Studies on Rocky Mountain spotted fever / U.S. Treasury Department, Public Health Service.

Date:
[1930]
Catalogue details

Licence: Public Domain Mark

Credit: Studies on Rocky Mountain spotted fever / U.S. Treasury Department, Public Health Service. Source: Wellcome Collection.

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    was added after each washing, and the cells were thoroughly mixed. This method of washing was followed in all subsequent tests. Results.—After the third washing the injection of 1/10 c. c. of red cells (diluted to the original volume) produced typical spotted fever in each of two guinea pigs and a moderate fever developed in one of two animals receiving 1/100 c. c. of cells. Smaller amounts failed to give fever. Two guinea pigs receiving 4 ¢c. c. each of the supernatant salt solution of the twelfth washing were negative for 12 days and sub- sequently were found susceptible by reinoculation of blood virus. (juinea pigs receiving 1 c. c. each of red cells (diluted to the original volume of the blood) after the twelfth washing and one of the pigs receiving 1/10 c. c. developed typical spotted fever. Less amounts failed to give fever. We have found it impossible to demonstrate organisms of any kind within the red cells either in fresh preparations or in smear preparations stained with Giemsa’s solution. Experiment No. 3: Association of the virus with washed white blood cells —An exudate of white cells obtained by injecting aleuronat inte the peritoneal cavity of an infected guinea pig was suspended in 10 c. c. of salt solution and washed twelve times in the same manner as in the case of the red blood cells. The supernatant fluid after each centrifugation could be poured off, leaving a volume of less than 1 ce. c. of white cells. The washing of these cells was therefore more thorough than that of the red cells. Result —Guinea pigs receiving 1/100 c. c. of unwashed cells devel- oped spotted fever. Less amounts failed. Guinea pigs receiving 1 c. c. and one animal receiving 1/10 ¢. ¢. of the white cells, after the twelfth washing, developed spotted fever. Less amounts were unsuccessful. Experiment No. 4: Adsorption of virus with normal red cells. — Five cubic centimeters of a cell-free serum obtained from an infected guinea pig was mixed with an equal volume of a suspension of washed normal red blood cells. After thorough agitation the mixture was permitted to stand one-half hour at room temperature. The red cells were then washed ten times as in previous tests and injected as before in graded amounts. Result—The two guinea pigs receiving 1 c. c. and the two receiv- ing 1/10 c. c. of the washed cells developed spotted fever. ELaperiment No. 5: Adsorption of virus with normal white blood cells.—F ive cubic centimeters of cell-free guinea-pig serum virus was mixed with equal amounts of a suspension of normal guinea-pig leucocytes (one-half gram of moist leucocytes in 5 ¢. c. of salt solu- tion). The mixture was thoroughly shaken and permitted to stand one-half hour at room temperature and then washed ten times by
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