猪链球菌9型ICR小鼠感染模型的建立及评分

Establishment of animal models of ICR mice infected with Streptococcus suis type 9 using scoring method

为验证小鼠是否可以替代猪作为猪链球菌9型的感染动物模型并做评分。将32只9周龄ICR小鼠随机分成5个攻毒组（每组6只）,1个PBS对照（2只）,计算LD50,观察小鼠的临床症状及脏器病变并评分;分离细菌做镜检及PCR鉴定。结果显示,LD50为3.92×109CFU;2.2×1010组小鼠意识消沉,腹泻、失明、食欲下降,临床症状分数最高为3分;肝肿大,内脏严重出血,病变评分为3~4分。其余组小鼠分数随着攻毒剂量的下降而降低。从病变组织中均分离到该病菌,鉴定为阳性。由临床症状及病理评分确定,ICR小鼠可作为猪链球菌9型的感染动物模型。

This study aims to establish and evaluate a Streptococcus suis type 9 infection model using mice instead of pigs.32 ICR mice（9 weeks-old） were randomly divided into 5 challenge groups（6 mice per group） exposed to different concentrations of bacteria supernatant and 1 PBS control group（2 mice）.The LD50 was calculated while the clinical symptoms and organ pathological changes were observed and scored.Following,bacteria were isolated for determination by PCR.In result,LD50 was 3.92×109 CFU,whereas the mice exposed to 2.2×1010 CFU bacteria showed serious clinical symptoms including depression,diarrhea,blindness,anorexia,and the score was up to 3.Hepatomegaly along with hemorrhage was observed and pathological lesions in these mice were scored between 3 and 4.The pathological scores were reduced in response to decreased infected dose.PCR analysis demonstrated a positive result for the bacteria isolated from pathological tissues of the dead mice.Based on the above-mentioned results,we concluded that ICR mouse can be a model for Streptococcus sui type 9 infection instead of pigs.