Determinant of HIV-1 mutational escape from cytotoxic T lymphocytes.

CD8+ class I-restricted cytotoxic T lymphocytes (CTLs) usually incompletely suppress HIV-1 in vivo, and while analogous partial suppression induces antiretroviral drug-resistance mutations, epitope escape mutations are inconsistently observed. However, escape mutation depends on the net balance of selective pressure and mutational fitness costs, which are poorly understood and difficult to study in vivo. Here we used a controlled in vitro system to evaluate the ability of HIV-1 to escape from CTL clones, finding that virus replicating under selective pressure rapidly can develop phenotypic resistance associated with genotypic changes. Escape varied between clones recognizing the same Gag epitope or different Gag and RT epitopes, indicating the influence of the T cell receptor on pressure and fitness costs. Gag and RT escape mutations were monoclonal intra-epitope substitutions, indicating limitation by fitness constraints in structural proteins. In contrast, escape from Nef-specific CTL was more rapid and consistent, marked by a polyclonal mixture of epitope point mutations and upstream frameshifts. We conclude that incomplete viral suppression by CTL can result in rapid emergence of immune escape, but the likelihood is strongly determined by factors influencing the fitness costs of the particular epitope targeted and the ability of responding CTL to recognize specific epitope variants

Determinants of HIV-1 Mutational Escape From Cytotoxic T Lymphocytes

CD8+ class I–restricted cytotoxic T lymphocytes (CTLs) usually incompletely suppress HIV-1 in vivo, and while analogous partial suppression induces antiretroviral drug-resistance mutations, epitope escape mutations are inconsistently observed. However, escape mutation depends on the net balance of selective pressure and mutational fitness costs, which are poorly understood and difficult to study in vivo. Here we used a controlled in vitro system to evaluate the ability of HIV-1 to escape from CTL clones, finding that virus replicating under selective pressure rapidly can develop phenotypic resistance associated with genotypic changes. Escape varied between clones recognizing the same Gag epitope or different Gag and RT epitopes, indicating the influence of the T cell receptor on pressure and fitness costs. Gag and RT escape mutations were monoclonal intra-epitope substitutions, indicating limitation by fitness constraints in structural proteins. In contrast, escape from Nef-specific CTL was more rapid and consistent, marked by a polyclonal mixture of epitope point mutations and upstream frameshifts. We conclude that incomplete viral suppression by CTL can result in rapid emergence of immune escape, but the likelihood is strongly determined by factors influencing the fitness costs of the particular epitope targeted and the ability of responding CTL to recognize specific epitope variants

Evolution of resistance to chytridiomycosis is associated with a robust early immune response

Potentiating the evolution of immunity is a promising strategy for addressing biodiversity diseases. Assisted selection for infection resistance may enable the recovery and persistence of amphibians threatened by chytridiomycosis, a devastating fungal skin disease threatening hundreds of species globally. However, knowledge of the mechanisms involved in the natural evolution of immunity to chytridiomycosis is limited. Understanding the mechanisms of such resistance may help speed-assisted selection. Using a transcriptomics approach, we examined gene expression responses of endangered alpine tree frogs (Litoria verreauxii alpina) to subclinical infection, comparing two long-exposed populations with a naïve population. We performed a blinded, randomized and controlled exposure experiment, collecting skin, liver and spleen tissues at 4, 8 and 14\ua0days postexposure from 51 wild-caught captively reared infection-naïve adult frogs for transcriptome assembly and differential gene expression analyses. We analysed our results in conjunction with infection intensity data, and the results of a large clinical survival experiment run concurrently with individuals from the same clutches. Here, we show that frogs from an evolutionarily long-exposed and phenotypically more resistant population of the highly susceptible alpine tree frog demonstrate a more robust innate and adaptive immune response at the critical early subclinical stage of infection when compared with two more susceptible populations. These results are consistent with the occurrence of evolution of resistance against chytridiomycosis, help to explain underlying resistance mechanisms, and provide genes of potential interest and sequence data for future research. We recommend further investigation of cell-mediated immunity pathways, the role of interferons and mechanisms of lymphocyte suppression

Adjunctive rifampicin for Staphylococcus aureus bacteraemia (ARREST): a multicentre, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Staphylococcus aureus bacteraemia is a common cause of severe community-acquired and hospital-acquired infection worldwide. We tested the hypothesis that adjunctive rifampicin would reduce bacteriologically confirmed treatment failure or disease recurrence, or death, by enhancing early S aureus killing, sterilising infected foci and blood faster, and reducing risks of dissemination and metastatic infection. METHODS: In this multicentre, randomised, double-blind, placebo-controlled trial, adults (≥18 years) with S aureus bacteraemia who had received ≤96 h of active antibiotic therapy were recruited from 29 UK hospitals. Patients were randomly assigned (1:1) via a computer-generated sequential randomisation list to receive 2 weeks of adjunctive rifampicin (600 mg or 900 mg per day according to weight, oral or intravenous) versus identical placebo, together with standard antibiotic therapy. Randomisation was stratified by centre. Patients, investigators, and those caring for the patients were masked to group allocation. The primary outcome was time to bacteriologically confirmed treatment failure or disease recurrence, or death (all-cause), from randomisation to 12 weeks, adjudicated by an independent review committee masked to the treatment. Analysis was intention to treat. This trial was registered, number ISRCTN37666216, and is closed to new participants. FINDINGS: Between Dec 10, 2012, and Oct 25, 2016, 758 eligible participants were randomly assigned: 370 to rifampicin and 388 to placebo. 485 (64%) participants had community-acquired S aureus infections, and 132 (17%) had nosocomial S aureus infections. 47 (6%) had meticillin-resistant infections. 301 (40%) participants had an initial deep infection focus. Standard antibiotics were given for 29 (IQR 18-45) days; 619 (82%) participants received flucloxacillin. By week 12, 62 (17%) of participants who received rifampicin versus 71 (18%) who received placebo experienced treatment failure or disease recurrence, or died (absolute risk difference -1·4%, 95% CI -7·0 to 4·3; hazard ratio 0·96, 0·68-1·35, p=0·81). From randomisation to 12 weeks, no evidence of differences in serious (p=0·17) or grade 3-4 (p=0·36) adverse events were observed; however, 63 (17%) participants in the rifampicin group versus 39 (10%) in the placebo group had antibiotic or trial drug-modifying adverse events (p=0·004), and 24 (6%) versus six (2%) had drug interactions (p=0·0005). INTERPRETATION: Adjunctive rifampicin provided no overall benefit over standard antibiotic therapy in adults with S aureus bacteraemia. FUNDING: UK National Institute for Health Research Health Technology Assessment

