Parasitology Commons^™

Individual, Social, And Environmental Factors Associated With Patterns Of Parasitic Infection In Capuchin Monkeys (Cebus Imitator), Megan C. Henriquez

Dissertations, Theses, and Capstone Projects

Parasites, and the infectious diseases they carry, are thought to have significantly impacted our evolutionary trajectory for millennia. Exploring how parasites are acquired and transmitted by their hosts in wild, natural populations is integral to understanding how similar processes may have shaped host-parasite co-evolutionary relationships over time. However, parasitological studies in humans and in non-human primates have produced inconsistent results, highlighting the dynamic, nuanced, and unique relationships individual parasites have with their hosts. These relationships are largely regulated by variation in factors at host, social, and environmental levels. Characteristics unique to the host (e.g., age and sex), factors pertaining to …

Characterizing Malaria Infections In Caribbean Lizards: Parasite Niche Expansion & Host Response, Sarah J. Pangburn

Dissertations, Theses, and Capstone Projects

Malaria is historically one of the most severe parasitic human diseases and is still responsible for over half a million deaths annually. Plasmodium species, the causative agents of malaria, are often characterized by two hallmark features of their asexual stages: the invasion of vertebrate red blood cells and the presence of hemozoin pigment as a byproduct of host hemoglobin digestion. Despite their evolutionary relatedness to mammalian Plasmodium, wildlife malaria parasites are understudied, leaving their vast genetic diversity to be explored. Lizard-infective malaria parasites, for example, include over 100 species of Plasmodium and present a diverse array of phenotypes, some …

Understanding Primate Immunity To African Trypanosomes Through The Characterization Of Trypanosome Lytic Factor Formation And Function, Sara Fresard

Dissertations, Theses, and Capstone Projects

African trypanosomes cause an annual loss of over 1 billion USD due to their economic and agricultural burden in Sub-Saharan Africa. These parasites are unicellular, extracellular parasites, that infect humans, cattle, and other livestock. Humans and some non-human primates are protected against most species of trypanosomes due to an innate immunity factor, Trypanosome Lytic Factor (TLF). This modified High Density Lipoprotein (HDL) contains two unique proteins, Haptoglobin Related Protein (HPR), a ligand to a trypanosome surface receptor, and Apolipoprotein-L1 (APOL1), the lytic component. Our overall goal is to use our understanding of primate immunity to create genetically modified cattle that …

Avian Symbionts Of Sulawesi: Identifying And Correlating Malaria Parasites And The Microbiome In Communities Of Endemic Avian Hosts, Rachael Joakim

Dissertations, Theses, and Capstone Projects

Since the evolution of complex organisms, there have been communities of symbionts inhabiting them. Thanks to the development of parallel sequencing techniques, DNA of entire microbial communities can be sequenced from a single sample. Some microbes can be parasitic in nature, such as Haemosporida, an order of eukaryotes causing malaria. While most symbionts form a more commensal host relationship in wild systems, host-symbiont dynamics can vary in pathogenicity based on biotic and abiotic factors. In vertebrates, microbial communities in the gut play a major role in host function, including immune responses to Haemosporida. Though this relationship is most commonly explored …

Insights Into Leptopilina Spp. Immune-Suppressive Strategies Using Mixed-Omics And Molecular Approaches, Brian Wey

Dissertations, Theses, and Capstone Projects

Host-parasite interactions influence the biology of each over the course of evolution. Parasite success allows for the passage of potent virulence strategies from generation to generation. Host success passes stronger immunity and resistance strategies to the following generations as well. Only by studying both partners within their natural contexts can we begin to understand the relationship between the two and how immune mechanisms and virulence strategies interact as a molecular arms race.

