Abstract
Through the adaptation of a strain of poliomyelitis virus to the mouse by Armstrong, 1 a mouse neutralization test has been made possible. Haas and Armstrong 2 have already applied this test to post-epidemic surveys, but with results which are difficult to interpret. Thus, we felt it wise to investigate its significance somewhat further by testing a series of acute and convalescent sera from poliomyelitis patients against this same virus. Twenty-three pairs of such sera have now been tested. They were collected from 3 different outbreaks over a period of 2 years. Sera from 1940 and 1941 from the Los Angeles County Hospital were supplied by Dr. John F. Kessel. Another group, collected during the Tacoma, Washington, epidemic in 1940, were obtained from Miss Beatrice Howitt. None of the patients were seen by us, but the clinical diagnoses were made and checked by clinicians well trained in infectious diseases. The diagnosis of the non-paralytic case, in particular, is liable to error, but spinal fluid examination in all instances, together with serum neutralization tests to eliminate the virus encephalitides in several instances, reduced the possibility of error. From one non-paralytic case poliomyelitis virus was isolated from the stool by Miss Howitt.
Method. Both the admission (acute) and the discharge (convalescent) serum from each patient were tested simultaneously to insure comparable results. Positive and negative controls were always tested at the same time. A minimum of 8 mice was used for each serum, and tests on many pairs were repeated to check results. The first series was run by the method described by Armstrong, 2 employing 3 twofold dilutions of virus, but later a technic was adopted which is more comparable to that used for the yellow fever virus, using a large number of mice and only one dilution.
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