Annual General Meeting 2019

Overview

Members are invited to be part of the approval process of Society matters, and witness incoming and outgoing members of Council and Division members. The day will include the Sir Howard Dalton Young Microbiologist of the Year competition and the 2019 Outreach Prize winner presentation.

Programme

13:00–13:30	Annual General Meeting registration and refreshments
13:30–13:40	Welcome from President (Reading Room)
13:40–16:05	Sir Howard Dalton Young Microbiologist of the Year 2019 presentations (Reading Room)
Virology Division
13:40	Modulation of arbovirus infection by mosquito saliva Daniella Lefteri (University of Leeds, UK)
13:55	Assembly of a portal-like structure in Feline calcivirus following receptor engagement Michaela Conley (University of Glasgow, UK)
Prokaryotic Division
14:10	The chemical ecology of protective microbiomes Sarah Worsley (University of East Anglia, UK)
14:25	Characterisation of rpoS alleles in Escherichia coli strain CFT073 Naoise McGarry (Trinity College Dublin, Ireland)
14:40	Comfort Break
Irish Division
14:50	Understanding how bacterial products from the microbiota can influence our immune cells at systemic sites Christine Jordan (Imperial College London, UK)
15:05	Worth their salt: coastal plants as a source of host plant salinity-stress reducing endophytic bacteria Gareth Raynes (Aberystwyth University, UK)
Eukaryotic Division
15:20	Shining new lights on chytrid cell biology: Quantitative live cell imaging of rhizoid development in an early-diverging fungus Davis Laundon (Marine Biological Association, UK)
15:35	The impact of natural genetic variation on protein aggregation in Saccharomyces species Laura Petch (University of Kent, UK)
15:50	Exploring the effects of viral exposure on Cryptococcus neoformans infection Paula Seoane (University of Birmingham, UK)
16:05–16:15	Comfort Break
16:15–16:45	Annual General Meeting (Reading Room)
16:45–17:45	Microbiology Outreach Prize: Antibiotic Hunters Matt Hutchings (University of East Anglia, UK) (Reading Room)
17:45	Meeting close

 

Young Microbiologist of the Year finalists' abstracts

The Microbiology Society awards a prize, recognising excellence in science communication, to an early-career member who presented a poster or offered paper at the Annual Conference or Irish Division meeting. All finalists are postgraduate students or postdoctoral researchers, having gained their PhD in the last two years. Finalists will give a 10-minute presentation about their research and will be given five minutes for questions.

Sir Howard Dalton Young Microbiologist of the Year Competition, 2019 Finalists

• Daniella Lefteri, University of Leeds, UK
• Michaela Conley, University of Glasgow, UK
• Sarah Worsley, University of East Anglia, UK
• Naoise McGarry, Trinity College Dublin, Ireland
• Christine Jordan, Imperial College London, UK
• Gareth Raynes, Aberystwyth University, UK
• Davis Laundon, Marine Biological Association, UK
• Laura Petch, University of Kent, UK
• Paula Seoane, University of Birmingham, UK

Virology Division

Daniella Lefteri, University of Leeds, UK

Talk title: Modulation of arbovirus infection by mosquito saliva

Abstract: Arboviruses constitute a major public health problem; in particular mosquito-borne arboviruses that continuously emerge and re-emerge. When mosquitoes bite, they cause tissue trauma and deposit a mixture of saliva, microbiota and arbovirus if infected. Arbovirus infection of mammals is enhanced by the presence of a mosquito-bite at the inoculation site, in comparison to virus experimentally administered by needle inoculation in the absence of a bite. However, the experimental inoculation of mosquito saliva with virus inoculum by needle, in the absence of bite trauma, also has the ability to enhance viral infections. Host responses elicited to saliva appear to be key in facilitating this enhancement. As such, we have studied the mechanistic basis for these observations by investigating mosquito-bite factors, as well as host responses, involved in facilitating viral enhancement. We have studied whether saliva from different mosquito species successfully enhance virus infection. Interestingly, whilst saliva from the Aedes genus enhanced virus infection, An.gambiae saliva did not. This could partly explain why An.gambiae mosquitos are unsuitable vectors for the transmission of the majority of arboviruses. By comparing the host responses that saliva from these different species have at the inoculation-site, we have further specified which inflammatory responses modulate arbovirus infection in the skin. Using an in vivo mouse-model we demonstrate that An.gambiae causes significantly less oedema than Ae.aegypti and that histamine induced oedema in the absence of salivary-factors also enhances infection. Also, measuring cytokine responses to Aedes and Anopheles saliva, showed that several key anti-viral chemokines such as CCL5 were significantly more upregulated by Anopheles. As such, we are providing important insights into how mosquito saliva modulates infection. A better understanding of this will aid the development of anti-viral treatments by targeting factors within the mosquito bite that are common to many distinct infections.

