Search results for "Aphthovirus"
showing 8 items of 8 documents
Comparison of vaccine strains and the virus causing the 1986 foot-and-mouth disease outbreak in Spain: epizootiological analysis
1990
RNAs of the most recent foot-and-mouth disease virus isolated in Spain (A5Sp86) during the 1986 outbreak, and of the three vaccine strains in use at that time in that country, have been compared. Although these viruses are serologically indistinguishable, differences have been found among them by T1 fingerprinting. This genetic heterogeneity affects the immunogenic VP1 gene, with amino acid changes located at the carboxyterminal end of the molecule. VP1-coding sequences obtained have been compared with those previously reported for European A5 FMDVs and it has been possible to trace their phylogenetic origin. The most parsimonious evolutionary tree obtained shows that the viruses analyzed a…
Split decomposition A technique to analyze viral evolution
1993
A clustering technique allowing a restricted amount of overlapping and based on an abstract theory of coherent decompositions of finite metrics is used to analyze the evolution of foot-and-mouth disease viruses. The emerging picture is compatible with the existence of viral populations with a quasispecies structure and illustrates various forms of evolution of this virus family. In addition, it allows the correlation of these forms with geographic occurrence.
Fixation of mutations at the VP1 gene of foot-and-mouth disease virus. Can quasispecies define a transient molecular clock?
1991
The number of nucleotide (nt) substitutions found in the VP1 gene (encoding viral capsid protein) between any two of 16 closely related isolates of foot-and-mouth disease virus (FMDV) has been quantified as a function of the time interval between isolations [Villaverde et al.,J. Mol. Biol. 204(1988)771-776]. One of them (isolate C-S12) includes some replacements found in isolates that preceded it and other replacements found in later isolates. The study has revealed alternating periods of rapid evolution and of relative genetic stability of VP1. During a defined period of acute disease, the rate of fixation of replacements at the VP1 coding segment was 6 × 10-3 substitutions per nt per year…
Does the VP1 gene of foot-and-mouth disease virus behave as a molecular clock?
1992
We have carried out a phylogenetic study of the evolution of the VP1 gene sequence from different serological types and subtypes of foot-and-mouth disease virus (FMDV). The maximum-likelihood method developed by Hasegawa and co-workers (Hasegawa et al. 1985) for the estimation of evolutionary parameters and branching dates has been used to decide between alternative models of evolution: constant versus variable rates. The results obtained indicate that a constant rate model, i.e., a molecular clock, seems to be the most plausible one. However, additional information suggests the possibility that the appearance of serotype CS has been accompanied by an episode of rapid evolution (Villaverde …
Gene encoding capsid protein VP1 of foot-and-mouth disease virus A quasispecies model of molecular evolution
1988
A phylogenetic tree relating the VP1 gene of 15 isolates of foot-and-mouth disease virus (FMDV) of serotypes A, C, and O has been constructed. The most parsimonious tree shows that FMDV subtypes and isolates within subtypes constitute sets of related, nonidentical genomes, in agreement with a quasispecies mode of evolution of this virus. The average number of nucleotide replacements per site for all possible pairs of VP1 coding segments is higher among representatives of serotype A than serotype C or O. In comparing amino acid sequences, the values of dispersion index (variance/mean value) are greater than 1, with the highest values scored when all sequences are considered. This indicates a…
Genetic lesions associated with Muller's ratchet in an RNA virus
1996
The molecular basis of Muller's ratchet has been investigated using the important animal pathogen foot-and-mouth disease virus (FMDV). Clones from two FMDV populations were subjected to serial plaque transfers (repeated bottleneck events) on host BHK-21 cells. Relative fitness losses were documented in 11 out of 19 clones tested. Small fitness gains were observed in three clones. One viral clone attained an extremely low plating efficiency, suggesting that accumulation of deleterious mutations had driven the virus near extinction. Nucleotide sequence analysis revealed unique genetic lesions in multiply transferred clones that had never been seen in FMDVs isolated in nature or subjected to m…
Genetic Variability and Antigenic Diversity of Foot-and-Mouth Disease Virus
1990
Foot-and-mouth disease (FMD) is an acute systemic disease of cloven-hooved animals, including cattle, swine, sheep, and goats. Despite mortality rates being generally below 5%, FMD severely decreases livestock productivity and trade. It is considered the economically most important disease of farm animals. Near two thousand million doses of vaccine are used annually to try to control FMD, which, nevertheless, is enzootic in most South American and African countries, parts of Asia, the Middle East, and the south of Europe. The causative agent, foot-and-mouth disease virus (FMDV), is an aphthovirus of the family Picornaviridae, a historically important virus as it was the first recognized vir…
Evidence for Positive Selection in the Capsid Protein-Coding Region of the Foot-and-Mouth Disease Virus (FMDV) Subjected to Experimental Passage Regi…
2001
We present sequence data from two genomic regions of foot-and-mouth disease virus (FMDV) subjected to several experimental passage regimens. Maximum-likelihood estimates of the nonsynonymous-to-synonymous rate ratio parameter (dN/dS) suggested the action of positive selection on some antigenic sites of the FMDV capsid during some experimental passages. These antigenic sites showed an accumulation of convergent amino acid replacements during massive serial cytolytic passages and also in persistent infections of FMDV in cell culture. This accumulation was most significant at the antigenic site A (the G-H loop of capsid VP1), which includes an Arg-Gly-Asp (RGD) cellular recognition motif. Our …