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Principal Investigator: JOHN M HAWDON
Organization: GEORGE WASHINGTON UNIVERSITY
Fiscal Year: 2024
Award: $201,875
Funding agency: National Institute of Allergy and Infectious Diseases
SUMMARY
Hookworm infection remains one of the most important public health threats worldwide, with an estimated 450
million infected. Heavy hookworm infection is the leading cause of anemia in the tropics, resulting in debilitating
and sometimes fatal iron-deficiency anemia. Children, pregnant women, and the elderly are particularly
susceptible to morbidity from hookworm infection. Control strategies are restricted to periodic de-worming of
infected individuals with benzimidazole (BZ) and other anthelmintics. There is concern that resistance to
anthelmintics will develop with increased use in mass drug administration (MDA) programs used to control
hookworms, which require annual or biannual treatment. The rapidity with which anthelmintic resistance (AR)
developed in parasitic nematodes infecting livestock and companion animals suggest that increasing the
selective pressure on human parasitic nematodes by MDA will rapidly generate resistant worm populations as
well. Resistance is also a major concern for other drugs such as ivermectin (IVM) and pyrantel (PYR) which
are commonly used to treat lymphatic filariasis and soil transmitted nematodes including hookworms.
Molecular tests to monitor the emergence of resistance are necessary, but the genetic mutations that confer
resistance to PYR and IVM are unknown in hookworm. Molecular tests that detect emerging AR in hookworms
can help tailor drug treatments during MDA to be more effective and will be critical to avoid losing the most
effective anthelmintics for hookworm control. Previously, we identified a hookworm strain, named KGR, which
was resistant to the BZ anthelmintic thiabendazole (TBZ) as well as ivermectin (IVM). More recently we
isolated a second independent strain, named BCR, which is resistant to three drugs, TBZ, IVM, and pyrantel
(PYR). We have observed a unique phenotype in the BCR isolate that our preliminary data suggests is linked
to PYR resistance. Activation of infective BCR larvae (iL3) is depressed in response to host signals when
compared to susceptible iL3, and this effect is partially rescued at increased incubation temperature.
Furthermore, our evidence points to a defect in the membrane guanylyl cyclase (mGC) which is a key effector
of activation. We propose to determine the underlying molecular mechanism for this phenotype, and its role in
PYR resistance. In Aim 1, we will identify single nucleotide polymorphisms (SNPs) in functional domains of
mGCs that are unique to the BCR strain and use Caenorhabditis elegans as a surrogate to test the sufficiency
of the mutations in conferring resistance. We will do this by introducing the SNPs in orthologous C. elegans
genes by CRISPR/Cas9 and testing the edited nematodes for PYR resistance. In Aim 2 we will investigate the
heat sensitivity of the defective activation response in BCR larvae. We will determine the role of the heat shock
response and specifically the chaperone HSP90 in rescue of the activation defect in BCR larvae. This proposal
will provide long sought after insight into the mechanism of PYR resistance in hookworms.
Terms: <0-11 years old><Albendazole><Ancylostomatidae><Anemia><Anthelmintics><Antihelminthic Agent><Antihelminthic Drugs><Area><Bancroftian Elephantiasis><C elegans><C. elegans><C.elegans><CRISPR approach><CRISPR based approach><CRISPR method><CRISPR methodology><CRISPR technique><CRISPR technology><CRISPR tools><CRISPR-CAS-9><CRISPR-based method><CRISPR-based technique><CRISPR-based technology><CRISPR-based tool><CRISPR/CAS approach><CRISPR/Cas method><CRISPR/Cas technology><CRISPR/Cas9><CRISPR/Cas9 technology><Caenorhabditis elegans><Canine Species><Canis familiaris><Cas nuclease technology><Cell Communication and Signaling><Cell Signaling><Chaperone><Child><Child Youth><Children (0-21)><Clustered Regularly Interspaced Short Palindromic Repeats approach><Clustered Regularly Interspaced Short Palindromic Repeats method><Clustered Regularly Interspaced Short Palindromic Repeats methodology><Clustered Regularly Interspaced Short Palindromic Repeats technique><Clustered Regularly Interspaced Short Palindromic Repeats technology><Cues><DNA Alteration><DNA Sequence Alteration><DNA mutation><Data><Defect><Deoxyguanylate Cyclase><Dependence><Depressed mood><Detection><Developing Countries><Developing Nations><Development><Dogs><Dogs Mammals><Drug Therapy><Drug resistance><Drugs><Elderly><Event><Exploratory/Developmental Grant><Exposure to><Family><Farm Animal><Female of child bearing age><Female of childbearing age><Filarial Elephantiases><Genes><Genetic><Genetic Alteration><Genetic Change><Genetic defect><Genetic mutation><Guanyl Cyclase><Guanylate Cyclase><HSP-90><HSP90><Heat Shock><Heat shock factor><Heat shock proteins><Heat-Shock Proteins 90><Heat-Shock Reaction><Heat-Shock Response><Helminths><Hookworm Infections><Hookworms><Human><In Vitro><Incubated><Individual><Infection><Inosinate Cyclase><Intervention><Intervention Strategies><Intracellular Communication and Signaling><Iron deficiency anemia><Ivermectin><Larva><Less-Developed Countries><Less-Developed Nations><Link><Livestock><Lymphatic Filariasis><Medication><Membrane><Modern Man><Molecular><Molecular Chaperones><Monitor><Morbidity><Morbidity - disease rate><Mutation><Names><Nature><Nematoda><Nematodes><Ortholog><Orthologous Gene><Parasitic Worms><Parasitic nematode><Pathway interactions><Periodicals><Persons><Pharmaceutical Preparations><Pharmacotherapy><Phenotype><Population><Predisposition><Pregnant Women><Public Health><Pyrantel><R21 Mechanism><R21 Program><Receptor Protein><Resistance><Resistance development><Resistant development><Role><Sequence Alteration><Signal Transduction><Signal Transduction Systems><Signaling><Single Base Polymorphism><Single Nucleotide Polymorphism><Soil><Susceptibility><Temperature><Testing><Third-World Countries><Third-World Nations><Time><Transmission><Under-Developed Countries><Under-Developed Nations><Vermifuges><Virulent><advanced age><antihelminthic><benzimidazole><benzimidazole resistance><benzimidazole resistant><biological signal transduction><canine><cognitive development><companion animal><companion cat><companion dog><companion pet><depressed><developing country><developing nation><developing resistance><developmental><domestic dog><drug resistant><drug treatment><drug/agent><entire genome><expectant mother><expecting mother><exploratory developmental study><feeding><full genome><genome mutation><genomic alteration><geriatric><guanylyl cyclase><hsp90 Family><inhibitor><insight><interventional strategy><kids><member><membrane structure><name><named><naming><novel><parasitic roundworm><pathway><periodic><periodical><pregnant mothers><pressure><programs><receptor><resistance mechanism><resistance strain><resistance to Drug><resistant><resistant mechanism><resistant strain><resistant to Drug><response><roundworm><sadness><senior citizen><single nucleotide variant><social role><stress protein><tool><transmission process><whole genome><women of child bearing age><women of childbearing age><youngster>