Understanding the emergence of bacterial pathogens in novel hosts

Our understanding of the ecological and evolutionary context of novel infections is largely based on viral diseases, even though bacterial pathogens may display key differences in the processes underlying their emergence. For instance, host-shift speciation, in which the jump of a pathogen into a novel host species is followed by the specialization on that host and the loss of infectivity of previous host(s), is commonly observed in viruses, but less often in bacteria. Here, we suggest that the extent to which pathogens evolve host generalism or specialism following a jump into a novel host will depend on their level of adaptation to dealing with different environments, their rates of molecular evolution and their ability to recombine. We then explore these hypotheses using a formal model and show that the high levels of phenotypic plasticity, low rates of evolution and the ability to recombine typical of bacterial pathogens should reduce their propensity to specialize on novel hosts. Novel bacterial infections may therefore be more likely to result in transient spillovers or increased host ranges than in host shifts. Finally, consistent with our predictions, we show that, in two unusual cases of contemporary bacterial host shifts, the bacterial pathogens both have small genomes and rapid rates of substitution. Further tests are required across a greater number of emerging pathogens to assess the validity of our hypotheses. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’.

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Rapid divergence in independent aspects of the compatibility phenotype in the Spiroplasma/Drosophila interaction

10.1101/2021.02.03.429608 ◽

2021 ◽

Author(s):

Joanne S. Griffin ◽

Michael Gerth ◽

Gregory D. D. Hurst

Keyword(s):

Vertical Transmission ◽

Host Species ◽

High Efficiency ◽

Host Shift ◽

Direct Selection ◽

New Host ◽

Host Shifts ◽

Species Pairs ◽

Novel Host ◽

Rapid Divergence

AbstractHeritable symbionts represent important components of host biology, both as antagonistic reproductive parasites and as beneficial protective partners. An important component of heritable microbes’ biology is their ability to establish in new host species, a process equivalent to a host shift for an infectiously transmitted parasite or pathogen. For a host shift to occur, the symbiont must be compatible with the host: it must not cause excess pathology, must have good vertical transmission, and possess a drive phenotype that enables spread. Classically, compatibility has been considered a declining function of genetic distance between novel and ancestral host species. Here we investigate the evolutionary lability of compatibility to heritable microbes by comparing the capacity for a symbiont to establish in two novel host species equally related to the ancestral host. Compatibility of the protective Spiroplasma from D. hydei with D. simulans and D. melanogaster was tested. The Spiroplasma had contrasting compatibility in these two host species. The transinfection showed pathology and low vertical transmission in D. melanogaster but was asymptomatic and transmitted with high efficiency in D. simulans. These results were not affected by the presence/absence of Wolbachia in either of the two species. The pattern of protection was not congruent with that for pathology/transmission, with protection being weaker in the D. simulans, the host in which Spiroplasma was asymptomatic and transmitted well. Further work indicated pathological interactions occurred in D. sechellia and D. yakuba, indicating that D. simulans was unusual in being able to carry the symbiont without damage. The differing compatibility of the symbiont with these closely related host species emphasises first the rapidity with which host-symbiont compatibility evolves despite compatibility itself not being subject to direct selection, and second the independence of the different components of compatibility (pathology, transmission, protection). This requirement to fit three different independently evolving aspects of compatibility, if commonly observed, is likely to be a major feature limiting the rate of host shifts. Moving forward, the variation between sibling species pairs observed above provides an opportunity to identify the mechanisms behind variable compatibility between closely related host species, which will drive hypotheses as to the evolutionary drivers of compatibility variation.

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The genetic architecture of a host shift: An adaptive walk protected an aphid and its endosymbiont from plant chemical defenses

Science Advances ◽

10.1126/sciadv.aba1070 ◽

2020 ◽

Vol 6 (19) ◽

pp. eaba1070

Author(s):

Kumar Saurabh Singh ◽

Bartlomiej J. Troczka ◽

Ana Duarte ◽

Vasileia Balabanidou ◽

Nasser Trissi ◽

...

