Potential of Polyethyleneimine as an Adjuvant To Prepare Long-Term and Potent Antifungal Nanovaccine.

Background: Candida albicans infections are particularly prevalent in immunocompromised patients. Even with appropriate treatment with current antifungal drugs, the mortality rate of invasive candidiasis remains high. Many positive results have been achieved in the current vaccine development. There are also issues such as the vaccine's protective effect is not persistent. Considering the functionality and cost of the vaccine, it is important to develop safe and efficient new vaccines with long-term effects. In this paper, an antifungal nanovaccine with Polyethyleneimine (PEI) as adjuvant was constructed, which could elicit more effective and long-term immunity via stimulating B cells to differentiate into long-lived plasma cells. Materials and Methods: Hsp90-CTD is an important target for protective antibodies during disseminated candidiasis. Hsp90-CTD was used as the antigen, then introduced SDS to "charge" the protein and added PEI to form the nanovaccine. Dynamic light scattering and transmission electron microscope were conducted to identify the size distribution, zeta potential, and morphology of nanovaccine. The antibody titers in mice immunized with the nanovaccine were measured by ELISA. The activation and maturation of long-lived plasma cells in bone marrow by nanovaccine were also investigated via flow cytometry. Finally, the kidney of mice infected with Candida albicans was stained with H&E and PAS to evaluate the protective effect of antibody in serum produced by immunized mice. Results: Nanoparticles (NP) formed by Hsp90-CTD and PEI are small, uniform, and stable. NP had an average size of 116.2 nm with a PDI of 0.13. After immunizing mice with the nanovaccine, it was found that the nano-group produced antibodies faster and for a longer time. After 12 months of immunization, mice still had high and low levels of antibodies in their bodies. Results showed that the nanovaccine could promote the differentiation of B cells into long-lived plasma cells and maintain the long-term existence of antibodies in vivo. After immunization, the antibodies in mice could protect the mice infected by C. albicans. Conclusion: As an adjuvant, PEI can promote the differentiation of B cells into long-lived plasma cells to maintain long-term antibodies in vivo. This strategy can be adapted for the future design of vaccines.

Responses of legume and non-legume crop species to heavy metals in soils with multiple metal contamination.

Field and glasshouse investigations were conducted on the responses of two legumes (field pea and fodder vetch) and three non-leguminous crops (maize, wheat and rapeseed) to the heavy metals Cd, Cr, Zn, Pb, Cu and Mn in soil with multiple metal contamination. In general, the results indicate that the two legumes and wheat were more susceptible to soil metals than were rapeseed and maize. The dry matter yields of field pea, wheat, fodder vetch, rapeseed and maize decreased by up to 169, 123, 113, 93 and 68%, respectively, in metal-contaminated soil. Among the crops, maize had the highest concentrations of Mn, Zn and Cd, rapeseed had the highest concentrations of Cr, the concentration of Cu was highest in fodder vetch, and wheat was the highest accumulator of Pb. The bioconcentration factors (BCF) of the metals decreased as the soil metal loading rates increased except for Cr in fodder vetch and Cd in wheat, whose BCF increased as the metal loading rate increased. Significant linear correlations were found between plant and soil metal concentrations. Patterns of metal distribution in plant parts varied with different crops and metals, with more Cd and Cu accumulating in the grain of wheat than of maize, suggesting that growing wheat would represent a higher risk of food contamination than growing maize in Cd- or Cu-contaminated soil. The results suggest that on sites with multiple metal contamination, growing maize and rapeseed would be safer than growing wheat or legumes. However, maize could perhaps be used for phytoremediation of lightly contaminated soils, providing that the crop residues were safely disposed of.

Soil contamination and plant uptake of heavy metals at polluted sites in China.

We investigated heavy metal contamination in soils and plants at polluted sites in China including some with heavy industries, metal mining, smelting and untreated wastewater irrigation areas. We report our main findings in this paper. The concentrations of heavy metals, including Cd and Zn, in the soils at the investigated sites were above the background levels, and generally exceeded the Government guidelines for metals in soil. The concentrations of metals in plants served to indicate the metal contamination status of the site, and also revealed the abilities of various plant species to take up and accumulate the metals from the soil. Substantial differences in the accumulation of heavy metals were observed among the plant species investigated. Polygonum hydropiper growing on contaminated soils in a sewage pond had accumulated 1061 mg kg(-1) of Zn in its shoots. Rumex acetosa L. growing near a smelter had accumulated more than 900 mg kg(-1) of Zn both in its shoots and roots. Therefore these species have potential for phytoremediation of metal-contaminated sites. Our results indicate the need to elucidate the dynamics of soil metal contamination of plants and the onward movement of metal contaminants into the food chain. Also our results indicate that the consumption of rice grown in paddy soils contaminated with Cd, Cr or Zn may pose a serious risk to human health, because from 24 to 22% of the total metal content in the rice biomass was concentrated in the rice grain. Platanus acerifolia growing on heavily contaminated soil accumulated only very low levels of heavy metals, and this mechanism for excluding metal uptake may have value in crop improvement. Sources of metal entering the environmental matrices studied included untreated wastewater, tailings or slurries and dust depositions from metal ore mining, and sewage sludge. Pb, Zn or Cd concentrations declined with the distance from metal smelter in accordance with a good exponential correlation (R2>0.9), and this shows that metal dust deposition is an important contributor to metal contamination of soils.