University of Georgia
Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Author: Donna Huber

A Target Site Mutation Associated With Diamide Insecticide Resistance in the Diamondback Moth Plutella xylostella (Lepidoptera: Plutellidae) is Widespread in South Georgia and Florida Populations

Donna Huber on November 26, 2021

Laboratory colonies of diamondback moth (DBM) larvae were established from larvae collected from four sites in Georgia and Florida where diamide, specifically chlorantraniliprole, insecticide resistance was recently documented. Based on dose-response experiments, these colonies exhibited 109- to 4,298-fold resistance to chlorantraniliprole, compared to a commercially available susceptible control colony. Colonies exhibited 50- to 107-fold resistance to another diamide, cyantraniliprole, based on similar dose-response experiments. All colonies were screened for the presence of four known mutations in the ryanodine receptor (RyR), the target of diamide insecticides, previously associated with resistance in Asian DBM populations. One mutation, G4946E, was identified in colonies from all four field sites, but not the susceptible control colony. Three additional RyR target site mutations, E1338D, Q4594L, and I4790M, were not identified in any of the screened samples. The estimated allele frequency of the G4946E mutation in these colonies ranged from 32 to 90%. These data are consistent with recently reported chlorantraniliprole control failures in Georgia and Florida. It is likely that the G4946E mutation is currently an important contributing factor to chlorantraniliprole resistance in Georgia and Florida DBM populations.

Thomas P ‘Sam’ Dunn, Donald E Champagne, David G Riley, Hugh Smith, John E Bennett. J Econ Entomol. 2021 Nov 26;toab223. doi: 10.1093/jee/toab223

Identifying bracovirus and ichnovirus genes involved in virion morphogenesis

Donna Huber on November 25, 2021

Bracoviruses (BVs) and ichnoviruses (IVs) evolved from different endogenized viruses but through convergence have been coopted by parasitoids in the families Braconidae and Ichneumonidae for similar functions in parasitizing hosts. Experimentally studying the role of endogenized viral genes in virion morphogenesis remains a key challenge in the study of BVs and IVs. Here we summarize how multiomics, electron microscopy, and RNA interference (RNAi) methods have provided new insights about BV and IV gene function.

Ange Lorenzi, Michael R Strand, Gaelen R Burke, Anne-Nathalie Volkoff. Curr Opin Insect Sci. 2021 Nov 25;S2214-5745(21)00127-9. doi: 10.1016/j.cois.2021.11.006.

Trainee Spotlight: Benjamin Phipps

Donna Huber on November 16, 2021

Benjamin Phipps

Benjamin Phipps is an NIH T32 trainee in Michael Strand‘s laboratory. Originally from Woodland, California, Benjamin earned his bachelor’s degrees in Spanish and biology and a minor in chemistry from the University of North Texas in May 2019. While at UNT, he studied the influence of mixed vehicle emissions on regulation of the renin-angiotensin system with Dr. Amie Lund and programmed translational frameshifts in Streptomyces bacteriophages with Dr. Lee Hughes. Benjamin earned research support and two travel grants to report his findings for his undergraduate projects. In August 2019, he enrolled in the Integrated Life Sciences (ILS) program at UGA and completed several laboratory rotations in parasitology before joining the Strand Research Group. He has served as treasurer of the Genetics Graduate Student Association and currently serves in that role for the CTEGD GSA.

Why did you choose UGA?

I chose UGA for its strong track record in research and breadth of research topics. I enrolled at UGA through Integrated Life Sciences, a gateway Ph.D. program that allows incoming students to explore several life sciences departments before choosing one for their dissertation home. This allowed me to experience a greater range of research topics than if I had enrolled directly in a single department. I also developed an interest in parasitology in the last year of my undergraduate program and therefore was drawn to CTEGD, one of the largest and most active centers for parasitology research in the world.

What is your research focus/project and why are you interested in the topic?

Many mosquito species must feed on vertebrate blood to produce eggs, and thereby can transmit several blood-borne pathogens of humans. Malaria is by far the deadliest of these, killing hundreds of thousands of people each year. Suppressing mosquito populations is an attractive approach to curbing transmission of malaria. Two promising targets for limiting mosquito reproductive capacity are the communities of microorganisms that reside in the mosquito gut, which are thought to influence fecundity by aiding blood digestion, and hormones mobilized in response to the blood meal that regulate egg formation. Malaria parasites have an antagonistic relationship with mosquito gut microbes and exploit resources generated for egg production after the blood meal. My dissertation project focuses on how mosquito gut microbes influence malaria infection by modulating reproductive signaling. This research has the potential to identify microbial species that might be exploited for malaria control, as well as elucidate important functions of gut microbes in preventing infections in animals.

What are your future professional plans?

I am presently most interested in a career in academia because I enjoy mentorship and science writing, but I remain open to other opportunities.

