Recombinant Echovirus E5 Capsid Protein [His]

Human parechovirus 1 (HPeV-1) (family Picornaviridae) is a global cause of pediatric respiratory and CNS infections for which there is no treatment. Although biochemical and in vitro studies have suggested that HPeV-1 binds to alpha V beta 1, alpha V beta 3 and alpha V beta 6 integrin receptor(s), the actual cellular receptors required for infectious entry of HPeV-1 remain unknown. In this paper we analyzed the expression profiles of alpha V beta 1, alpha V beta 3, alpha V beta 6 and alpha 5 beta 1 in susceptible cell lines (A549, HeLa and SW480) to identify which integrin receptors support HPeV-1 internalization and/or replication cycle. We demonstrate by antibody blocking assay, immunofluorescence microscopy and RT-qPCR that HPeV-1 internalizes and replicates in cell lines that express alpha V beta 1 integrin but not alpha V beta 3 or alpha V beta 6 integrins. To further study the role of beta 1 integrin, we used a mouse cell line, GE11-KO, which is deficient in beta 1 expression, and its derivate GE11-beta 1 in which human integrin beta 1 subunit is overexpressed. HPeV-1 (Harris strain) and three clinical HPeV-1 isolates did not internalize into GE11-KO whereas GE11-beta 1 supported the internalization process. An integrin beta 1-activating antibody, TS2/16, enhanced HPeV-1 infectivity, but infection occurred in the absence of visible receptor clustering. HPeV-1 also co-localized with beta 1 integrin on the cell surface, and HPeV-1 and beta 1 integrin co-endocytosed into the cells. In conclusion, our results demonstrate that in some cell lines the cellular entry of HPeV-1 is primarily mediated by the active form of alpha V beta 1 integrin without visible receptor clustering.

Background: Echovirus 14 (E-14) causes various clinical recognized syndromes, mostly with gastrointestinal syndrome and paralysis. The current study summarized the Shandong E-14 strains isolated from a 26-year acute flaccid paralysis (AFP) surveillance, and elucidated the characterization of phylogenetic and phylogeographic relationships of E-14 worldwide. Results: As a predominant serotype circulating in AFP surveillance, phylogenetic analysis showed that E-14 exhibited both time and geographic subdivision worldwide. In order to know the evolutionary history and spatial temporal dynamics of E-14, evolutionary phylogeography was reconstructed using BEAST and SPREAD software based on the VP1 sequences. The time of the most recent common ancestor of E-14 was estimated around 85 years and evolved with 9.17 x 10(-3) substitutions/site/year. Phylogeographic analysis suggested that two regional transmissions of E-14 were mainly detected, with one located between Europe and Africa countries and the other was in the Asia-Pacific region. Conclusions: Our study investigates the molecular evolution and phylogeographic of E-14, and brings new insight to the dispersal of E-14 worldwide. Regional transmission was mainly detected and Australia may be responsible for the spread of E-14 in recent years.