[Objective] To determine the effect of Schistosoma japonicum infection on the testoterone level in the sera from male C57BL/6 mice. [Methods] Radioimmunoassay was used to examine testosterone levels in sera of 9 male mice experimentally infected with Schistosoma japonicum. [Results] The serum testosterone levels reduced significantly in all experimentally infected animals 45 days after infection, as compared with the uninfected controls. [Conclusion] Infection with Schistosoma japonicum decreases testosterone levels in the mouse host.

To investigate the prevalence of specific anti-Toxocara IgG and IgE antibodies in ocular toxocariasis by means of ELISA and Western blotting, serum samples of 105 cases with uveitis of unidentified etiology were randomly selected from our stocked sera, which were referred to the Section of of Environmental Parasitology of Tokyo Medical and Dental University for detection of the anti-Toxocara antibody. By using ELISA, 82 of them (78.1%) were negative for both IgG and IgE antibodies, 12 (11.4%) were positive only for IgG, three (2.9%) were positive only for IgE, and eight (7.6%) were positive for IgG and IgE. Among the positive samples, as demonstrated by western bloting the IgG reacting bands were found to distribute in the whole range of molecular weights (97.2-14.3kDa)of excretory-secretory products of T. canis larvae. On the other hand,IgE antigenic molecules were concentrated on a relatively narrow range from 45kDa to 29kDa. In this study, we clearly demonstrated that some of the patients with uveitis showed specific anti-Toxocara IgE antibody but not IgG antibody in serum sample, suggesting that the demonstration of specific IgE antibody should be considered for the precise diagnosis of ocular toxocariasis. Further studies are needed to clarify the diagnosis significance of specific IgE antibody in ocular toxocariasis.

Background: Plasmodium, the causative agent of malaria, exports many proteinsto the surface of the infected red blood cell (iRBC) in order to modify ittoward a structure more suitable for parasite development and survival. Onesuch exported protein, SURFIN_4.2, from the parasite of humanmalignant malaria, P. falciparum, wasidentified in the trypsin-cleaved protein fraction from the iRBC surface, andis thereby inferred to be exposed on the iRBC surface. SURFIN_4.2 alsolocalize to Maurer’s clefts – parasite-derived membranous structures establishedin the RBC cytoplasm and tethered to the RBC membrane – and their role intrafficking suggests that they are a pathway for SURFIN_4.2 transportto the iRBC surface. It has not been determined the participation of proteindomains and motifs within SURFIN_4.2 in transport from Maurer’sclefts to the iRBC surface; and herein we examined if the SURFIN_4.2 intracellularregion containing tryptophan-rich (WR) domain is required for its exposure on theiRBC surface. Results: We generated two transgenic parasite lineswhich express modified SURFIN_4.2, with or without a part of the intracellularregion. Both recombinant SURFIN_4.2 proteins were exported to Maurer’sclefts. However, only SURFIN_4.2 possessing the intracellular region wasefficiently cleaved by surface treatment of iRBC with proteinase K. Conclusions: These results indicate that SURFIN_4.2is exposed on the iRBC surface and that the intracellular region containing WRdomain plays arole on the transport from Maurer’s clefts to the iRBC membrane.

Background: Plasmodium, the causative agent of malaria, exports many proteins to the surface of the infected red blood cell (iRBC) in order to modify it toward a structure more suitable for parasite development and survival. One such exported protein, SURFIN_4.2, from the parasite of human malignant malaria, P. falciparum, was identified in the trypsin-cleaved protein fraction from the iRBC surface, and is thereby inferred to be exposed on the iRBC surface. SURFIN_4.2 also localize to Maurer’s clefts—parasite-derived membranous structures established in the RBC cytoplasm and tethered to the RBC membrane—and their role in trafficking suggests that they are a pathway for SURFIN_4.2 transport to the iRBC surface. It has not been determined the participation of protein domains and motifs within SURFIN_4.2 in transport from Maurer’s clefts to the iRBC surface; and herein we examined if the SURFIN_4.2 intracellular region containing tryptophan-rich (WR) domain is required for its exposure on the iRBC surface. Results: We generated two transgenic parasite lines which express modified SURFIN_4.2, with or without a part of the intracellular region. Both recombinant SURFIN_4.2 proteins were exported to Maurer’s clefts. However, only SURFIN_4.2 possessing the intracellular region was efficiently cleaved by surface treatment of iRBC with proteinase K. Conclusions: These results indicate that SURFIN_4.2 is exposed on the iRBC surface and that the intracellular region containing WR domain plays a role on the transport from Maurer’s clefts to the iRBC membrane.