Keyword(s):

Host Shift ◽

Chemical Defenses ◽

Buchnera Aphidicola ◽

Mutualistic Symbiosis ◽

Host Shifts ◽

Plant Chemical ◽

Novel Host ◽

Plant Chemical Defenses ◽

Genetic Novelty ◽

Adaptive Walk

Host shifts can lead to ecological speciation and the emergence of new pests and pathogens. However, the mutational events that facilitate the exploitation of novel hosts are poorly understood. Here, we characterize an adaptive walk underpinning the host shift of the aphid Myzus persicae to tobacco, including evolution of mechanisms that overcame tobacco chemical defenses. A series of mutational events added as many as 1.5 million nucleotides to the genome of the tobacco-adapted subspecies, M. p. nicotianae, and yielded profound increases in expression of an enzyme that efficiently detoxifies nicotine, both in aphid gut tissue and in the bacteriocytes housing the obligate aphid symbiont Buchnera aphidicola. This dual evolutionary solution overcame the challenge of preserving fitness of a mutualistic symbiosis during adaptation to a toxic novel host. Our results reveal the intricate processes by which genetic novelty can arise and drive the evolution of key innovations required for ecological adaptation.

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Dynamics of viral index infections in novel hosts

10.1101/2020.04.09.033928 ◽

2020 ◽

Author(s):

Nardus Mollentze ◽

Daniel G. Streicker ◽

Pablo R. Murcia ◽

Katie Hampson ◽

Roman Biek

Keyword(s):

Rabies Virus ◽

Host Species ◽

Host Shift ◽

Single Infection ◽

Limiting Factor ◽

New Host ◽

Host Shifts ◽

Virus Excretion ◽

Novel Host ◽

Meta Analyses

AbstractWhether a pathogen entering a new host species results in a single infection or in onward transmission, and potentially an outbreak, depends upon the progression of infection in the index case. Although index infections are rarely observable in nature, experimental inoculations of pathogens into novel host species have a long history in biomedical research. This provides a rich and largely unexploited data source for meta-analyses to identify the host and pathogen determinants of variability in infection outcomes. Here, we analysed the progressions of 514 experimental cross-species inoculations of rabies virus, a widespread zoonotic pathogen which in nature exhibits both dead end infections and varying levels of sustained transmission in novel hosts. Inoculations originating from bats rather than carnivores, and from warmer to cooler-bodied species caused infections with shorter incubation periods that were associated with diminished virus excretion. Inoculations between distantly related hosts tended to result in shorter clinical disease periods, which will also impede transmission. All effects were modulated by infection dose and together suggest that increased virulence as host species become more dissimilar is the limiting factor preventing onward transmission. These results explain observed constraints on rabies virus host shifts, allow us to evaluate the risk of novel reservoirs establishing, and give mechanistic insights into why host shifts are less likely between genetically distant species. More generally, our study highlights meta-analyses of experimental infections as a tractable approach to quantify the complex interactions between virus, reservoir, and novel host that shape the outcome of cross-species transmission.Significance statementEmerging disease epidemics often result from a pathogen establishing transmission in a novel host species. However, most cross-species transmissions fail to establish in the newly infected species for reasons that remain poorly understood. Examining cross-species inoculations involving rabies, a widespread viral zoonosis, we show that mismatches in virulence, which are predictable from host and viral factors, make sustained transmission in the novel host less likely. In particular, disease progression was accelerated and virus excretion decreased when the reservoir and novel host were physiologically or genetically more dissimilar. These mechanistic insights help to explain and predict host shift events and highlight meta-analyses of existing experimental inoculation data as a powerful and generalisable approach for understanding the dynamics of index infections in novel species.

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Ecological and evolutionary drivers of hemoplasma infection and bacterial genotype sharing in a Neotropical bat community

10.1101/2019.12.21.885921 ◽

2019 ◽

Author(s):

Daniel J. Becker ◽

Kelly A. Speer ◽

Alexis M. Brown ◽

M. Brock Fenton ◽

Alex D. Washburne ◽

...

Keyword(s):

Genetic Diversity ◽

Host Specificity ◽

Bacterial Pathogens ◽

Infection Prevalence ◽

Emerging Pathogens ◽

High Genetic Diversity ◽

Evolutionary Patterns ◽

Host Shifts ◽

Multiple Species ◽

Bacterial Genotypes

AbstractMost emerging pathogens can infect multiple species, underscoring the importance of understanding the ecological and evolutionary factors that allow some hosts to harbor greater infection prevalence and share pathogens with other species. However, our understanding of pathogen jumps is primarily based around viruses, despite bacteria accounting for the greatest proportion of zoonoses. Because bacterial pathogens in bats (Order: Chiroptera) can have conservation and human health consequences, studies that examine the ecological and evolutionary drivers of bacterial prevalence and barriers to pathogen sharing are crucially needed. We here studied hemotropic Mycoplasma spp. (i.e., hemoplasmas) across a species-rich bat community in Belize over two years. Across 469 bats spanning 33 species, half of individuals and two-thirds of species were hemoplasma positive. Infection prevalence was higher for males and for species with larger body mass and colony sizes. Hemoplasmas displayed high genetic diversity (21 novel genotypes) and strong host specificity. Evolutionary patterns supported co-divergence of bats and bacterial genotypes alongside phylogenetically constrained host shifts. Bat species centrality to the network of shared hemoplasma genotypes was phylogenetically clustered and unrelated to prevalence, further suggesting rare—but detectable—bacterial sharing between species. Our study highlights the importance of using fine phylogenetic scales when assessing host specificity and suggests phylogenetic similarity may play a key role in host shifts for not only viruses but also bacteria. Such work more broadly contributes to increasing efforts to understand cross-species transmission and epidemiological consequences of bacterial pathogens.

