3株O3血清型鳗弧菌灭活疫苗的免疫原性和免疫保护效果

Immunogenicity and Protective Efficacy of Three Inactivated Vibrio anguillarum Serotype O3 Vaccine Preparations

鳗弧菌(Vibrio anguillarum)O3血清型菌株是感染鱼类的重要病原菌,本文研究了3株O3血清型鳗弧菌(SMP1、SMP3和SMP4)灭活疫苗的免疫原性和免疫保护。首先在牙鲆(Paralichthys olivaceus)体内对3株鳗弧菌进行复壮;检测复壮后的菌株毒力,检测的3株鳗弧菌对蓝蔓龙(Trichogaser trichopterus)的半数致死量(LD50)分别为105.1 CFU/ml(SMP1)、104.7 CFU/ml(SMP3)和105.4 CFU/ml(SMP4);制备了3株菌的甲醛灭活疫苗,注射免疫牙鲆,免疫后第7天可检测到牙鲆的血清特异性抗体产生,免疫后第28天的血清特异性抗体效价为1︰1280(SMP1)、1︰640(SMP3)和1︰905(SMP4),提供的免疫保护率(Relative percent survival rate,RPS)为94.4%(SMP1)、100%(SMP3)和73.7%(SMP4)。研究表明,3株致病性O3血清型鳗弧菌菌株具有良好的免疫原性,其中SMP3为最适疫苗候选株。本研究为鳗弧菌O3血清型疫苗的开发应用奠定了基础。

Vibrio anguillarum,an etiological agent of fish septicemia,has caused great economic losses in many marine and fresh water fish.Vaccination is an effective and safe approach to control fish septicemia.The pathogenicity V.anguillarum serotype O3 in cultured marine fish of China promotes us to evaluate the immunogenicity and protective efficacy of three V.anguillarum serotype O3 inactivated vaccine.Three V.anguillarum serotype O3 strains(SMP1,SMP3,and SMP4)were rejuvenated in flounder Paralichthys olivaceus and then were determined for lethal dose 50%(LD50)in Trichogaster trichopterus which had been acclimated to 10 salinity.The result showed that LD50 of SMP1,SMP3 and SMP4 were 105.1 CFU/ml,104.7 CFU/ml and 105.4 CFU/ml,respectively.Three inactivated vaccine were obtained by incubation of V.anguillarum with 0.2%formaldehyde for 36 h at 28℃.Each vaccine was used to vaccinate flounder P.olivaceus via intraperitoneal injection with a dosage of 108 CFU/ml.Specific serum antibody titers against V.anguillarum cells were detected evidently(P<0.05)at 7 d post vaccination,and the highest titers of 1:1280(SMP1),1:640(SMP3)and 1:905(SMP4)were detected at 4 weeks post vaccination(P<0.05).Meanwhile,the relative percent survival rates(RPS)were 94.4%(SMP1),100%(SMP3)and 73.7%(SMP4).These results indicated that V.anguillarum serotype O3 inactivated vaccines were able to induce immune response in fish and provide effective protection against V.anguillarum infection,and SMP3 is the best candidate for vaccine development and application.