Cross-presentation of a CMV pp65 epitope by human dendritic cells using bee venom PLA2 as a membrane-binding vector

We have used bee venom phospholipase A2 as a vector to load human dendritic cells ex vivo with a major histocompatibility complex (MHC) class I-restricted epitope fused to its C-terminus. The fusion protein bound to human monocyte-derived dendritic cells and was internalized into early endosomes. In vitro immunization experiments showed that these dendritic cells were able to generate specific CD8 T cell lines against the epitope carried by the fusion protein. Cross-presentation did not require proteasome, transporter associated with antigen processing, or endosome proteases, but required newly synthesized MHC molecules. Comparison of the antigen presentation pathway observed in this study to that followed by other toxins used as vectors is discussed.     

Stereoselectivity of the demethylation of nicotine piperidine homologues by Nicotiana plumbaginifolia cell suspension cultures

The metabolism of (R,S)-N-methylanabasine and (R,S)-N-methylanatabine has been studied in a cell suspension culture of Nicotiana plumbaginifolia. Both substrates are effectively demethylated, anabasine or anatabine, respectively, accumulating in the medium. Similarly, there is strong stereoselectivity for the (R)-isomers of both substrates. The kinetics of metabolism of (R,S)-N-methylanabasine differ significantly from those of nicotine in that no further degradation of the initial demethylation product occurs. (R,S)-N-Methylanatabine, however, shows kinetics closer to those of nicotine, with loss of alkaloid from the system. Further more, (R,S)-N-methylanabasine does not diminish (S)-nicotine demethylation, indicating a lack of competition. However, the metabolism of (S)-nicotine is affected by the presence of (R,S)-N-methylanabasine. Hence, the demethylation of the piperidine homologues of nicotine is seen to be similar but not identical to that of the pyridine analogues. The implications of these different metabolic profiles in relation to the demethylation activity are discussed.     

Anchoring cytokines to cancer cells using diphtheria toxin: better than immunotherapy by gene transfer?

Many cytokines are able to stimulate the antitumor immune response. However, in order to avoid the toxic effects due to systemic injection, it is necessary to concentrate the cytokines in the tumor microenvironment. Current methods, based on the transfer of cytokine genes into tumor cells, still suffer drawbacks. We describe an alternative approach using recombinant cytokines genetically conjugated to a membrane anchor derived from diphtheria toxin. Interleukin-2 anchored to lymphoma and melanoma cells remained displayed on their surface and were not internalized. Injection of these cell preparations to mice led to an immune response able to prevent or slow tumor growth following tumor challenge.     

Isotherm Modelling,Kinetic Study and Optimization of Batch Parameters Using Response Surface Methodology for Effective Removal of Cr(VI) Using Fungal Biomass

Biosorption is a promising alternative method to replace the existing conventional technique for Cr(VI) removal from the industrial effluent. In the present experimental design, the removal of Cr(VI) from the aqueous solution was studied by Aspergillus niger MSR4 under different environmental conditions in the batch systems. The optimum conditions of biosorption were determined by investigating pH (2.0) and temperature (27°C). The effects of parameters such as biomass dosage (g/L), initial Cr(VI) concentration (mg/L) and contact time (min) on Cr(VI) biosorption were analyzed using a three parameter Box–Behnken design (BBD). The experimental data well fitted to the Langmuir isotherm, in comparison to the other isotherm models tested. The results of the D-R isotherm model suggested that a chemical ion-exchange mechanism was involved in the biosorption process. The biosorption process followed the pseudo-second-order kinetic model, which indicates that the rate limiting step is chemisorption process. Fourier transform infrared (FT-IR) spectroscopic studies revealed the possible involvement of functional groups, such as hydroxyl, carboxyl, amino and carbonyl group in the biosorption process. The thermodynamic parameters for Cr(VI) biosorption were also calculated, and the negative ∆Gº values indicated the spontaneous nature of biosorption process.     

A Gammaherpesvirus Uses Alternative Splicing to Regulate Its Tropism and Its Sensitivity to Neutralization

Human gammaherpesviruses are associated with the development of lymphomas and epithelial malignancies. The heterogeneity of these tumors reflects the ability of these viruses to route infection to different cell types at various stages of their lifecycle. While the Epstein Barr virus uses gp42 – human leukocyte antigen class II interaction as a switch of cell tropism, the molecular mechanism that orientates tropism of rhadinoviruses is still poorly defined. Here, we used bovine herpesvirus 4 (BoHV-4) to further elucidate how rhadinoviruses regulate their infectivity. In the absence of any gp42 homolog, BoHV-4 exploits the alternative splicing of its Bo10 gene to produce distinct viral populations that behave differently based on the originating cell. While epithelial cells produce virions with high levels of the accessory envelope protein gp180, encoded by a Bo10 spliced product, myeloid cells express reduced levels of gp180. As a consequence, virions grown in epithelial cells are hardly infectious for CD14+ circulating cells, but are relatively resistant to antibody neutralization due to the shielding property of gp180 for vulnerable entry epitopes. In contrast, myeloid virions readily infect CD14+ circulating cells but are easily neutralized. This molecular switch could therefore allow BoHV-4 to promote either, on the one hand, its dissemination into the organism, or, on the other hand, its transmission between hosts.