我国传统猪丹毒疫苗及流行株灭活疫苗的免疫保护效力评估

Immune protective efficacy of China's traditional vaccines against the prevalent strains of Erysipelothrix rhusiopathiae

为评估我国传统猪丹毒灭活疫苗(C43-5株,2型)及其衍生的猪丹毒活疫苗(GC42株和G4T10株)对当前流行株HG-1、Er-2、Er-3和Er-4(1a型)的免疫保护效力,本研究将2种猪丹毒活疫苗(GC42株和G4T10株)分别经皮下注射免疫小鼠,14 d后采用ELISA方法检测小鼠血清中的抗体水平,免疫后15 d,以10 LD50/只分别经腹腔注射攻击传统疫苗检验株C43-6、C43-8,当前流行株HG-1、Er-2、Er-3和Er-4菌液并观察、记录各组小鼠的临床症状和死亡情况,共观察14 d。死亡小鼠立即剖检,采集心、肺、肝等组织进行细菌的分离与鉴定。结果显示,2种活疫苗均能刺激小鼠产生较高的抗体水平,且极显著高于PBS对照组(P<0.01),但两种活疫苗之间无显著差异(P>0.05);攻毒结果显示,分别对应GC42株和G4T10株的6个攻毒组小鼠均无任何临床症状,且均获得100%的保护率;对照组小鼠攻毒后24 h出现相应发病症状,5 d内全部死亡;死亡小鼠各组织器官主要出现败血症的剖检病变;从死亡小鼠的心血、肺、肝等脏器均能分离到猪丹毒丝菌。将我国传统猪丹毒灭活疫苗株C43-5及其检验株C43-6和C43-8,以及当前流行株HG-1、Er-2、Er-3和Er-4分别制备灭活疫苗免疫小鼠2次(间隔21 d),于首免后20 d和35 d分别采用ELISA方法检测抗体水平;小鼠首免后35 d,按上述方法攻毒,并检测相应指标。结果显示,上述7种灭活疫苗免疫小鼠20 d后,均诱导小鼠产生了极显著高于对照组的Ig G抗体水平(P<0.01),但7种灭活疫苗之间均无显著差异(P>0.05);首免后35 d与首免后20 d相比,7种灭活疫苗免疫组小鼠的Ig G抗体水平虽有所升高,但均无显著差异(P>0.05)。攻毒结果显示,C43-5、C43-6、C43-8和HG-1株灭活疫苗免疫组小鼠均获得80%(4/5)及以上的保护率,Er-2、Er-3和Er-4株的灭活疫苗仅能对小鼠提供20%~60%(1/5~3/5)的保护率,6个菌株攻击的对照组小鼠均于攻毒后24 h开始发病,5 d内全部死亡。本研究首次将我国3种传统猪丹毒疫苗对当前流行菌株的免疫保护效力进行综合评估,结果表明我国传统猪丹毒活疫苗(GC42株和G4T10株)和灭活疫苗(C43-5株)针对当前流行的猪丹毒丝菌仍具有良好的免疫保护效力。为我国当前猪丹毒疫苗的防控应用提供了借鉴。

To evaluate the immune protective efficacy of Chinese traditional swine erysipelas inactivated vaccine(C43-5strain,type 2) and its derived live vaccines( GC42 and G4T10),against the current prevalent Erysipelothrix rhusiopathiae strains HG-1,Er-2,Er-3 and Er-4(type 1a).In this study,two live swine erysipelas vaccines(GC42 strain and G4T10 strain) were injected subcutaneously immunized mice and 14 days later,the serum antibody levels of the mice were detected by ELISA method.Fifteen days after immunization,the conventional vaccine test strains C43-6 and C43-8,as well as the currently prevalent strains HG-1,Er-2,Er-3 and Er-4,were challenged intraperitoneally to immunized mice at a dose of 10LD50,respectively.The clinical symptoms and death of mice in each group were observed for 14 days.The dead mice were immediately dissected,and the heart,lung,liver and other tissues were collected for bacteria isolation and identification.The results showed that both kinds of live vaccines could stimulate mice to produce higher antibody level,which was significantly higher than that of PBS control group(P0.01),but there was no significant difference between the two kinds of vaccines(P0.05).The challenge results showed that the 6 challenge groups of mice corresponding to GC42 strain and G4T10 strain had no clinical symptoms,and all obtained 100%protection rate.The mice in the control group began to show corresponding symptoms 24 hours after the challenge,and all died within 5 days.The autopsy of the dead mice mainly showed septic pathological changes characterized by bleeding of various tissues and organs.E.rhusiopathiae can be isolated from the heart,blood,lungs,liver and other organ tissues of dead mice.The inactivated Chinese traditional swine erysipelas vaccine strain C43-5,its test strains C43-6 and C43-8,and the current epidemic strains HG-1,Er-2,Er-3 and Er-4 were prepared and immunized mice twice(at an interval of 21 days),and the antibody levels were detected by ELISA at 20 and 35 days after the first immunization,respectively.35 days after the first immunization,the mice were challenged by the above methods,and the corresponding indexes were detected.The results showed that after immunizing the mice with the seven inactivated vaccines for 20 days,the Ig G antibody level of the mice was significantly higher than that of the control group(P0.01),but there was no significant difference among the seven inactivated vaccines(P0.05).Compared with 21days after first immunization,Ig G antibody levels of mice immunized with 7 kinds of inactivated vaccines were increased at 35days after first immunization,but there was no significant difference(P0.05).The results of challenge showed that the inactivated vaccines of C43-5,C43-6,C43-8 and HG-1 strains obtained 80%(4/5) or above protection rate,while the inactivated vaccines of Er-2,Er-3 and Er-4 strains could only provide 20%-60%(1/5-3/5) protection rate for mice.The control mice challenged by 6strains all began to develop disease 24 hours after the challenge,and all died within 5 days.In this study,for the first time,the immune protection efficacy of three traditional Chinese swine erysipelas vaccines against the current epidemic strains was comprehensively evaluated.The results showed that the traditional Chinese live swine erysipelas vaccines(GC42 strains and G4T10 strains) and inactivated vaccines(C43-5 strains) still had good immune protection efficacy against the current endemic swine Erysipelothrix rhusiopathiae.This study provides reference for the prevention and control of swine erysipelas in China.