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J. Virol., Aug 1995, 4607-4618, Vol 69, No. 8
Z Tu, NM Chapman, G Hufnagel, S Tracy, JR Romero, WH Barry, L Zhao, K Currey and B Shapiro
We report the construction of chimeric coxsackievirus B3 (CVB3) strains in
which sequences of an infectious cDNA copy of a noncardiovirulent CVB3
genome were replaced by the homologous sequences from a cardiovirulent CVB3
genome to identify which of 10 predicted genetic sites determine
cardiovirulence. Cardiovirulent phenotype expression was consistently
linked to nucleotide 234 (U in cardiovirulent CVB3 and C in avirulent CVB3)
in the 5' nontranslated region. Reconstructions of the parental
noncardiovirulent CVB3 genome from chimeras restored the noncardiovirulent
phenotype when tested in mice. Inoculation of severe combined
immunodeficient (scid) mice with the noncardiovirulent CVB3 strain resulted
in massive cardiomyocyte necrosis in all animals. Sequence analysis of
viral genomes isolated from twelve scid mouse hearts showed that only
nucleotide position 234 was different (a C-->U transition) from that in
the input parental noncardiovirulent CVB3 genome. Higher-order RNA
structures predicted by two different algorithms did not demonstrate an
obvious local effect caused by the C-- >U change at nucleotide 234.
Initial studies of parental and chimeric CVB3 replication in primary
cultures of fetal murine heart fibroblasts and in adult murine cardiac
myocytes demonstrated that viral RNA transcriptional efficiency is
approximately 10-fold lower for noncardiovirulent CVB3 than for
cardiovirulent CVB3. CVB3 did not shut off protein synthesis in murine
cardiac fibroblasts, nor were levels of viral protein synthesis
significantly different as a function of viral phenotype. Taken together,
these data support a significant role for determination of the CVB3
cardiovirulence phenotype by nucleotide 234 in the 5' nontranslated region,
possibly via a transcriptional mechanism.
Copyright © 1995, American Society for Microbiology
The cardiovirulent phenotype of coxsackievirus B3 is determined at a single site in the genomic 5' nontranslated region
Department of Pathology and Microbiology, University of Nebraska Medical Center 68198-6495, USA.
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