Immunity in Human Subjects Artificially Infected with Influenza Virus, Type B

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Abstract
A study was made of the immune response of humans artifically infected with influenza virus, Type B, to subsequent exposure to the same virus 4 months later. The Lee strain was used throughout. The source of infective material was the extra-embryonic fluid from infected hen''s eggs, 48 hrs. after inoculation, harvested and concentrated in physiol. salt soln. [see B. A. 17(4): entry 11784]. For the 1st exposure, concentrate was used from the 20th and 21st egg passages after 8 passages in ferrets and 137 in mice. The material was stored at 4[degree]C for one month prior to use. For the 2d exposure (reinfection), material from the 34th and 35th egg passages was used after 7-16 days'' storage at 4[degree]C. 30 subjects were designated as untreated controls and an additional 30 were divided into 3 groups of 10 to receive the virus. Group 1 received conc. virus diluted to strength of original material, group 2 received virus concentrated 2-fold, and group 3 received virus con-centrated 10-fold. Exposure was accomplished by inhalation of a spray of infective material through the nostrils. A mild form of the natural disease was produced with the severity of febrile reaction somewhat related to the amt. of virus received. Four-fold rise in antibody titer was noted on all but 4 of the treated subjects. 11 controls showed significant serol. changes indicating infection incurred while residing in the same quarters with treated subjects. No other recognizable symptoms were noted in the controls. Reinfection with a 10-fold conc. of the same virus induced a milder illness in the majority of previously infected individuals than in controls inoculated at the same time. No uniform correlation between antibody titer of an individual and his response to inoculation was found.