Detection limit of H5N1 viruses by RT-PCR.

<p>Viral RNA at a volume of 40 µl was extracted from 3 ml of the H5N1 viruses at a concentration of 0.647 mg/ml. Subsequently, cDNA was achieved using 5 ul extracted RNA and the resulting cDNA was ten-fold serially diluted and subjected to PCR. Lane 1: DNA marker; Lane 1, PCR product from undiluted cDNA; Lanes 2–4 were PCR products of 10-fold serially diluted cDNA. The size of amplified partial HA gene is indicated.