Comparison of multiplex nested RT-PCR with virus isolation for detection of influenza viruses A and B

Background: Influenza A viruses bearing all known HA and NA subtypes have been isolated from avian hosts: but only the A/H1N1,A/H2N2 and A/H3N2 influenza subtypes have been associated with widespread epidemics in humans until now While influenza B detected only in humans. Subtype H5 infection in humans occurred for the first time during 1997-1998 in Hong Kong, then China in 2003, Vietnam and Thailand in 2004 and continued to 2005-2006 in Turkey and Egypt. In this study a Multiplex Nested RT-PCR was developed for simultaneous detection of influenza virus A and B in clinical samples. Methods: Throat swab and throat wash was collected between October 2005 and September 2006 from 689 patients with a suspected influenza virus infection. Samples were transported to the National Influenza Center (Tehran University of Medical Science, School of Public Health). Each sample is divided into two parts in order to virus isolation and nested RT-PCR. Results: The RT-PCR detected in 75 cases of influenza A and B, compared to 26 cases by virus isolation and 74 cases are positive by RT-PCR. In total, 50 out of 74 RT-PCR positive specimens were negative by virus isolation. The RTPCR provides a sensitive and specific method for detecting and typing influenza viruses A and B. Conclusion: The RT-PCR provides a sensitive and specific method for detecting and typing influenza viruses A and B. Multiplex RT-PCR can also be used to accurately detect more than one viral template in the same reaction mixture, allowing viral confections to be identified with the same respiratory specimen.