Abstract
Previously, the authors reported""" the pathogenicity, immunity and distribution ofthe infectious canine hepatitis (H.c.c.) virus, in Japan.The results obtained in the present study with the D43 and D78 strains of the virusof the disease in dog kidney tissue culture were as follows.J) TCID5. of the fluid phase, at various passage levels, were in the range of TO "to 10 . Both strains neutralized each other in the cross-neutralization test. The neutrali-zation test, in tissue culture, proved to be the most useful and sensitive methods for thediagnosis of H.e.c.2) The studies on the complement-fixing antigen, the hemagglutinating propertyand the infective virus in vitro (initial inoculum : 2000 to 6000 TCID5g) indicated thatthe infective fiter increased on the 2nd day accompanied by the inclusion bodies, reachedthe maximum Liter on the 5th or 6th day after virus inoculation, and after that, re-mained at the same level with slight fluctuations. On the other hand, the complement-fixing antigen was first detected on the 2nd day after inoculation, when a cytopathogeniceffect appeared. And then the complement-fixing antigen Liter increased continuouslyreaching ]:16 on the 6th or 7th day after the virus inoculation.3) The effects of various temperatures on the xirus were studied. It was foundthat the infectivity of the virus was destroyed by hcating at 50C for 150 minutes or60C for 3 -5 minutes. At 37C both viruses were inactivated until the 26th and 29thday after inoculation, respectively. The virus was infective to tissue culture when heldat the frozen state with dry ice for l year or at 4C for 9 months. At room tempera-lure the virus kept its infectixzity for 10 to 13 weel<s.4) Stability of the virus at 37C was studied. The results indicated that the corn-plement-fixing antigen, hemagglutinating property and its infectivity were stable, in turn, at this temperature.5) The viruses, at various passage levels, were inoculated into dogs to test theirvirulence. Between the forty-first and forty-fourth passages, the