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Label-Free Electrochemical Biosensor Based on Au@MoS₂–PANI for Escherichia coli Detection

Chemosensors ◽

10.3390/chemosensors9030049 ◽

2021 ◽

Vol 9 (3) ◽

pp. 49

Author(s):

Pushap Raj ◽

Man Hwan Oh ◽

Kyudong Han ◽

Tae Yoon Lee

Keyword(s):

Escherichia Coli ◽

Bacterial Infections ◽

Limit Of Detection ◽

Bacterial Pathogens ◽

Cost Effective ◽

Covalent Immobilization ◽

Label Free ◽

Self Assembled Monolayer ◽

Detection Range ◽

Linear Detection

Bacterial infections have become a significant challenge in terms of public health, the food industry, and the environment. Therefore, it is necessary to address these challenges by developing a rapid, cost-effective, and easy-to-use biosensor for early diagnosis of bacterial pathogens. Herein, we developed a simple, label-free, and highly sensitive immunosensor based on electrochemical detection using the Au@MoS₂–PANI nanocomposite. The conductivity of the glassy carbon electrode is greatly enhanced using the Au@MoS₂–PANI nanocomposite and a self-assembled monolayer of mercaptopropionic acid on the gold nanoparticle surface was employed for the covalent immobilization of antibodies to minimize the nonspecific adsorption of bacterial pathogens on the electrode surface. The biosensor established a high selectivity and sensitivity with a low limit of detection of 10 CFU/mL, and detected Escherichia coli within 30 min. Moreover, the developed biosensor demonstrated a good linear detection range, practical utility in urine samples, and electrode regenerative studies.

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A Drug-free Strategy to Combat Bacterial Infections with Magnetic Nanoparticles Biosynthesized in the Bacterial Pathogens

Nanoscale ◽

10.1039/d1nr07435k ◽

2022 ◽

Author(s):

Deepa Ghosh ◽

Swati Kaushik ◽

Jijo Thomas ◽

Vineeta Panwar ◽

Preethi Murugesan ◽

...

Keyword(s):

Magnetic Nanoparticles ◽

Bacterial Infections ◽

Bacterial Pathogens ◽

Multiple Drug ◽

Drug Resistant ◽

Multiple Drug Resistant ◽

Drug Free

The extensive and indiscriminate use of antibiotics in the ongoing COVID-19 pandemic might significantly contribute to the growing number of multiple drug resistant (MDR) bacteria. With the dwindling pipeline of...

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A novel host shift and invaded range of a seed predator,Acanthoscelides macrophthalmus(Coleoptera: Chrysomelidae: Bruchinae), of an invasive weed,Leucaena leucocephala

Entomological Science ◽

10.1111/j.1479-8298.2009.00297.x ◽

2009 ◽

Vol 12 (1) ◽

pp. 1-8 ◽

Cited By ~ 22

Author(s):

Midori TUDA ◽

Li-Hsin WU ◽

Yoichi TATEISHI ◽

Chawalit NIYOMDHAM ◽

Sawai BURANAPANICHPAN ◽

...

Keyword(s):

Leucaena Leucocephala ◽

Host Shift ◽

Invasive Weed ◽

Seed Predator ◽

Novel Host

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The global dissemination of bacterial infections necessitates the study of reverse genomic epidemiology

Briefings in Bioinformatics ◽

10.1093/bib/bbz010 ◽

2019 ◽

Vol 21 (2) ◽

pp. 741-750 ◽

Cited By ~ 12

Author(s):

Zhi Ruan ◽

Yunsong Yu ◽

Ye Feng

Keyword(s):

