Comparative proteomics identifies Schlafen 5 (SLFN5) as a herpes simplex virus restriction factor that suppresses viral transcription

Intrinsic antiviral host factors confer cellular defence by limiting virus replication and are often counteracted by viral countermeasures. We reasoned that host factors that inhibit viral gene expression could be identified by determining proteins bound to viral DNA (vDNA) in the absence of key viral antagonists. Herpes simplex virus 1 (HSV-1) expresses E3 ubiquitin-protein ligase ICP0 (ICP0), which functions as an E3 ubiquitin ligase required to promote infection. Cellular substrates of ICP0 have been discovered as host barriers to infection but the mechanisms for inhibition of viral gene expression are not fully understood. To identify restriction factors antagonized by ICP0, we compared proteomes associated with vDNA during HSV-1 infection with wild-type virus and a mutant lacking functional ICP0 (ΔICP0). We identified the cellular protein Schlafen family member 5 (SLFN5) as an ICP0 target that binds vDNA during HSV-1 ΔICP0 infection. We demonstrated that ICP0 mediates ubiquitination of SLFN5, which leads to its proteasomal degradation. In the absence of ICP0, SLFN5 binds vDNA to repress HSV-1 transcription by limiting accessibility of RNA polymerase II to viral promoters. These results highlight how comparative proteomics of proteins associated with viral genomes can identify host restriction factors and reveal that viral countermeasures can overcome SLFN antiviral activity

Transcriptional Activation of the Adenoviral Genome Is Mediated by Capsid Protein VI

Gene expression of DNA viruses requires nuclear import of the viral genome. Human Adenoviruses (Ads), like most DNA viruses, encode factors within early transcription units promoting their own gene expression and counteracting cellular antiviral defense mechanisms. The cellular transcriptional repressor Daxx prevents viral gene expression through the assembly of repressive chromatin remodeling complexes targeting incoming viral genomes. However, it has remained unclear how initial transcriptional activation of the adenoviral genome is achieved. Here we show that Daxx mediated repression of the immediate early Ad E1A promoter is efficiently counteracted by the capsid protein VI. This requires a conserved PPxY motif in protein VI. Capsid proteins from other DNA viruses were also shown to activate the Ad E1A promoter independent of Ad gene expression and support virus replication. Our results show how Ad entry is connected to transcriptional activation of their genome in the nucleus. Our data further suggest a common principle for genome activation of DNA viruses by counteracting Daxx related repressive mechanisms through virion proteins

Characterizing living ocular bacterial communities and the effects of antibiotic perturbation in house finches

Abstract DNA‐based methods to measure the abundance and relative abundance of bacterial taxa can be skewed by the presence of dead or transient bacteria. Consequently, the active, functional members of the community may be a small subset of the detected bacterial community. This mismatch can make inferences about the roles of communities in host health difficult and can be particularly problematic for low‐abundance microbiomes, such as those on conjunctival surfaces. In this study, we manipulated bacterial communities on bird conjunctiva with a bacteriostatic antibiotic, reducing bacterial activity while preserving viability, to identify the living and active conjunctival communities using comparisons of 16S ribosomal DNA and RNA in paired samples. DNA amplicons included many more sequence variants than RNA amplicons from the same communities, with consequent differences in diversity. While we found that changes in communities in DNA samples broadly represent shifts in the living (RNA‐amplicon) communities, assessments of community function may be better described by RNA samples, reducing background noise from dead cells. We further used these data to test RNA:DNA ratios, used in other microbiological contexts, to detect shifts in bacterial activity after antibiotic disruption but were unable to detect changes in bacterial activity with this method

Antibiotic perturbation of gut bacteria does not significantly alter host responses to ocular disease in a songbird species

Bacterial communities in and on wild hosts are increasingly appreciated for their importance in host health. Through both direct and indirect interactions, bacteria lining vertebrate gut mucosa provide hosts protection against infectious pathogens, sometimes even in distal body regions through immune regulation. In house finches (Haemorhous mexicanus), the bacterial pathogen Mycoplasma gallisepticum (MG) causes conjunctivitis, with ocular inflammation mediated by pro- and anti-inflammatory cytokines and infection triggering MG-specific antibodies. Here, we tested the role of gut bacteria in host responses to MG by using oral antibiotics to perturb bacteria in the gut of captive house finches prior to experimental inoculation with MG. We found no clear support for an impact of gut bacterial disruption on conjunctival pathology, MG load, or plasma antibody levels. However, there was a non-significant trend for birds with intact gut communities to have greater conjunctival pathology, suggesting a possible impact of gut bacteria on pro-inflammatory cytokine stimulation. Using 16S bacterial rRNA amplicon sequencing, we found dramatic differences in cloacal bacterial community composition between captive, wild-caught house finches in our experiment and free-living finches from the same population, with lower bacterial richness and core communities composed of fewer genera in captive finches. We hypothesize that captivity may have affected the strength of results in this experiment, necessitating further study with this consideration. The abundance of anthropogenic impacts on wildlife and their bacterial communities, alongside the emergence and spread of infectious diseases, highlights the importance of studies addressing the role of commensal bacteria in health and disease, and the consequences of gut bacterial shifts on wild hosts

Team communication patterns in emergency resuscitation: a mixed methods qualitative analysis

Abstract Background In order to enhance patient safety during resuscitation of critically ill patients, we need to optimize team communication and enhance team situational awareness but little is known about resuscitation team communication patterns. The objective of this study is to understand how teams communicate during resuscitation; specifically to assess for a shared mental model (organized understanding of a team’s relationships) and information needs. Methods We triangulated 3 methods to evaluate resuscitation team communication at a tertiary care academic trauma center: (1) interviews; (2) simulated resuscitation observations; (3) live resuscitation observations. We interviewed 18 resuscitation team members about shared mental models, roles and goals of team members and procedural expectations. We observed 30 simulated resuscitation video recordings and documented the timing, source and destination of communication and the information category. We observed 12 live resuscitations in the emergency department and recorded baseline characteristics of the type of resuscitations, nature of teams present and type and content of information exchanges. The data were analyzed using a qualitative communication analysis method. Results We found that resuscitation team members described a shared mental model. Respondents understood the roles and goals of each team member in order to provide rapid, efficient and life-saving care with an overall need for situational awareness. The information flow described in the interviews was reflected during the simulated and live resuscitations with the most responsible physician and charting nurse being central to team communication. We consolidated communicated information into six categories: (1) time; (2) patient status; (3) patient history; (4) interventions; (5) assistance and consultations; 6) team members present. Conclusions Resuscitation team members expressed a shared mental model and prioritized situational awareness. Our findings support a need for cognitive aids to enhance team communication during resuscitations

Additional file 1: of Team communication patterns in emergency resuscitation: a mixed methods qualitative analysis

Appendix A. Questionnaire for stakeholder interviews. Appendix B. Communication categories observed during live resuscitation observations. Appendix C. Types of information exchanges observed during live resuscitations. Appendix D. Examples of team communication in live resuscitation observations. (DOC 160 kb