8 research outputs found
Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells
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.</p
High frequency and diversity of parechovirus A in a cohort of Malawian children
Parechoviruses (PeVs) are highly prevalent viruses worldwide. Over the last decades, several studies have been published
on PeV epidemiology in Europe, Asia and North America, while information on other continents is lacking. The aim of this
study was to describe PeV circulation in a cohort of children in Malawi, Africa. A total of 749 stool samples obtained from
Malawian children aged 6 to 60 months were tested for the presence of PeV by real-time PCR. We performed typing by
phylogenetic and Basic Local Alignment Search Tool (BLAST) analysis. PeV was found in 57% of stool samples. Age was
signifcantly associated with PeV positivity (p = 0.01). Typing by phylogenetic analysis resulted in 15 diferent types, while
BLAST typing resulted in 14 diferent types and several indeterminate strains. In total, six strains showed inconsistencies
in typing between the two methods. One strain, P02-4058, remained untypable by all methods, but appeared to belong to
the recently reclassifed PeV-A19 genotype. PeV-A1, -A2 and -A3 were the most prevalent types (26.8%, 13.8% and 9.8%,
respectively). Both the prevalence and genetic diversity found in our study were remarkably high. Our data provide an
important contribution to the scarce data available on PeV epidemiology in Africa