Search

By analyzing the inhibitory effects of Mg2+on the three-stage urea in-activation curve of poliovirus, it was concluded that urea inactivates poliovirus via a two-step reaction as follows: urea initially converts the native virus into an intermediate state which is still infectious but is now highly sensitive to inactivation. This reaction is unaffected by Mg2+and is reversible. In the subsequent reaction, the sensitized virus is either irreversibly inactivated by urea or reversibly stabilized by Mg2+. In addition, the inactivation curve revealed that a fraction of relatively stable virus population was established in the presence of urea and that the size of this persistent virus population depended on the concentration of urea. It was not determined whether urea induced the formation of this stable fraction of virus or merely selected for a preexisting stable population of virus. However, evidence was presented that (1) the persistent virus population was not due to the depletion or inactivation of urea in the sample, (2) whatever stabilized the virus, it could not be removed or reversed by simple dilution as in the case of Mg2+, (3) no excess stabilizing material was made to stabilize the addition of untreated virus and finally (4) the persistent virus population was resistant to that concentration of urea in which it was observed but could be further inactivated by a higher concentration of urea, only to result in a smaller fraction of persistent virus population.

The kinetics of inactivation of poliovirions were determined in the presence of various concentrations of monovalent and divalent ions, methionine, guanidine and combinations of these at various temperatures. Four states of the virion, under control of the ionic environment, could be recognized which were reversibly interchangeable and yet retained infectious potential. These states were detected by differential sensitivity of the virion to inactivation of infectivity by heat, urea and guanidine. The data are interpreted in terms of conformational structural changes under control of the ionic environment. It is proposed that these various structural conformations are meaningful to the various biologic functional states of the virus.

Hepatitis B antigen of the D (a+, d+, y-) subtype was purified from plasma of apparently healthy persons and from hepatitis patients. The original samples contained 20- and 42-nm particles and tubular forms (20-nm diameter). Ultracentrifugation during the purification procedure yielded pellets which were then treated at pH 2.4. Both the large, 42-nm Dane particles and the tubular forms were lost during the acid treatment of the pelleted particles, yielding a preparation containing a mixture of particles approximately 20 and 25 nm in diameter. This difference in size was substantiated in that two distinct molecular weights were calculated from high-speed equilibrium data, 3.6 × 106and 4.5 × 106. Further heterogeneity was observed in that hepatitis B antigenic activity was present in purified particles with an isoelectric pH of 4.0 and also in those with a pH of 4.4. No significant differences were observed in the gross amino acid composition of purified antigen obtained from plasma of three different persons. 125I-labeled, purified antigen was found to contain six distinct polypeptides with molecular weights ranging from 10,000 to 39,000.