Tick–host interactions: saliva-activated transmission

The skin site at which ticks attach to their hosts to feed is the critical interface between the tick and its host, and tick-borne pathogens. This site is highly modified by the pharmacologically active molecules secreted in tick saliva. For pathogens, it is an ecologically privileged niche that many exploit. Such exploitation is referred to as saliva-activated transmission (SAT) – the indirect promotion of tick-borne pathogen transmission via the actions of bioactive tick saliva molecules on the vertebrate host. Here we review evidence for SAT and consider what are the most likely candidates for SAT factors among the tick pharmacopoeia of anti-haemostatic, anti-inflammatory and immunomodulatory molecules identified to date. SAT factors appear to differ for different pathogens and tick vector species, and possibly even depend on the vertebrate host species. Most likely we are searching for a suite of molecules that act together to overcome the redundancy in host response mechanisms. Whatever they turn out to be, the quest to identify the tick molecules that mediate SAT is an exciting one, and offers new insights to controlling ticks and tick-borne diseases.

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Toward a unified dilution effect theory: How competence, competition, and the transmission mechanism influence disease prevalence

10.1101/2020.01.31.928820 ◽

2020 ◽

Author(s):

Michael H. Cortez ◽

Meghan A. Duffy

Keyword(s):

Host Species ◽

Dilution Effect ◽

Disease Prevalence ◽

Pathogen Transmission ◽

Transmission Mechanism ◽

Infection Prevalence ◽

Host Interactions ◽

Host Diversity ◽

Disease Patterns ◽

Effect Theory

ABSTRACTBiodiversity in communities is changing globally, including the gain and loss of host species in host-pathogen communities. The dilution effect argues for a mechanistic link between increased host diversity and decreased disease in a focal host. However, we currently have a limited understanding of how the pathogen transmission mechanism and between-host interactions influence whether increased host diversity leads to increased (amplification) or decreased (dilution) infection prevalence. We use a two-host-one-pathogen model to unify theory for pathogens with environmental transmission and density-dependent and frequency-dependent direct transmission. We then identify general rules governing how the pathogen transmission mechanism and characteristics of the introduced host (disease competence and competitive ability) influence whether the introduction of a second host species increases or decreases disease prevalence in a focal host. We discuss how our results yield insight into how specific biological mechanisms shape host biodiversity-disease patterns.

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Induced Transient Immune Tolerance in Ticks and Vertebrate Host: A Keystone of Tick-Borne Diseases?

Frontiers in Immunology ◽

10.3389/fimmu.2021.625993 ◽

2021 ◽

Vol 12 ◽

Cited By ~ 1

Author(s):

Nathalie Boulanger ◽

Stephen Wikel

Keyword(s):

Immune Tolerance ◽

Pathogen Transmission ◽

Bioactive Molecules ◽

Vertebrate Host ◽

Infectious Agents ◽

Global Public Health ◽

Tick Feeding ◽

Tick Saliva ◽

Immune Defenses ◽

Tick Infection

Ticks and tick transmitted infectious agents are increasing global public health threats due to increasing abundance, expanding geographic ranges of vectors and pathogens, and emerging tick-borne infectious agents. Greater understanding of tick, host, and pathogen interactions will contribute to development of novel tick control and disease prevention strategies. Tick-borne pathogens adapt in multiple ways to very different tick and vertebrate host environments and defenses. Ticks effectively pharmacomodulate by its saliva host innate and adaptive immune defenses. In this review, we examine the idea that successful synergy between tick and tick-borne pathogen results in host immune tolerance that facilitates successful tick infection and feeding, creates a favorable site for pathogen introduction, modulates cutaneous and systemic immune defenses to establish infection, and contributes to successful long-term infection. Tick, host, and pathogen elements examined here include interaction of tick innate immunity and microbiome with tick-borne pathogens; tick modulation of host cutaneous defenses prior to pathogen transmission; how tick and pathogen target vertebrate host defenses that lead to different modes of interaction and host infection status (reservoir, incompetent, resistant, clinically ill); tick saliva bioactive molecules as important factors in determining those pathogens for which the tick is a competent vector; and, the need for translational studies to advance this field of study. Gaps in our understanding of these relationships are identified, that if successfully addressed, can advance the development of strategies to successfully disrupt both tick feeding and pathogen transmission.

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Systems Biology and Bile Acid Signalling in Microbiome-Host Interactions in the Cystic Fibrosis Lung

Antibiotics ◽

10.3390/antibiotics10070766 ◽

2021 ◽

Vol 10 (7) ◽

pp. 766

Author(s):

David F. Woods ◽

Stephanie Flynn ◽

Jose A. Caparrós-Martín ◽

Stephen M. Stick ◽

F. Jerry Reen ◽

...

