Host–Parasite Interactions in African Buffalo: A Community- Level Perspective

Consequent Effects of Parasitism on Population Dynamics, Food Webs, and Human Health Under Climate Change

Evolution of Cyclic Sexual Reproduction Under Host–Parasite Interactions

Parasitic plants, including the root holoparasites Orobanche spp., cause devastating damage to crops worldwide. Arabidopsis thaliana is widely used as an amenable model plant system to study host–pathogen interactions. Understanding the molecular basis involved in host–parasite interactions will provide practical tools for the detection of genes responsible for incompatibility and resistance responses. In preliminary petri dish experiments, A. thaliana induced seed germination of O. aegyptiaca, O. minor, and O. ramosa at the rate of 87, 72, and 67% of maximum seed germination, respectively. Arabidopsis thaliana induction of O. crenata and O. cumana seeds was negligible (less than 2% of maximum germination). In additional polyethylene bag studies, A. thaliana was parasitized by O. aegyptiaca, O. ramosa, and O. minor resulting in 12, 5, and 2 parasites per host plant, respectively. The results facilitate the use of A. thaliana in host-parasitic plant interaction research.

Behavioral feedbacks in host–parasite interactions have received growing attention in recent years, emphasizing how host behavior (e.g., movement and social connections) is simultaneously affecting—and affected by—parasite transmission and infection. This conceptual development highlights the need to obtain longitudinal data on individuals, their movements, and their social interactions. Conveniently, parallel developments in collecting and analyzing animal tracking data offer an opportunity to better integrate movement ecology into host–parasite dynamics. Tracking devices like miniaturized Global Positioning System (GPS) tags and complementary sensors such as accelerometers provide data on the effects of host movement on their potential to transmit parasites (e.g., how far, when, where, and to whom can parasites be transmitted). Tracking can also demonstrate the influence of parasites on host behavior and movement (e.g., via indirect physiological illness effects, or through direct manipulation of the hosts internal state). This chapter discusses the potential of movement data to bridge knowledge gaps in behavioral feedbacks of host–parasite dynamics and to account for the variation among individual hosts and across heterogeneous environments. It outlines the diverse pathways of mutual influence between host movement and parasite dynamics and the insights that can be gained from collecting movement data. It also provides basic guidance on the relevant tracking methods required for achieving these goals, and for parameterizing modern modeling approaches that include social network analyses and individual-based models.

The zoonotic disease fasciolosis poses a significant global threat to both humans and livestock. The causative agent of fasciolosis is Fasciola hepatica, which is commonly referred to as liver fluke. The emergence of drug resistance has underscored the urgent need for new therapeutic treatments against F. hepatica. The tegument surface of F. hepatica is characterized by a dynamic syncytial layer surrounded by a glycocalyx, which serves as a crucial interface in host–parasite interactions, facilitating functions such as nutrient absorption, sensory input, and defense against the host immune response. Despite its pivotal role, only recently have we delved deeper into understanding glycans at the host–parasite interface and the glycosylation of hidden antigens. These glycan antigens have shown promise for vaccine development or as targets for drug manipulation across various pathogenic species. This review aims to consolidate current knowledge on the glycosylation of F. hepatica, exploring glycan motifs identified through generic lectin probing and mass spectrometry. Additionally, it examines the interaction of glycoconjugates with lectins from the innate immune systems of both ruminant and human host species. An enhanced understanding of glycans’ role in F. hepatica biology and their critical involvement in host–parasite interactions will be instrumental in developing novel strategies to combat these parasites effectively. In the future, a more comprehensive approach may be adopted in selecting and designing potential vaccine targets, integrating insights from glycosylation studies to improve efficacy.

A walk on the tundra: Host–parasite interactions in an extreme environment

A cross-talk between the host and the parasites is fundamentally important to understand pathophysiology of the diseases they cause. During the adaptation-driven co-evolution of both the host and the parasites, the familiar ‘arms race’ takes place. Over the years, host–parasite interactions have been studied extensively from both the host and parasitic points of view, which led to new insights into novel strategies exploited by the parasites to manipulate host–parasite cross-talk. Such molecular strategies used by different parasites attacking their hosts often share many similarities. Parasites secrete a number of effector molecules to invade and create the habitat for growth inside the host, as well as to evade the host defense mechanisms. An overview is presented on these parasite secretory molecules used by both intra- and extracellular parasites during host-parasite interactions in important parasitic diseases. Questions with regard to new direction of research that are needed to discover the generic and specific molecular strategies used by the parasite to invade, survive, and grow inside their hosts, and to finally discover parasitic molecular mechanism associated with their development are also discussed.

