Sulfur Mustard-Inactivated Influenza Virus as Interfering Agent

[摘要] One of the more favorable systems in studies of the interference phenomenon involves utilization of inactivated influenza viruses as interfering agent followed by a challenge dose of active homologous or heterologous virus. A common method for preparing interfering suspensions requires heating of virus (either as infected allantoic fluid or after dilution of virus in citrate-borate buffer of pH 8.5) at 56 C for one hour. The simplicity of this procedure is highly desirable, but not all strains of influenza viruses are of equal susceptibility in this respect. As reported herein, temperatures causing complete destruction of the infective component(s) of the two relatively heat-resistant strains of viruses under consideration also resulted in a striking reduction of the interfering quality. Apparently variations in heat resistance of influenza viruses are not necessarily accompanied by a corresponding variability in their interfering capacities.The use of sulfur mustard in preparing inactivated but interfering suspensions of virus was suggested by previous studies of the action of mustards upon influenza virus (9, 10). Virus treated in this manner retained much of its interfering capacity. Prior injections of 128 agglutinating doses of inactivated virus resulted in more or less complete interference with the development of 100 ID50 of homologous challenge virus. With 256 agglutinating doses, injection of challenge virus before interfering virus produced only a minor change in the interfering potential of mustard-inactivated virus. A prior injection of 512 agglutinating doses of inactivated virus proved ineffectual against 107 ID50 of challenge virus, but partial interference was manifested against 103 to 105 ID50 of virus.Studies of the effects of minor variations in concentration of sulfur mustard have demonstrated that it is better to err in the direction of a slight excess of mustard since lower concentrations of chemical (4 × 10-3 M) may result in incomplete destruction of virus. Despite the somewhat greater destruction of the interfering components of virus by 6 × 10-3 M mustard, a satisfactory interfering preparation was attainable.While comparative tests with ultraviolet irradiated virus were not made, the simplicity and ease of control inherent in mustard inactivation of virus is lacking in the former. The relative stability of refrigerated samples of interfering virus prepared with sulfur mustard is of advantage. Preliminary tests on the infective and interfering capacities of the preparation may be made, and experimentation with a single batch of interfering virus is rendered possible. A specific though probably minor limitation of mustard-inactivated virus is related to the retention of viral enzymatic activity (10). This limitation, however, has not impaired its usefulness in our studies of the interference phenomenon which are reported in another paper.

[学科分类] 生物科学（综合）