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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2018

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Abstract

Hepatitis B Virus (HBV) infection can be prevented by vaccination. Vaccines containing the small (S)envelope protein are currently used in universal vaccination programs and achieve protective immuneresponse in more than 90% of recipients. However, new vaccination strategies are necessary for successfulimmunization of the remaining non- or low-responders. We have previously characterized a novel HBVchimeric antigen, which combines neutralization epitopes of the S and the preS1 domain of the large (L)envelope protein (genotype D). The S/preS121–47chimera produced in mammalian cells and Nicotianabenthamiana plants, induced a significantly stronger immune response in parenterally vaccinated micethan the S protein. Here we describe the transient expression of the S/preS121–47antigen in an edibleplant, Lactuca sativa, for potential development of an oral HBV vaccine. Our study shows that oral admin-istration of adjuvant-free Lactuca sativa expressing the S/preS121–47antigen, three times, at 1lg/dose,was sufficient to trigger a humoral immune response in mice. Importantly, the elicited antibodies wereable to neutralize HBV infection in an NTCP-expressing infection system (HepG2-NTCP cell line) moreefficiently than those induced by mice fed on Lactuca sativa expressing the S protein. These results sup-port the S/preS121–47antigen as a promising candidate for future development as an edible HBV vaccine.

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Abstract

Degradation of organic chemicals in natural soils depends on oxidation-reduction conditions. To protect our groundwater resources we need to understand the degradation processes under anaerobic conditions. Available iron and manganese oxides are used as electron acceptors for anaerobic degradation and are reduced to the dissolved form of metallic cations in pore water. To monitor this process is a challenge, because anaerobic conditions are difficult to sample directly without introducing oxygen. A few studies have shown an impact of iron reduction on spectral induced polarisation (SIP) signature, often associated with bacterial growth. Our objective is to study the impact of iron and manganese oxide dissolution, caused by degradation of an organic compound, with spectral induced polarisation signatures. Twenty-six vertical columns (30 cm high, inner diameter 4.6 cm) were filled with a sand rich in oxides (manganese and iron) with a static water table in the middle. In half of the columns, a 2 cm high contaminated layer was installed just above the water table. As the contaminant degrades, the initial oxygen is consumed and anaerobic conditions form Every three days over a period of one month, spectral induced polarisation (twenty frequencies between 5mHz and 10 kHz) data were collected on six columns: three contaminated replicates and three control replicates. Chemical analysis was done on twenty columns assigned for destructive water sampling, ten contaminated columns and ten control. The results show an increase of the real conductivity associated with the degradation processes, independent of frequency. Compared with the pore water electrical conductivity in the saturated zone, the real conductivity measurement revealed the formation of surface conductivity before iron was released in the pore water. In parallel, we also observed an evolution of the imaginary conductivity in both saturated and unsaturated zones at frequencies below 1 Hz. Overall, the anaerobic reduction of iron and manganese oxide during the organic degradation increased both the conductive and polarisation component of the complex conductivity.