Virus Isolation and Propagation from H3N2 Influenza Infected Human Clinical Samples Under Distinct Sample Storage Conditions

Abstract

Listen

Translate article

Isolation and propagation of influenza virus from Influenza Like Illness (ILI) clinical sample is essential for the surveillance of circulating virus, such as antigenic and genetic analyses, antiviral sensitivity surveillance, as well as annual influenza vaccine selection. Madin-Darby canine kidney (MDCK) cell is conventionally used for virus isolation in public health laboratories. Throat swap samples of Influenza like Illness (ILI) were collected from two sentinel hospitals and screened seasonal influenza by real-time reverse transcription polymerase chain reaction (RT–PCR). H3N2 positive samples were performed virus isolation in MDCK cells. Samples were stored under different conditions before inoculation, 1-2 days at 2-8°C, 4-5 day or 8-9 days at 2-8°C, and no less than two months at -80°C. The results showed that long term (>2 month) -80°C storage of clinical samples (15.12%) had significantly lower virus isolation rate compare to short term (1-2 days and 4-9 days) under 2-8°C storage (88.37% for 1-2 days and 52.33% for 4-9 days). For those samples stored at 4°C, the shorter of the storage time, the better of sample quality and virus activity could be obtained, resulting in higher isolation rate. This study provides evidence for influenza surveillance and sample quality control.