Schistosome infection typically induces a polarized Th2 type host immune response. As egg antigen molecules play key roles in this immunoregulatory process, clarifying their functions in schistosomiasis would facilitate the development of vaccine and immunotherapeutic methods. Schistosoma japonicum (Sj) CP1412 (GenBank: AY57074.1) has been identified as a new member of the RNase T2 family with immune regulatory functions. The expression plasmid Sj CP1412-pET28a was constructed and transformed into bacteria for production of recombinant Sj CP1412 protein (rSj CP1412) via IPTG induction. The RNase activity of Sj CP1412 was predicted by bioinformatic analysis and confirmed by digesting the yeast tRNA with rSj CP1412.C57BL/6j mice were immunized with rSj CP1412, and its immune regulatory effects in vivo and in vitro were investigated. Meanwhile, the relationship between the RNase activity of Sj CP1412 and its immune regulation was observed. Sj CP1412 was confirmed as a novel RNase T2 family protein with RNase activity. Immunoblotting and RT-PCR analyses demonstrated Sj CP1412 as a protein exclusively secreted/excreted from eggs, but not cercariae and adult worms. Stimulating RAW264.7 macrophages with rSj CP1412 raised the expression of CD206, Arg-1 and IL-10, which are related to M2 type macrophage differentiation. Stimulating dendritic cells (DCs) with rSjCP1412 failed to induce their maturation, and the recombinant protein also inhibited LPS-stimulated DC maturation. Depletion of Sj CP1412 from soluble egg antigen (SEA) impaired the ability of SEA to induce M2 type polarization of RAW264.7 macrophages. Immunizing mice with rSj CP1412 induced high antibody titers, increased serum IL-4 and TGF-β levels and splenic CD4 + CD25 + Foxp3 + T cells, downregulated serum IFN-γ levels and alleviated the egg granuloma pathology of schistosome infection. In vitro stimulation by rSj CP1412 significantly increased CD4 + CD25 + Foxp3 + T cell numbers in splenocytes of healthy mice. The rSj CP1412 protein with RNase activity inactivated by DEPC failed to induce M2 surface marker CD206 expression in RAW264.7 macrophages. The Sj CP1412 protein expressed specifically in S. japonicum eggs is a novel member of the RNase T2 family. Similar to Omega-1 of Schistosoma mansoni, the Sj CP1412 protein drives polarization of the host Th2 immune response, which is dependent on its RNase activity. These data provide new evidence towards understanding the immune regulatory role of RNase T2 family proteins during schistosome infection.

Schistosomiasis is one of the world’s major public health problems. Besides praziquantel (PZQ), there is currently no other effective treatment against schistosomiasis. The development of new antischistosomal agents to curb the emergence of PZQ resistance should be a high priority. Oxadiazole-2-oxides have been identified as potential antischistosomal reagents, with thioredoxin glutathione reductase (TGR) being one of their molecular targets. To develop novel treatment reagents against Schistosoma japonicum, 30 novel oxadiazole-2-oxides were synthesised and their antischistosomal activities on juvenile and adult S. japonicum were evaluated in vitro and in vivo. Their inhibitory activities against S. japonicum thioredoxin glutathione reductase (SjTGR) were also analysed. Most of the oxadiazole-2-oxides showed good juvenile and adult S. japonica killing activities in vitro. However, the antischistosomal effects of these compounds were not positively correlated with either their inhibition of SjTGR, or with nitric oxide (NO) release. Compounds 4a, 4b, 7c, 13, 16 and 20 resulted in 87.7 %, 83.1 %, 87.1 %, 84.6 %, 90.8 % and 69.5 %, respectively, mortality in the adult worms, when used to treat infected mice at schistosomula stage. These mortality rates were similar to or higher than that of artemisinin. Furthermore, compounds 4a and 16 resulted in 66.7 % and 69.4 % reductions in the worm burdens, respectively, when infected mice were treated at the adult worm stage. These treatment effects were similar to PZQ. No differences in activity of the oxadiazole-2-oxides against female and male adult worms were observed. The toxicity of the oxadiazole-2-oxides on mammalian cells appeared to be similar to, or less than, that of PZQ. The antischistosomal activity of the oxadiazole-2-oxides does not depend on NO production or the inhibition of SjTGR activity. There may be other functional targets of the oxadiazole-2-oxides in S. japonicum. Several of the novel oxadiazole-2-oxides synthesised in this study could be used to develop novel antischistosomal drugs and explore potential molecular targets.

