Abstract
BackgroundThe equine influenza (EI) is an infectious and contagious disease of the upper respiratory tract of horses. Two outbreaks were notified in Morocco during 1997 and 2004 respectively in Nador and Essaouira. The aims of the present study concern the amino acids sequences comparison with reference strain A/equine/Miami/1963(H3N8) of the HA2 subunit including the cleavage site of three equine influenza viruses (H3N8) isolated in Morocco: A/equine/Nador/1/1997(H3N8), A/equine/Essaouira/2/2004 (H3N8) and A/equine/Essaouira/3/2004 (H3N8).ResultsThe obtained results demonstrated that the substitutions were located at Ectodomain (ED) and transmembrane domain (TD), and they have only one arginine in cleavage site (HA1-PEKQI-R329-GI-HA2). In the Ectodomain, the mutation N/154 2 /T deleted the NGT glycosylation site at position 154 for both strains A/equine/Essaouira/2/2004(H3N8) and A/equine/Essaouira/3/2004(H3N8). Except for mutation D/1602/Y of the A/equine/Nador/1/1997(H3N8) strain, the other mutations were involved in non conserved sites. While the transmembrane domain (TM) of the strain A/equine/Essaouira/3/2004(H3N8) exhibits a substitution at residue C/199 2 /F. For the A/equine/Nador/1/1997(H3N8) strain the HA2 shows a mutation at residue M/207 2 /L. Three Moroccan strains reveals a common substitution at the residue E/211 2 /Q located between transmembrane domain TM and the cytoplasmic domain (CD).ConclusionThe given nature virulence of three Moroccan strains, the identified and reported mutations certainly played a permissive role of infection viral process.
Highlights
The equine influenza (EI) is an infectious and contagious disease of the upper respiratory tract of horses
In Morocco horses play a significant socio-economic role, but their health status is threatened by the occurrence of many infectious and contagious diseases such as equine influenza (EI), equine viral arteritis, rhino-pneumonia and West Nile disease
The isolates from Essaouira outbreaks were passaged on Madin-Darby canine kidney (MDCK) cells at 34°C in an atmosphere of 5% CO2 in Eagle’s minimum essential medium supplemented with 5% FCS [34]
Summary
The equine influenza (EI) is an infectious and contagious disease of the upper respiratory tract of horses. Two outbreaks were notified in Morocco during 1997 and 2004 respectively in Nador and Essaouira. The aims of the present study concern the amino acids sequences comparison with reference strain A/equine/Miami/1963(H3N8) of the HA2 subunit including the cleavage site of three equine influenza viruses (H3N8) isolated in Morocco: A/equine/ Nador/1/1997(H3N8), A/equine/Essaouira/2/2004 (H3N8) and A/equine/Essaouira/3/2004 (H3N8). In Morocco horses play a significant socio-economic role, but their health status is threatened by the occurrence of many infectious and contagious diseases such as equine influenza (EI), equine viral arteritis, rhino-pneumonia and West Nile disease. The second subtype (H3N8) continues to circulate worldwide, and was responsible of all recent reported outbreaks [9,10]. The last lineage subsequently diverged into three sublineages: south America, Florida (Clades 1 and 2) and Kentucky [4]
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