Keyword(s):

Cystic Fibrosis ◽

Bile Acids ◽

Host Response ◽

Signal Molecules ◽

Therapeutic Approaches ◽

Related Factors ◽

Host Interactions ◽

Important Host ◽

Respiratory Microbiota

The study of the respiratory microbiota has revealed that the lungs of healthy and diseased individuals harbour distinct microbial communities. Imbalances in these communities can contribute to the pathogenesis of lung disease. How these imbalances occur and establish is largely unknown. This review is focused on the genetically inherited condition of Cystic Fibrosis (CF). Understanding the microbial and host-related factors that govern the establishment of chronic CF lung inflammation and pathogen colonisation is essential. Specifically, dissecting the interplay in the inflammation–pathogen–host axis. Bile acids are important host derived and microbially modified signal molecules that have been detected in CF lungs. These bile acids are associated with inflammation and restructuring of the lung microbiota linked to chronicity. This community remodelling involves a switch in the lung microbiota from a high biodiversity/low pathogen state to a low biodiversity/pathogen-dominated state. Bile acids are particularly associated with the dominance of Proteobacterial pathogens. The ability of bile acids to impact directly on both the lung microbiota and the host response offers a unifying principle underpinning the pathogenesis of CF. The modulating role of bile acids in lung microbiota dysbiosis and inflammation could offer new potential targets for designing innovative therapeutic approaches for respiratory disease.

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Equine piroplasmosis status in the UK: an assessment of laboratory diagnostic submissions and techniques

Veterinary Record ◽

10.1136/vr.104855 ◽

2018 ◽

Vol 184 (3) ◽

pp. 95-95 ◽

Cited By ~ 9

Author(s):

Robert M Coultous ◽

Paul Phipps ◽

Charlie Dalley ◽

Jane Lewis ◽

Toni-Ann Hammond ◽

...

Keyword(s):

Animal Health ◽

Health Agency ◽

Clinical Samples ◽

Vector Species ◽

Equine Piroplasmosis ◽

Tick Vector ◽

Increased Risk ◽

The Uk ◽

Tick Vectors ◽

Health Trust

Equine piroplasmosis (EP) has historically been of minor concern to UK equine practitioners, primarily due to a lack of competent tick vectors. However, increased detection of EP tick vector species in the UK has been reported recently. EP screening is not currently required for equine importation, and when combined with recent relaxations in movement regulations, there is an increased risk regarding disease incursion and establishment into the UK. This study evaluated the prevalence of EP by both serology and PCR among 1242 UK equine samples submitted for EP screening between February and December 2016 to the Animal and Plant Health Agency and the Animal Health Trust. Where information was available, 81.5 per cent of submissions were for the purpose of UK export testing, and less than 0.1 per cent for UK importation. Serological prevalence of EP was 8.0 per cent, and parasite DNA was found in 0.8 per cent of samples. A subsequent analysis of PCR sensitivity in archived clinical samples indicated that the proportion of PCR-positive animals is likely to be considerably higher. The authors conclude that the current threat imposed by UK carrier horses is not adequately monitored and further measures are required to improve national biosecurity and prevent endemic disease.

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Do parasites adopt different strategies in different intermediate hosts? Host size, not host species, influences Coitocaecum parvum (Trematoda) life history strategy, size and egg production

Parasitology ◽

10.1017/s0031182012001564 ◽

2012 ◽

Vol 140 (2) ◽

pp. 275-283 ◽

Cited By ~ 11

Author(s):

R. RUIZ DANIELS ◽

S. BELTRAN ◽

R. POULIN ◽

C. LAGRUE

Keyword(s):

Host Species ◽

Egg Production ◽

Life History Strategy ◽

Host Size ◽

Life Strategy ◽

Amphipod Species ◽

Intermediate Hosts ◽

Host Interactions ◽

Resource Limitations ◽

Coitocaecum Parvum

SUMMARYHost exploitation induces host defence responses and competition between parasites, resulting in individual parasites facing highly variable environments. Alternative life strategies may thus be expressed in context-dependent ways, depending on which host species is used and intra-host competition between parasites. Coitocaecum parvum (Trematode) can use facultative progenesis in amphipod intermediate hosts, Paracalliope fluviatilis, to abbreviate its life cycle in response to such environmental factors. Coitocaecum parvum also uses another amphipod host, Paracorophium excavatum, a species widely different in size and ecology from P. fluviatilis. In this study, parasite infection levels and strategies in the two amphipod species were compared to determine whether the adoption of progenesis by C. parvum varied between these two hosts. Potential differences in size and/or egg production between C. parvum individuals according to amphipod host species were also investigated. Results show that C. parvum life strategy was not influenced by host species. In contrast, host size significantly affected C. parvum strategy, size and egg production. Since intra-host interactions between co-infecting parasites also influenced C. parvum strategy, size and fecundity, it is highly likely that within-host resource limitations affect C. parvum life strategy and overall fitness regardless of host species.

