Abstract
Panzootic goose/Guangdong (gs/Gd)-lineage H5 clade 2.3.4.4b highly pathogenic avian influenza viruses (HPAIVs) pose a significant threat to animal and public health due to their capacity to infect a wide range of avian and mammalian species, often causing severe disease with associated high mortality.
As part of pandemic preparedness frameworks, the antigenic drift of gs/Gd-lineage H5 HPAIVs are closely monitored to ensure that candidate vaccine viruses are protective against circulating strains. The influenza surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), are the primary targets of the host immunological response to infection. Hence, it is essential to understand specific substitutions in epitopes of HA and NA that lead to immune evasion and antigenic drift of H5 HPAIVs.
This study characterised the antigenic drift of the Southeast Asian 2.3.4.4b HPAIV isolate, A/duck/Pampanga(Philippines)/22-0524-1/2022 (H5N1) (dk/Pampanga), under immunological pressure. Immune escape variants were generated by incubating dk/Pampanga with increasing concentrations of chicken homologous antisera or naïve chicken serum before passaging in embryonated chicken eggs. Viral genetic diversity was monitored by next generation sequencing to identify substitutions in HA and NA antigenic epitopes. Hemagglutination inhibition and neuraminidase inhibition assays were used to characterise the impact of substitutions on H5 antigenicity and identify immunodominant antigenic epitopes in 2.3.4.4b isolates. This research informs on efficacy of vaccine candidates to circulating viruses, vaccine design and helps us forecast the antigenic drift of H5N1 clade 2.3.4.4b HPAIVs.
As part of pandemic preparedness frameworks, the antigenic drift of gs/Gd-lineage H5 HPAIVs are closely monitored to ensure that candidate vaccine viruses are protective against circulating strains. The influenza surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), are the primary targets of the host immunological response to infection. Hence, it is essential to understand specific substitutions in epitopes of HA and NA that lead to immune evasion and antigenic drift of H5 HPAIVs.
This study characterised the antigenic drift of the Southeast Asian 2.3.4.4b HPAIV isolate, A/duck/Pampanga(Philippines)/22-0524-1/2022 (H5N1) (dk/Pampanga), under immunological pressure. Immune escape variants were generated by incubating dk/Pampanga with increasing concentrations of chicken homologous antisera or naïve chicken serum before passaging in embryonated chicken eggs. Viral genetic diversity was monitored by next generation sequencing to identify substitutions in HA and NA antigenic epitopes. Hemagglutination inhibition and neuraminidase inhibition assays were used to characterise the impact of substitutions on H5 antigenicity and identify immunodominant antigenic epitopes in 2.3.4.4b isolates. This research informs on efficacy of vaccine candidates to circulating viruses, vaccine design and helps us forecast the antigenic drift of H5N1 clade 2.3.4.4b HPAIVs.
Co-Author(s)
Joanne Grimsey1 and Jasmina Luczo1
1Australian Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), Geelong, Victoria, Australia
Abstract Category
Transmission pathways, pathobiology, immune responses