It is revealed that the unique properties of ultrathin metasurface resonators can improve magnetic resonance imaging dramatically. A metasurface formed when an array of metallic wires is placed inside a scanner under the studied object and a substantial enhancement of the radio-frequency magnetic field is achieved by means of subwavelength manipulation with the metasurface, also allowing improved image resolution.

IntroductionLive attenuated influenza vaccines (LAIVs) are being developed to protect humans against future epidemics and pandemics. This study describes the results of a double–blinded randomized placebo–controlled phase I clinical trial of cold–adapted and temperature sensitive H7N3 live attenuated influenza vaccine candidate in healthy seronegative adults.ObjectiveThe goal of the study was to evaluate the safety, tolerability, immunogenicity and potential shedding and transmission of H7N3 LAIV against H7 avian influenza virus of pandemic potential.Methods and FindingsTwo doses of H7N3 LAIV or placebo were administered to 40 randomly divided subjects (30 received vaccine and 10 placebo). The presence of influenza A virus RNA in nasal swabs was detected in 60.0% and 51.7% of subjects after the first and second vaccination, respectively. In addition, vaccine virus was not detected among placebo recipients demonstrating the absence of person–to–person transmission. The H7N3 live attenuated influenza vaccine demonstrated a good safety profile and was well tolerated. The two–dose immunization resulted in measurable serum and local antibody production and in generation of antigen–specific CD4+ and CD8+ memory T cells. Composite analysis of the immune response which included hemagglutinin inhibition assay, microneutralization tests, and measures of IgG and IgA and virus–specific T cells showed that the majority (86.2%) of vaccine recipients developed serum and/or local antibodies responses and generated CD4+ and CD8+ memory T cells.ConclusionsThe H7N3 LAIV was safe and well tolerated, immunogenic in healthy seronegative adults and elicited production of antibodies broadly reactive against the newly emerged H7N9 avian influenza virus.Trial registrationClinicalTrials.gov NCT01511419

H2N2 influenza viruses have not circulated in the human population since 1968, but they are still being regularly detected in the animal reservoir, suggesting their high pandemic potential. To prepare for a possible H2N2 pandemic, a number of H2N2 vaccine candidates have been generated and tested in preclinical and clinical studies. Here we describe the results of a randomized, double-blind placebo-controlled phase 1 clinical trial of an H2N2 live attenuated influenza vaccine (LAIV) candidate prepared from a human influenza virus isolated in 1966. The vaccine candidate was safe and well-tolerated by healthy adults, and did not cause serious adverse events or an increased rate of moderate or severe reactogenicities. The H2N2 vaccine virus was infectious for Humans. It was shed by 78.6% and 74.1% volunteers after the first and second dose, respectively, most probably due to the human origin of the virus. Importantly, no vaccine virus transmission to unvaccinated subjects was detected during the study. We employed multiple immunological tests to ensure the adequate assessment of the H2N2 pandemic LAIV candidate and demonstrated that the majority (92.6%) of the vaccinated subjects responded to the H2N2 LAIV in one or more immunological tests, including 85.2% of subjects with antibody responses and 55.6% volunteers with cell-mediated immune responses. In addition, we observed strong correlation between the H2N2 LAIV virus replication in the upper respiratory tract and the development of antibody responses.

Live attenuated influenza vaccine (LAIV) represent reassortant viruses with hemagglutinin (HA) and neuraminidase (NA) gene segments inherited from circulating wild-type (WT) parental influenza viruses recommended for inclusion into seasonal vaccine formulation, and the 6 internal protein-encoding gene segments from cold-adapted attenuated master donor viruses (genome composition 6:2). In this study, we describe the obstacles in developing LAIV strains while taking into account the phenotypic peculiarities of WT viruses used for reassortment. Genomic composition analysis of 849 seasonal LAIV reassortants revealed that over 80% of reassortants based on inhibitor-resistant WT viruses inherited WT NA, compared to 26% of LAIV reassortants based on inhibitor-sensitive WT viruses. In addition, the highest percentage of LAIV genotype reassortants was achieved when WT parental viruses were resistant to non-specific serum inhibitors. We demonstrate that NA may play a role in influenza virus sensitivity to non-specific serum inhibitors. Replacing NA of inhibitor-sensitive WT virus with the NA of inhibitor-resistant master donor virus significantly decreased the sensitivity of the resulting reassortant virus to serum heat-stable inhibitors.

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