Inconsistent Protective Efficacy and Marked Polymorphism Limits the Value of Schistosoma japonicum Tetraspanin-2 as a Vaccine Target

Schistosoma mansoni tetraspanin 2 (Sm-TSP-2) is considered a lead target for vaccine development against schistosomiasis mansoni because: (1) It is located in the schistosome tegument and is involved in tegument formation; (2) It is strongly recognized by IgG1 and IgG3 antibodies from individuals putatively resistant to schistosome infection, but not chronically infected people, and (3) It induces high levels of protection against challenge infection in the mouse model. We amplified 211 homologous TSP-2 sequences from male and female S. japonicum worms, which revealed 7 different cDNA subclasses. We expressed in E. coli a region of one of the clusters which exhibited a high frequency of transcription in female worms, and showed the purified recombinant protein (Sj-TSP-2e) was recognised by 43.1% of sera obtained from confirmed schistosomiasis japonica patients. Vaccination of mice with the recombinant protein induced high levels of IgG1 and IgG2 antibodies, but no consistent protective efficacy against challenge infection was elicited in three independent trials. The highly polymorphic nature of the Sj-TSP-2 gene at the transcriptional level may limit the value of Sj-TSP-2 as a target for future S. japonicum vaccine development. Further analysis of the distribution of the different subclasses/alleles of the Sj-TSP-2 gene in S. japonicum populations from different endemic areas would be informative

Nonparametric Evaluation of Dynamic Disease Risk: A Spatio-Temporal Kernel Approach

Quantifying the distributions of disease risk in space and time jointly is a key element for understanding spatio-temporal phenomena while also having the potential to enhance our understanding of epidemiologic trajectories. However, most studies to date have neglected time dimension and focus instead on the “average” spatial pattern of disease risk, thereby masking time trajectories of disease risk. In this study we propose a new idea titled “spatio-temporal kernel density estimation (stKDE)” that employs hybrid kernel (i.e., weight) functions to evaluate the spatio-temporal disease risks. This approach not only can make full use of sample data but also “borrows” information in a particular manner from neighboring points both in space and time via appropriate choice of kernel functions. Monte Carlo simulations show that the proposed method performs substantially better than the traditional (i.e., frequency-based) kernel density estimation (trKDE) which has been used in applied settings while two illustrative examples demonstrate that the proposed approach can yield superior results compared to the popular trKDE approach. In addition, there exist various possibilities for improving and extending this method

A Pilot Study for Control of Hyperendemic Cystic Hydatid Disease in China

Cystic hydatid disease (CHD), caused by the dog tapeworm, Echinococcus granulosus, is hyperendemic in western China. However, until recently the disease had been grossly neglected there due primarily to a weak economy and the primitive control measures used. The situation is now changing because of China's growing economy and the availability of the cheap and effective drug praziquantel (PZQ), which makes control programs practicable through mass preventive treatment of dogs in these endemic areas. In this study, we used a strategy to prevent parasite eggs from being released into the environment by dosing dogs monthly with baited PZQ and culling unwanted and stray dogs, as a result of which infection in humans and domestic animals can be reduced considerably. We undertook a pilot control study in two counties involving a population of 255,504 in 52,300 households and 30,380 dogs in Xinjiang, China, and showed that monthly PZQ treatment of dogs is an efficient, practicable, and affordable control method for communities to reduce considerably hyperendemic CHD. As a result, the Chinese Ministry of Health has extended the control measure to 117 counties in western China

Cloning and Characterisation of Schistosoma japonicum Insulin Receptors

Background: Schistosomes depend for growth and development on host hormonal signals, which may include the insulin signalling pathway. We cloned and assessed the function of two insulin receptors from Schistosoma japonicum in order to shed light on their role in schistosome biology

Environmental drivers of the leaf nitrogen and phosphorus stoichiometry characteristics of critically endangered Acer catalpifolium

Acer catalpifolium is a perennial deciduous broad-leaved woody plant, listed in the second-class protection program in China mainly distributed on the northwest edge of Chengdu plain. However, extensive anthropogenic disturbances and pollutants emissions (such as SO2, NH3 and NOX) in this area have created a heterogeneous habitat for this species and its impacts have not been systematically studied. In this study, we investigated the leaf nitrogen (N) and phosphorus (P) content of A. catalpifolium in the natural distribution areas, and a series of simulation experiments (e.g., various water and light supply regimes, different acid and N deposition levels, reintroduction management) were conducted to analyze responses of N and P stoichiometric characteristics to environmental changes. The results showed that leaf nitrogen content (LNC) was 14.49 ~ 25.44 mg g-1, leaf phosphorus content (LPC) was 1.29~3.81 mg g-1 and the N/P ratio of the leaf (L-N/P) was 4.87~13.93. As per the simulation experiments, LNC of A. catalpifolium is found to be relatively high at strong light conditions (80% of full light), high N deposition (100 and 150 kg N ha-1), low acidity rainwater, reintroduction to understory area or N fertilizer applications. A high level of LPC was found when applied with 80% of full light and moderate N deposition (100 kg N ha-1). L-N/P was high under severe shade (8% of full light), severe N deposition (200 kg N ha-1), and reintroduction to gap and undergrowth habitat; however, low L-N/P was observed at low acidity rainwater or P fertilizer application. The nutrient supply facilitates corresponding elements uptake, shade tends to induce P limitation and soil acidification shows N limitation. Our results provide theoretical guidance for field management and nutrient supply regimes for future protection, population rejuvenation of this species and provide guidelines for conservation and nutrient management strategies for the endangered species