微小巴贝虫在不同免疫状态小鼠体内消长规律研究

Infection dynamics of Babesia microtiin mice in different immune status

目的观察微小巴贝虫感染不同免疫状态小鼠后的消长规律。方法实验分正常BALB/c小鼠组、免疫抑制BALB/c小鼠组、SCID小鼠组和NOD-SCID小鼠组等,每组5只小鼠。免疫抑制BALB/c小鼠,每只经腹腔注射0.5mg地塞米松,连续5d。随后,各组小鼠每只腹腔注射100μL含微小巴贝虫鼠血(红细胞染虫率约20%)。每组留1只小鼠作未感染对照鼠。自接种当天每d尾部采血涂薄血片,吉姆萨染色,镜检观察红细胞染虫状况。结果正常BALB/c小鼠感染微小巴贝虫第3d在红细胞内查见虫体,感染后第7d染虫率最高为82.4%,染虫率在20%以上约持续7d;短暂免疫抑制BALB/c小鼠在感染后第5d染虫率达到高峰为73.18%,染虫率在20%以上约持续14d,而后染虫率处于0%～2%的较低水平状态。NOD-SCID小鼠组分别于第7d(72.45%)、第16d(67.4%)、第24d(58.9%)多次出现染虫率高峰,微小巴贝虫在NOD-SCID小鼠体内不会被大量清除,染虫率一直处于较高状态,平均为41.9%。SCID小鼠组于第8d出现第1次染虫率高峰,为86.4%,至第18d出现第2次高峰为62.23%,染虫率也一直处于较高状态,平均为38.2%。在薄血片中观察到小点状体,马耳他十字,小环状体,环状体,长丝状体,以及游离在红细胞外的虫体等多种巴贝虫形态。结论微小巴贝虫在正常BALB/c小鼠和短期免疫抑制BALB/c小鼠体内虫密度出现先升高又下降的宿主自限性现象;而在SCID小鼠和NOD-SCID小鼠体内虫密度出现多个高峰,且能持续较高水平。

To observe the infection dynamics of Babesia microti in the mice of different immune status, BALB/c mice, BALB/c mice of immune suppression, SCID mice, and NOD-SCID mice were divided into 4 groups（5 in each）. Dexametha- sone, one kind of immunosuppressant, was intraperitoneally injected into BALB/c mice for five consecutive times （0. 5mg/ dose/day） to form BALB/c mice of immune suppression. Of 100 I%L BALB/c mice blood （20% RBC infection rate） with Babes- ia microti was intraperitoneally injected into four of BALB/c mice, BALB/c mice of immune suppression, SCID mice and NOD- SCID mice, respectively, and left one normal control in each group. Tail blood was used to prepare thin blood films and giemsa staining to observe the infection changes. On the third days after infection, Babesia microti were firstly found in RBC of BALB/c mice. The highest infection rate （82.40//oo） of Babesia microti in BALB/c mice appeared on the seventh day after infec- tion, and the infection rate were higher than 20O/oo for 7 days% on the fifth day after infection, the infection rate of BALB/c mice of immune suppression was up to a peak of 73.18%, and the infection rate were higher than 20% for 14 days; after that, the rate of the Babesia microti in these two kind of mice blood was in a very low state （0%--2%）. The peak of infection rates of Babesia microti in NOI）-SCID mice group were appeared on the seventh day after infection （72.5%）, the 16th day （67.4%） and the 24th day （58.9%）, and the rate of Babesia microti in NOD SCID mice blood was high. The average rate was 41.9% and could not heal by itself. The highest infection rate of Babesia rnicroti in SCID mice was first appeared on the 8th day after infection, and the rate was 86.4%. The sec- ond rate peak was appeared on the 18th day, and the rate was 62. 230/00. The rate of Babesia rnicroti in SCID miceblood was high, and the average rate was 38.2%. From the thin blood films, many form of Babesia microti were observed, such as small point-like body, the Maltese cross, a small circular ring, circular ring, long threadlike body and parasites free outside of red blood cells. In normal and short-term suppression BALI3/c mice, insect density of Babesia microti first raised to a higher level, and then dropped to a lower level, which was called host self-limiting phenomenon; while in SCID and NOD- SCID mice, density of Babesia rnicroti appeared more than one peak, and could sustained in a higher level.