Bacterial Infections ◽

Bacterial Pathogens ◽

Bacterial Species ◽

Bacterial Genome ◽

Disease Outbreaks ◽

International Travel ◽

Source Tracking ◽

Common Source ◽

Genomic Epidemiology ◽

Cross Border

Abstract Whole genome sequencing (WGS) has revolutionized the genotyping of bacterial pathogens and is expected to become the new gold standard for tracing the transmissions of bacterial infectious diseases for public health purposes. Traditional genomic epidemiology often uses WGS as a verification tool, namely, when a common source or epidemiological link is suspected, the collected isolates are sequenced for the determination of clonal relationships. However, increasingly frequent international travel and food transportation, and the associated potential for the cross-border transmission of bacterial pathogens, often lead to an absence of information on bacterial transmission routes. Here we introduce the concept of ‘reverse genomic epidemiology’, i.e. when isolates are inspected by genome comparisons to be sufficiently similar to one another, they are assumed to be a consequence of infection from a common source. Through BacWGSTdb (http://bacdb.org/BacWGSTdb/), a database we have developed for bacterial genome typing and source tracking, we have found that almost the entire analyzed 20 bacterial species exhibit the phenomenon of cross-border clonal dissemination. Five networks were further identified in which isolates sharing nearly identical genomes were collected from at least five different countries. Three of these have been documented as real infectious disease outbreaks, therefore demonstrating the feasibility and authority of reverse genomic epidemiology. Our survey and proposed strategy would be of potential value in establishing a global surveillance system for tracing bacterial transmissions and outbreaks; the related database and techniques require urgent standardization.

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Chemical Inhibitors of the Type Three Secretion System: Disarming Bacterial Pathogens

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00975-12 ◽

2012 ◽

Vol 56 (11) ◽

pp. 5433-5441 ◽

Cited By ~ 69

Author(s):

Miles C. Duncan ◽

Roger G. Linington ◽

Victoria Auerbuch

Keyword(s):

Bacterial Infections ◽

Pathogenic Bacteria ◽

Bacterial Pathogens ◽

Secretion System ◽

Effector Proteins ◽

Host Cells ◽

Magic Bullet ◽

Antimicrobial Drugs ◽

Type Three Secretion System ◽

Type Three Secretion

ABSTRACTThe recent and dramatic rise of antibiotic resistance among bacterial pathogens underlies the fear that standard treatments for infectious disease will soon be largely ineffective. Resistance has evolved against nearly every clinically used antibiotic, and in the near future, we may be hard-pressed to treat bacterial infections previously conquered by “magic bullet” drugs. While traditional antibiotics kill or slow bacterial growth, an important emerging strategy to combat pathogens seeks to block the ability of bacteria to harm the host by inhibiting bacterial virulence factors. One such virulence factor, the type three secretion system (T3SS), is found in over two dozen Gram-negative pathogens and functions by injecting effector proteins directly into the cytosol of host cells. Without T3SSs, many pathogenic bacteria are unable to cause disease, making the T3SS an attractive target for novel antimicrobial drugs. Interdisciplinary efforts between chemists and microbiologists have yielded several T3SS inhibitors, including the relatively well-studied salicylidene acylhydrazides. This review highlights the discovery and characterization of T3SS inhibitors in the primary literature over the past 10 years and discusses the future of these drugs as both research tools and a new class of therapeutic agents.

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Diseases as Impediments to Livestock Production and Wildlife Conservation Goals

10.5772/intechopen.94467 ◽

2021 ◽

Author(s):

Y.J. Atuman ◽

C.A. Kudi ◽

P.A. Abdu ◽

O.O. Okubanjo ◽

A. Abubakar

Keyword(s):

Bacterial Infections ◽

Wildlife Conservation ◽

Viral Infections ◽

Animal Health ◽

Disease Outbreaks ◽

Foot And Mouth Disease ◽

Domestic Animal ◽

Livestock Production ◽

Emerging Pathogens ◽

Livestock Diseases

Disease outbreaks, epidemics or pandemics have been of importance for human and animal health worldwide and sparked enormous public interest. These outbreaks might be caused by known endemic pathogens or by emerging or re-emerging pathogens. Wildlife are the major reservoirs and responsible for most of these outbreaks. They play significant role in the transmission of several livestock diseases and pathogen spill-over may occur in complex socio-ecological systems at the wildlife-domestic animal interface which have been seldom studied. Interspecific pathogen spill-over at the wildlife-livestock interface have been of growing concern in the scientific community over the past years due to their impact on wildlife, livestock and human health. In this section the epidemiology of some viral infections (Foot and Mouth Disease and rabies), bacterial infections (Tuberculosis and brucellosis) and parasites (haemo and endo-parasites) at the wildlife-livestock interface and potential impacts to livestock production and conservation goal is described.

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