Michaela Conley, University of Glasgow, UK

Talk title: Assembly of a portal-like structure in feline calicivirus following receptor engagement

Abstract: The Caliciviridae are a family of viruses which include many important human and animal pathogens, most notably norovirus which causes winter vomiting disease. Until recently, norovirus was unable to be propagated in the laboratory and so feline calicivirus (FCV) is often employed as a tractable model for calicivirus studies. FCV, like other caliciviruses, enters cells via endocytosis following engagement with its cellular receptor feline junctional adhesion molecule-A (fJAM-A) at the cell surface. The conformational changes in the viral capsid that allow delivery of the viral genome from the endosome into the cytoplasm are not known. We used cryo-electron microscopy and newly developed asymmetric three-dimensional reconstruction techniques to investigate structural changes in the capsid of FCV that occur upon fJAM-A binding. Atomic models of the major capsid protein, VP1, were calculated in the presence and absence of fJAM-A, revealing conformational changes induced by the interaction. Surprisingly, we also discovered a unique large portal-like structure which assembles at a single three-fold symmetry axis in each capsid. The portal-like complex comprises 12 copies of the minor capsid protein VP2, which is known to play a critical role in the formation of infectious particles for all caliciviruses but whose structure and function were previously unknown. We calculated an atomic model of VP2 and revealed structural changes in VP1 that lead to the formation of a pore in the capsid shell at the portal vertex. Our results suggest that the VP2 portal-like assembly is the means by which caliciviruses escape the endosome to initiate infection. We hypothesise that VP2 forms a channel through the endosomal membrane that allows the delivery of the viral genome into the cytoplasm for replication to then ensue.

Prokaryotic Division

Sarah Worsley, University of East Anglia, UK

Talk title: The Chemical Ecology of Protective Microbiomes

Abstract: Actinobacteria are ubiquitous in soil and well-known for producing antimicrobial compounds. Increasingly, members of this phylum are found to form symbiotic relationships, for example with plants and insects, and are thought to provide protection against host infection. However, it remains poorly understood how Actinobacteria are recruited to microbiomes and whether secondary metabolites are produced in vivo. Acromyrmex echinatior leafcutter ants transmit Pseudonocardia bacteria between generations and also recruit Streptomyces to their cuticular microbiome. We show that Pseudonocardia species isolated from the ant cuticle inhibit the fungal nest pathogen Escovopsis weberi and dual RNA-sequencing confirmed that Pseudonocardia secondary metabolite gene clusters are expressed in vivo on the ant cuticle. RNA stable isotope probing showed that ants supply cuticular resources to their microbiome which may fuel interference competition and select for antibiotic-producing bacteria. Similar to leafcutter ants we also show that plant roots recruit growth-promoting and antibiotic-producing Streptomyces bacteria, but appear not to transmit them via their seeds. Root exudates are hypothesised to play a major role in root microbiome recruitment and Illumina sequencing coupled with DNA stable isotope probing showed that these were actively utilised by many bacterial genera. However, Streptomyces appeared to be outcompeted by more abundant Proteobacteria, despite the fact that isolates could grow on purified exudates in the absence of competition. Defining the factors that influence the competitiveness of protective bacteria when colonising microbiomes has implications for the development of more consistent biocontrol strategies as well as probiotic and prebiotic techniques.

