For regular PCR, 2 ml of first strand complementary DNA (cDNA) was amplified in a 50-ml reactions in the presence of 1Â PCR buffer, 1.5 mM MgCl 2 , 2.5 mM of dNTPs, 5 U of Taq DNA Polymerase (New England Biolab). A first cycle of 5 min at 94 C was followed by 30 cycles of 30 s at 94 C, 30 s at a different annealing temperature (based on different primer pairs), and 1 min at 72 C. The final extension step was at 72 C for 15 min. For real-time PCR, first strain cDNA was diluted 1:20 and quantified using an ABI 7900HT Sequence Detection System (Applied Biosystems). The sequences of the primers used for regular and real-time PCR were indicated in Table 1 .