Schistosoma japonicum: some parameters affecting the development of protective immunity induced by a cryopreserved, irradiated schistosomula vaccine in guinea-pigs

Synergistic effect of bacillus calmette guerin and a tuberculosis subunit vaccine in cationic liposomes: increased immunogenicity and protection

In the present work, we evaluated a new TB vaccine approach based on a combination of the Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine and a subunit vaccine consisting of the proteins Ag85B and ESAT-6. We demonstrate that in addition to its vaccine efficacy BCG is an immune modulator that can potentiate a Th1 immune response better than the well-known adjuvant mono phosphoryl lipid A, leading to enhanced recognition of the subunit vaccine Ag85B-ESAT-6. Importantly, adding a vehicle to the vaccine, such as the cationic liposome dimethyl dioctadecyl ammonium bromide (DDA), significantly increased the potentiating effect of BCG. This synergistic effect between BCG and Ag85B-ESAT-6/liposome required drainage to the same lymph node of all vaccine components but did not require direct mixing of the components and was therefore also observed when BCG and Ag85B-ESAT-6/liposome were given as separate injections at sites draining to the same lymph node. The resulting optimized vaccine protocol consisting of BCG and subunit in liposomes (injected side by side) followed by boosting with the subunit in conventional adjuvant resulted in an impressive increase in the protective efficacy of up to 7-fold compared with BCG alone and 3-fold compared with unaugmented BCG boosted by the subunit vaccine. Thus, these studies suggest an immunization strategy where a novel TB subunit vaccine is administered as part of the child vaccination program together with BCG in neonates and followed by subunit boosting.

Vaccination of bovines against Schistosomiasis japonica with cryopreserved-irradiated and freeze-thaw schistosomula

Four laboratory tests and one field trial with cryopreserved irradiated (CI) schistosomula vaccine and a freeze-thaw (F/T) vaccine against bovine Schistosomiasis japonica were carried out in 1979 and 1980 with the following results: (1) Single intradermal vaccination in buffalo calves each with 10,000 20 krad CI Schistosomula plus 1 ml BCG gave 62% worm reduction (P < 0.05). Using the same protocol 55% worm reduction (P < 0.01) was obtained in cattle. (2) Buffalo calves immunized twice, at a 1.5 month interval, with 10,000 and 20,000 CI schistosomula, respectively, resulted in a worm reduction 65%. (3) In a preliminary field trial with 10,000 CI schistosomula plus 1 ml BCG resulted in a worm reduction of 53% in buffalo calves. (4) Intradermal vaccination of 30,000 F/T schistosomula with 1 ml BCG was also tried in cattle and revealed a worm reduction of 57% but increasing the number of vaccinations did not improve the protective effect. (5) Evidence regarding the effects of immunization with CI vaccine in buffaloes and F/T vaccine in cattle, on the number of eggs and miracidia and that of female worms themselves was obtained. (6) Immune responses, cellular and humoral, elicited in buffaloes vaccinated with CI schistosomula were detected by means of Lymphocyte Transformation Assay and Enzyme Linked Immunosorbent Assay.