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Internalization of human rhinovirus 14 into HeLa and ICAM-1-transfected BHK cells
H P Grunert1, K U Wolf, K D Langner
1Institut für Klinische und Experimentelle Virologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Germany.
Abstract:
Virus adsorption and uptake of human rhinovirus 14 (HRV14) were studied with HeLa cells and baby hamster kidney (BHK) cells which were transfected with the HRV14 receptor intercellular adhesion molecule-1 (ICAM-1). Transmission electron microscopy of HeLa cells revealed that HRV14 was internalized via clathrin-coated pits and -coated vesicles. A minority of virus particles also used uncoated vesicles for entry. The internalization showed the characteristics of receptor-mediated endocytosis. Presence of the carboxylic ionophore monensin inhibited viral uncoating, indicating a pH-dependent entry mechanism. The expression of ICAM-1 on the surface of the ICAM-1 transfected baby hamster kidney cells (BHK-ICAM cells) allowed extensive virus adsorption and internalization through membrane channels. Virus particles were lined up in these channels like pearls on a string, but did not induce a productive infection. Although ICAM-1 was expressed to the same degree on BHK-ICAM and HeLa cells, HRV14 induced neither viral protein and RNA syntheses nor infectious virus progeny in BHK-ICAM cells. ICAM-1 on the transfected BHK cells was a functional active receptor as it rendered these cells permissive to coxsackievirus A21. These results suggest that HRV14 uptake into BHK-ICAM cells is blocked directly in or shortly after its final step of internalization, the uncoating. Our findings underline that the receptor ICAM-1 determines virus uptake into cells, however, is not sufficient to confer susceptibility of BHK cells to HRV14 infection.
Insights
Human rhinovirus 14 (HRV14) uses intercellular adhesion molecule-1 (ICAM-1) for cell entry, but this receptor alone is insufficient for HRV14 infection in baby hamster kidney cells, suggesting a post-entry block.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Human rhinovirus 14 (HRV14) is a common respiratory pathogen.
- Intercellular adhesion molecule-1 (ICAM-1) is a known receptor for HRV14.
- Understanding virus-host interactions is crucial for developing antiviral strategies.
Purpose of the Study:
- To investigate the mechanism of HRV14 adsorption and uptake mediated by ICAM-1.
- To determine the role of ICAM-1 in HRV14 entry and subsequent infection.
- To identify potential cellular blocks to HRV14 infection.
Main Methods:
- Transmission electron microscopy (TEM) to visualize virus entry in HeLa and BHK-ICAM cells.
- Use of monensin to assess the pH-dependence of viral uncoating.
- Functional assays to evaluate ICAM-1 as a receptor for HRV14 and coxsackievirus A21.
Main Results:
- HRV14 enters HeLa cells via clathrin-coated pits and vesicles, consistent with receptor-mediated endocytosis.
- Monensin treatment inhibits viral uncoating, indicating a pH-dependent entry mechanism.
- ICAM-1 expression on BHK cells facilitates HRV14 adsorption and internalization but does not lead to productive infection.
Conclusions:
- ICAM-1 mediates HRV14 uptake into cells, but is not sufficient to confer susceptibility to infection in BHK cells.
- HRV14 infection in BHK-ICAM cells is likely blocked at or shortly after the uncoating stage.
- The findings highlight the complexity of viral entry and the necessity of multiple cellular factors for productive infection.