Genetic screens to identify factors pertinent to host defence against bacterial infection

Antibiotic resistance is a growing concern for healthcare providers across the world. Indeed, resistance is now being found to those ‘last-ditch’ antibiotics reserved for antibiotic-resistant infections. There is great need for research into alternative therapies for globally important pathogens, as well as those that pose a bioterror threat due to their infectivity and high morbidity (e.g. Francisella tularensis). Host-directed therapy as a concept for infection treatment seeks either to block bacterial invasion and growth within host cells or enhance host bactericidal activity. This approach has the potential to treat a broad range of bacterial infections, as well as to reduce the likelihood of developing resistance. As a first step, we explored a host infection response network (including the gene PCDH7) defined on the basis of results from a previous HEK-293 host infection screen. Cellular knockout of human PCDH7 showed reduced intracellular Salmonella enterica serotype Typhimurium (STM) and Shigella sonnei burden in vitro, suggesting resistance to bacterial growth. To identify further targets, a ‘gene trap’ mutation library was generated in a macrophage-like human cell line, U937, which was then differentiated and infected with STM and F. tularensis LVS in independent screens. RNA-Seq was performed on the infected and control populations to identify functionally vital host defence gene mutations. The most statistically significant gene mutations were assessed using pathway analysis tools and literature searches. Multiple pathway analyses converged on electron transport chain subunits MT-ND5, MT-ND6 and MT-CO1, the trapped versions of which were identified as protective in the STM screen. Furthermore, another trapped protective hit, SLC7A11, shows promise from initial validation using a CRISPR knockout (lower intracellular STM burden) as well as pharmacological modulation with the inhibitor sulfasalazine. This work has provided a starting point for the investigation of human genes and cellular processes that might be amenable to pharmacological manipulation to provide protection against, or recovery from, bacterial infection. Therefore host-directed therapies merit further exploration as a novel route to counter the potentially devastating impact of bacteria largely resistant to current antimicrobial drugs.Antibiotic resistance is a growing concern for healthcare providers across the world. Indeed, resistance is now being found to those ‘last-ditch’ antibiotics reserved for antibiotic-resistant infections. There is great need for research into alternative therapies for globally important pathogens, as well as those that pose a bioterror threat due to their infectivity and high morbidity (e.g. Francisella tularensis). Host-directed therapy as a concept for infection treatment seeks either to block bacterial invasion and growth within host cells or enhance host bactericidal activity. This approach has the potential to treat a broad range of bacterial infections, as well as to reduce the likelihood of developing resistance. As a first step, we explored a host infection response network (including the gene PCDH7) defined on the basis of results from a previous HEK-293 host infection screen. Cellular knockout of human PCDH7 showed reduced intracellular Salmonella enterica serotype Typhimurium (STM) and Shigella sonnei burden in vitro, suggesting resistance to bacterial growth. To identify further targets, a ‘gene trap’ mutation library was generated in a macrophage-like human cell line, U937, which was then differentiated and infected with STM and F. tularensis LVS in independent screens. RNA-Seq was performed on the infected and control populations to identify functionally vital host defence gene mutations. The most statistically significant gene mutations were assessed using pathway analysis tools and literature searches. Multiple pathway analyses converged on electron transport chain subunits MT-ND5, MT-ND6 and MT-CO1, the trapped versions of which were identified as protective in the STM screen. Furthermore, another trapped protective hit, SLC7A11, shows promise from initial validation using a CRISPR knockout (lower intracellular STM burden) as well as pharmacological modulation with the inhibitor sulfasalazine. This work has provided a starting point for the investigation of human genes and cellular processes that might be amenable to pharmacological manipulation to provide protection against, or recovery from, bacterial infection. Therefore host-directed therapies merit further exploration as a novel route to counter the potentially devastating impact of bacteria largely resistant to current antimicrobial drugs

Gendered sexual risk patterns and polygamy among HIV sero-discordant couples in Uganda

