ON THE PRECIPITIN REACTION IN BOVINE CONTAGIOUS PLEURO-PNEUMONIA

In the previous report (Journal of the Japanese Society of Veterinary Science, Vol. IV, No. 1) the author called attention to the precipitin reaction regarding the differential diagnosis of bovine contagious pleuro-pneumonia. In the experiment which he has made later on, he used as precipitin the serum obtainee from affected cattle or calves infected by inoculation with the virus, and found that the precipitin serum prepared in this way was not fit for use, because the normal cattle serum may sometimes contain precipitin. For this reason he intended to get a precipitin serum from rabbit and found it very suitable for the object.Preparation of precipitin serum: From a horse-serum-broth-agar slant culture of the virus kept for 10 days in an incubator at 70°C., an emulsion was prepared with 20c.c. of physiological salt solution (precipitogen). One half (10c.c.) of this emulsion was injected into testicle and the other half into thoracic cavity of a rabbit. At an interval of 4 days, the injection was repeated in the same way, and after 15 days the serum was taken from the animal and tested upon precipitin, as shown in the following table, the results being read after one hour at room temperature (10-15°C.).Precipitation experiments have been made in 4 cases of naturally affected cattle, 9 cases of artificially infected calves and 57 cases of controls. The results obtained are shown in the following table:It must be noted here that in the precipitation experiment, all 4 cases of the affected cattle gave positive reaction in a dilution of from 1:640 to 1:1280 and all 9 cases of infected calves inoculated with the virus the same result in a dilution of from 1:40 to 1:1280, while cases of pericarditis (1), pleuro-pneumonia (1), tuberculosis (1), and influenza (1), as well as 53 cases of controls gave negative results.