Host–parasite interactions are characterised by a lack of stable species-specific traits that limits generalisations one can make even about particular host or parasite species. For instance, the virulence, life history traits or transmission mode of a given parasite species can depend on which of its suitable hosts it infects. In the search for general rules or patterns, meta-analysis provides a possible solution to the challenges posed by the highly variable outcomes of host–parasite interactions. It allows an estimate of the overall association between any factor and its biological response that transcends the particulars of given host and parasite taxonomic combinations. In this review, we begin with a historical overview of the use of meta-analysis in research on the ecology and evolution of host–parasite interactions. We then identify several key conceptual advances that were made possible only through meta-analytical synthesis. For example, meta-analysis revealed the predominant association between rates of host and parasite gene flow and local adaptation, as well as an unexpected latitudinal gradient in parasite virulence, or parasite-induced host mortality. Finally, we propose some areas of research on host–parasite interactions that are based on a mature theoretical foundation and for which there now exist sufficient primary results to make them ripe for meta-analysis. The search for the processes causing variability in parasite species richness among host species, and the link between the expression of host resistance and the specificity of parasites, are two such research areas. The main objective of this review is to promote meta-analysis as a synthetic tool overriding the idiosyncrasies of specific host–parasite combinations and capable of uncovering the universal trends, if any, in the evolutionary ecology of parasitism.

A three-way perspective of stoichiometric changes on host–parasite interactions

Proteomic characterization of larval and adult developmental stages in Echinococcus granulosus reveals novel insight into host–parasite interactions

Chapter Three - Host–Parasite Interactions and the Evolution of Immune Defense

Toward a General Theory for How Climate Change Will Affect Infectious Disease

Red Queen strange attractors in host–parasite replicator gene-for-gene coevolution

1. Parasites that infect multiple species cause major health burdens globally, but for many, the full suite of susceptible hosts is unknown. Predicting undocumented host-parasite associations will help expand knowledge of parasite host specificities, promote the development of theory in disease ecology and evolution, and support surveillance of multi-host infectious diseases. The analysis of global species interaction networks allows for leveraging of information across taxa, but link prediction at this scale is often limited by extreme network sparsity and lack of comparable trait data across species. 2. Here we use recently developed methods to predict missing links in global mammal-parasite networks using readily available data: network properties and evolutionary relationships among hosts. We demonstrate how these link predictions can efficiently guide the collection of species interaction data and increase the completeness of global species interaction networks. 3. We amalgamate a global mammal host-parasite interaction network (>29,000 interactions) and apply a hierarchical Bayesian approach for link prediction that leverages information on network structure and scaled phylogenetic distances among hosts. We use these predictions to guide targeted literature searches of the most likely yet undocumented interactions, and identify empirical evidence supporting many of the top 'missing' links. 4. We find that link prediction in global host-parasite networks can successfully predict parasites of humans, domesticated animals and endangered wildlife, representing a combination of published interactions missing from existing global databases, and potential but currently undocumented associations. 5. Our study provides further insight into the use of phylogenies for predicting host-parasite interactions, and highlights the utility of iterated prediction and targeted search to efficiently guide the collection of information on host-parasite interactions. These data are critical for understanding the evolution of host specificity, and may be used to support disease surveillance through a process of predicting missing links, and targeting research towards the most likely undocumented interactions.

Antagonistic coevolution between hosts and parasites is a ubiquitous process in nature. The theory of coevolution describes how reciprocal changes in genotype frequencies occur in the interacting species over time. Host–parasite coevolution is driven by two types of frequency‐dependent selection (FDS): indirect FDS arises from the host–parasite interaction, while direct FDS arises from ecological features which affect coevolution. Depending on the balance between indirect and direct FDS and the strength of stochastic processes in natural populations coevolution, two main outcomes occur: trench warfare dynamics as the long‐term maintenance of genetic and phenotypic diversity and an arms race with ultimate fixation of genotypes in both species. Coevolution is a prime example of eco–evo processes in which there is feedback between short‐term ecological dynamics and the evolutionary dynamics of allele frequencies. With new sequencing technologies, it is possible to reveal how coevolution shapes the genomic diversity and genome evolution of antagonistic species. Hosts can vary in the specificity of their resistance to parasites, and parasites can vary in the corresponding infectivity. The specificity of the host–parasite interaction is governed by genes which coevolve. Hosts can further vary in their quantitative resistance and parasite in their virulence. These traits and the underlying genotypes change frequency in time due to indirect and direct frequency‐dependent selection (FDS). Indirect FDS arises from the host–parasite interaction, while direct FDS arises from ecological features which affect coevolution. The balance between these two types of FDS determines the stability of the polymorphism of the coevolving genotypes. The further role of stochastic processes, such as genetic drift, is to generate either arms race or trench warfare dynamics of gene frequencies. The costs of resistance and infectivity are necessary to generate coevolutionary cycles in time but not sufficient to promote stable long‐term polymorphism. Ecological–evolutionary (eco–evo) feedbacks and trade‐offs due to fitness costs can explain the dynamics of coevolution and the stability of coevolutionary outcomes. The genomes of antagonistic species can be partitioned into major, minor and neutral genes which present different signatures of genetic diversity and can be used to study coevolution based on the theoretical framework described here.