In this work, we focus on a natural host-parasite pair, the Drosophila-Leptopilina model. Leptopilina species are parasites of several fruit fly species, including Drosophila melanogaster. This model …

Mutational Analysis And Domain Characterization Of The Apolipoprotein L-1 Ion Channel, Charles M. Schaub

Dissertations, Theses, and Capstone Projects

The human innate immunity factor Apolipoprotein L-1 (APOL1) protects against Trypanosoma brucei brucei infection. Recent studies have shown recombinant APOL1 (rAPOL1) inserts into planar lipid bilayers at an acidic pH 5.6 and forms a cation-selective channel, which opens upon subsequent neutralization, pH 7.2. This corresponds with the pH changes APOL1 would encounter during endosome recycling, suggesting that APOL1 forms a pH-gated ion channel in the plasma membrane of the parasite, leading to uncontrolled ion flux and osmotic imbalance. However, structural and domain characteristics of the APOL1 channel are poorly understood, despite potential similarities to diphtheria and colicin toxins. Utilizing E. …

Innate Antibodies, Murine Models, And Evolution: A Study Of Trypanosome Lytic Factor Functions And Their Translational Applications, Joseph P. Verdi

Dissertations, Theses, and Capstone Projects

Trypanosome lytic factors (TLFs) are primate-specific antimicrobial protein complexes that lyse African trypanosome parasites by delivering the channel-forming toxin APOL1 to the invading microorganisms. Human serum contains two TLFs that are delivered to the parasite by separate mechanisms, only one of which has been characterized. TLF1 is endocytosed by a receptor that is typically blocked by other serum factors in vivo, suggesting that TLF2 is the more relevant lytic factor in the context of trypanosome immunity. TLF2 is non-covalently associated with polyclonal immunoglobulin M (IgM) antibodies, which we report here to be involved in the uptake mechanism. The TLF2-IgMs …

Evidence For Organelle-Like Extracellular Vesicles From A Parasite Of Drosophila And Their Function In Suppressing Host Immunity, Mary Heavner

Dissertations, Theses, and Capstone Projects

Parasitic wasps act as keystone species in natural ecosystems. Adept at suppressing immunity of their insect hosts, these natural enemies of insect pests are used for biocontrol in many parts of the world. Female parasitic wasps of the closely-related species Leptopilina heterotoma (Lh), a generalist of many Drosophilia flies, and Leptopilina boulardi (Lb), a specialist on flies of the melanogaster subgroup, produce venom and virus-like particles (VLPs) in their long gland-reservoir complexes, a secretory organ connected to ovipositors. Venom and VLPs are deposited, along with wasp eggs, into the body of the wasp’s larval fly host …

Trypanosome Lytic Factor Mediated Immunity Against Leishmania Sp., Jyoti Pant

Dissertations, Theses, and Capstone Projects

Trypanosome Lytic Factor (TLF) is an innate immunity complex that was originally discovered to protect against African Trypanosomes. The major components of TLF are Apolipoprotein A1 (APOA1), Apolipoprotein L1 (APOL1) and HPR (Haptoglobin Related Protein), where APOL1 is necessary and sufficient for trypanolysis. Recently we have shown that TLF ameliorates infections by cutaneous Leishmania species. Here we investigated the effect of different primate and human TLF against different Leishmania sp. Our result shows that TLF kills metacyclic promastigotes of cutaneous Leishmania sp. within immune cells such as neutrophils and macrophages by two different mechanism. Using transiently transfected and germline transgenic …

Evolution Of Bat-Trypanosome Associations And The Origins Of Chagas Disease, Christian Miguel Pinto

Dissertations, Theses, and Capstone Projects

Trypanosoma cruzi is a genetically diverse parasite that causes Chagas disease, one of the most important zoonoses in the Americas. This generalist parasite of mammals belongs to a clade mostly comprised of bat parasites, the T. cruzi clade. The origins (i.e., biogeographic history and evolution of hosts associations) of this parasite are far from being understood, and the main areas that need further study are: species limits within T. cruzi sensu lato, further studies on the diversity of T. cruzi clade members and their hosts, and research on adaptations of the hosts to trypanosome infections. In this dissertation I explore …