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Pathogens
. 2021 Mar 19;10(3):368.
doi: 10.3390/pathogens10030368.
Impact of Individual Viral Gene Segments from Influenza A/H5N8 Virus on the Protective Efficacy of Inactivated Subtype-Specific Influenza Vaccine
Yassmin Moatasim 1 , Ahmed Kandeil 1 , Ahmed Mostafa 1 , Omnia Kutkat 1 , Mohamed El Sayes 1 , Ahmed N El Taweel 1 , Maha AlKhazindar 2 , Elsayed T AbdElSalam 2 , Rabeh El-Shesheny 1 3 , Ghazi Kayali 4 5 , Mohamed A Ali 1
Affiliations
- PMID: 33808583
- DOI: 10.3390/pathogens10030368
Abstract
Since its emergence in 2014, the highly pathogenic avian influenza H5N8 virus has continuously and rapidly spread worldwide in the poultry sector resulting in huge economic losses. A typical inactivated H5N8 vaccine is prepared using the six internal genes from A/PR8/1934 (H1N1) and the two major antigenic proteins (HA and NA) from the circulating H5N8 strain with the HA modified to a low pathogenic form (PR8HA/NA-H5N8). The contribution of the other internal proteins from H5N8, either individually or in combination, to the overall protective efficacy of PR8-based H5N8 vaccine has not been investigated. Using reverse genetics, a set of PR8-based vaccines expressing the individual proteins from an H5N8 strain were rescued and compared to the parent PR8 and low pathogenic H5N8 strains and the commonly used PR8HA/NA-H5N8. Except for the PR8-based vaccine strains expressing the HA of H5N8, none of the rescued combinations could efficiently elicit virus-neutralizing antibodies. Compared to PR8, the non-HA viral proteins provided some protection to infected chickens six days post infection. We assume that this late protection was related to cell-based immunity rather than antibody-mediated immunity. This may explain the slight advantage of using full low pathogenic H5N8 instead of PR8HA/NA-H5N8 to improve protection by both the innate and the humoral arms of the immune system.
Keywords: H5N8; PR8-based influenza vaccine; humoral immunity; innate immunity; vaccine efficacy.