Mbao V, Berkvens D, Dorny P, Van den Bossche P, Marcotty T
Department of Animal Health, Institute of Tropical Medicine, Nationalestraat 155, B-2000 Antwerp, Belgium.
Onderstepoort J Vet Res. 2007 Mar;74(1):9-15. doi: 10.4102/ojvr.v74i1.134.
Stabilates of Theileria parva sporozoites are mostly delivered in liquid nitrogen tanks to the East Coast fever immunization points. Using an in vitro titration model, we assessed the loss of infectivity of several stabilates when they are stored in ice baths for up to 24 h. Comparisons, with respect to rates of loss of infectivity, were made between T. parva stocks (Chitongo and Katete), cryoprotectants (sucrose and glycerol) and method of assessment (in vivo and in vitro techniques). Chitongo and Katete stabilates showed similar loss dynamics. The losses were 1-4% (depending on parasite stock) and 3% per hour of storage for glycerol and sucrose stabilates respectively, and the loss rates were not significantly different. The results suggest that Chitongo stabilates and sucrose cryoprotected suspensions can be delivered on ice as is done for Katete. A graphical relationship of in vitro effective dose at 50% infectivity (ED50) and in vivo protection rate was made. The relationship showed a 35% loss of protection for a relatively low corresponding increase of ED50 from 0.006 to 0.007 tick equivalent.
泰勒虫裂殖子的稳定株大多在液氮罐中被运送到东海岸热免疫接种点。我们使用体外滴定模型，评估了几种稳定株在冰浴中储存长达24小时后的感染力损失情况。对泰勒虫毒株（奇通戈和卡特特）、冷冻保护剂（蔗糖和甘油）以及评估方法（体内和体外技术）的感染力损失率进行了比较。奇通戈和卡特特稳定株显示出相似的损失动态。甘油和蔗糖稳定株的损失分别为1 - 4%（取决于寄生虫毒株）和每储存1小时损失3%，损失率无显著差异。结果表明，奇通戈稳定株和蔗糖冷冻保护悬浮液可以像卡特特稳定株那样在冰上运输。绘制了50%感染力时的体外有效剂量（ED50）与体内保护率的关系图。该关系表明，当ED50从0.006蜱当量相对较低地增加到0.007蜱当量时，保护作用损失了35%。
