Phylogenetic analysis of Echovirus 30 isolated during the 2005 outbreak in France reveals existence of multiple lineages and suggests frequent recombination events.

BACKGROUND

Echovirus 30 (E-30) was responsible in France for a major aseptic meningitis outbreak during 2005 summer season. However, the virological mechanisms responsible for the periodic emergence of the epidemic strains remain to be investigated.

OBJECTIVES

To assess the genetic diversity of two genome regions, VP1 and 3Dpol, of echovirus 30 strains isolated during the 2005 aseptic meningitis outbreak in Champagne Ardenne (CA) area (France).

STUDY DESIGN

Partial VP1 genomic region of 23 E-30 strains isolated in CA was sequenced and compared with 73 E-30 strains originating from different French areas to estimate the number and the diversity of E-30 lineages. Partial sequences for 3D polymerase (3Dpol) were analyzed to detect potential recombination events within the non-structural (NS) region of the genome of EV neurotropic strains.

RESULTS

Phylogenetic analysis of the VP1 evidenced the co-circulation of 6 distinct E-30 lineages responsible for the 2005 aseptic meningitis outbreak in France of which three had co-circulated in CA. Partial sequencing of the 3Dpol coding region showed that all of the E-30 strains exhibited different phylogenetic links between VP1 and 3Dpol genomic regions, suggesting multiple intra- or inter-serotypic recombination events within the NS part of the genome.

CONCLUSIONS

Our findings revealed existence of multiple lineages and suggested frequent recombination events among E-30 strains having co-circulated in a restricted area during a short time outbreak period. Moreover, our data demonstrated that study of single VP1 genome region analysis could not accurately describe the phylogenetic origin of E-30 isolates.