Nonhomologous recombination between defective poliovirus and coxsackievirus genomes suggests a new model of genetic plasticity for picornaviruses.
Bottom Line: We found some homologous (H) recombinants and, mostly, nonhomologous (NH) recombinants presenting duplications of parental sequences preferentially located in the regions encoding proteins 2A, 2B, and 3A.For further studies of the genetic exchanges between PV and CA17, we have developed a model of recombination, making it possible to rescue defective PV RNA genomes with a short deletion by cotransfecting cells with the defective PV genome and CA17 genomic RNA.Numerous recombinants were found, including homologous PV/CA17 recombinants, but mostly nonhomologous recombinants presenting duplications of parental sequences preferentially located in particular regions.
Affiliation: Institut Pasteur, Biologie des Virus Entériques, Paris, France INSERM U994, Institut National de La Santé et de La Recherche Médicale, Paris, France.Show MeSH
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Mentions: The passaging of the NH-2 recombinant S2CA17 cl 4.4 with an insertion of intermediate size (70 codons) led to a mixture of H and NH recombinants at passage 18 in both passage series (Table 1). The genomes of the viruses in the mixture were analyzed in both series. RT-PCR products overlapping recombination sites were inserted into bacterial plasmids for sequencing (190 bacterial clones analyzed). The original 70-codon insert (Fig. 4A) was found in 166 clones, whereas diverse H recombinants with different recombination sites were identified in 20 clones (Fig. 4B). A few clones displayed short insertions and/or deletions and frameshifts, suggesting the presence of nonfunctional genomes. We followed the evolution of the viral population further, by continuing the passaging process until passage 35 (Fig. 4C). We analyzed 43 bacterial clones containing RT-PCR products. The initial duplication (70-codon insert) was retained in 11 clones but lost in the other 32, leading to the generation of homologous recombination sites. Most of the homologous recombination sites were located at sites similar to those previously identified at passage 18, but several new sites were also identified.
Affiliation: Institut Pasteur, Biologie des Virus Entériques, Paris, France INSERM U994, Institut National de La Santé et de La Recherche Médicale, Paris, France.