Modification of the poliovirus capsid by ultraviolet light

Abstract

Ultraviolet (UV) irradiation of type I poliovirus resulted in a modified (M) particle that had lost infectivity, lacked ability to adsorb to HeLa cells, lacked VP4, and was reduced in S value. Additional irradiation resulted in the loss of VP2, further reduction in S value, and permeability of the capsid to RNAse, This particle (C) as well as M contain the genome. Acid pH (5.5–6.5) and sulfhydryl-reducing substances (dithiothreitol, reduced glutathione, and L-cysteine) inhibited UV-induced modification of the capsid. UV irradiation at alkaline pH (7.5–8.5) resulted in more extensive modification of the capsid than irradiation at neutral pH. Ionic compounds were found to inhibit the modifying reaction.