Enhanced transmission efficiency of magneto-inductive wave propagating in non-homogeneous 2-D magnetic metamaterial array

In this work, we investigate the propagation of magneto-inductive waves (MIWs) in ordering magnetic metamaterial (MM) structures. The proposed non-homogeneous MM slab consists of 9 × 9 MM unit cells constructed from a five-turn spiral embedded on an FR-4 substrate. External capacitors with the value of 40 pF or 50 pF were added to control the resonant frequency of each unit cell in accordance with the waveguide configurations. The characteristics of metamaterial structures, such as negative permeability, current ratio, transmission response, and field distribution in the waveguide, have been thoroughly analyzed by simulation and experiment. Because of the strong magnetic field confinement in the waveguide, the transmittance after nine elements of the non-homogeneous MM slab is 5.2 times greater than that of the homogeneous MM slab. This structure can be applied to the planar near-field wireless power transfer, position sensor, and low-frequency communication.

Divergence of delta and beta variants and SARS-CoV-2 evolved in prolonged infection into distinct serological phenotypes

SARS-CoV-2 continues to evolve variants of concern (VOC) which escape antibody neutralization and have enhanced transmission. One variant may escape immunity elicited by another, and the delta VOC has been reported to escape beta elicited immunity. Systematic mapping of the serological distance of current and emerging variants will likely guide the design of vaccines which can target all variants. Here we isolated and serologically characterized SARS-CoV-2 which evolved from an ancestral strain in a person with advanced HIV disease and delayed SARS-CoV-2 clearance. This virus showed evolving escape from self antibody neutralization immunity and decreased Pfizer BNT162b2 vaccine neutralization sensitivity. We mapped neutralization of evolved virus and ancestral, beta and delta variant viruses by antibodies elicited by each VOC in SARS-CoV-2 convalescent individuals. Beta virus showed moderate (7-fold) and delta slight escape from neutralizing immunity elicited by ancestral virus infection. In contrast, delta virus had stronger escape from beta elicited immunity (12-fold), and beta virus even stronger escape from delta immunity (34-fold). Evolved virus had 9-fold escape from ancestral immunity, 27-fold escape from delta immunity, but was effectively neutralized by beta immunity. We conclude that beta and delta are serologically distant, further than each is from ancestral, and that virus evolved in prolonged infection during advanced HIV disease is serologically close to beta and far from delta. These results suggest that SARS-CoV-2 is diverging into distinct serological phenotypes and that vaccines tailored to one variant may become vulnerable to infections with another.

Long-Term Evolution of SARS-CoV-2 in an Immunocompromised Patient with Non-Hodgkin Lymphoma

Tracking the within-patient evolution of SARS-CoV-2 is key to understanding how this pandemic virus shapes its genome toward immune evasion and survival. In the present study, by monitoring a long-term COVID-19 immunocompromised patient, we observed the concurrent emergence of mutations potentially associated with immune evasion and/or enhanced transmission, mostly targeting the SARS-CoV-2 key host-interacting protein and antigen.

Enhanced fitness of SARS-CoV-2 variant of concern B.1.1.7, but not B.1.351, in animal models

Emerging variants of concern (VOCs) drive the SARS-CoV-2 pandemic. We assessed VOC B.1.1.7, now prevalent in several countries, and VOC B.1.351, representing the greatest threat to populations with immunity to the early SARS-CoV-2 progenitors. B.1.1.7 showed a clear fitness advantage over the progenitor variant (wt-S614G) in ferrets and two mouse models, where the substitutions in the spike glycoprotein were major drivers for fitness advantage. In the superspreader hamster model, B.1.1.7 and wt-S614G had comparable fitness, whereas B.1.351 was outcompeted. The VOCs had similar replication kinetics as compared to wt-S614G in human airway epithelial cultures. Our study highlights the importance of using multiple models for complete fitness characterization of VOCs and demonstrates adaptation of B.1.1.7 towards increased upper respiratory tract replication and enhanced transmission in vivo.

SARS-CoV-2 B.1.1.7 Infection of Syrian Hamster Does Not Cause More Severe Disease, and Naturally Acquired Immunity Confers Protection

The rapid emergence of several variants of concern of SARS-CoV-2 calls for evaluations of viral fitness and pathogenicity in animal models in order to understand the mechanism of enhanced transmission and the possible increases in morbidity and mortality rates. Here, we demonstrated that immunity naturally acquired through a prior infection with the first-wave variant does confer nearly complete protection against the B.1.1.7 variant in Syrian hamsters upon reexposure.