Analysis and Comparison of Detection and Quantification Methods for Influenza Virus

Influenza virus is a major pathogen of acute respiratory infectious diseases and poses a serious global public health threat. Rapid, accurate detection and quantification are essential for clinical diagnosis, epidemic control, and evaluation of therapeutic efficacy. This article compares four commonly used methods for influenza virus detection and quantification: hemagglutination assay (HA assay), 50% tissue culture infectious dose (TCID50) assay, plaque-forming unit (PFU) assay, and reverse transcription quantitative PCR (RT-qPCR), in terms of principle, quantitative capacity, sensitivity, detection time, and applicable scenarios. HA assay semi-quantifies the virus through hemagglutinin binding to red blood cells, it is simple and remains a classical method for WHO surveillance. TCID50 and PFU assays rely on cell culture and quantify infectious viral particles, they are core virological tools but require long turnaround times. RT-qPCR monitors amplification in real time and, with a standard curve, absolute quantification of viral RNA, offering the highest sensitivity and specificity as the gold standard for clinical molecular diagnosis. These methods represent three quantification levels: antigen-based (HA assay), infectivity-based (TCID50/PFU), and nucleic acid-based absolute quantification (RT-qPCR). They suit different scenarios, including virological research, vaccine development, and clinical diagnosis, providing a systematic reference for method selection.