Comparison of Multiplex Nested RT-PCR with Vi­rus Isolation for Detection of Influenza Viruses A and B

Abstract

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 RT-PCR 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.