FIG 1.
Experimental mallard model with IAV shedding and NA 222 amino acid residues. The values 2.5 ± 0.28, 7.2 ± 0.79, and 24 ±1.4 μg/liter are the means ± standard deviations of 11, 9, and 7 water samples, respectively. The dashed horizontal lines indicate changes in OC concentrations. G1 represents generation one consisting of two mallards, G2 represents the second pair of mallards introduced in the experimental room, etc. Closed rectangles represent the presence of mallards in the experimental room and dotted lines indicate days. Note that birds were introduced into and removed from the experiment room in the daytime such that each bird was part of the experiment during 5 ′ 24 h, with a 24-h gap between every second generation. Shading indicates detection of IAV by RRT-PCR of the matrix gene from daily fecal samples (CT values of ≥45 were determined to be negative). I, isoleucine at NA residue 222; T*, threonine in shared proportions with isoleucine at NA residue 222; T, threonine at NA residue 222, as determined by Sanger sequencing of fecal samples; W, water from the 170-liter pool in the experimental room. Closed rectangles represent change of water and shading indicates detection of IAV by RRT-PCR of the matrix gene.