BACKGROUNDThe development of new adjuvants for human use has been the focus of attention. This study's aim is to explore the possibility of using nanoparticle Ca nanoparticles (CA) as a vaccine adjuvant of anti-idiotypic antibody NP30 against schistosomiasis and its protective mechanisms.

METHODSNanoparticle CA-NP30 conjugate (CA-NP30) was fabricated. BALB/c mice were immunized actively with CA-NP30 to evaluate its effects of protective immunity on mice. The serum levels of specific IgG, IgG1 and IgG2a antibodies against NP30 and the concentrations of IFN-gamma and IL-4 in supernatant of splenocytes were determined via ELISA.

RESULTSNanoparticle CA could enhance significantly the protective immunity of NP30 against infection of Schistosoma japonicum and the worm reduction rose from 36.0% (NP30 alone) to 52.6%. The serum levels of specific IgG, IgG1 and IgG2a antibodies against NP30 increased remarkably, as compared with those of the group immunized with NP30 alone. The concentration of IFN-gamma in supernatant of splenocyte was drastically elevated [the groups immunized with CA-NP30 and NP30 alone were (493.80 +/- 400.74) pg/ml and (39.03 +/- 39.58) pg/ml, respectively], but the concentration of IL-4 showed no significant difference from that of NP30 alone [(27.94 +/- 9.84) pg/ml vs (27.28 +/- 14.44) pg/ml].

CONCLUSIONSNanoparticle CA could act as a vaccine adjuvant of anti-idiotypic antibody NP30 against schistosomiasis. The mechanism could be that CA-NP30 enhances humoral and cellular immune responses in mice.