Effect of K31R and S450G Substitutions of Influenza A Nucleoprotein on Viral Replication

摘要

Influenza A viruses cause severe pandemics and epidemics annually and pose a great global health threat Among 8 RNA segments of viral genome the multiple functions of NP are to form homo-oligomers encapsidate the virus genomes to maintain the structure and play roles in viral replication and transcription Previously we have sequenced clinical isolates of H3N2 from National Cheng Kung Hospital and identified substitutions in NP from 1999 to 2015 To understand the effects of genetic variations on NP we used the mini-genome assay to examine the polymerase activity and identified mutations Among substitutions of Taiwan/N1215/07 which displayed highest polymerase activity we found that S450G of NP gene increased the polymerase activity but K31R decreased it In addition we generated infectious viruses by reverse genetics system and examined their growth properties Results of growth curve of viral titer quantitative detection of RNA level and translational protein amount displayed the similar findings as polymerase activity assay Thus we demonstrated two substitutions affected the viral replication transcription translation Furthermore results revealed that K31R may regulate protein degradation and impairing the balance of polymerase proteins Taken together NP protein alterations may due to counterbalancing stabilizing and destabilizing which may have the great impact on viral properties Substitutions K31R and S450G of NP contribute to functional change of influenza virus and may play the roles in epistasis in the viral evolution

獎項日期	2016 7月 26
原文	English
監督員	Jen-Ren Wang (Supervisor)