恙虫病立克次体的液氮保存

STORING Rickettsia tsutsugamushiIN LIQUID NITROGEN

用恙虫病立克次体感染小鼠使其产生腹水，取腹水原液与部分提纯的恙虫病立克次体悬液加或不加二甲基亚砜、采用四级或二级降温方法作液氮保存，并分别于保存１、３、６和１２个月后取出作形态观察及感染小鼠能力测定。结果证明恙虫病立克次体经液氮保存１年后仍具有对小鼠的感染能力。其中以腹水原液，加二甲基亚砜，采用二级降温法作液氮保存效果较好。采用液氮保存恙虫病立克次体具有节时省物、可靠程度高的优点，为对恙虫病立克次体的生物特性和恙虫病的预防。

A method for storing Rickettsia tsutsugamushi(R. tsutsugamushi)in liquid nitrogen was studied. Ascites produced by mice infected with R. tsutsugamushi and its partially purified R. tsutsugamushi. both treated with or without adding dimethyl sulfoxide (DMSO) were kept frozen in cryovials and stored in liquid nitrogen by means of four or two step methods to lower down the temperature stepwise to -196℃. The frozen vials were removed out from liquid nitrogen at one, three, six and twelve months after storage, respectively. Microscopy and the test of mouse infectability of the rickettsia were examined. Results indicated that R. tsutsugamushi retained their mouse infectability in liquid nitrogen for over one year. It is apparent that the storage of the rickettsia would be better with infected mouse ascites freezing process with two step than with partially purified preparation and with four step freezing process. In conclusion, store of R. tsutsugamushi in the form of infected mouse ascites in liquid nitrogen may prove to be a simple and useful method for preservation of the rickettsia.