The efficacy of killed Trypanosoma evansi vaccines in mice.

Four strains of Trypanosoma evarsi (D3, D4, D5 and D6) isolated from German shepherd dogs were inoculated into mice, and infected blood was used to prepare 9 separate killed vaccines. White mice inoculated with 1:100 diluted PBS vaccine, 0.5% carbol vaccine, or 100% Lugol vaccine showed survival rates of more than 60%. Among these 3 vaccines PBS vaccine and 0.5% carbol vaccine showed higher survival rates at 1:500 and 1:1000 dilutions, respectively. When young mice (15-20 g) were immunized with PBS vaccine, they resisted challenge with homologous strains, D3 strain in single injection, D6 strain in double injections and all strains in 5 injections. Protection however was not observed in old mice (25-30 g) give the same vaccine preparation. When mice were vaccinated with a single injection of D3 vaccine and challenged with heterologous strains, only those challenged with D4 strain at 10-5 dilution showed a survival rate of more than 60%. There was no difference in protective ability among PBS vaccine, agar adjuvant and kaolin adjuvant vaccines. Agglutinating antibody was demonstrated in mice receiving 5 injections of PBS vaccine.     

Live and killed vaccines against toxoplasmosis in mice

Mice were immunized with live organisms of the different stages (i.e., tachyzoites, bradyzoites, or sporozoites) of Toxoplasma gondii, or with killed tachyzoites with or without adjuvants. The adjuvants used were liposomes, anhydrides of myristic or lauric acid, levamisole and Freund's complete or incomplete adjuvant. The following strains of T. gondii were used: RH, M-7741, the nonpersisting, temperature-sensitive mutants ts-1, ts-4, or ts-5, and the "back mutant" of ts-1 (Pfefferkorn and Pfefferkorn, 1976). The protection afforded was measured by challenge with the pathogenic M-7741 strain. Killed tachyzoites alone, or with adjuvants, offered only slight protection against challenge with M-7741 and no protection against challenge doses that were lethal to all control mice. Chronic infection and live nonpersisting vaccines conveyed a strong immunity to challenge, except strain ts-1. Because it was less pathogenic and did not require chemoprophylaxis, strain ts-4 best fulfilled the requirements for a good vaccine; its effect in hosts other than the mouse remains to be determined. The immunity induced by tachyzoites, bradyzoites, or sporozoites appeared equally strong when challenged with sporozoites.     

炭疽灭活和裂解芽胞抗原免疫家兔后血清中的IgG抗体应答

炭疽杆菌芽胞在炭疽免疫中发挥基本作用。实验中以炭疽活芽胞疫苗为原形,建立了制备灭活和裂解炭疽芽胞的方法,研究了各种灭活和裂解炭疽芽胞疫苗不同浓度、不同剂次免疫家兔的抗芽胞和毒素IgG应答,总结分析了各种灭活和裂解炭疽芽胞疫苗用于新疫苗成分之一的可能性。甲醛灭活炭疽芽胞疫苗设芽胞浓度2.5×108剂量组、5×108剂量组、1×109剂量组,于0、4、8周时3次免疫。在3剂免疫后血清抗炭疽芽胞IgG水平持续升高,首次免疫后4、8、12周时家兔血清中抗芽胞IgG几何平均滴度可达到600～16000。裂解炭疽芽胞疫苗的制备和动物免疫中,只采取了2.5×108芽胞浓度,两剂免疫,免疫时间为0、4周。在首次免疫后4、8、12周时家兔血清中抗芽胞IgG几何平均滴度分别为362、776和388。各时间点采集的家兔血清未能测出或只测出极微量的抗炭疽毒素IgG。通过上述研究认为,以裂解炭疽芽胞抗原作为炭疽疫苗成分之一,其抗原性和免疫原性是适宜的;免疫剂量可以设定为2.5×108芽胞浓度上下;免疫次数可定为2剂间隔1个月。     

Assessment of effectivity of oral killed typhoid and paratyphoid B vaccines and aerosol chemical typhoid vaccine in controlled field trials.

A total of 3 controlled field trials were carried out. One of them (1963) showed that aerosol chemical typhoid vaccine did not protect vaccinated subjects from the disease. Two other tests (1964 and 1965) assessing the effectivity of killed orally administered typhoid vaccine revealed a short term (up to 3 months) protective effect expressed by an effectivity coefficient of 45%, fiducial limits being 8-70%. In the assessment of oral paratyphoid B vaccine, the difference in morbidity in the experimental and control groups was statistically insignificant due to a small number of cases of disease.