To evaluate the approach, we cloned eight fragments from viruses PR8 and A/Chicken/Jiangsu/WS1/2012(H9N2) (WS1)respectively. All eight influenza genes from the cDNA of PR8 andWS1 were efficiently amplified by the fragment specific primers and had the expected molecular mass (Fig. 2). After the recombination of the PCR amplicon with the linear vector mediated by enzyme ExnaseTM II, the positive clones were screened by PCR and sequenced. During the screening of positive clones, we found that more than 90% of the selected clones were positive. This positive rate of clones was similar to that claimed by the Clon-ExpressTM II kit. Through this cloning strategy, we rapidly and efficiently got all positive clones for the eight influenza genes from the cDNA of PR8 and WS1 during a single ground of PCRand in vitro recombination