This study examined the multiple sexual partnerships and HIV sero-discordant relationships are among the most at-risk for HIV transmission.Multiple sexual partnerships and HIV sero-discordant relationships are among the most at-risk for HIV transmission. Polygamy is a common form of multiple-partnered relationships in Eastern Uganda. We investigated the association between HIV risk patterns and polygamy among HIV sero-discordant couples at The AIDS Support Organization in Jinja, Uganda Methods Participants were enrollees in a prospective cohort of HIV sero-discordant couples, the Highly Active Antiretroviral therapy as Prevention (HAARP) Study at TASO Jinja. Descriptive nand bivariate analyses to compare sexual risk patterns among HIV sero-discordant men; in polygamous as compared to single-spouse relationship

Can trials of spatial repellents be used to estimate mosquito movement?

Knowledge of mosquito movement would aid the design of effective intervention strategies against malaria. However, data on mosquito movement through mark-recapture or genetics studies are challenging to collect, and so are not available for many sites. An additional source of information may come from secondary analyses of data from trials of repellents where household mosquito densities are collected. Using the study design of published trials, we developed a statistical model which can be used to estimate the movement between houses for mosquitoes displaced by a spatial repellent. The method uses information on the different distributions of mosquitoes between houses when no households are using spatial repellents compared to when there is incomplete coverage. The parameters to be estimated are the proportion of mosquitoes repelled, the proportion of those repelled that go to another house and the mean distance of movement between houses. Estimation is by maximum likelihood.; We evaluated the method using simulation and found that data on the seasonal pattern of mosquito densities were required, which could be additionally collected during a trial. The method was able to provide accurate estimates from simulated data, except when the setting has few mosquitoes overall, few repelled, or the coverage with spatial repellent is low. The trial that motivated our analysis was found to have too few mosquitoes caught and repelled for our method to provide accurate results.; We propose that the method could be used as a secondary analysis of trial data to gain estimates of mosquito movement in the presence of repellents for trials with sufficient numbers of mosquitoes caught and repelled and with coverage levels which allow sufficient numbers of houses with and without repellent. Estimates from this method may supplement those from mark-release-recapture studies, and be used in designing effective malaria intervention strategies, parameterizing mathematical models and in designing trials of vector control interventions

Quantifying imperfect detection in an invasive pest fish and the implications for conservation management

In managing non-native species, surveillance programmes aim to minimise the opportunity for invasions to develop from initial introductions through early detection. However, this is dependent on surveillance methods being able to detect species at low levels of abundance to avoid false-negative recordings through imperfect detection. We investigated through field experimentation the ability to detect Pseudorasbora parva, a highly invasive pest fish in Europe, in relation to their known density and sampling method. Secure pond mesocosms of area 100 m2 contained P. parva densities from 0.02 to 5.0 m"122; each density was in triplicate. These were searched using point sampling electric fishing and deployment of fish traps (non-baited and baited). No fish were captured at densities 0.5 m"122, whereas for electric fishing it only exceeded 0.95 at 5.0 m"122 using high searching effort. These data reveal that small pest fishes such as P. parva may be prone to imperfect detection when at low densities and this is consistent with a number of other invasive species. This indicates the importance of designing surveillance programmes using methods of known statistical power to optimise conservation resource expenditure and enhance management outcomes

Mini review : structure and function of nematode phosphorylcholine-containing glycoconjugates

