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標題: Evolution of infectious bronchitis virus in Taiwan: Positively selected sites in the nucleocapsid protein and their effects on RNA-binding activity
作者: Kuo, Shu-Ming
Kao, Hsiao-Wei
Hou, Ming-Hon
Wang, Ching-Ho
Lin, Siou-Hong
Su, Hong-Lin
關鍵字: Infectious bronchitis virus;RNA recombination;Coronavirus;Nucleocapsid;Positive selection
Project: Veterinary Microbiology, Volume 162, page(s) 408–418.
RNA recombination has been shown to underlie the sporadic emergence of new variants of
coronavirus, including the infectious bronchitis virus (IBV), a highly contagious avian
pathogen. We have demonstrated that RNA recombination can give rise to a new viral
population, supported by the finding that most isolated Taiwanese (TW) IBVs, similar to
Chinese (CH) IBVs, exhibit a genetic rearrangement with the American (US) IBV at the 50
end of the nucleocapsid (N) gene. Here, we further show that positive selection has
occurred at two sites within the putative crossover region of the N-terminal domain (NTD)
of the TW IBV N protein. Based on the crystal structure of the NTD, the stereographic
positions of both predicted selected sites do not fall close to the RNA-binding groove.
Surprisingly, converting either of the two residues to the amino acid present in most CH
IBVs resulted in significantly reduced affinity of the N protein for the synthetic RNA repeats
of the viral transcriptional regulatory sequence. These results suggest that modulating the
amino acid residue at either selected site may alter the conformation of the N protein and
affect the viral RNA–N interaction. This study illustrates that the N protein of the current
TW IBV variant has been shaped by both RNA recombination and positive selection and
that the latter may promote viral survival and fitness, potentially by increasing the RNAbinding
capacity of the N protein.
ISSN: 0378-1135
DOI: 10.1016/j.vetmic.2012.10.020
Appears in Collections:基因體暨生物資訊學研究所

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