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Multiple alignment comparison of the non-structural genes of three strains of equine influenza viruses (H3N8) isolated in Morocco.

ABSTRACT: Three equine influenza viruses, A/equine/Nador/1/1997(H3N8), A/equine/Essaouira/2/2004(H3N8), and A/equine/Essaouira/3/2004(H3N8), were isolated from different Equidae during local respiratory disease outbreaks in Morocco in 1997 and 2004. Their non-structural (NS) genes were amplified and sequenced.The results show high homology of NS nucleotide sequences of A/equine/Nador/1/1997 with European strains (i.e., A/equine/newmarket/2/93 and A/equine/Grobois/1/1998) and clustered into the European lineage. However, NS gene of A/equine/Essaouira/2/2004(H3N8) and A/equine/Essaouira/3/2004(H3N8) strains indicated high homology with equine influenza strains that had circulated before 1990 (A/equine/Fontainbleu/1/1979(H3N8), which belonged to a pre-divergent phase Amino acid sequence comparison of the NS1 protein with reference strain A/equine/Miami/1963(H3N8) shows that the A/equine/Nador/1/1997(H3N8) strain has 12 substitutions at the residues D/24/N, R/44/K, S/48/I, R/67/Q, A/86/V, E/139/K, A/112/T, E/186/K, L/185/F, A/223/E, S/213/T and S/228/P. In both A/equine/Essaouira/2/2004(H3N8) and A/equine/Essaouira/3/2004(H3N8) strains, the NS1 sequences present one common mutation at the residue: S/228/P.It seems that all of these substitutions are not produced at the key residues of the RNA-binding domain (RBD) and the effector domain (ED). Consequently, we can suppose that they will not affect the potency of inhibition of cellular defences, and the virulence of the Moroccan equine strains will be maintained.

SUBMITTER: Boukharta M

PROVIDER: S-EPMC4581100 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Multiple alignment comparison of the non-structural genes of three strains of equine influenza viruses (H3N8) isolated in Morocco.

Boukharta Mohamed M Azlmat Souad S Elharrak Mehdi M Ennaji My Mustapha MM

BMC research notes 20150924

<h4>Background</h4>Three equine influenza viruses, A/equine/Nador/1/1997(H3N8), A/equine/Essaouira/2/2004(H3N8), and A/equine/Essaouira/3/2004(H3N8), were isolated from different Equidae during local respiratory disease outbreaks in Morocco in 1997 and 2004. Their non-structural (NS) genes were amplified and sequenced.<h4>Results</h4>The results show high homology of NS nucleotide sequences of A/equine/Nador/1/1997 with European strains (i.e., A/equine/newmarket/2/93 and A/equine/Grobois/1/1998) ...[more]

PMID: 26404167

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Project description:Equine influenza viruses (EIV) are a major cause of acute respiratory disease in horses worldwide and occasionally also affect vaccinated animals. Like other influenza A viruses, they undergo antigenic drift, highlighting the importance of both surveillance and virus characterisation in order for vaccine strains to be kept up to date. The aim of the work reported here was to monitor the genetic and antigenic changes occurring in EIV circulating in the UK from 2013 to 2015 and to identify any evidence of vaccine breakdown in the field. Virus isolation, reverse transcription polymerase chain reaction (RT-PCR) and sequencing were performed on EIV-positive nasopharyngeal swab samples submitted to the Diagnostic Laboratory Services at the Animal Health Trust (AHT). Phylogenetic analyses were completed for the haemagglutinin-1 (HA1) and neuraminidase (NA) genes using PhyML and amino acid sequences compared against the current World Organisation for Animal Health (OIE)-recommended Florida clade 2 vaccine strain. Substitutions between the new isolates and the vaccine strain were mapped onto the three-dimensional structure protein structures using PyMol. Antigenic analyses were carried out by haemagglutination inhibition assay using a panel of post-infection ferret antisera. Sixty-nine outbreaks of equine influenza in the UK were reported by the AHT between January 2013 and December 2015. Forty-seven viruses were successfully isolated in eggs from 41 of the outbreaks. Only three cases of vaccine breakdown were identified and in each case the vaccine used contained a virus antigen not currently recommended for equine influenza vaccines. Nucleotide sequencing of the HA and NA genes revealed that all of the viruses belonged to the Florida clade 2 sub-lineage of H3N8 EIV. Phylogenetic and sequence analyses showed that the two sub-populations, previously identified within clade 2, continued to circulate and had accrued further amino acid substitutions. Antigenic characterisation using post-infection ferret antisera in haemagglutination inhibition assays however, failed to detect any marked antigenic differences between the isolates. These findings show that Florida clade 2 EIV continue to circulate in the UK and support the current OIE recommendation to include an example of Florida clade 2 in vaccines.

Dataset Information

Multiple alignment comparison of the non-structural genes of three strains of equine influenza viruses (H3N8) isolated in Morocco.

Publications

Multiple alignment comparison of the non-structural genes of three strains of equine influenza viruses (H3N8) isolated in Morocco.

Similar Datasets

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