Acquisition of Susceptibility to Coxsackievirus A2 by the Rat L8 Cell Line During Myogenic Differentiation

Coxsackievirus A2 was propagated to high titres in the established rat L₈ myogenic cell line during the stage of differentiation characterized by fusion of myoblasts into multinucleated myotubes (192 h post-plating cultures). In contrast, pre-fusion mononucleated L₈ cultures infected 24 h after plating were refractory to Coxsackievirus A2 infection, as was a non-fusing clonal variant of the L₈ line (L₈CL3-U) regardless of the age of the latter cultures. The development of virus susceptibility in the older L₈ cultures correlated with a marked virus-specific c.p.e. as evidenced by vacuolated degenerating myotubes with disrupted cytoplasm, whereas no c.p.e. was seen following infection of the young L₈ or variant L₈CL3-U cultures. The restriction of Coxsackievirus A2 replication in young L₈ and L₈CL3-U cultures occurred after virus attachment.