Serological status, as determined by hemagglutination inhibition, of wood ducks (Aix sponsa) 21 days after experimental pre-exposure to low pathogenicity avian influenza (LPAI) virusesa, and 10 days after challenge with the highly pathogenic avian influenza (HPAI) virus A/whooper swan/Mongolia/244/05 (H5N1)b.

a

Birds were inoculated via choanal cleft with a dose of 106EID50 of different LPAI viruses. Serologic data of the naïve group were omitted due the 100% mortality observed in this group, and data of the A/mallard/Netherlands/2/05 (H5N2) group were omitted due to lack of seroconversion.

b

Birds were challenged via choanal cleft with a dose of 104EID50 of A/whooper swan/Mongolia/244/05 (H5N1), 21 days after experimental pre-exposure to different subtypes of LPAI viruses.

c

Samples with HI titer≥8 were considered positive.

d

HI using antigen against homosubtypic LPAI virus, either H1N1, H5N1, or H5N2.

e

HI using antigen against A/whooper swan/Mongolia/244/05 (H5N1).

f

Abbreviations: LPAIV-dpe = days after LPAI pre-exposure; HPAIV-dpc = days after H5N1 HPAI challenge; † = succumbed to HPAI H5N1 infection.