Isolation and characterization of a new simian rotavirus, YK-1

BACKGROUND: To effectively analyze the requirements for protection to rotavirus infection, a reliable animal model that reasonably mimics infection and disease in humans is needed. A requirement for an effective animal model is the availability of appropriate rotavirus stocks for challenge. RESULTS: A new simian rotavirus, designated YK-1, was isolated from a 2-year-old immunodeficient pigtailed macaque with chronic diarrhea. YK-1 was distinguishable by electropherotype from the other simian rotavirus strains, SA11 and RRV. One variant of YK-1, clone 311, which was isolated after adaptation and plaque purification in cell cultures, displayed an unusual RNA electropherotype with an abnormally migrating gene 11 segment. Sequence analysis demonstrated a genetic rearrangement that involved a partial duplication of the gene 11 ORF encoding NSP5. YK-1 was identified as a Group A rotavirus belonging to subgroup 1. To further characterize the YK-1 strain, the genes encoding VP4, VP7, and NSP4 were sequenced. Analysis of VP4 and VP7 gene fragments suggests that this strain is a G3P[3] rotavirus and is closely related to the simian rotavirus strain RRV. Serotype analysis also identified YK-1 as a G3 rotavirus. The NSP4 genotype of YK-1 is C, the same genotype as RRV. CONCLUSION: This newly isolated rotavirus, YK-1, is being used to establish a nonhuman primate model for studying the infectivity, immunity, and pathogenesis of rotavirus and for evaluating candidate rotavirus vaccines

Active excitation and damping rate measurement of intermediate-n Toroidal Alfvén Eigenmodes in JET, C-Mod and MAST plasmas

The stability properties of Alfvén Eigenmodes (AEs) are investigated directly using external antenna excitation and detection of stable modes in a variety of plasma configurations in different devices. Dedicated methods to measure the AE damping rate separately from the fast ion drive have been pioneered at JET, using low toroidal mode number internal saddle coil antennas. Other experiments have since installed localised in-vessel antennas to drive and detect MHD modes in the Alfvén frequency range, first on C-Mod, then on MAST. Experiments on C-Mod proved for the first time that intermediate-n TAEs can be driven and detected, and point out significant differences with respect to the low-n regime on JET in the values and scaling of the damping rate with plasma parameters, e.g. the edge shape. On JET, a new antenna system, comprising two assemblies of four toroidally spaced coils each, was developed to replace the low-n saddle coil structure and excite AE modes in the toroidal mode number range that is expected to be most unstable in ITER, with n up to ~10. Experiments with the new JET antennas confirm that excitation is possible in a large volume plasma, together with real time tracking of core modes throughout the limiter and divertor phases of high performance discharges, with significant additional heating. The similarities and differences between the active MHD antenna systems, as well as a comparison of the results on C-Mod, JET and MAST are illustrated. Both C-Mod and JET results underline the fact that a precise reconstruction of the mode structure and its spectrum, important for a quantitative comparison with theoretical models, represents a significant challenge in the intermediate-n range and in the presence of several modes