Expression of a single inhibitory Ly49 receptor is sufficient to license NK cells for effector functions.

Natural killer (NK) cells recognize target cells through germline-encoded activation and inhibitory receptors enabling effective immunity against viruses and cancer. The Ly49 receptor family in the mouse and killer immunoglobin-like receptor family in humans play a central role in NK cell immunity through recognition of MHC class I and related molecules. Functionally, these receptor families are involved in licensing and rejection of MHC-I-deficient cells through missing-self. The Ly49 family is highly polymorphic, making it challenging to detail the contributions of individual Ly49 receptors to NK cell function. Herein, we showed mice lacking expression of all Ly49s were unable to reject missing-self target cells in vivo, were defective in NK cell licensing, and displayed lower KLRG1 on the surface of NK cells. Expression of Ly49A alone on a H-2Dd background restored missing-self target cell rejection, NK cell licensing, and NK cell KLRG1 expression. Thus, a single inhibitory Ly49 receptor is sufficient to license NK cells and mediate missing-self in vivo.

Cis-regulatory evolution of the recently expanded Ly49 gene family.

Comparative genomics has revealed the rapid expansion of multiple gene families involved in immunity. Members within each gene family often evolved distinct roles in immunity. However, less is known about the evolution of their epigenome and cis-regulation. Here we systematically profile the epigenome of the recently expanded murine Ly49 gene family that mainly encode either inhibitory or activating surface receptors on natural killer cells. We identify a set of cis-regulatory elements (CREs) for activating Ly49 genes. In addition, we show that in mice, inhibitory and activating Ly49 genes are regulated by two separate sets of proximal CREs, likely resulting from lineage-specific losses of CRE activity. Furthermore, we find that some Ly49 genes are cross-regulated by the CREs of other Ly49 genes, suggesting that the Ly49 family has begun to evolve a concerted cis-regulatory mechanism. Collectively, we demonstrate the different modes of cis-regulatory evolution for a rapidly expanding gene family.

Tracking the prevalence and emergence of SARS-CoV-2 variants of concern using a regional genomic surveillance program.

SARS-CoV-2 molecular testing coupled with whole-genome sequencing is instrumental for real-time genomic surveillance. Genomic surveillance is critical for monitoring the spread of variants of concern (VOCs) as well as discovery of novel variants. Since the beginning of the pandemic, millions of SARS-CoV-2 genomes have been deposited into public sequence databases. This is the result of efforts of both national and regional diagnostic laboratories. In this study, we describe the results of SARS-CoV-2 genomic surveillance from February 2021 to June 2022 at a metropolitan hospital in the United States. We demonstrate that consistent daily sampling is sufficient to track the regional prevalence and emergence of VOCs and recapitulate national trends. Similar sampling efforts should be considered a viable option for local SARS-CoV-2 genomic surveillance at other regional laboratories. IMPORTANCE: In our manuscript, we describe the results of SARS-CoV-2 genomic surveillance from February 2021 to June 2022 at a metropolitan hospital in the United States. We demonstrate that consistent daily sampling is sufficient to track the regional prevalence and emergence of variants of concern (VOCs). Similar sampling efforts should be considered a viable option for local SARS-CoV-2 genomic surveillance at other regional laboratories. While the SARS-CoV-2 pandemic has evolved into a more endemic form, we still believe that additional real-world information about sampling, procedures, and data interpretation is valuable for ongoing as well as future genomic surveillance efforts. Our study should be of substantial interest to clinical virologists.

Plasmon-Enhanced Digital Fluoroimmunoassay for Subfemtomolar Detection of Protein Biomarkers.

Rapid and accurate quantification of low-abundance protein biomarkers in biofluids can transform the diagnosis of a range of pathologies, including infectious diseases. Here, we harness ultrabright plasmonic fluors as "digital nanolabels" and demonstrate the detection and quantification of subfemtomolar concentrations of human IL-6 and SARS-CoV-2 alpha and variant proteins in clinical nasopharyngeal swab and saliva samples from COVID-19 patients. The resulting digital plasmonic fluor-linked immunosorbent assay (digital p-FLISA) enables detection of SARS-CoV-2 nucleocapsid protein, both in solution and in live virions. Digital p-FLISA outperforms the "gold standard" enzyme-linked immunosorbent assay (ELISA), having a nearly 7000-fold lower limit-of-detection, and outperforms a commercial antigen test, having over 5000-fold improvement in analytical sensitivity. Detection and quantification of very low concentrations of target proteins holds potential for early detection of pathological conditions, treatment monitoring, and personalized medicine.