Heat therapy of virus-infected cultures of the cultivated mushroom Agaricus bisporus

Abstract

A procedure for elimination of viruses by heat treatment of virus-infected isolates of the cultivated mushroom Agaricus bisporus has been perfected. A minimum treatment time of 3 weeks at 33�_C was required. The effect of heat treatment was assessed in terms of increased growth of the isolates in vitro and absence of virus particles. Growth rate was not always a good measure of effective heat treatment. Some virus-infected isolates were found which can act as symptomless carriers. The effect of heat treatment appeared to depend on the pre-treatment which the isolates had received. Elimination of viruses did not occur when the isolates were grown at 25�_ prior to heat treatment. It appears, therefore, that thermal inactivation of viruses is not complete in mature mycelium.