Pomacea canaliculata, one of the 100 most destructive invasive species in the world, and it is an important intermediate host of Angiostrongylus cantonensis. The molluscicides in current use are an effective method for controlling snails. However, most molluscicides have no slow-release effect and are toxic to nontarget organisms. Thus, these molluscicides cannot be used on a large scale to effectively act on snails. In this study, gelatin, a safe and nontoxic substance, was combined with sustained-release molluscicide and was found to reduce the toxicity of niclosamide to nontarget organisms. We assessed the effects of gelatin and molluscicide in controlling P. canaliculata snails and eggs. The results demonstrated that the niclosamide retention time with 1.0% and 1.5% gelatin sustained-release agents reached 20 days. Additionally, the mortality rate of P. canaliculata and their eggs increased as the concentration of the niclosamide sustained-release agents increased. The adult mortality rate of P. canaliculata reached 50% after the snails were exposed to gelatin with 0.1 mg/L niclosamide for 48 h. The hatching rate of P. canaliculata was only 28.5% of the normal group after the treatment was applied. The sustained-release molluscicide at this concentration was less toxic to zebrafish, which means that this molluscicide can increase the safety of niclosamide to control P. canaliculata in aquatic environments. In this study, we explored the safety of using niclosamide sustained-release agents with gelatin against P. canaliculata. The results suggest that gelatin is an ideal sustained-release agent that can provide a foundation for subsequent improvements in control of P. canaliculata.

Background: Schistosomiasis remains a major public health concern that afflicts millions of people worldwide. Low levels of Schistosoma infection require more sensitive diagnostic methods. In this study, a time-resolved fluoroimmunoassay (TRFIA) was developed for detecting the signal transduction protein 14-3-3, a circulating antigen of Schistosoma japonicum. Results: The detection limit of 14-3-3-TRFIA was 0.78 ng/ml, with a linear measurement range from 0.78 to 800 ng/ml. The average intra-assay and inter-assay variability of this TRFIA was 8.9% and 12.2% respectively, and the mean recovery rate ranged from 92.1% to 115.5%. Within the first 21 days post-infection in rabbits, the positive rates of the 14-3-3-TRFIA were distinctly higher compared to ELISA. All these findings illustrate that 14-3-3-TRFIA has a higher detection efficacy and is a good early diagnostic method for active Schistosoma infection. Conclusions: A sandwich TRFIA for detecting the circulating antigen 14-3-3 of S. japonicum has been developed, and has demonstrated to be a good potential diagnostic method for schistosomiasis.

Background: Schistosomiasis remains an important public health problem throughout tropical and subtropical countries. Humans are infected through contact with water contaminated with schistosome cercariae. Therefore, issuing early warnings on the risk of infection is an important preventive measure against schistosomiasis. Sentinel mice are used to monitor water body infestations, and identifying appropriate antibody responses to schistosome antigens for early detection of infection would help to improve the efficiency of this system. In this study we explored the potential of detecting antibodies to the hydrophilic domain (HD) of the 23-kDa membrane protein (Sj23HD) and soluble egg antigen (SEA) ofSchistosome japonicumfor early detection of schistosome infection in sentinel mice.Results: Development of IgM and IgG antibody levels against Sj23HD and SEA inS. japonicuminfected mice was evaluated over the course of 42 days post-infection by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. The Sj23HD and SEA specific IgM and IgG levels in mice all increased gradually over the course of infection, but IgM and IgG antibodies against Sj23HD presented earlier than those against SEA. Furthermore, the rates of positive antibody responses against Sj23HD were higher than those against SEA in the early stage of schistosome infection, suggesting that the likelihood of detecting early infection using anti-Sj23HD responses would be higher than that with anti-SEA responses. The use of immunoblotting could further improve the early detection of schistosome infection due to its greater sensitivity and specificity compared to ELISA. Additionally, the levels of Sj23HD and SEA specific antibodies positively correlated with the load of cercariae challenge and the duration of schistosome infection.Conclusions: This study demonstrated that antibody responses to the Sj23HD antigen could be monitored for early detection of schistosome infection in mice, especially by immunoblotting which demonstrated greater sensitivity and specificity than ELISA for detection Sj23HD antibodies.

Schistosomiasis, typically characterized by chronic infection in endemic regions, has the potential to affect liver tissue and pose a serious threat to human health. Detecting and screening for this disease early on is crucial for its prevention and control. However, existing methods encounter challenges such as low sensitivity, time-consuming processes, and complex sample handling. To address these challenges, we report a soluble egg antigen (SEA)-based functionalized gridless and meander-type AlGaN/GaN high electron mobility transistors (HEMT) sensor for the highly sensitive detection of antibodies to Schistosoma japonicum. Immobilization of the self-assembled membrane on the gate surface was verified using a semiconductor parameter analyzer, scanning electron microscope (SEM), and atomic force microscopy (AFM). The developed biosensor demonstrates remarkable performance in detecting anti-SEA, exhibiting a linear concentration range of 10 ng/mL to 100 μg/mL and a sensitivity of 0.058 mA/log (ng/mL). It also exhibits similar excellent performance in serum systems. With advantages such as rapid detection, high sensitivity, miniaturization, and label-free operation, this biosensor can fulfill the requirements for blood defense.