From January 2004 through June 2008, surveillance of dead wild birds in Hong Kong, People's Republic of Chi-na, periodically detected highly pathogenic avian in. uenza (HPAI) viruses (H5N1) in individual birds from different spe-cies. During this period, no viruses of subtype H5N1 were detected in poultry on farms and in markets in Hong Kong despite intensive surveillance. Thus, these fi ndings in wild birds demonstrate the potential for wild birds to disseminate HPAI viruses (H5N1) to areas otherwise free from the vi-ruses. Genetic and antigenic characterization of 47 HPAI (H5N1) viruses isolated from dead wild birds in Hong Kong showed that these isolates belonged to 2 antigenically dis-tinct virus groups: clades 2.3.4 and 2.3.2. Although research has shown that clade 2.3.4 viruses are established in poul-try in Asia, the emergence of clade 2.3.2 viruses in nonpas-serine birds from Hong Kong, Japan, and Russia raises the possibility that this virus lineage may have become estab-lished in wild birds
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