Mosquito eggs laid within two hours are necessary for transgenic (injection) studies, because mosquito eggs become hard after that period. Thus, in order to have eggs available within this two-hour window, it is important for transgenic studies to understand the ovipositional behavior of Anopheles gambiae s.s.. In the present study, the ovipositional behavior of An. gambiae s.s. (Kisumu) was investigated in several different conditions: age of mosquitoes, time post blood meal to access oviposition substrate, and light conditions. Two groups of mosquitoes, 3–5 day old and 9–11 day old mosquitoes were blood-fed. For those mosquito groups, an oviposition dish was set either at 48 hours or 72 hours after the blood meal either in a light condition or in an artificial dark condition. The number of laid eggs was compared among different conditions. The 3–5 day old mosquitoes apparently produced a higher number of eggs than 9–11 day old ones, while there was no significant difference between the 2 groups. The number of laid eggs per one surviving blood-fed mosquito in the dark condition was significantly higher than that in the light condition (p = 0.03). Providing an oviposition dish at 72 hours after blood meal resulted in a significantly higher number of laid eggs per one surviving blood-fed mosquito compared to providing an oviposition dish at 48 hours after blood meal (p = 0.03). In conclusion, the optimal condition to have readily available egg supply in the present study for transgenic analysis was as follows: 3–5 days old mosquitoes with an oviposition dish placed at 72 hours after the blood meal in a dark environment.

Mosquito eggs laid within two hours are necessary for transgenic (injection) studies, because mosquito eggs become hard after that period. Thus, in order to have eggs available within this two-hour window, it is important to understand the ovipositional behavior of Anopheles gambiae s.s.. In the present study, the ovipositional behavior of An. gambiae s.s. (Kisumu) was investigated in several different conditions: age of mosquitoes, time post blood meal to access oviposition substrate, and light conditions. Two groups of mosquitoes, 3–5 days old and 9–11 days old were blood-fed. For those mosquito groups, an oviposition dish was set either at 48 hours or 72 hours after the blood meal either in a light condition or in an artificial dark condition. The number of laid eggs was compared among the different conditions. The 3–5 day-old mosquitoes apparently produced a higher number of eggs than 9–11 day-old mosquitoes, while there was no significant difference between the two groups. The number of laid eggs per one surviving blood-fed mosquito in the dark condition was significantly higher than that in the light condition (p = 0.03). Providing an oviposition dish at 72 hours after blood meal resulted in a significantly higher number of laid eggs per one surviving blood-fed mosquito than at 48 hours after blood meal (p = 0.03). In conclusion, the optimal condition to have readily available egg supply for transgenic analysis was as follows: 3–5 day-old mosquitoes with an oviposition dish placed at 72 hours after the blood meal in a dark environment.

Immunobiological roles of schistosome eggs during murine experimental infection were investigated with special reference to the induction of basophilic leukocytes. After single- or bisexual infection with Schistosoma mansoni in BALB⁄c mice, splenomegaly and liver granulomas were observed only in bisexual infection in parallel with deposition of mature parasite eggs. Comparison of the kinetics of basophil response revealed a marked increase in number in the bone marrow of mice with bisexual infection at the 7^th week post infection as opposed to a marginal increase in single- sex infections. In the spleen, bimodal response was observed in the basophil responses; a small but repeatable peak at the 4^th week after infection, increasing again at the 8^th week, which corresponded to the initiation and maturation of parasite eggs in the affected organs of infected mice. The same time course was observed for IL-4 production by the splenocytes from mice of bisexual infection. To obtain more concrete evidence of the role of eggs in the induction of basophils, we tested using the intravenous egg injection model. Injection of eggs induced basophilia, and it was accompanied by the up-regulation of IL-4 production in splenocytes from the 8^th day. Basophils induced in this model showed a high level of IL-4 production confirmed by flow cytometry, while faint levels of IL-4 production were observed for CD4⁺ T cells at this time point. In addition, we demonstrate that egg deposition is the trigger of basophil induction and activation in the murine experimental model of S. mansoni infection, which might play an essential role in the initiation of Th1⁄2 conversion during the course of S. mansoni infection in vivo.