Hongyan Bai1, Jiashen Zhao2, Chunyan Ma2, Hejiang Wei1, Xiyan Li1, Qiongqiong Fang1, Peng Yang2, Quanyi Wang2, Dayan Wang1, Li Xin3. 1. Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Centers for Disease Control and Prevention, WHO Collaborating Center for Reference and Research on Influenza, Key Laboratory for Medical Virology, National Health Commission, Beijing, People's Republic of China. 2. Beijing Center for Disease Prevention and Control, Beijing, People's Republic of China. 3. Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Centers for Disease Control and Prevention, WHO Collaborating Center for Reference and Research on Influenza, Key Laboratory for Medical Virology, National Health Commission, Beijing, People's Republic of China. Electronic address: xinli@cnic.org.cn.
Abstract
BACKGROUND: The continuous evolution of influenza viruses is monitored by the World Health Organization Global Influenza Surveillance and Response System. Sample quality is essential for surveillance quality. METHODS: To evaluate the RNA degradation of clinical samples, influenza-like illness samples were collected from four sentinel hospitals, and seasonal influenza was tested by real-time reverse transcription polymerase chain reaction and quantified by digital reverse transcription polymerase chain reaction at different time points. RESULTS: RNA degradation was observed in the majority of samples eight days after sample collection. A significant and faster rate of RNA content reduction was observed in low viral load samples (<10 copies/µl) than in high viral load samples (>10 copies/μl), stored at 2 to 8°C for up to eight days. RNase P (RNP) RNA, which is a key indicator to evaluate sample collection quality, was detected. Sample collection quality was uneven in different hospitals. CONCLUSION: Low viral load samples increase the risk of false negatives due to RNA degradation to undetectable levels.
BACKGROUND: The continuous evolution of influenza viruses is monitored by the World Health Organization Global Influenza Surveillance and Response System. Sample quality is essential for surveillance quality. METHODS: To evaluate the RNA degradation of clinical samples, influenza-like illness samples were collected from four sentinel hospitals, and seasonal influenza was tested by real-time reverse transcription polymerase chain reaction and quantified by digital reverse transcription polymerase chain reaction at different time points. RESULTS: RNA degradation was observed in the majority of samples eight days after sample collection. A significant and faster rate of RNA content reduction was observed in low viral load samples (<10 copies/µl) than in high viral load samples (>10 copies/μl), stored at 2 to 8°C for up to eight days. RNase P (RNP) RNA, which is a key indicator to evaluate sample collection quality, was detected. Sample collection quality was uneven in different hospitals. CONCLUSION: Low viral load samples increase the risk of false negatives due to RNA degradation to undetectable levels.