Trace identification was performed
using Sequence Scanner Ver. 1.0 (Applied Biosystems: http://www.
appliedbiosystems.com). Nucleotide and deduced amino acid
sequence alignments were completed using Mega4 software
(Tamura et al., 2007). The sequence of each isolate was judged
based on at least two independent RT-PCR products. In some cases,
a third product was required to confirm the consensus sequence.