In order to know the basic properi ties of passaged-Lapinized Hog Cholera virtis of rabbit kidney cells, the pathogenici ty and immunogenici ty were studies. The results are as follows:
Pyrectic responses were studied in rabbit inoculated intravenously with HC LPC 820 th rabbits-passaged and RK-LPC 10th passage viruses. Significant pyre-ctic response was ovserved 70 hours after inoculation in the rabbits inoculated with RK-LPC virus.
The same viruses were also tested in pigs, but no pyrectic response after i-noculated with RK-LPC 10th virus or after being challenged with 5ml ( 1: 10) of virulent HC ALD blood virus, was noted their appetites were normal, and there was no leucopenia or shift to the left in the neutrophils on the tested pigs.
Tonsils spleen, mandibular lymph nodes, mesentric lymph nodes and inguinalymph nodes were found to be virus positive on day 4 after inoculation. From 4th to 10th days all tests on the tonsils were found to be virus positive. The hig-hest vira'l titer 103•0 TCID5o /g, was between the 7th and 8th days.
The results after 10 reverse passages in pigs, revealed no abnormal clinical signs or shift in the neutropils er virus shedding in urine. However the WBC cotm.ts showed slight, but in significant decrease.
he cross meutralization test of HC LPC, RK-LPC 10th and 15th viruses, using the antiserum of hormlogus and hetrogous BVD T20-5 viruses, showed hight SN antibody titers able to neutralize several types of Hog Cholera viruses. It also showed the HC A76 virus, HC field isolated chronic group B Kanagawa /'74 virus, HC attenuated GPE-and HC RK-LPC viruses. Therefore no antigenic difference in the cross immunity was found.
The immunogenicity of RK-LPC 20th passaged virus had a potency of 103•5 in the test pigs. The pig with serwn neu_tralization t SN) titer, 1: 4 reaiisted the challenge with 10,000 MID of HC ALD virulent blood virus. Pigs with titers of 1 : 2 , Mwever, died after the challenge.
Pig with maternal antibody titer of 1: 4 showed an increase of SN antibody 2 weeks later. However pigs with maternal titers of 1: 8 and 1: 16 showed an increase at 6 weeks. But the SN antibody titers reponse was not constant at the titers of 1 : 32.
The immunized pigs were challenged from 2 to 6 days after immunization. Pigs challenged on the 5th and 6th day after inoculation surived with no abnormal reactions.