Viral heat resistance and infectious ribonucleic acid.

High-titer suspensions of poliovirus 1 and coxsackievirus B-2 were shown to contain a heat-resistant fraction when heated for 65 min at temperature ranging from 56 to 70 degrees C. The addition of ribonuclease to the heated suspensions eliminated plaque production in the cell cultures, indicating that the resistant fraction was infectious ribonucleic acid that had been liberated from ruptured viruses during the heating process.