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Two lot hog cholera OP tissne cultire vaccine were erqrerimentlly manufactned aaxding to Dr. Seashore formula with GPE stain infrcducai from Jan. The fl-vaccinal reactions and immunity efficiency of the two trial vaccines were carefully discussed in the previous report. In the present report, the result of their preservation and duration of immunity t are summaried as follows:
1.For preservation test, the vaccines (Trial lot l&2) were kept in refrigerator at 5? and then virus titration of the vaccines alen out at random and oombinerl were conducted ey month for one year by means of in vito-interference method. As the result, the two trial vaccines could almost remain the original virus titers for 4months and thenonlyalittledropof 10 1-25 TCID 5(Mnlinvirus titers aft l2months. The vaccine, therefore could keep a oonsiclerably high virus titers aft 12 months.
2.The vaccines preserved in refrigerator were suboutansously inoculated to 2-4 SPF pigs with one dose each xesceDtively aft 3A9 and 1 2months preservation, All the exrerimental pigs showed no Dl post-vaccinal reaction with 10 days close oblervation and survived with only shght or no reaction from the challenge with one ml of AU) virulent blood (1Cfl).
3.The Lot 2 vaccine was employed to vaccinate 1 2pigs (6wek okl) with various titers of colostral antibody, then challenged 4 pigs each with one ml of AU) virulent blood (xl (0) at oth,Qth and 12th month after vaccination. All pigs with cdostral antibody titers ofxloorlowrweresurvivedfromthevirus challengeevenas loizgas for 12 months after vaccination. while the exrerirnental pig with colostral antibody titer of x& acquired no immunity acquired aft vaccination could last at least for one year.
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