Diversité génétique d’un génotype rare du virus de l’hépatite A

Purpose of the study

Very few is known on genotype II hepatitis A virus (HAV) since it is rarely isolated. From 2002 to 2007, the French observatory of HAV identified six sub-genotype IIA strains of which one from a patient having travelled to West Africa. To investigate the possible African origin of sub-genotype IIA, we determined its prevalence among French travellers in 2008 and characterised its genetic variability.

Patients and methods

The 2008 mandatory notification records were screened for travel to Africa. Viral genotype was determined on the nucleotide sequencing of the VP1/2A junction region. The P1 region coding for capsid proteins was used to compare the genetic diversity of IIA isolates to those of other genotypes.

Results

In 2008, five out of 54 patients returning from West Africa were infected by IIA strains and an additional “autochthonous” case was identified. Two more African cases were identified in 2009. A total of 14 IIA isolates (eight African and six “autochthonous”) were analysed. Nucleotide and amino-acid variability of IIA sequences was lower than that of the other genotypes. Phylogenetic analysis revealed the clustering of two “autochthonous” cases with African isolates whereas the other ones belonged to a different lineage.

Conclusion

Most IIA strains isolated in France are imported by travellers returning from West Africa. However, the unexplained contamination mode of some “autochthonous” cases suggests another geographical origin to discover or a French reservoir to explore.