JLE

Virologie

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Diversity and variability in enteroviruses Volume 3, issue 4, Juillet - Août 1999

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Enteroviruses are RNA viruses of the Picornaviridae family, and include several human and animal serotypes. Their variability is determined by epidemiological factors such as enteric tropism, prolonged replication in the infected host, excretion of high virus load and cocirculation of multiple serotypes. Their genomic plasticity depends on point mutations, insertions/deletions and recombination. The variability of the 5’ untranslated region, particularly the internal ribosome entry site (IRES), and that of capsid protein VP1 are given as two representative examples. IRES efficiency varies between viral groups (enterovirus/rhinovirus) and viruses of the same taxonomic group (poliovirus/echovirus). In polypeptide VP1, variation is greatest in the N and C termini and in external loops, in response to the host’s immune pressure. Interspecies transmissions and convergent or divergent evolution may be major factors in the complex phylogenetic relationships between human and animal enteroviruses. Monitoring their variability make it possible to identify virus types with increased virulence or specific disease attributes, to establish a collection of strains with clinical information, to develop a molecular typing system and, in the long term, to monitor drug resistance.