A readability analysis of online mental health resources

Analyzing the reading grade level of online mental health information is an important first step in ensuring that information is largely accessible by the general public, so as not to perpetuate existing health disparities across socioeconomic groups. The present study systematically examined grade-level readability of mental health information related to various psychiatric diagnoses, obtained from 6 highly utilized mental health websites, using a generalized estimating equations approach. Results suggest that, in general, the readability of mental health information is largely well above the 6th-to-8th grade level recommended by several national health organizations, including the CDC and NIH (Kutner, Greenberg, Jin, & Paulsen, 2006; National Institutes of Health, 2001, 2017), with reading-grade-level estimates from the model ranging from 5.62 to 17.9. Further efforts are required to ensure that writers of online health information do not exacerbate existing health disparities by ignoring these guidelines

Patterns of Predation and Antipredator Behavior in the Australian Water Dragon, Physignathus Lesuerii

Although lizards are more diverse in arid environments, many lizard taxa have independently invaded aquatic habitats. Adaptations in aquatic lizards are often straightforward (e.g., dorsolaterally compressed tails facilitate swimming), but what made these species invade aquatic habitats in the first place? Although this question is not directly testable, one possible reason is to reduce predation risk. Here we examine the fit of a species\u27 antipredator behaviors to the predation risk associated with its known and suspected predators. We reviewed the literature for records of predation on the Australian Water Dragon, Physignathus lesueurii, a semi-aquatic lizard that uses aquatic escape and aquatic sleeping, but does not forage underwater. We then examined these two behaviors in relation to the patterns of predation revealed by our review. Our review identified 25 species of predators, most of which were aerial (mainly raptors) or terrestrial/arboreal (snakes, lizards, and mammals). Aquatic predators were rare. Our review supports the hypothesis that Water Dragons invaded and persist in aquatic habitats to decrease predation risk from terrestrial and aerial predators, although we cannot rule out the exploitation of an abundance of available (riparian) food as the primary reason for invading aquatic habitats. Future studies should test how well Water Dragons can thermoregulate by sleeping underwater (vs. in air), and could test the antipredator responses of Water Dragons to mock predators

Dataset 7.8 Skin matrix.isoforms.TPM.not_cross_norm.TMM_info

Dataset 7 contains the raw gene/transcript counts data for each frog tissue sample (Experiment B, n = 61) resulting from allocation of sequence reads to genes from the transcriptome assemblies. These data are contained in Dataset 7, as 12 individual tab-separated text files (.txt) [Data Citation 1]. The four files for each tissue type (skin, liver and spleen) represent raw (1) counts, (2) TMM.EXPR files, (3) TPM.not_cross_norm files, and (4) normalisation information (as per the standard output from RSEM). The first row of these files (1-3 above) represents frog ID, and the first element of all subsequent rows represents transcript/isoform ID

Data from: Survival, gene and metabolite responses of Litoria verreauxii alpina frogs to fungal disease chytridiomycosis

PLEASE NOTE, THESE DATA ARE ALSO REFERRED TO IN ANOTHER PUBLICATION. PLEASE SEE http://dx.doi.org/10.1111/mec.14493. The fungal skin disease chytridiomycosis has caused the devastating decline and extinction of hundreds of amphibian species globally, yet the potential for evolving resistance, and the underlying pathophysiological mechanisms remain poorly understood. We exposed 406 naïve, captive-raised alpine tree frogs (Litoria verreauxii alpina) from multiple populations (one evolutionarily naïve to chytridiomycosis) to the aetiological agent Batrachochytrium dendrobatidis in two concurrent and controlled infection experiments. We investigated (A) survival outcomes and clinical pathogen burdens between populations and clutches, and (B) individual host tissue responses to chytridiomycosis. Here we present multiple interrelated datasets associated with these exposure experiments, including animal signalment, survival and pathogen burden of 355 animals from Experiment A, and the following datasets related to 61 animals from Experiment B: animal signalment and pathogen burden; raw RNA-Seq reads from skin, liver and spleen tissues; de novo assembled transcriptomes for each tissue type; raw gene expression data; annotation data for each gene; and raw metabolite expression data from skin and liver tissues. These data provide an extensive baseline for future analyses

Dataset 5.5 Spleen-filtered-condensed

Dataset 5 consists of de novo assembled transcriptomes for each tissue type from frogs in Experiment B (n = 61). These data are contained in Dataset 5, as six individual .fasta text files, including both nucleotide sequence assembly files and amino acid sequence assembly files (translated using TransDecoder) for each of the three tissue types (skin, liver and spleen) [Data Citation 1]. Descriptions of the sequence identifier lines are contained in the associated readme file