Viral RNA was extracted from cloacal and tracheal
swabs using a MagNA Pure LC Total Nucleic Acid Extraction
Kit with a MagNA Pure LC instrument. All samples were
first tested for influenza A presence/absence by a qRT-PCR
targeting the M gene with a OneStep Real-Time PCR Kit on
a Stratagene MX3005P RT-PCR machine using primers and
probes from Spackman et al. (2003). Influenza positive
samples were then screened for H5N1 via a second RT-PCR
test utilizing the RocheAIV H5N1 RealTime RT-PCR Kit on a
Roche LightCycler 2.0 machine. Serological responses to
H5-specific antibodies were detected via hemagglutination inhibition (HI) assays using four hemagglutinin units
following World Organisation for Animal Health protocols
(OIE, 2012). We used a 1% suspension of chicken
erythrocytes in V-bottom, 96-wellmicrotiter plates (Hassan et al., 2012). Serum samples were considered positive
for H5N1 at a HI titer of 1:80 (Wang et al., 2012).