Studies on the adaptation of influenza virus replicated at low temperature. V. Isoelectric focusing studies

Cold adapted variants of influenza viruses replicated at 30 degrees C and 37 degrees C were tested for isoelectric points (pl's) before and after passages in susceptible animals to check the stability of this marker. No differences were found in pI's for 3 strains--A/Pol/L/71, A/Phil/2/82 and A/Pol/79/85 which are really cold adapted viruses. On the other hand some differences in pI's for other strains were observed.