RESUMO
The major group human rhinovirus type 8 can enter cells via heparan sulphate. When internalized into ICAM-1 negative rhabdomyosarcoma (RD) cells, HRV8 accumulated in the cells but caused CPE only after 3 days when used at high MOI. Adaptation by three blind passages alternating between RD and HeLa cells resulted in variant HRV8v with decreased stability at acidic pH allowing for productive infection in the absence of ICAM-1. HRV8v produced CPE at 10 times lower MOI within 1 day. Confocal fluorescence microscopy colocalization and the use of pharmacological and dominant negative inhibitors revealed that viral uptake is clathrin, caveolin, and flotillin independent. However, it is blocked by dynasore, amiloride, and EIPA. Furthermore, HRV8v induced FITC-dextran uptake and colocalized with this fluid phase marker. Except for the complete inhibition by dynasore, the entry pathway of HRV8v via HS is similar to that of HRV14 in RD cells that overexpress ICAM-1.
Assuntos
Dinamina II/metabolismo , Interações Hospedeiro-Patógeno , Molécula 1 de Adesão Intercelular/metabolismo , Rhinovirus/fisiologia , Internalização do Vírus , Caveolinas/genética , Caveolinas/metabolismo , Linhagem Celular , Clatrina/genética , Clatrina/metabolismo , Efeito Citopatogênico Viral , Dinamina II/genética , Humanos , Molécula 1 de Adesão Intercelular/genética , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Rhinovirus/genética , Inoculações SeriadasRESUMO
Intercellular adhesion molecule 1 (ICAM-1) mediates binding and entry of major group human rhinoviruses (HRVs). Whereas the entry pathway of minor group HRVs has been studied in detail and is comparatively well understood, the pathway taken by major group HRVs is largely unknown. Use of immunofluorescence microscopy, colocalization with specific endocytic markers, dominant negative mutants, and pharmacological inhibitors allowed us to demonstrate that the major group virus HRV14 enters rhabdomyosarcoma cells transfected to express human ICAM-1 in a clathrin-, caveolin-, and flotillin-independent manner. Electron microscopy revealed that many virions accumulated in long tubular structures, easily distinguishable from clathrin-coated pits and caveolae. Virus entry was strongly sensitive to the Na(+)/H(+) ion exchange inhibitor amiloride and moderately sensitive to cytochalasin D. Thus, cellular uptake of HRV14 occurs via a pathway exhibiting some, but not all, characteristics of macropinocytosis and is similar to that recently described for adenovirus 3 entry via alpha(v) integrin/CD46 in HeLa cells.
