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Zika virus (ZIKV), an arbovirus of global concern, remodels intracellular membranes to form replication sites. How ZIKV dysregulates lipid networks to allow this, and consequences for disease, is poorly understood. Here, we perform comprehensive lipidomics to create a lipid network map during ZIKV infection. We find that ZIKV significantly alters host lipid composition, with the most striking changes seen within subclasses of sphingolipids. Ectopic expression of ZIKV NS4B protein results in similar changes, demonstrating a role for NS4B in modulating sphingolipid pathways. Disruption of sphingolipid biosynthesis in various cell types, including human neural progenitor cells, blocks ZIKV infection. Additionally, the sphingolipid ceramide redistributes to ZIKV replication sites, and increasing ceramide levels by multiple pathways sensitizes cells to ZIKV infection. Thus, we identify a sphingolipid metabolic network with a critical role in ZIKV replication and show that ceramide flux is a key mediator of ZIKV infection.

Sensory experience during developmental critical periods has lifelong consequences for circuit function and behavior, but the molecular and cellular mechanisms through which experience causes these changes are not well understood. The Drosophila antennal lobe houses synapses between olfactory sensory neurons (OSNs) and downstream projection neurons (PNs) in stereotyped glomeruli. Many glomeruli exhibit structural plasticity in response to early-life odor exposure, indicating a general sensitivity of the fly olfactory circuitry to early sensory experience. We recently found that glia shape antennal lobe development in young adults, leading us to ask if glia also drive experience-dependent plasticity during this period. Here we define a critical period for structural and functional plasticity of OSN-PN synapses in the ethyl butyrate (EB)-sensitive glomerulus VM7. EB exposure for the first two days post-eclosion drives large-scale reductions in glomerular volume, presynapse number, and post-synaptic activity. Crucially, pruning during the critical period has long-term consequences for circuit function since both OSN-PN synapse number and spontaneous activity of PNs remain persistently decreased following early-life odor exposure. The highly conserved engulfment receptor Draper is required for this critical period plasticity as ensheathing glia upregulate Draper, invade the VM7 glomerulus, and phagocytose OSN presynaptic terminals in response to critical-period EB exposure. Loss of Draper fully suppresses the morphological and physiological consequences of critical period odor exposure, arguing that phagocytic glia engulf intact synaptic terminals. These data demonstrate experience-dependent pruning of synapses and argue that Drosophila olfactory circuitry is a powerful model for defining the function of glia in critical period plasticity.

As the COVID-19 pandemic continues, long-term immunity against SARS-CoV-2 will be globally important. Official weekly cases have not dropped below 2 million since September of 2020, and continued emergence of novel variants have created a moving target for our immune systems and public health alike. The temporal aspects of COVID-19 immunity, particularly from repeated vaccination and infection, are less well understood than short-term vaccine efficacy. In this study, we explore the impact of combined vaccination and infection, also known as hybrid immunity, and the timing thereof on the quality and quantity of antibodies produced by a cohort of 96 health care workers. We find robust neutralizing antibody responses among those with hybrid immunity against all variants, including Omicron BA.2, and we further found significantly improved neutralizing titers with longer vaccine-infection intervals up to 400 days. These results indicate that anti-SARS-CoV-2 antibody responses undergo continual maturation following primary exposure by either vaccination or infection for at least 400 days after last antigen exposure. We show that neutralizing antibody responses improved upon secondary boosting with greater impact seen after extended intervals. Our findings may also extend to booster vaccine doses, a critical consideration in future vaccine campaign strategies.

A comprehensive understanding of host dependency factors for SARS-CoV-2 remains elusive. We mapped alterations in host lipids following SARS-CoV-2 infection using nontargeted lipidomics. We found that SARS-CoV-2 rewires host lipid metabolism, altering 409 lipid species up to 64-fold relative to controls. We correlated these changes with viral protein activity by transfecting human cells with each viral protein and performing lipidomics. We found that lipid droplet plasticity is a key feature of infection and that viral propagation can be blocked by small-molecule glycerolipid biosynthesis inhibitors. We found that this inhibition was effective against the main variants of concern (alpha, beta, gamma, and delta), indicating that glycerolipid biosynthesis is a conserved host dependency factor that supports this evolving virus.

We compared the serum neutralizing antibody titers before and after two doses of the BNT162b2 COVID-19 vaccine in ten individuals who recovered from SARS-CoV-2 infection prior to vaccination to 20 individuals with no history of infection, against clinical isolates of B.1.1.7, B.1.351, P.1, and the original SARS-CoV-2 virus. Vaccination boosted pre-existing levels of anti-SARS-CoV-2 spike antibodies 10-fold in previously infected individuals, but not to levels significantly higher than those of uninfected vaccinees. However, neutralizing antibody titers increased in previously infected vaccinees relative to uninfected vaccinees against every variant tested: 5.2-fold against B.1.1.7, 6.5-fold against B.1.351, 4.3-fold against P.1, and 3.4-fold against original SARS-CoV-2. Our study indicates that a first-generation COVID-19 vaccine provides broad protection from SARS-CoV-2 variants in individuals with previous infection., Competing Interests: Competing interests Authors declare that they have no competing interests.

We tested human sera from large, demographically balanced cohorts of BNT162b2 vaccine recipients (n=51) and COVID-19 patients (n=44) for neutralizing antibodies against SARS-CoV-2 variants B.1.1.7 and B.1.351. Although the effect is more pronounced in the vaccine cohort, both B.1.1.7 and B.1.351 show significantly reduced levels of neutralization by vaccinated and convalescent sera. Age is negatively correlated with neutralization in vaccinee, and levels of variant-specific RBD antibodies are proportional to neutralizing activities.

There is currently a lack of biological tools to study the replication cycle and pathogenesis of SARS-CoV-2, the etiological agent of COVID-19. Repurposing the existing tools, including antibodies of SARS-CoV, is an effective way to accelerate the development of therapeutics for COVID-19. Here, we extensively characterized antibodies of the SARS-CoV structural proteins for their cross-reactivity, experimental utility, and neutralization of SARS-CoV-2. We assessed a total of 10 antibodies (six for Spike, two for Membrane, and one for Nucleocapsid and Envelope viral protein). We evaluated the utility of these antibodies against SARS-CoV-2 in a variety of assays, including immunofluorescence, ELISA, biolayer interferometry, western blots, and micro-neutralization. Remarkably, a high proportion of the antibodies we tested showed cross-reactivity, indicating a potentially generalizable theme of cross-reactivity between SARS-CoV and SARS-CoV-2 antibodies. These antibodies should help facilitate further research into SARS-CoV-2 basic biology. Moreover, our study provides critical information about the propensity of SARS-CoV antibodies to cross-react with SARS-CoV-2 and highlights its relevance in defining the clinical significance of such antibodies to improve testing and guide the development of novel vaccines and therapeutics.