SARS-CoV-2 spike (S) mediates viral entry into cells and is critical for vaccine development against COVID-19. Structural studies have revealed distinct conformations of S, but real-time information that connects these structures, is lacking. Here we apply single-molecule Fluorescence (Förster) Resonance Energy Transfer (smFRET) imaging to observe conformational dynamics of S on virus particles. Virus-associated

The human genome encodes an arsenal of proteins that protect us against deadly viruses. Could microbes provide clues regarding the origin of these pathogen defenses? In a recent study published in Nature, Bernheim et al. demonstrate that the mammalian antiviral protein viperin is far more ancient and conserved than previously appreciated.

Clearance of pathogens by Kupffer cells is an important innate immune process in the liver. In this issue of Cell Host & Microbe, McDonald et al. reveal that microbial-derived D-lactate promotes Kupffer-cell-mediated killing of circulating pathogens.

In this issue of Cell Host & Microbe, Liu et al. elucidates how Legionella-infected macrophages use the alveolar epithelium to metabolically process myeloid cells and advance antibacterial inflammation. This highlights the alveolar epithelium’s importance as a key signaling bridge and could yield a metabolism-based blueprint for hampering Legionnaires’ disease.

We know little about factors that ordain the composition of the diverse community of viruses (virome) in the human gut. In this issue of Cell Host & Microbe, Zuo et al. highlight the importance of geography, urbanization, ethnicity, and diet on the shape of the adult gut DNA virome.

When SARS-CoV-2 emerged at the end of 2019, no approved therapeutics or vaccines were available. An urgent need for countermeasures during this crisis challenges the current paradigm of traditional drug discovery and development, which usually takes years from start to finish. Approaches that accelerate this process need to be considered. Here we propose the minimum data package required to move a

The Preclinical Working Group of Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV), a public-private partnership spearheaded by the National Institutes of Health, has been charged with identifying, prioritizing, and communicating SARS-CoV-2 preclinical resources. Reviewing SARS-CoV-2 animal model data facilitates standardization and harmonization and informs knowledge gaps and prioritization

In this issue of Cell Host & Microbe, Nielsen and colleagues sequence antibody repertoires of patients with severe COVID-19 to reveal potentially convergent features on the background of a larger, polyclonal response. Their findings suggest that, as databases improve, it may be possible to monitor virus-specific B cells after infection or vaccination using antibody sequencing.

The intestinal microbiota promote myriad functions that affect the host. In this issue of Cell Host & Microbe, Caballero-Flores et al. (2020) demonstrate that resident microbes can thwart gut colonization by the enteric bacterial pathogen Citrobacter rodentium by consuming amino acids, thus starving the invading organism of essential nutrients.

Bacterial competition within host-associated polymicrobial communities shapes their composition, often with far-reaching consequences for human health. In this issue of Cell Host & Microbe, Perault et al. reveal how competition between two opportunistic pathogens could account for the epidemiology of chronic lung infections in people with cystic fibrosis.

Whole-organism vaccination is a promising approach to prevent malaria. In this issue of Cell Host & Microbe, McNamara and colleagues identify epitope masking as a hindrance to antibody boosting after repeated administration of attenuated Plasmodium falciparum sporozoite vaccine.

The features that permit or prevent a virus from becoming a zoonotic threat is an ongoing area of investigation. In this issue of Cell Host & Microbe, Herfst et al. and Henritzi et al. help define the molecular and host determinants of influenza virus spillover from animal to human populations.

Cryptosporidium emerged as a leading global cause of severe diarrheal disease in children. The parasite occupies a unique intracellular niche at the brush border of intestinal epithelial cells, where it undergoes a complex sexual life cycle. How this life cycle unfolds and how host and parasite interact remain largely to be discovered. A series of technical advances now offer genetic and immunological

Chloroplasts are the home of innumerable metabolic pathways for plant growth and environmental responses. Recently, in an issue of Cell, Medina-Puche et al. revealed a novel mechanism by which plant pathogens dampened host defense responses, orchestrated from chloroplasts. This mechanism encompassing the plasma membrane and chloroplasts has likely been established via host-pathogen co-evolution.

Although bacteriophages are highly abundant in the gut microbiome, little is known about their potential effects on gut bacteria. In this issue of Cell Host & Microbe, Hryckowian et al. (2020) and Fujimoto et al. (2020) combined metagenomic analysis and experiments to study phage-bacteria associations in order to develop future research tools and therapies.

How do we explain the co-existence of bacteria and bacteriophages in complex environments? In this issue of Cell Host & Microbe, Lourenço et al. highlight the importance of spatial structure in facilitating the persistence of sensitive bacterial hosts and their virulent bacteriophages in the mammalian gut.

In this issue of Cell Host & Microbe, publications from Bushman et al. (2020) and Knippel et al. (2020) outline elements of host epithelial damage or inflammation that Clostridioides difficile subverts, enabling continued growth. These mechanisms provide insight into how this important pathogen influences the gut environment to promote its metabolic strategy during infection.

In this issue of Cell Host & Microbe, three papers describe the pseudotyping of vesicular stomatitis virus (VSV) with the SARS-CoV-2 spike. This VSV-CoV-2-S platform allows virus neutralization assays to be performed at BSL-2 and also has applications as a candidate vectored vaccine to elicit protective immunity against SARS-CoV-2.

The explosive spread of SARS-CoV-2 suggests that a vaccine will be required to end this global pandemic. Progress in SARS-CoV-2 vaccine development to date has been faster than for any other pathogen in history. Multiple SARS-CoV-2 vaccine candidates have been evaluated in preclinical models and are currently in clinical trials. In this Perspective, we discuss three topics that are critical for SARS-CoV-2

Every animal is in constant communication with populations of microbes. In a recent study, O’Donnell and colleagues (2020) uncover an inter-domain conversation, defining a relationship in which a non-pathogenic microbe directly synthesizes a signal that alters host behavior for a mutually beneficial outcome.

In this issue of Cell Host & Microbe, Adebayo et al. (2020) examine the urobiome of older community-dwelling women within the TwinUK Cohort. They define a core genitourinary microbiome for older women with many heritable microbial taxa. Some taxa appear to co-occur, suggesting the existence of specific microbial consortia.

Human milk harbors its own microbiota, but whether the microbes seed the infant gut and are modified by breastfeeding practices is unresolved. In this issue, Fehr et al. (2020) sequence breastmilk and infant stool samples from mother-infant dyads to investigate the co-occurrence of milk-gut bacteria and the impact of breastfeeding practices.

The story of twentieth century biomedical breakthroughs could be told through cholesterol. Revolutions in genetics, molecular biology, genomics, and antibody-based therapies defined cholesterol’s impact on human health and cholesterol-lowering strategies. In this issue, Kenny et al. (2020) bring a key twenty-first century biomedical development—the microbiome revolution—to cholesterol.

Gut microbes exhibit diurnal rhythmicity, and disruptions in this rhythmicity potentially impact host health. In this issue of Cell Host & Microbe, Reitmeier et al. (2020) employ timestamped gut microbiome sequencing data from human subjects coupled with machine learning to identify microbial rhythmicity patterns that predict Type 2 Diabetes incidence.