Virulence Evolution of Pathogens That Can Grow in Reservoir Environments

Pandey, Aakash; Mideo, Nicole; Platt, Thomas G.

doi:10.1086/717177

Cited by 16 publications

(10 citation statements)

References 74 publications

(91 reference statements)

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“…Pathogen virulence can also differ across the landscape, producing additional variation in disease prevalence [15, 16]. Areas can maintain highly virulent strains due to multiple factors, including the introduction of novel strains to new locations or hosts [17, 18], ease or independence of transmission from affected hosts [19, 20], and the development of novel mutations or adaptations that facilitate the escape from host resistance [21]. Although the interaction between host and pathogen identity is rarely examined, theory suggests that presence of highly resistant species could modify the effects of pathogen virulence creating cold spots of transmission across the landscape [22].…”

Section: Introductionmentioning

confidence: 99%

Contribution of host species and pathogen clade to snake fungal disease hotspots in Europe

Blanvillain

Lorch

Joudrier

et al. 2022

Preprint

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Infectious diseases are influenced by interactions between host and pathogens in variable environments and are rarely homogenous across the landscape. Areas with elevated pathogen burden and transmission may indicate a disruption to steady-state disease dynamics. However, isolating processes that result in increases in infection prevalence and intensity remains a challenge. Here we elucidate the contribution of host species, and pathogen clade in disease hotspots. We examined broad-scale patterns of infection of O. ophidiicola, the pathogen that causes snake fungal disease, in 21 species of snakes across 10 countries in Europe. Disease hotspots were evident across several regions in Europe, and our analyses revealed significant differences in infection based on host species and pathogen clade. Over 80% of positive detections were from host species in the Natrix genus, indicating potential higher susceptibility in this group. The presence of O. ophidiicola genotypes that have been associated with more severe disease in North America, also resulted in high rates of infection compared to genotypes only described from Europe. Elevated infection prevalence was best explained by an interaction between host and pathogen identity which was not uniform across all species. More broadly, these findings present important mechanisms underlying disease hotspots across a disease endemic region.

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Section: Introductionmentioning

confidence: 99%

Contribution of host species and pathogen clade to snake fungal disease hotspots in Europe

Blanvillain

Lorch

Joudrier

et al. 2022

Preprint

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“…Indeed, future work aimed at elucidating the mode(s) of Spirobacillus transmission could help us to make new insights about the evolutionary dynamics of virulence, as well as carotenoid’s role in it. The dynamics of virulence evolution in pathogens capable of both horizontal and vertical (i.e., “mixed-mode”) transmission and/or environmental replication are poorly understood as compared to pathogens with strictly horizontal and/or direct transmission (56); virulence evolution in obligate killers is also relatively poorly studied. Our work suggests that mixed-mode transmission and/or environmental replication is possible in Spirobacillus .…”

Section: Discussionmentioning

confidence: 99%

Virulence and transmission biology of the widespread, ecologically important pathogen of zooplankton,Spirobacillus cienkowskii

Wale,

Freimark,

Ramirez

et al. 2023

Preprint

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Spirobacillus cienkowskii(Spirobacillus,hereafter) is a widely distributed bacterial pathogen of zooplankton (Daphniasp.) that has significant impacts on zooplankton population dynamics. Despite its ecological importance, little is known aboutSpirobacillus’virulence and transmission biology. These knowledge gaps stymie our understanding ofDaphnia-Spirobacillusinteractions and the ecology of the newly described familySilvanigrellaceae,of whichSpirobacillusis the longest studied member. Here, we present our work to fill these gaps, experimentally. We found thatSpirobacillusis among the most virulent ofDaphniapathogens, killing its host within a week of exposure and reducing host fecundity. Our experiments further suggest thatSpirobacillusrequires host death to transmit horizontally i.e., it is an “obligate killer”, since it did not transmit horizontally among hosts unless the host died or was destroyed. In a series of further experiments characterizing the dynamics of horizontal transmission, we found thatSpirobacillus’per capita rate of transmission is low, does not change with host density or pathogen inoculum size, and decreases rapidly with time spent in the environment. Lastly, we complemented our experimental work with a field survey ofSpirobacillus’prevalence within ephippia, seed-like cases containingDaphniaoffspring. We foundSpirobacillusDNA in almost 40% of ephippia, suggesting thatSpirobacillusis vertically transmitted and/or can invade ephippia and use them to endure environmental stress, as their hosts do. Our work fills critical gaps in our understanding of this ecologically important pathogen’s biology.ImportanceSpirobacillus cienkowskiiis a bacterial pathogen of zooplankton, first described in the 19thCentury and recently placed in a new family of bacteria, theSilvanigrellaceae.Spirobacilluscauses large epidemics in lake zooplankton populations and increases the probability that zooplankton will be eaten by predators. However, little is known about howSpirobacillustransmits among hosts, to what extent it reduces host survival and reproduction (i.e., how virulent it is) and what role virulence plays inSpirobacillus’life cycle. Here, we experimentally quantifiedSpirobacillus’ virulence and showed thatSpirobacillusmust kill its host to transmit horizontally. We also found evidence thatSpirobacillusmay transmit vertically viaDaphnia’s seed-like egg sacks. Our work will help scientists to (i) understandSpirobacillusepidemics, (ii) useSpirobacillusas a model pathogen for the study of host-parasite interactions and (iii) better understand the unusual group of bacteria to whichSpirobacillusbelongs.

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“…Much of the theoretical literature on virulence evolution has focused on processes affecting members of the same species (e.g. [15,23]), yet here we focus on competitive interactions between different species. We do this because interspecific host competition is expected to modify the three trade-offs (virulence–transmission, virulence–recovery and specialist–generalist).…”

Section: Interspecific Host Competition As a Driver Of Virulence Evol...mentioning

confidence: 99%

“…Understanding virulence evolution requires not only a consideration of within-host dynamics, but of between-host processes [2,[12][13][14], as some ecological factors at various biological scales directly affect virulence evolution. For example, theoretical [15] and empirical studies [16] suggest that changes in abiotic and biotic factors within the local environment can drive the evolution of virulence. Friman et al [17] established the first step towards exploring the influence of interrelated ecological factors, finding that avian predators of a moth host induced a cascading effect on virulence evolution.…”

Section: Introduction: the Evolution Of Virulencementioning

confidence: 99%

Interspecific host competition and parasite virulence evolution

2023

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Virulence, the harm to hosts caused by parasite infection, can be selected for by several ecological factors acting synergistically or antagonistically. Here, we focus on the potential for interspecific host competition to shape virulence through such a network of effects. We first summarize how host natural mortality, body mass changes, population density and community diversity affect virulence evolution. We then introduce an initial conceptual framework highlighting how these host factors, which change during host competition, may drive virulence evolution via impacts on life-history trade-offs. We argue that the multi-faceted nature of both interspecific host competition and virulence evolution still requires consideration and experimentation to disentangle contrasting mechanisms. It also necessitates a differential treatment for parasites with various transmission strategies. However, such a comprehensive approach focusing on the role of interspecific host competition is essential to understand the processes driving the evolution of virulence in a tangled bank.

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Virulence Evolution of Pathogens That Can Grow in Reservoir Environments

Cited by 16 publications

References 74 publications

Contribution of host species and pathogen clade to snake fungal disease hotspots in Europe

Contribution of host species and pathogen clade to snake fungal disease hotspots in Europe

Virulence and transmission biology of the widespread, ecologically important pathogen of zooplankton,Spirobacillus cienkowskii

Interspecific host competition and parasite virulence evolution

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