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. 2023 Jun 16;67(2):147-154.
doi: 10.2478/jvetres-2023-0034. eCollection 2023 Jun.

Protein sequence features of H1N1 swine influenza A viruses detected on commercial swine farms in Serbia

Jelena Maksimović Zorić  1 , Ljubiša Veljović  1 , Vladimir Radosavljević  1 , Dimitrije Glišić  1 , Jasna Kureljušić  2 , Jelena Maletić  3 , Božidar Savić  4
Affiliations

Protein sequence features of H1N1 swine influenza A viruses detected on commercial swine farms in Serbia

Jelena Maksimović Zorić et al. J Vet Res. .

Abstract

Introduction: Swine influenza A viruses (swIAVs) are characterised by high mutation rates and zoonotic and pandemic potential. In order to draw conclusions about virulence in swine and pathogenicity to humans, we examined the existence of molecular markers and accessory proteins, cross-reactivity with vaccine strains, and resistance to antiviral drugs in five strains of H1N1 swIAVs.

Material and methods: Amino acid (AA) sequences of five previously genetically characterised swIAVs were analysed in MEGA 7.0 software and the Influenza Research Database.

Results: Amino acid analysis revealed three virus strains with 590S/591R polymorphism and T271A substitution within basic polymerase 2 (PB2) AA chains, which cause enhanced virus replication in mammalian cells. The other two strains possessed D701N and R251K substitutions within PB2 and synthesised PB1-F2 protein, which are the factors of increased polymerase activity and virulence in swine. All strains synthesised PB1-N40, PA-N155, PA-N182, and PA-X proteins responsible for enhanced replication in mammalian cells and downregulation of the immune response of the host. Mutations detected within haemagglutinin antigenic sites imply the antigenic drift of the five analysed viruses in relation to the vaccine strains. All viruses show susceptibility to neuraminidase inhibitors and baloxavir marboxil, which is important in situations of incidental human infections.

Conclusion: The detection of virulence markers and accessory proteins in the analysed viruses suggests their higher propensity for replication in mammalian cells, increased virulence, and potential for transmission to humans, and implies compromised efficacy of influenza vaccines.

Keywords: accessory proteins; antigenicity; drug resistance; molecular markers; swine influenza A viruses.

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Conflict of interest statement

Conflict of Interests Statement: The authors declare that there is no conflict of interests regarding the publication of this article.

Figures

Fig. 1.
Fig. 1.
PB1-F2 amino acid sequences of Serbian swine influenza A virus strains in comparison to the sequence of A/California/04/2009reference strain. The red frames at positions 39, 46 and 51highlight methionine * – STOP codons
Fig. 2.
Fig. 2.
Partial amino acid sequences of basic polymerase protein 1 of Serbian swine influenza A virus strains. The red frame at position 40 indicates methionine
Fig. 3.
Fig. 3.
Partial amino acid sequences of the acidic polymerase protein of Serbian swine influenza A virus strains. The red frameat position 38 indicates isoleucine and those at positions 155 and 182 highlight methionine
Fig. 4.
Fig. 4.
Amino acid sequences of the PA-X protein of Serbian swine influenza A virus strains * – STOP codons
See this image and copyright information in PMC

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