Electrophoretic mobility confirms reassortment bias among geographic isolates of segmented RNA phages. - Inserm - Institut national de la santé et de la recherche médicale Access content directly
Journal Articles BMC Evolutionary Biology Year : 2013

Electrophoretic mobility confirms reassortment bias among geographic isolates of segmented RNA phages.


BACKGROUND: Sex presents evolutionary costs and benefits, leading to the expectation that the amount of genetic exchange should vary in conditions with contrasting cost-benefit equations. Like eukaryotes, viruses also engage in sex, but the rate of genetic exchange is often assumed to be a relatively invariant property of a particular virus. However, the rates of genetic exchange can vary within one type of virus according to geography, as highlighted by phylogeographic studies of cystoviruses. Here we merge environmental microbiology with experimental evolution to examine sex in a diverse set of cystoviruses, consisting of the bacteriophage [greek small letter phi]6 and its relatives. To quantify reassortment we manipulated -- by experimental evolution -- electrophoretic mobility of intact virus particles for use as a phenotypic marker to estimate genetic exchange. RESULTS: We generated descendants of [greek small letter phi]6 that exhibited fast and slow mobility during gel electrophoresis. We identified mutations associated with slow and fast phenotypes using whole genome sequencing and used crosses to establish the production of hybrids of intermediate mobility. We document natural variation in electrophoretic mobility among environmental isolates of cystoviruses and use crosses against a common fast mobility [greek small letter phi]6 strain to monitor the production of hybrids with intermediate mobility, thus estimating the amount of genetic exchange. Cystoviruses from different geographic locations have very different reassortment rates when measured against [greek small letter phi]6, with viruses isolated from California showing higher reassortment rates than those from the Northeastern US. CONCLUSIONS: The results confirm that cystoviruses from different geographic locations have remarkably different reassortment rates --despite similar genome structure and replication mechanisms-- and that these differences are in large part due to sexual reproduction. This suggests that particular viruses may indeed exhibit diverse sexual behavior, but wide geographic sampling, across varying environmental conditions may be necessary to characterize the full repertoire. Variation in reassortment rates can assist in the delineation of viral populations and is likely to provide insight into important viral evolutionary dynamics including the rate of coinfection, virulence and host range shifts. Electrophoretic mobility may be an indicator of important determinants of fitness and the techniques herein can be applied to the study of other viruses.
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inserm-00868807 , version 1 (02-10-2013)



Samuel Díaz-Muñoz, Olivier Tenaillon, Daniel Goldhill, Kristen Brao, Paul Turner, et al.. Electrophoretic mobility confirms reassortment bias among geographic isolates of segmented RNA phages.. BMC Evolutionary Biology, 2013, 13 (1), pp.206. ⟨10.1186/1471-2148-13-206⟩. ⟨inserm-00868807⟩
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