Naoise McGarry, Trinity College Dublin, Ireland

Talk title: Characterisation of rpoS alleles in Escherichia coli strain CFT073

Abstract: Escherichia coli is a major cause of urinary tract infections, bacteraemia and sepsis. CFT073 is a well-studied, prototypic urosepsis isolate. This laboratory has previously shown that strain CFT073 is serum-resistant, with resistance being imparted by factors including capsule and extracellular polysaccharides inter alia. It has become apparent that not all CFT073 strains are identical; some harbour a 5 bp insertion in the rpoS gene which results in a truncated, non-functional RpoS. In this study, we compare CFT073 wild-type and an rpoS mutant. The gene sequence of rpoS in each isolate was verified. Next, the sensitivity of the bacteria to hydrogen peroxide was determined. Finally, the contribution of RpoS to serum resistance was examined by serum killing assays.

Irish Division

Christine Jordan, Imperial College London, UK

Talk title: Understanding how bacterial products from the microbiota can influence our immune cells at systemic sites

Abstract: The microbiota is crucial for gut homeostasis by aiding in food breakdown, nutrient uptake, and protecting against pathogens. Recent evidence suggests the benefits provided by the microbiota are not restricted to the intestine but also extend to systemic sites. Systemic benefits are hypothesized to be mediated by bacterial products, derived from the microbiota, such as peptidoglycan and lipopolysaccharide, entering the bloodstream and acting as novel signalling molecules at distal sites. However, the precise way in which these microbial products enter the bloodstream remains largely unclear. Here we show that bacterial products cross the intestinal epithelium, suggesting a route of entry into circulation. Our data suggest routes across the intestinal epithelium may vary between different bacterial products. Using in vitro and in vivo models, we find that host processing of cell molecules from the microbiota, by host antimicrobial lysozyme, promotes their translocation across the epithelium. Once they have traversed the intestinal barrier our preliminary data provide support that the liver plays a role in clearing bacterial products from the blood, as here we see a reservoir of peptidoglycan at this site. This increased dissemination of the cell wall due to lysozyme enhances resistance to pulmonary infection. Therefore, lysozyme treatment enhances bacterial product migration and increases host protection against systemic pathogens. Our work provides mechanistic insight into how the gut microbiota exerts systemic effects. Furthermore, it provides a basis on which to launch further investigations, including examining the influence these aggregated cell wall proteins have over innate immune cells at these sites. This will give us greater insight into how the host controls microbial signalling and the benefits provided to our innate immune system.

Gareth Raynes, Aberystwyth University, UK

Talk title: Worth Their Salt: Coastal Plants as a Source of Host Plant Salinity-Stress Reducing Endophytic Bacteria

Abstract: It is estimated that 20% of irrigated agricultural land globally is currently contaminated by high salinity levels (>40mM NaCl), and more land is contaminated each year. Plant growth promoting bacteria (PGPB) have the potential to mitigate the impact this has on growth of agricultural crop plants worldwide, as they can be capable of promoting plant growth and minimising the effects of salt stress. Plants already living in saline environments, such as coastal soils, are a potential target for discovering novel PGPB for agricultural application. As a less-well-explored bacterial niche, the endophytic compartment of plants represents a potential reservoir of new bacterial strains and species.

Halotolerant bacterial endophytes were isolated from plants living in saline coastal environments near Aberystwyth and identified by 16S sequencing. All 61 isolates were screened for halotolerance in vitro; all showed rapid growth on salt concentrations up to 5%w/v, while 26 isolates were capable of growth on Nutrient Agar supplemented with 2 Molar NaCl. Model grass Brachypodium distachyon BD21 plants were inoculated with individual isolates and subjected to salt stresses of 0mM, 100mM and 200mM NaCl in a large-scale screen in the National Plant Phenomics Centre in Aberystwyth.

Traditional plant growth traits including vegetative biomass, tiller number and seed yield were monitored in addition to image analysis growth curves and water usage data in order to screen for growth promotion or salt stress amelioration potential of the endophytes relative to uninoculated plants under these conditions.  A number of Isolates were identified that reduce the severity of the stress response of the plant under salt stress conditions. These isolates have begun further testing to evaluate mechanisms of action and their potential use as agricultural crop enhancers.

