Gravitational vortices and clump formation in Saturn's F ring during an encounter with Prometheus.

Saturn rings are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-ring have been attributed to encounters by Prometheus on the F ring, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-ring structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated growth and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km width and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet.

Local immune responses following nasal delivery of an adjuvanted influenza vaccine.

A key barrier to producing effective nasal immunisations is the low efficiency of uptake of vaccines across the nasal mucosa. Using a recently developed cannulation system, we examined the antibody response induced by nasal immunisation with an ISCOMATRIX influenza vaccine. This showed for the first time, that following nasal vaccination, specific antibodies enter the circulation of primed animals via the draining lymphatics as a wave that peaks approximately 5-6 days after vaccination. These antibodies included some of the IgA isotype and possessed functional haemagglutination inhibition activity. These responses, though small, were induced using a very simple delivery system, emphasising the applicability of this cannulation model for evaluation of excipients and adjuvants aimed at improving intranasal vaccine efficacy.

A sheep cannulation model for evaluation of nasal vaccine delivery.

We have developed and validated a novel model to investigate the efficacy of nasal vaccine delivery. Based on lymphatic cannulation of the tracheal lymph trunk of sheep, the model allows collection of lymph draining from the Nasal Associated Lymphoid Tissue. The model is suitable for determining both the amount of material that is absorbed into the lymphatic system, following intra-nasal delivery and the immune response that occurs following vaccination into the nasal area. The cell populations that track in this duct were phenotyped and found to be similar to those previously reported to be present in efferent lymph draining from peripheral lymph nodes. Following intra-nasal spray, we demonstrated that the amount of material recovered in draining lymph is only a very small fraction of the total delivered. Nevertheless, intra-nasal spraying of a vaccine could activate local immune cells. The method described will be invaluable for optimising intra-nasal delivery systems by allowing a separate optimisation of vaccine uptake and immune responses induction.

Intranasal vaccination with ISCOMATRIX adjuvanted influenza vaccine.

Mucosal delivery of inactivated vaccines that are able to elicit protective immune responses against respiratory diseases has been a long time goal of vaccinologists. Such vaccines would enable a more appropriate means of vaccination against respiratory diseases than those currently delivered by a parenteral route. The intranasal delivery of inactivated influenza vaccine plus the ISCOMATRIX (IMX) adjuvant, simply mixed together, was able to induce serum haemagglutination inhibition (HAI) titres in mice far superior to those obtained with unadjuvanted vaccine delivered subcutaneously. Furthermore, the IMX adjuvanted vaccine delivered intranasally induced mucosal IgA responses in the lung, nasal passages and large intestine, together with high levels of serum IgA. Intranasal delivery of IMX adjuvanted influenza vaccine in sheep gave antibody responses in both serum and nasal secretions that surpassed the levels obtained with unadjuvanted vaccine administered subcutaneously. These observations suggest that it may be possible to induce effective immunity to influenza in humans by intranasal vaccination with an IMX adjuvanted inactivated vaccine.