Evaluation of Novel Molecular Assays for the Detection of Influenza Virus

I. Background

• Seasonal influenza virus causes an estimated 0.3-0.6 million deaths per year. Avian influenza virus H5N1, H7N9 and H5N6 has fatality rate of over 30%. Swine influenza viruses from pigs have also infected humans.
• Molecular assays are now used routinely in the detection of influenza viruses. The M gene is often used as the target for all influenza A viruses because the nucleotide sequence of this gene is relatively conserved among all the influenza A viruses. The World Health Organization and the US Centers for Disease Control and Prevention (CDC) have published protocols for molecular detection of influenza A virus M gene.
• However, recent studies have shown that mutations in the M gene have led to a reduced sensitivity of RT-PCR assay targeting this gene. Therefore, it is important to use alternative conserved genes as the target of RT-PCR. In this study, our aim is to evaluate two new RT-PCR assays that are based on PB2 and NS gene segment

II. Study objective -To evaluate the sensitivity and specificity of 2 new RT-PCR assays

III. Overall study design

• The investigators will randomly retrieve archived nasopharyngeal and saliva specimens that were previously tested for influenza A virus using commercially available assays in our laboratory, tested for influenza A virus at the Public Health Laboratory Service Branch in Hong Kong. These specimens will be tested for influenza A virus by 4 different RT-PCR assays as listed below: