RESUMO
Objective To summarize the experience of isolating influenza virus from MDCK cell , and to optimize the isolation method for influenza isolation and raise the ability of influenza surveillance. Methods Sixty-one cases of influenza viruses positive specimens identified with PCR method by the influenza network laboratory in Xianyang CDC were used to infect the MDCK cells. The influenza viruses-infected MDCK cells were collected and characterized by hemagglutination test and hemagglutination inhibition assay. Meanwhile , different concentrations of glutamine liquid were added to the medium to investigate the effect of glutamine on the growth of MDCK cells. Results Twenty five flu strains were isolated from 61 cases influenza viruses positive specimens , of which 18 were A (H3N2) subtype strains and 7 were A (H1N1) subtype strains. The titer of HA was higher than 1∶16, and the titer of HI was higher than 1 ∶ 640. The proliferation rate of MDCK cells was low, and the cell activity was also decreased at 48 h after incubation with glutamine concentration lower than 0.1%. Conclusions The influenza viruses were isolated from the MDCK cells. The glutamine concentration is strongly associated with the activity of MDCK cells and cell apoptosis.