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The effects of seasonality on host–bat fly ecological networks in a temperate mountain cave

Parasitology ◽

10.1017/s0031182016002390 ◽

2016 ◽

Vol 144 (5) ◽

pp. 692-697 ◽

Cited By ~ 9

Author(s):

KARINA D. RIVERA-GARCÍA ◽

CÉSAR A. SANDOVAL-RUIZ ◽

ROMEO A. SALDAÑA-VÁZQUEZ ◽

JORGE E. SCHONDUBE

Keyword(s):

Species Composition ◽

Host Species ◽

Rainy Season ◽

Ecological Networks ◽

Host Interactions ◽

Bat Flies ◽

Bat Fly ◽

Low Prevalence ◽

Host Parasite

SUMMARYChanges in the specialization of parasite–host interactions will be influenced by variations in host species composition. We evaluated this hypothesis by comparing the composition of bats and bat flies within a roost cave over one annual. Five bat and five bat fly species occupied the cave over the course of the study. Bat species composition was 40% different in the rainy season compared with the dry–cold and dry–warm seasons. Despite the incorporation of three new bat species into the cave during the rainy season, bat fly species composition was not affected by seasonality, since the bats that arrived in the rainy season only contributed one new bat fly species at a low prevalence. Bat–bat fly ecological networks were less specialized in the rainy season compared with the dry–cold and dry–warm seasons because of the increase of host overlap among bat fly species during this season. This study suggests that seasonality promote: (1) differences in host species composition, and (2) a reduction in the specialization of host–parasite ecological networks.

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Microbial-Host Interactions at Mucosal Sites. Host Response to Pathogenic Bacteria at Mucosal Sites

Defense of Mucosal Surfaces: Pathogenesis, Immunity and Vaccines - Current Topics in Microbiology and Immunology ◽

10.1007/978-3-642-59951-4_9 ◽

1999 ◽

pp. 163-189 ◽

Cited By ~ 6

Author(s):

A. Phalipon ◽

P. J. Sansonetti

Keyword(s):

Host Response ◽

Pathogenic Bacteria ◽

Host Interactions ◽

Microbial Host

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Composition patterns and network structure of epiphyte–host interactions in Chilean and New Zealand temperate forests

10.26686/wgtn.14399225.v1 ◽

2021 ◽

Author(s):

A Taylor ◽

A Saldaña ◽

G Zotz ◽

C Kirby ◽

I Díaz ◽

...

Keyword(s):

New Zealand ◽

Host Species ◽

Species Interactions ◽

Temperate Forests ◽

Null Model ◽

Host Interactions ◽

Host Trees ◽

Specific Host ◽

Random Patterns ◽

Epiphyte Species

Ecological networks are becoming increasingly used as a framework to study epiphyte–host interactions. However, efforts to quantify the properties of epiphyte–host networks have produced inconsistent results. Epiphyte–host interactions in New Zealand and Chilean temperate forests were quantified to test for non-random patterns in nestedness, negative co-occurrences, number of links, and network specialisation. Results showed that three out of five New Zealand networks were significantly more nested than null model expectations, compared with just one out of four Chilean networks. Epiphytes co-occurred more often than null model expectations in one New Zealand network and one in Chile. In all cases, the number of links maintained by each epiphyte and host species was consistent with null model expectations. Lastly, two New Zealand networks and one in southern Chile were significantly less specialised than null model expectations, with all remaining networks returning low specialisation scores. As such, aside from the tendency for greater nestedness in New Zealand networks, most epiphyte species were distributed on their host trees at random. We attribute the result of nestedness in New Zealand to the abundance of large nest epiphytes (Astelia spp. in particular), which may facilitate the sequential colonisation of epiphyte species on developing host trees. The lack of negative co-occurrences suggests that negative species interactions are not an important determinant of species assemblage structure. Low network specialisation scores suggest that epiphytes are selecting for specific host traits, rather than specific host species for colonisation.

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Three Colopterus Beetle Species Carry the Oak Wilt Fungus to Fresh Wounds on Red Oak in Missouri

Plant Disease ◽

10.1094/pdis-92-2-0270 ◽

2008 ◽

Vol 92 (2) ◽

pp. 270-275 ◽

Cited By ~ 14

Author(s):

Maya Hayslett ◽

Jennifer Juzwik ◽

Bruce Moltzan

Keyword(s):

Abundant Species ◽

Pathogen Transmission ◽

Red Oak ◽

Beetle Species ◽

Vector Species ◽

Oak Wilt ◽

Ceratocystis Fagacearum ◽

Oak Trees ◽

The Family ◽

Nitidulid Beetles

Beetles in the family Nitidulidae can transmit the oak wilt fungus, Ceratocystis fagacearum, to fresh wounds on healthy oak trees, leading to infection and disease development. Historically, nitidulid beetles have not been considered important vectors of the pathogen in Missouri. Studies were conducted in the spring of 2005 and 2006 to determine frequencies of nitidulid beetle species contaminated with C. fagacearum visiting fresh wounds on red oak trees in central Missouri. Colopterus truncatus, C. niger, and C. semitectus were the most abundant species collected from fresh wounds and the only species found to be contaminated with Ceratocystis fagacearum. Of 230 beetles assayed for C. fagacearum, 23 yielded the fungus. Contamination frequencies were higher for beetles collected in April than May; no beetles collected in June were contaminated. We hypothesize that Colopterus truncatus, C. niger, and C. semitectus are principal nitidulid beetle vector species in Missouri during spring. The risk for pathogen transmission by these beetles appears to be greatest in April and least in June.

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