evidencing animal-to-animal cross-species transmission.

Virus
IAV H5N1
Host
Mammalia Aves
Location
Not specified
Supporting text

Highly pathogenic avian influenza H5N1 viruses of clade 2.3.4.4b have spread globally since 2021, causing extensive outbreaks in avian populations and repeated spillovers into diverse mammalian hosts, including humans.

Study design
field surveillance
Transmission direction
animal-to-animal
Serological Evidence 1 records
Serological Evidence Extraction confidence 0.95
Key finding

Ferret sera produced by immunization with clade 2.3.4.4b H5N1 vaccine strains contained cross-reactive antibodies detected by HI and MN assays against a feline-origin H5N1 field isolate.

Virus
IAV H5N1
Location
Not specified
Supporting text

Antibody responses and cross-reactive activity were evaluated using hemagglutination inhibition (HI) and microneutralization (MN) assays against homologous vaccine strains and a feline-origin clade 2.3.4.4b H5N1 field isolate from Korea. Antisera induced by clade 2.3.4.4b CVVs showed cross-reactive antibody responses and measurable HI and MN responses against the feline-origin field isolate.

Method
hemagglutination inhibition (HI); microneutralization (MN)
Sample type
antisera
Spillover Event 1 records
Spillover Event Extraction confidence 0.90
Key finding

Avian influenza H5N1 clade 2.3.4.4b viruses repeatedly spilled over from birds to humans and other mammals.

Virus
IAV H5N1
Location
Not specified
Supporting text

Highly pathogenic avian influenza H5N1 viruses of clade 2.3.4.4b have spread globally since 2021, causing extensive outbreaks in avian populations and repeated spillovers into diverse mammalian hosts, including humans.

Transmission direction
animal-to-human