[The Effect of Influenza Type B Inter-lineage Reassortment on the Growth Characteristics of Influenza].

This study aims to research the effect of inter-lineage reassortment of type B influenza virus on its biological characteristics. The representative strains isolated in 2013~2015were selected, which included wild type viruses and inter-lineage reassortment viruses. We tested the growth curve of each virus based on the value of TCID50 at different time point. And further detected the Km value of virus to analysis the activity of neuraminidase of each virus. The growth curve of viruses in 2013 and 2014reached peak 48 hours after infection, maintained at high level until 72 hours, then the virus titer declined gradually, however the virus isolated in 2015 reached peak 24 hours after infection. The reassortment strain B/Fujian Tongan/1565/2013 has the similar growth characteristics with the wild type virus on the same year. Meanwhile the growth curve of other inter-lineage viruses in 2014 and 2015is lower than that of wild type viruses. We determined neuraminidase kinetic constants of all viruses. The reassortment strain B/Fujian Tongan/1565/2013 has the strongest affinity of neuraminidase. The results of 2014~2015virus suggest that the stronger affinity of neuraminidase of virus the better growth characteristics of virus. But the virus in 2013 is lack of such relationship between the growth characteristics and activity of neuraminidase. The neuraminidase activity and growth characteristics of inter-lineage reassortments due to surface protein gene exchange is not consistent, suggesting internal virus protein might have affected the growth characteristics of the viruses2013-2015,and pending further study.