Eukaryotic Division

Davis Laundon, Marine Biological Association, UK

Talk title: Shining new lights on chytrid cell biology: Quantitative live cell imaging of rhizoid development in an early-diverging fungus

Abstract: Chytridiomycota (chytrids) are one of the most basal lineages within the true fungi, however they have largely remained in the dark in terms of their fundamental cell biology. In aquatic ecosystems, chytrids can dominate ‘dark matter’ diversity surveys and are important saprotrophs of recalcitrant organic carbon. They therefore play an integral biogeochemical role in carbon cycling. Unlike ‘higher’ dikaryon fungi that feed via multicellular hyphae, chytrids are unicellular and develop an anucleate rhizoid that acts as the trophic interface of the cell. It is hypothesized that extant chytrids retain many ancestral aspects of cell biology present in the last common ancestor of the true fungi, and that a rhizoid-like structure may represent a precursor to the dikaryon hypha. Understanding the functions of the rhizoid therefore has the potential to shed light on the trophic biology of ‘dark matter’ chytrids, as well as provide insights into the evolution of feeding in the fungal kingdom. I applied 3D and 4D live-cell confocal microscopy to morphometrically quantify rhizoid development in the model saprotrophic chytrid Rhizoclosmatium globosum under different nutrient treatments. I have shown that cell development shares strikingly similar features to dikaryon hyphae and is adaptive to resource availability. Rhizoid morphogenesis is analogous to hyphal forms regarding tip production, branching and decreased fractal geometry at the growing edge, while sharing underpinning molecular machinery. Chytrid rhizoids also demonstrate adaptive morphological plasticity in response to substrate availability. My results show strong similarities between unicellular early-diverging and ‘higher’ multicellular hyphal fungi, shedding new insights on chytrid cell biology, ecological prevalence and wider fungal evolution.

Laura Petch, University of Kent, UK

Talk title: The impact of natural genetic variation on protein aggregation in Saccharomyces species

Abstract: Phenotypic heterogeneity in the yeast Saccharomyces cerevisiae has input from both genetic and epigenetic determinants. The epigenetic factors are largely based on inherited changes in protein structure resulting in the aggregation of the alternative conformational form of a protein. Such epigenetic factors include prions, protein-based epigenetic determinants that undergo self-perpetuating, heritable changes in their conformation. To date prions have been almost exclusively studied in laboratory-bred strains of S. cerevisiae and we are broadening their study to wild strains i.e. non-laboratory strains of S. cerevisiae and three related Saccharomyces species. In addition to searching for prion-related phenotypes in these yeast species we are also examining the ability of these genetically-related species to facilitate and perpetuate the formation of other amyloid-forming proteins, specifically the Alzheimer’s disease associated protein A-beta 42 and Huntingtin (Htt)-associated polyglutamine (polyQ) and to define their impact on the microbial host. Our results to date indicate that each of these species can propagate the amyloid forms of A-beta 42 and polyQ, but these amyloid states are differentially impacted upon by the endogenous prion state of the host yeast species.

Paula Seoane, University of Birmingham, UK

Talk title: Exploring the effects of viral exposure on Cryptococcus neoformans infection

Abstract: Cryptococcus neoformans is an opportunistic human pathogen, which causes serious disease in immunocompromised hosts. Infection with this pathogen is particularly relevant in HIV⁺ patients, where it leads to around 200,000 deaths per annum. A key feature of cryptococcal pathogenesis is the ability of the fungi to survive and replicate within the phagosome of macrophages, as well as its ability to escape via a novel non-lytic mechanism known as vomocytosis. The impact of vomocytosis on the outcome of infection is not fully understood, although it has been seen to affect dissemination of the fungal pathogen.

Given its relevance within HIV⁺ patients, we have been exploring whether viral infection affects the interaction between C. neoformans and macrophages. Here we show that viral infection in fact enhances cryptococcal vomocytosis events, without altering phagocytosis or intracellular proliferation of the fungus. The effect was observed using different viral infections, and is recapitulated when macrophages are stimulated with the anti-viral cytokines interferon alpha or beta. Importantly, the effect is abrogated when type-I interferon signalling is blocked, thus underscoring the importance of type-I interferons in this phenomenon.

Our results highlight the importance of incorporating specific context ques while studying host-pathogen interactions. By doing so, we found that acute viral infection may trigger the release of latent cryptococci from intracellular compartments, with significant consequences for disease progression.