Expression of the Myxoma Virus Tumor Necrosis Factor Receptor Homologue and M11L Genes Is Required to Prevent Virus-Induced Apoptosis in Infected Rabbit T Lymphocytes

AbstractMyxoma virus is a leporipoxvirus that causes a highly lethal virulent disease known as myxomatosis in the European rabbit. An important aspect of myxoma virus pathogenesis is the ability of the virus to productively infect lymphocytes and spread to secondary sites via lymphatic channels. We investigated the infection of the CD4+T lymphoma cell line RL-5 with myxoma virus and Shope fibroma virus, a related but benign leporipoxvirus, and observed that myxoma virus, but not Shope fibroma virus, was able to productively infect RL-5 cells. We also discovered that infection of RL-5 cells with Shope fibroma virus or attenuated myxoma virus mutants containing disruptions in either the T2 or the M11L gene resulted in the rapid induction of DNA fragmentation, followed by morphological changes and loss in cell integrity characteristic of cell death by apoptosis. Purified exogenous T2 protein was unable to prevent apoptosis, suggesting that T2 functions intracellularly. Thus, myxoma virus T2, originally described as a secreted homologue of the tumor necrosis factor receptor, and M11L, a novel transmembrane species with no known cellular homologue, function to extend virus host range for replication in rabbit T lymphocytes through the inhibition of apoptosis in infected T lymphocytes

Physical, rheological and sensorial properties, and bloom formation of dark chocolate made with cocoa butter substitute (CBS)

This study examined the physical properties of enzymatically produced palm oil-based cocoa butter substitute (CBS) in dark chocolate. Melting profile, particle size distribution (PSD), rheological, textural behaviors, bloom formation and polymorphism were analysed using differential scanning calorimetry (DSC), master-sizer/polarized light microscopy (PLM), rheometer, stereomicroscope and x-ray diffraction (XRD), respectively. Dark chocolates were produced with cocoa butter (CB, without CBS), 5 g CBS (formulation-1) and 20 g CBS/100 g blend (formulation-2). Both chocolates with addition of CBS showed maximum melting temperature similar to CB-chocolate. However, the peak area and melting enthalpy for formulation-2 were significantly (P<0.05) different from CB-chocolate. Significant differences (P < 0.05) in PSD, flow behavior, hardness and sensory characteristics were observed for formulation-2 whilst no significant difference (P ≥ 0.05) was observed for formulation-1. Stereomicroscope images of all the chocolate samples did not show bloom at 24 °C for up to 8 weeks. Conversely, at 29 ± 1 °C, bloom formation was only observed for CB-chocolate and formulation-1 after two weeks of storage. Noticeable changes in XRD peaks were observed for bloomed chocolate. Overall, chocolate with formulation-1 was similar to CB-chocolate in terms of physical and sensory properties. However, chocolate with formulation-2 exhibited significantly lower sensory profiles particularly taste acceptance and hardness compared to CB-chocolate

Cocoa butter substitute (CBS) produced from palm mid-fraction/palm kernel oil/palm stearin for confectionery fillings

This study investigated the physicochemical properties of ternary mixtures of palm mid‐fraction (PMF):refined bleached deodorized palm kernel oil (RBDPKO):refined bleached deodorized palm stearin (RBDPS) for cocoa butter substitute (CBS). Fatty acid constituents, triacylglycerol constituents, solid fat contents (SFCs), melting behavior, polymorphism and crystal morphology were determined using gas chromatography (GC), high‐performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), pulsed nuclear magnetic resonance (p‐NMR), X‐ray diffraction (XRD) and polarized light microscopy (PLM), respectively. Eight blends of various ratios of ternary mixtures were investigated based on the previously studied binary fat mixtures. The composition of palmitic (P) and oleic (O), POP, and crystal morphology (size and shape) of the PMF/RBDPKO/RBDPS [14.9/59.6/25.5 (%w/w)] mixture were comparable to cocoa butter (CB), while its melting profile (18.5 and 37 °C), SFC at 20 °C and polymorphism were different from CB. The iso‐solid diagrams of the mixture displayed a monotectic effect at 20–25 °C. Therefore, the 14.9/59.6/25.5 PMF/RBDPKO/RBDPS mixture could be used as a CBS in confectionery fillings because of the crystal morphology and monotectic behaviors comparable to those of CB

The Myxoma Poxvirus Protein, M11L, Prevents Apoptosis by Direct Interaction with the Mitochondrial Permeability Transition Pore

M11L, an antiapoptotic protein essential for the virulence of the myxoma poxvirus, is targeted to mitochondria and prevents the loss of mitochondrial membrane potential that accompanies cell death. In this study we show, using a cross-linking approach, that M11L physically associates with the mitochondrial peripheral benzodiazepine receptor (PBR) component of the permeability transition (PT) pore. Close association of M11L and the PBR is also indicated by fluorescence resonance energy transfer (FRET) analysis. Stable expression of M11L prevents the release of mitochondrial cytochrome c induced by staurosporine or protoporphyrin IX (PPIX), a ligand of the PBR. Transiently expressed M11L also prevents mitochondrial membrane potential loss induced by PPIX, or induced by staurosporine in combination with PK11195, another ligand of the PBR. Myxoma virus infection and the associated expression of early proteins, including M11L, protects cells from staurosporine- and Fas-mediated mitochondrial membrane potential loss and this effect is augmented by the presence of PBR. We conclude that M11L regulates the mitochondrial permeability transition pore complex, most likely by direct modulation of the PBR

Influence of soya lecithin, sorbitan and glyceryl monostearate on physicochemical properties of organogels

The objective of this study is to investigate the effects of three different organogelators, sorbitan monostearate (SMS), soya lecithin (SL) and glyceryl monostearate (GMS) prepared at different concentrations (12%, 15% and 18%, w/w) on the structural, thermal and mechanical properties of palm olein (PO)-based organogels. Polarized light microscopy analysis revealed needle-like crystals in SMS-PO, rod-shaped tubules in SL-PO and rosette-like aggregates in GMS-PO organogels. Intermolecular hydrogen bonding and van der Waals forces were the main drivers for the self-aggregation of these organogelators in PO, as observed in Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) results indicated β’-type polymorphic structure in SL-PO and GMS-PO. As the concentration of organogelators increased, there was a corresponding increase in the firmness, gel-sol transition (Tgs) and melting temperatures of the organogels. SMS-PO with amorphous structure had the lowest firmness, thus produced weaker gel with lower thermal stability. The oil binding capacity (OBC) of both SL-PO and GMS-PO were over 90%, significantly higher than that of SMS-PO organogels. These findings indicate that crystallization is the key determinant factor to the final properties of the organogel networks. This is influenced by the molecular structure and the concentration of the organogelators used