Abstract Title
Age-related variation in anti-neuraminidase antibodies to A(H5N1): cross-sectional, population-based evaluation among children and adults <5 to >80 years old
Abstract
Background: Globally since 1997, reported human cases of highly pathogenic avian influenza (HPAI) A(H5N1) have been relatively young, with median age <20 years. With enhanced surveillance, recent cases among animal workers have been mild. Relative to human-adapted A(H1N1) viruses since 1918, H5N1 viruses share >85% amino acid identity in the homosubtypic N1 head, notably in relation to 1918 and 2009 H1N1 pandemic strains (>90%), and exceeding identities within the heterosubtypic HA1 head (<60%) or HA2 stalk (80-85%) domains. To partially explain the epidemiological profile of H5N1 cases, we tested whether cross-reactive anti-N1 titres increase with age, notably among those with childhood H1N1 priming and repeat boost opportunities, including to H1N1pdm09.
Methods: We sourced 1000 anonymized residual sera for anti-N1 testing, including 100 by age group (equally by sex) spanning 0-4, 5-9 and by 10-year category through >80 years, collected August 18-28, 2024 by an outpatient laboratory network in the Greater Vancouver Area, British Columbia, Canada. The National Microbiology Laboratory validated an enzyme-linked lectin assay for anti-N1 testing to both clade 2.3.4.4b H5N1 and contemporary H1N1pdm09 viruses, generating reverse genetic H7 reassortment strains to address potential anti-HA inhibition of NA activity.
Results: Among participants with median age 39 years (IQR: 16-63), anti-N1 inhibitory concentrations (IC50) are currently being assessed, to be presented and compared by age and subtype.
Conclusions: Understanding age-related variation in anti-N1 is critical to A(H5N1) risk assessment, including likelihood of infection or severe outcome among human-zoonotic cases, and in the event of human-adaptation and pandemic spread.
Methods: We sourced 1000 anonymized residual sera for anti-N1 testing, including 100 by age group (equally by sex) spanning 0-4, 5-9 and by 10-year category through >80 years, collected August 18-28, 2024 by an outpatient laboratory network in the Greater Vancouver Area, British Columbia, Canada. The National Microbiology Laboratory validated an enzyme-linked lectin assay for anti-N1 testing to both clade 2.3.4.4b H5N1 and contemporary H1N1pdm09 viruses, generating reverse genetic H7 reassortment strains to address potential anti-HA inhibition of NA activity.
Results: Among participants with median age 39 years (IQR: 16-63), anti-N1 inhibitory concentrations (IC50) are currently being assessed, to be presented and compared by age and subtype.
Conclusions: Understanding age-related variation in anti-N1 is critical to A(H5N1) risk assessment, including likelihood of infection or severe outcome among human-zoonotic cases, and in the event of human-adaptation and pandemic spread.
Co-Author(s)
Samantha Kaweski, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC;
Charlene Ranadheera, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg MB;
Suzana Sabaiduc, Public Health Laboratory, BC Centre for Disease Control, Vancouver BC;
Lea Separovic, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC;
Romina C Reyes, LifeLabs, Burnaby BC, Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver BC;
Bonnie Henry, Ministry of Health, Office of the Provincial Health Officer, Victoria BC, School of Population and Public Health, University of British Columbia, Vancouver BC;
Darwyn Kobasa, Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg MB;
Nathalie Bastien, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg MB;
Danuta M Skowronski, Immunization Programs and Vaccine Preventable Diseases Service, BC Centre for Disease Control, Vancouver BC, School of Population and Public Health, University of British Columbia, Vancouver BC
Abstract Category
Avian influenza in mammals, pandemic preparedness, and one health