Figure 1

Phylogenetic tree obtained by comparing amino acid sequences for 30 strains derived from the hemagglutinin gene HA1 (1–329 aa). Accession numbers: A/equine/Miami/1963, AAA43164; A/equine/Uruguay/1/1963, AAA43114 ; A/equine/Tokyo/1971, AAA43111; A/equine/Algiers/1972 , ACF22126; A/equine/Fontainbleu/1/1979, ACD85396; A/equine/Romania/1/1980, ACD85374; A/equine/Kentucky/1/1987, ACA24568;A/equine/Suffolk/89, CAA48482; A/equine/Yvelines/2136/89 ,BAA33940 ; A/equine/Ibadan/6/91, CAA64893; A/equine/Rome/5/1991, ACD85341; A/equine/Italy/1199/1992 ,ACD85308; A/equine/Florida/1/93, AAB36978; A/equine/LaPlata/1/93,BAA33947; A/equi 2/Avesta/93, CAA74385 ; A/eq/Newmarket/2/93, CAA59416; A/equine/Dubai/48/1995, AEI26218; A/equine/Nador/1/1997, AFJ69903; A/equine/Grobois/1/1998, ACH95594; A/equine/Ohio/1/2003, ABA39846 ; A/equine/Essaouira/3/2004, AFJ69909; A/equine/Spain/1/2007, ADO78886; A/equine/Egypt/6066NAMRU3-VSVRI/2008 (A/equine/Egypt/2008), ACH95682; A/equine/Essaouira/2/2004 ,AFJ69905; A/equine/Athens/04/2007, ADF55752; A/equine/Berlin/13/02, ABP35588 ; equine/Brescia/1999 ,ABU46321 ; A/equine/Brno/1/1997 , AEI26221; A/equine/South Africa/4/2003, ADB45165; A/equine/Richmond/1/2007, ACH95569; A/equine/Tiaret/1/2011, AGR54591; A/equine/Tiaret/2/2011, AGR54592; A/equine/Tiaret/3/2011, AGR54593; A/equine/Tiaret/4/2011, AGR54594; A/equine/Tiaret/5/2011, AGR54595; A/equine/Tiaret/6/2011, AGR54596 ;A/equine/Tiaret/7/2011, AGR54597 ; A/equine/Tiaret/8/2011 ,AGR54598; A/equine/Tiaret/9/2011, AGR54599; A/equine/Tiaret/10/2011, AGR54600.