Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells

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Heikkilä , O , Merilahti , P , Hakanen , M , Karelehto , E , Alanko , J , Sukki , M , Kiljunen , S & Susi , P 2016 , ' Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells ' , Virology Journal , vol. 13 , 171 .

Title: Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells
Author: Heikkilä, Outi; Merilahti, Pirjo; Hakanen, Marika; Karelehto, Eveliina; Alanko, Jonna; Sukki, Maria; Kiljunen, Saija; Susi, Petri
Contributor organization: Medicum
Department of Bacteriology and Immunology
Date: 2016-10-18
Language: eng
Number of pages: 10
Belongs to series: Virology Journal
ISSN: 1743-422X
Abstract: Background: Coxsackievirus A9 (CV-A9) is a pathogenic enterovirus type within the family Picornaviridae. CV-A9 infects A549 human epithelial lung carcinoma cells by attaching to the alpha V beta 6 integrin receptor through a highly conserved Arg-Gly-Asp (RGD) motif, which is located at the exposed carboxy-terminus of the capsid protein VP1 detected in all studied clinical isolates. However, genetically-modified CV-A9 that lacks the RGD motif (CV-A9-RGDdel) has been shown to be infectious in some cell lines but not in A549, suggesting that RGD-mediated integrin binding is not always essential for efficient entry of CV-A9. Methods: Two cell lines, A549 and SW480, were used in the study. SW480 was the study object for the integrin-independent entry and A549 was used as the control for integrin-dependent entry. Receptor levels were quantitated by cell sorting and quantitative PCR. Antibody blocking assay and siRNA silencing of receptor-encoding genes were used to block virus infection. Peptide phage display library was used to identify peptide binders to CV-A9. Immunofluorescence and confocal microscopy were used to visualize the virus infection in the cells. Results: We investigated the receptor use and early stages of CV-A9 internalization to SW480 human epithelial colon adenocarcinoma cells. Contrary to A549 infection, we showed that both CV-A9 and CV-A9-RGDdel internalized into SW480 cells and that function-blocking anti-alpha V integrin antibodies had no effect on the binding and entry of CV-A9. Whereas siRNA silencing of beta 6 integrin subunit had no influence on virus infection in SW480, silencing of beta 2-microglobulin (beta 2M) inhibited the virus infection in both cell lines. By using a peptide phage display screening, the virus-binding peptide identical to the N-terminal sequence of HSPA5 protein was identified and shown to block the virus infection in both A549 and SW480 cell lines. HSPA5 was also found to co-localize with CV-A9 at the SW480 cell periphery during the early stages of infection by confocal microscopy. Conclusions: The data suggest that while alpha V beta 6 integrin is essential for CV-A9 in A549 cell line, it is not required in SW480 cell line in which beta 2M and HSPA5 alone are sufficient for CV-A9 infection. This suggests that the choice of CV-A9 receptor(s) is dependent on the tissue/cellular environment.
Subject: beta 2-microglobulin
Coxsackievirus A9
3111 Biomedicine
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion

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