Antigenic and genetic variations in European and North American equine influenza virus strains (H3N8) isolated from 2006 to 2007.
Equine influenza virus (EIV) surveillance is important in the management of equine influenza. It provides data on circulating and newly emerging strains for vaccine strain selection. To this end, antigenic characterisation by haemaggluttination inhibition (HI) assay and phylogenetic analysis was carried out on 28 EIV strains isolated in North America and Europe during 2006 and 2007. In the UK, 20 viruses were isolated from 28 nasopharyngeal swabs that tested positive by enzyme-linked immunosorbent assay. All except two of the UK viruses were characterised as members of the Florida sublineage with similarity to A/eq/Newmarket/5/03 (clade 2). One isolate, A/eq/Cheshire/1/06, was characterised as an American lineage strain similar to viruses isolated up to 10 years earlier. A second isolate, A/eq/Lincolnshire/1/07 was characterised as a member of the Florida sublineage (clade 1) with similarity to A/eq/Wisconsin/03. Furthermore, A/eq/Lincolnshire/1/06 was a member of the Florida sublineage (clade 2) by haemagglutinin (HA) gene sequence, but appeared to be a member of the Eurasian lineage by the non-structural gene (NS) sequence suggesting that reassortment had occurred. A/eq/Switzerland/P112/07 was characterised as a member of the Eurasian lineage, the first time since 2005 that isolation of a virus from this lineage has been reported. Seven viruses from North America were classified as members of the Florida sublineage (clade 1), similar to A/eq/Wisconsin/03. In conclusion, a variety of antigenically distinct EIVs continue to circulate worldwide. Florida sublineage clade 1 viruses appear to predominate in North America, clade 2 viruses in Europe.
Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Kentford, Newmarket CB8 7UU, UK. neil.bryant@aht.org.uk
Neil A
NA
Bryant
Adam S
AS
Rash
Colin A
CA
Russell
Julie
J
Ross
Annie
A
Cooke
Samantha
S
Bowman
Shona
S
MacRae
Nicola S
NS
Lewis
Romain
R
Paillot
Reto
R
Zanoni
Hanspeter
H
Meier
Lowri A
LA
Griffiths
Janet M
JM
Daly
Ashish
A
Tiwari
Thomas M
TM
Chambers
J Richard
JR
Newton
Debra M
DM
Elton
D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D002645:Chickens / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000821:virology; D005060:Europe; D005814:Genes, Viral; D014644:Genetic Variation; D006734:Horse Diseases / Q000821:virology*; D006736:Horses; D053123:Influenza A Virus, H3N8 Subtype / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D008171:Lung Diseases / Q000662:veterinary / Q000821:virology; D009305:Nasopharynx / Q000821:virology; D009656:North America; D009976:Orthomyxoviridae Infections / Q000662:veterinary*; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D017361:Viral Nonstructural Proteins / Q000235:genetics
D000914:Antibodies, Viral; C085820:INS1 protein, influenza virus; D017361:Viral Nonstructural Proteins