Molecular characterization of emerging Echovirus 11 (E11) shed light on the recombinant origin of a variant associated with severe hepatitis in neonates.

Echovirus 11 (E11) has gained attention owing to its association with severe neonatal infections. Due to the limited data available, the World Health Organization (WHO) considers public health risk to the general population to be low. The present study investigated the genetic variation and molecular evolution of E11 genomes collected from May to December 2023. Whole genome sequencing (WGS) was performed for 16 E11 strains. Phylogenetic analysis on WG showed how all Italian strains belonged to genogroup D5, similarly to other E11 strains recently reported in France and Germany all together aggregated into separate clusters. A cluster-specific recombination pattern was also identified using phylogenetic analysis of different genome regions. Echovirus 6 was identified as the major recombinant virus in 3Cpro and 3Dpol regions. The molecular clock analysis revealed that the recombination event probably occurred in June 2018 (95% HPD interval: Jan 2016-Jan 2020). Shannon entropy analyses, within P1 region, showed how 11 amino acids exhibited relatively high entropy. Five of them were exposed on the canyon region which is responsible for receptor binding with the neonatal Fc receptor. The present study showed the recombinant origin of a new lineage of E11 associated with severe neonatal infections.