A Reverse transcription-PCR assay for detection of type A influenza virus and differentiation of avian H7 subtype

Avian influenza virus (AIV) infection is a major cause of influenza mortality in birds and can cause human mortality and morbidity. Although the risk of infection with avian influenza virus (AIV) is generally low for most people, the pathogen ivcirus can cross the species barrier and acquires the ability to infect and be transmitted among the human population; therefore the rapid identification of the virus is of important clinical and epidemiological implication. A reverse transcriptase-polymerase chain reaction (RT-PCR) was optimized for the detection of type A influenza virus. The assay differentiates avian H7 hemagglutinin subtypes. Two sets of specific oligonucleotide primers were used in this test for type A influenza virus and H7 heamagglutinin subtypes. The RT-PCR DNA products were visualized by gel electrophoresis and consisted of fragments of 98 bp for H7 hemagglutinin subtypes and 101 bp for type A influenza virus. The common set of primers for type A influenza virus were able to amplify a 101 bp DNA band for any of the other subtypes of influenza A virus. The RT-PCR assay developed in this study was found to be sensitive and specific. No specific amplification bands of the same sizes (98 bp) could be amplified for RNA of other influenza hemagglutinin subtypes, specific amplification bands of type A influenza (101 bp) for Influenza B, C, or other viral or bacterial pathogens was not tested in this study.