A myocarditic coxsackievirus type B3 ŽCB3. was used ŽWoodruff and Kilbourne, 1970.. The virus was propagated in HeLa cells that were grown in Eagle’s minimal essential medium supplemented with 5% foetal calf serum and antibiotics. Virus titres were determined on HeLa cells as plaque-forming units Žp.f.u.. and a stock solu- tion was stored at