In JoVE (1)
Articles by Marta Sanz-Ramos in JoVE
Isolation of Fidelity Variants of RNA Viruses and Characterization of Virus Mutation Frequency Stéphanie Beaucourt1, Antonio V. Bordería1, Lark L. Coffey1, Nina F. Gnädig1, Marta Sanz-Ramos1, Yasnee Beeharry1, Marco Vignuzzi1 1Viral Populations and Pathogenesis lab and CNRS 3015, Institut Pasteur The present article describes the steps required to isolate and characterize RNA polymerase fidelity variants of RNA viruses and how to use mutation frequency data to confirm fidelity changes in tissue culture.
Other articles by Marta Sanz-Ramos on PubMed
Hidden Virulence Determinants in a Viral Quasispecies in Vivo Journal of Virology. Nov, 2008 | Pubmed ID: 18715925 The characterization of virulence determinants of pathogenic agents is of utmost relevance for the design of disease control strategies. So far, two classes of virulence determinants have been characterized for viral populations: those imprinted in the nucleotide sequence of some specific genomic regions and those that depend on the complexity of the viral population as such. Here we provide evidence of a virulence determinant that depends neither on a genomic sequence nor on detectable differences in population complexity. Foot-and-mouth disease virus is lethal for C57BL/6 mice showing the highest viral load in pancreas. Virus isolated from pancreas after one passage in mice showed an attenuated phenotype, with no lethality even at the highest dose tested. By contrast, virus from sera of the same mice displayed a virulence similar to that of the parental wild-type clone and virus isolated from spleen displayed an intermediate phenotype. However, viral populations from pancreas, spleen, and serum showed indistinguishable consensus genomic nucleotide sequences and mutant spectrum complexities, as quantified according to the mutation frequencies of both entire genomic nucleotide sequences of biological clones. The results show that the populations with differing virulences cannot be distinguished either by the consensus sequence or by the average complexity of the mutant spectrum. Differential harvesting of virus generated by cell transfection of RNA from serum and pancreas failed to reveal genetic differences between subpopulations endowed with differing virulences. In addition to providing evidence of hidden virulence determinants, this study underlines the capacity of a clone of an RNA virus to rapidly diversify phenotypically in vivo.
New Vaccine Design Based on Defective Genomes That Combines Features of Attenuated and Inactivated Vaccines PloS One. 2010 | Pubmed ID: 20454676 New vaccine designs are needed to control diseases associated with antigenically variable RNA viruses. Foot-and-mouth disease (FMD) is a highly contagious disease of livestock that inflicts severe economic losses. Although the current whole-virus chemically inactivated vaccine has proven effective, it has led to new outbreaks of FMD because of incomplete inactivation of the virus or the escape of infectious virus from vaccine production premises. We have previously shown that serial passages of FMD virus (FMDV) C-S8c1 at high multiplicity of infection in cell culture resulted in virus populations consisting of defective genomes that are infectious by complementation (termed C-S8p260).
A Replication Analysis of Foot-and-mouth Disease Virus in Swine Lymphoid Tissue Might Indicate a Putative Carrier Stage in Pigs Veterinary Research. Jan-Feb, 2011 | Pubmed ID: 21314905 ABSTRACT: Foot-and-mouth disease virus (FMVD), one of the most contagious viruses of cloven-hoofed animals, may cause a prolonged, asymptomatic but persistent infection in ruminants, named the "carrier state". However, it remains an open question whether this carrier state occurs in pigs. Here we present quantitative analyses of the duration of FMDV RNA and infectivity in lymphoid and epithelial tissues in experimentally infected pigs with FMDV C-S8c1. The data indicated that although FMDV RNA remained in blood until day 14 post-infection (pi), viremia was cleared by day 7 pi. However, all tissues tested were positive for FMDV until day 14-17 pi. Interestingly, the specific infectivity of FMDV in these tissues was in some cases even higher than the FMDV C-S8c1. We therefore propose that a "pseudopersistent state" may occur in pigs in which virus replicates in lymphoid tissues for a prolonged period of time, thereby representing a potential source of virus.