Nucleic acid extraction
Viral RNA was extracted from 200 uL of each specimen using Roche High Pure Viral RNA (Roche Applied Sciences, Manheim, Germany) kit based on manufacturer’s instructions.. RNA were eluted in 50 μL of elution buffer and were stored at -20oC prior to RSV screening [9]. cDNA was synthesized using primed viral RNA, 5x first strand buffer, 10mM DTT, one unit of RNAseOUT and five units of M-MLV RT (Moloney Murine Leukemia Virus Reverse Transcriptase ) (Invitrogen, Carlsbad, CA, USA) for genotype identification.