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J. Virol., Dec 1995, 7445-7452, Vol 69, No. 12
HH Lu, X Li, A Cuconati and E Wimmer
The poliovirus (PV) genome was manipulated by replacing its 2A-encoding
sequence with the corresponding sequence of coxsackie B4 virus (CBV4) or
human rhinovirus type 2 (HRV2). In vitro translation of the resulting
chimeric PV genomes revealed a normal cis-cleavage activity for both
heterologous 2A(pro) proteinases in the chimeric PV polyproteins. However,
only the genome containing the 2A-encoding sequence of CBV4 (PV/CBV4-2A)
yielded viable virus in transfected cells, producing a mixture of large and
small plaques on HeLa cell monolayers. The large-plaque variants were found
to contain single- amino-acid mutations at a specific site near the C
terminus of the CBV4 2A(pro) protein. When the same single-amino-acid
mutations were directly introduced into the parental PV/CBV4-2A genome,
chimeric viruses with a large-plaque phenotype and a wild-type PV-like
growth pattern were obtained upon transfection, an observation
demonstrating that these point mutations alone had a drastic effect on the
growth of the PV/CBV4 chimeric virus. On the other hand, the chimeric
genome containing the 2A-encoding sequence of HRV2 (PV/HRV2-2A) produced a
null phenotype in transfected HeLa cells, although low-level replication of
this chimeric genome was evident. We conclude that only 2A(pro) of the more
closely related enterovirus CBV4 is able to functionally substitute for
that of PV in vivo, and a subtle genetic modification of the CBV4 2A(pro)
protein results in a drastic improvement in the growth of the chimeric
PV/CBV4-2A virus. In addition, this chimeric cDNA approach enabled us to
dissect multiple biological functions encoded by the 2A(pro) proteins.
Copyright © 1995, American Society for Microbiology
Analysis of picornavirus 2A(pro) proteins: separation of proteinase from translation and replication functions
Department of Molecular Genetics and Microbiology, State University of New York, Stony Brook, New York 11794-5222, USA.
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