Refereed journal article or data article (A1)

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

List of Authors: Heikkila O, Merilahti P, Hakanen M, Karelehto E, Alanko J, Sukki M, Kiljunen S, Susi P


Place: London, UK

Publication year: 2016

Journal: Virology Journal

Journal name in source: VIROLOGY JOURNAL

Journal acronym: VIROL J

Volume number: 13

Number of pages: 10

ISSN: 1743-422X

eISSN: 1743-422X



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 aVβ6 integrin receptor through a highly conserved Arg-Gly-Asp (RGD)
motif, which is located at the exposed carboxy-terminus of the capsid protein
VP1 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-αV
integrin antibodies had no effect on the binding and entry of CV-A9. Whereas
siRNA silencing of β6 integrin subunit had no influence on virus infection in
SW480, silencing of β2-microglobulin (b2M) 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 aVβ6 integrin is essential for CV-A9
in A549 cell line, it is not required in SW480 cell line in which β2M 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.

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Last updated on 2021-24-06 at 12:02