Epidemiological and virological findings during multiple outbreaks of equine influenza in South America in 2012

Abstract

BackgroundIn 2012, equine influenza (EI) virus was confirmed as the cause of outbreaks of respiratory disease in horses throughout South America. In Uruguay and Argentina, hundreds of vaccinated thoroughbred horses in training and racing facilities were clinically affected.ObjectiveTo characterise the EI viruses detected during the outbreak in Uruguay and Argentina.MethodsVirus was detected in nasopharyngeal swabs by a pan‐reactive influenza type A real‐time RT‐PCR. The nucleotide sequence of the HA1 gene was determined and analysed phylogenetically using mega 5 software. Amino acid sequences alignments were constructed and virus was antigenically characterised with specific ferret antisera. Paired serum samples were tested by haemagglutination inhibition and single radial haemolysis.ResultsThe diagnosis of EIV was confirmed by real‐time RT‐PCR, virus isolation and serological testing. The phylogenetic analysis of HA1 gene sequences of 18 EI viruses indicated that all of them belong to clade 1 of the Florida sublineage of the American lineage and are closely related to viruses isolated in the United States in 2012. The HA1 of viruses identified in horses in racing facilities in Maroñas, Uruguay, and in Palermo, Argentina, displayed 100% amino acid sequence identity and were identical to that of a virus isolated in Dubai in 2012, from vaccinated endurance horses recently imported from Uruguay.ConclusionsThe surveillance data reported illustrate the international spread of EI viruses and support the recommendations of the OIE expert surveillance panel to include viruses of the Florida sublineage in vaccines.

Molecular Epidemiology of the Two Internal Genes of Equine Influenza H3N8 Virus Isolated in Pakistan 2015-16

“…The mix farming system in Pakistan, keeping backyard poultry, canine, domesticated ducks, and equine species under one roof in indoor stables adds in the occurrence of interspecies transmission. Ultimately, genetic and antigenic re-assortments chance increases, as also reported previously (Guan et al, 1999;Perglione et al, 2016). Notably, antibodies against viruses from poultry origin (H1N1) in equines have also been reported in the same study region in past (Sajid et al, 2013).…”

Molecular Epidemiology and Spatio-Temporal Dynamics of the H3N8 Equine Influenza Virus in South America

“…These clades are made up of strains that circulated exclusively in South America between 1993 and 2006; yet, the clades would have different ancestors. Finally, the causative virus of the multiple large-scale outbreak of EI in 2012 in South America belongs to the Florida clade 1, and spread among several countries, yielding important economic losses [1,16,29]. In addition, the same virus was also detected in Dubai in 2012, in an outbreak in a quarantine facility after the entry of a group of endurance horses from Uruguay [1].…”

“…Nowadays, the Florida sub-lineage is predominant and has evolved into two antigenically different clades: Florida clade 1 and Florida clade 2 [9]. Florida clade 1 strains have been isolated in North America since 2003 [9] and have been associated with EI outbreaks in South Africa, Japan, Australia, Europe, Dubai and South America [1,12,13,14,15,16,17]. Florida clade 2 predominates in Europe, but has been also identified in some countries of Asia [18,19,20].…”

“…Regarding the EI situation in Uruguay, the extensive outbreak occurred in 2012 was the only one reported [16]. Nevertheless, previous evidence of the circulation of the virus is the HA gene nucleotide sequences of two strains available at the GenBank database, the H3N8, A/eq/Uruguay/1/1963 (GenBank accession number CY032421) and the H7N7, A/eq/Uruguay/1063/1976 (GenBank accession number CY036887).…”

“…All the EIVs identified between 1993 and 2005 were grouped within the South American sub-lineage of the American lineage [11,33]. The last extensive outbreak of EI registered in Argentina was in 2012 [16]. …”