11型鸭疫里默菌的生物学特性

Main biological characteristics of serotype 11 Riemerella anatipestifer isolates

目的分析11型鸭疫里默菌(Riemerella anatipestifer,RA)的药物敏感性、致病性及其免疫保护力。方法纸片扩散法检测73株11型RA分离株的药物敏感性;将2×108和2×107CFU/ml的RA菌株悬浮液分别经皮下注射10羽10日龄的樱桃谷鸭,0.5 ml/羽,攻菌后连续观察5 d,记录死亡数,并从死亡鸭肝脏中分离细菌,计算死亡率;用分离的菌株RA1229制备灭活油乳剂疫苗,分别经皮下注射50羽7日龄樱桃谷鸭,0.3 ml/羽,14 d后,各组樱桃谷鸭均经皮下注射RAf74、RA234、RA1067、RA1156和RA1229的新鲜培养液(含菌量为2×107CFU/ml),0.5 ml/羽,攻菌后连续观察5 d,记录死亡数,并从死亡鸭肝脏中分离细菌,计算死亡率。结果 90%以上菌株敏感的药物有头孢唑啉、氟苯尼考和头孢氨苄,其他敏感药物依次为阿莫西林、氨苄西林、强力霉素、壮观霉素、丁胺卡那霉素和利福平;死亡鸭肝脏分离株中有10株的致病性相似,注射1×108及1×107CFU/ml RA的樱桃谷鸭死亡率分别为100%及80%,RA1229的致病性略强;RA1229制备的疫苗对樱桃谷鸭的保护率高于90%。结论 11型RA对多种抗生素敏感,有较强的致病性,RA1229具有良好的免疫保护力,可作为制备RA灭活疫苗的候选菌株。

Objective To analyze the drug sensitivity,pathogenicity and immune protection of serotype 11 Riemerella anatipestifer（RA）. Methods The drug-sensitivities of 73 RA strains were analyzed by paper strip assay. Ten 10-day-old Cherry Valley ducks were injected s.c. with 2 × 10^8and 2 × 10^7CFU / ml RA suspension respectively,0. 5 ml for each, observed for 5 d after challenge and recorded for death. RA was extracted from the livers of dead ducks,and the death rate was calculated. The isolated RA1229 strain was prepared into inactivated oil emulsion vaccine and injected s.c. into 50 7-day-old ducks,0. 3 ml for each. The ducks in various groups were challenged with the 2 × 10^7 CFU / ml fresh cultures of RAf74,RA234,RA1067,RA1156 and RA1229 14 d later,0. 5 ml for each,then observed for 5 d,recorded for death and calculated for death rate,and RA was extracted for the livers of dead ducks. Results More than 90% of the RA strains were sensitive to cefazolin,florfenicol and cefalexin. In the turn of sensitivity,other drugs were amoxicillin, ampicillin,doxycycline,aiprofloxacin,amikacin and rifampicin. The pathogenicities of 10 isolates from livers of dead ducks were similar. The death rates of ducks immunized with 1 × 10^8and 1 × 10^7CFU / ml RA were 100% and 80% respectively. RA1229 showed a slightly strong pathogenicity,with which the prepared vaccine showed a protective rate of more than 90% to Cherry Valley ducks. Conclusion RA serotype 11 was sensitive to several antibiotics and showed strong pathogenicity,of which RA1229 showed good protective immunity and might be used as a candidate strain for preparation of inactivated RA vaccine.