An unusual aspect of the biology of nematodes is the covalent attachment of phosphorylcholine (PC) to carbohydrate in glycoconjugates. Investigation of the structure of these molecules by ever-increasingly sophisticated analytical procedures has revealed that PC is generally in phosphodiester linkage with C6 of N-acetylglucosamine (GlcNAc) in both N-type glycans and glycosphingolipids. Up to five PC groups have been detected in the former, being located on both antenna and core GlcNAc. The PC donor for transfer to carbohydrate appears to be phosphatidylcholine but the enzyme responsible for transfer remains to be identified. Work primarily involving the PC-containing Acanthocheilonema viteae secreted product ES-62, has shown that the PC attached to nematode N-glycans possesses a range of immunomodulatory properties, subverting for example, pro-inflammatory signalling in various immune system cell-types including lymphocytes, mast cells, dendritic cells and macrophages. This has led to the generation of PC-based ES-62 small molecule analogues (SMAs), which mirror the parent molecule in preventing the initiation or progression of disease in mouse models of a number of human conditions associated with aberrant inflammatory responses. These include rheumatoid arthritis, systemic lupus erythematosus and lung and skin allergy such that the SMAs are considered to have widespread therapeutic potential

Factors associated with long‐term antiretroviral therapy attrition among adolescents in rural Uganda: a retrospective study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138247/1/jia20841.pd

CD36 Mediates the Innate Host Response to β-Amyloid

Accumulation of inflammatory microglia in Alzheimer's senile plaques is a hallmark of the innate response to β-amyloid fibrils and can initiate and propagate neurodegeneration characteristic of Alzheimer's disease (AD). The molecular mechanism whereby fibrillar β-amyloid activates the inflammatory response has not been elucidated. CD36, a class B scavenger receptor, is expressed on microglia in normal and AD brains and binds to β-amyloid fibrils in vitro. We report here that microglia and macrophages, isolated from CD36 null mice, had marked reductions in fibrillar β-amyloid–induced secretion of cytokines, chemokines, and reactive oxygen species. Intraperitoneal and stereotaxic intracerebral injection of fibrillar β-amyloid in CD36 null mice induced significantly less macrophage and microglial recruitment into the peritoneum and brain, respectively, than in wild-type mice. Our data reveal that CD36, a major pattern recognition receptor, mediates microglial and macrophage response to β-amyloid, and imply that CD36 plays a key role in the proinflammatory events associated with AD

Genetic influences on externalizing psychopathology overlap with cognitive functioning and show developmental variation

Background: Questions remain regarding whether genetic influences on early life psychopathology overlap with cognition and show developmental variation. Methods: Using data from 9,421 individuals aged 8-21 from the Philadelphia Neurodevelopmental Cohort, factors of psychopathology were generated using a bifactor model of item-level data from a psychiatric interview. Five orthogonal factors were generated: anxious-misery (mood and anxiety), externalizing (attention deficit hyperactivity and conduct disorder), fear (phobias), psychosis-spectrum, and a general factor. Genetic analyses were conducted on a subsample of 4,662 individuals of European American ancestry. A genetic relatedness matrix was used to estimate heritability of these factors, and genetic correlations with executive function, episodic memory, complex reasoning, social cognition, motor speed, and general cognitive ability. Gene × Age analyses determined whether genetic influences on these factors show developmental variation. Results: Externalizing was heritable (h2 = 0.46, p = 1 × 10-6), but not anxious-misery (h2 = 0.09, p = 0.183), fear (h2 = 0.04, p = 0.337), psychosis-spectrum (h2 = 0.00, p = 0.494), or general psychopathology (h2 = 0.21, p = 0.040). Externalizing showed genetic overlap with face memory (ρg = -0.412, p = 0.004), verbal reasoning (ρg = -0.485, p = 0.001), spatial reasoning (ρg = -0.426, p = 0.010), motor speed (ρg = 0.659, p = 1x10-4), verbal knowledge (ρg = -0.314, p = 0.002), and general cognitive ability (g)(ρg = -0.394, p = 0.002). Gene × Age analyses revealed decreasing genetic variance (γg = -0.146, p = 0.004) and increasing environmental variance (γe = 0.059, p = 0.009) on externalizing. Conclusions: Cognitive impairment may be a useful endophenotype of externalizing psychopathology and, therefore, help elucidate its pathophysiological underpinnings. Decreasing genetic variance suggests that gene discovery efforts may be more fruitful in children than adolescents or young adults