Abstract
Recently, a reliable technic for complement fixation for diagnosis of rabies was devised by Casals and Palacios. 1 The procedure for preparing antigen is, however, complicated and it seemed desirable to develop a simpler technic for complement fixation which might find application in routine laboratory diagnosis. At first, specific and sharp results were obtained by following the technic developed by Howitt; 2 subsequent experiments showed, however, that further simplification was possible and the following technic was finally evolved, which offers a practical procedure for routine diagnosis.
Antigen. One to 2 g of rabies-infected brain are minced in a Petri dish, spread in a thin layer, and dried in a desiccator over sulphuric acid, at 37°C for 24 hours.∗ The dried material is scraped off and stored in rubber-stoppered tubes in the ice box. Material thus preserved keeps at least 9 months. For the preparation of antigen, the dried material is ground in a mortar, taken up in neutral physiological saline and added gradually to give a final concentration of 2%. The suspension is centrifuged for 15 minutes at 3000 r.p.m. The supernatant fluid serves as the antigen. This type of antigen can be prepared from the brains of rabbits, guinea pigs, mice, and dogs, infected intracerebrally or peripherally with mouse passage fixed virus, virus from tissue cultures, 3 , 4 egg passage virus, 5 or with a local strain of street virus. Antigens prepared from brains of guinea pigs and mice infected with equine encephalitis virus (eastern strain), brains of guinea pigs infected with murine typhus, and normal brains of mice, guinea pigs, rabbits, and dogs served as negative controls.
Sera. Sera of immunized guinea pigs were employed as source of antibody.
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