# Construction and Immune Strategy Optimization of a Vaccine Strain for Influenza A (H5N8) Subtype

## TL;DR

Researchers developed a vaccine strain for H5N8 avian influenza and found the best way to administer it for strong immune protection in mice.

## Contribution

A novel H5N8 vaccine strain was constructed and its optimal immunization strategy was experimentally determined.

## Key findings

- A 10 μg dose of inactivated rH5N8/PR8 with MF59 adjuvant induced the strongest immune response.
- Intramuscular administration twice at 7-day intervals provided effective protection against H5N8 challenge.
- The optimized strategy offers insights for developing vaccines against pandemic influenza strains.

## Abstract

Multiple subtypes of avian influenza virus (AIV), including H5N1, H5N6, and H5N8 viruses, are currently co-circulating in wild birds and poultry and causing sporadic human infections. Vaccine development is essential for pandemic preparedness. In this study, we constructed a candidate vaccine virus (CVV) using reverse genetics (RG) based on the sequence of the first human-infected H5N8 subtype AIV, A/Astrakhan/3212/2020 (H5N8). We evaluated the immunogenicity of the rH5N8/PR8 vaccine strain in combination with Alum, ISA51, and MF59 adjuvants, and we optimized immunization strategies including dosage, administration route, and immunization interval in BALB/c mice. Our results demonstrated that a 10 μg dose of inactivated rH5N8/PR8 with MF59 adjuvant, administered intramuscularly twice at 7-day intervals, induced the strongest immune response and effectively protected mice against challenge with wild-type H5N8 AIVs. Since pandemic influenza vaccines typically require tailored vaccination doses and routes specific to their characteristics, this study provides valuable insights for the development of similar vaccine strains with pandemic potential.