Objective To understand the sensitivity of cytopathogenic effect (CPE) in MadinDarby canine kidney cells(MDCK) that cultured influenza A pharyngeal swab specimens of patients for one,two and three passages. Methods Influenza A pharyngeal swab specimens of patients were inoculated in MDCK for three blind passages. The presence of CPE of every passage was observed by inverted microscope. Results Of the 279 influenza A pharyngeal swab specimens of patients tested by colloidal gold, the presence of CPE in MDCK for one,two and three passages was 65.9%(184/279),91.4%(255/279) and 96.4%(269/279), respectively. Two hundred and seventy-one of 279specimens were identified as influenza A by multiplex reverse transcription-polymerase chain reaction (RT-PCR). Conclusion The positive separation rate can reach more than 95% by inoculating influenza A pharyngeal swab specimens of patients in MDCK for three blind passages.

Objective To establish a clinical test assay for detecting common respiratory viruses and enteroviruses (EV) by using mixed cultured Madin-Darby canine kidney cells (MDCK), human epidermoid cancer cells (Hep-2) and African green monkey kidney cells (Vero) to isolate common respiratory viruses and enteroviruses. Methods Throat swabs with influenza A and B viruses,adenovirus and EV71 were incubated with mixed cultured MDCK, Hep-2 and Vero in a single vial to observe the presence of cytopathic effects. Polymerase chain reaction (PCR), reverse transcription (RT)-PCR and monoclonal antibody-based immunofluorescene assay were also used for confirmatory test. Results The sensitive cell lines developed obvious cytopathic effects to the corresponding viruses, which were confirmed by the specific green particles observed by immunofluorescence assay and specific target PCR segments. Conclusions The shell-vial of mixed cells can simultaneously isolate different common respiratory viruses and EV. The isolated pathogens can be further confirmed by antigen test and PCR. This assay may improve the diagnosis of clinical viral diseases.