Cytolytic replication of coxsackievirus B2 in CAR-deficient rhabdomyosarcoma cells

The six coxsackievirus B serotypes (CVB1-6) use the coxsackie- and adenovirus receptor (CAR) for host cell entry. Four of these serotypes, CVB1, 3, 5 and 6, have also shown the capacity to replicate and cause cytolysis in rhabdomyosarcoma (RD) cells, a CAR-deficient cell line. This extended tropism has been associated with an acquired ability to bind decay accelerating factor (DAF). In this study, we have adapted the CVB2 prototype strain Ohio-1 (CVB2/O) to replicate in RD cells. Two types of infection were identified: (I) an enterovirus-typical, lytic infection, and (II) a non-lytic infection. Both CVB2/O-RD variants retained the prototype-ability to cause cytopathic effect in HeLa cells using CAR as receptor. Phenotypic and genotypic changes in the CVB2/O-RD-variants were determined and compared to the prototype cultured in HeLa cells. Inhibition studies using antibodies against CAR and DAF revealed a maintained ability of the CVB2/O-RD-variants to bind CAR, but no binding to DAF was observed. In addition, neither the prototype nor the CVB2/O-RD-variants were able to cause hemagglutination in human red blood cells, an enterovirus feature associated with affinity for DAF. Sequence analysis of the CVB2/O-RD-variants showed acquired mutations in the capsid region, suggesting extended receptor usage towards an alternative, yet unidentified, receptor for CVB2.