What do you hope to do for your capstone experience? 

For my capstone experience, I would like to draw on my training in both parasitology and Spanish language to travel to Colombia or Venezuela, where malaria is declining but still endemic. Potential activities there would involve characterizing endemic anopheline populations and their vectorial capacity.

What is your favorite thing about UGA?

I really enjoy the collaborative atmosphere of life sciences at UGA. Groups such as CTEGD provide many opportunities to interact with students and faculty from diverse departments.

Any advice for a student interested in this field? 

Be sure to get involved in research as soon as possible, preferably early in your undergraduate program. Reach out to professors whose work interests you, as well as members of their team. It’s fine not to know what specific topics you want to pursue right away; your initial research experience will help you determine what interests you most, and there will be many opportunities to explore diverse fields in graduate school and beyond.

 

Support trainees like Benjamin by giving today to the Center for Tropical & Emerging Global Diseases.

[button size=’large’ style=” text=’Give Now’ icon=” icon_color=’BA0C2F’ link=’https://ctegd.uga.edu/give/’ target=’_self’ color=” hover_color=” border_color=” hover_border_color=” background_color=” hover_background_color=” font_style=” font_weight=” text_align=’center’ margin=”]

Diagnostic Characteristics of Lactate Dehydrogenase on a Multiplex Assay for Malaria Detection Including the Zoonotic Parasite Plasmodium knowlesi

Donna Huber on November 15, 2021

Plasmodium lactate dehydrogenase (pLDH) is a common target in malaria rapid diagnostic tests (RDTs). These commercial antibody capture assays target either Plasmodium falciparum-specific pLDH (PfLDH), P. vivax-specific pLDH (PvLDH), or a conserved epitope in all human malaria pLDH (PanLDH). However, there are no assays specifically targeting P. ovale, P. malariae or zoonotic parasites such as P. knowlesi and P. cynomolgi. A malaria multiplex array, carrying the specific antibody spots for PfLDH, PvLDH, and PanLDH has been previously developed. This study aimed to assess potential cross-reactivity between pLDH from various Plasmodium species and this array. We tested recombinant pLDH proteins, clinical samples for P. vivax, P. falciparum, P. ovale curtisi, and P. malariae; and in vitro cultured P. knowlesi and P. cynomolgi. P. ovale-specific pLDH (PoLDH) and P. malariae-specific pLDH (PmLDH) cross-reacted with the PfLDH and PanLDH spots. Plasmodium knowlesi-specific pLDH (PkLDH) and P. cynomolgi-specific pLDH (PcLDH) cross-reacted with the PvLDH spot, but only PkLDH was recognized by the PanLDH spot. Plasmodium ovale and P. malariae can be differentiated from P. falciparum by the concentration ratios of PanLDH/PfLDH, which had mean (range) values of 4.56 (4.07-5.16) and 4.56 (3.43-6.54), respectively, whereas P. falciparum had a lower ratio of 1.12 (0.56-2.61). Plasmodium knowlesi had a similar PanLDH/PvLDH ratio value, with P. vivax having a mean value of 2.24 (1.37-2.79). The cross-reactivity pattern of pLDH can be a useful predictor to differentiate certain Plasmodium species. Cross-reactivity of the pLDH bands in RDTs requires further investigation.

Becky Barney, Miguel Velasco, Caitlin Cooper, Andrew Rashid, Dennis Kyle, Robert Moon, Gonzalo Domingo, Ihn Kyung Jang. Am J Trop Med Hyg. 2021 Nov 15;tpmd210532. doi: 10.4269/ajtmh.21-0532

Diagnostics to support elimination of lymphatic filariasis-Development of two target product profiles

Donna Huber on November 15, 2021

As lymphatic filariasis (LF) programs move closer to established targets for validation elimination of LF as a public health problem, diagnostic tools capable of supporting the needs of the programs are critical for success. Known limitations of existing diagnostic tools make it challenging to have confidence that program endpoints have been achieved. In 2019, the World Health Organization (WHO) established a Diagnostic Technical Advisory Group (DTAG) for Neglected Tropical Diseases tasked with prioritizing diagnostic needs including defining use-cases and target product profiles (TPPs) for needed tools. Subsequently, disease-specific DTAG subgroups, including one focused on LF, were established to develop TPPs and use-case analyses to be used by product developers. Here, we describe the development of two priority TPPs for LF diagnostics needed for making decisions for stopping mass drug administration (MDA) of a triple drug regimen and surveillance. Utilizing the WHO core TPP development process as the framework, the LF subgroup convened to discuss and determine attributes required for each use case. TPPs considered the following parameters: product use, design, performance, product configuration and cost, and access and equity. Version 1.0 TPPs for two use cases were published by WHO on 12 March 2021 within the WHO Global Observatory on Health Research and Development. A common TPP characteristic that emerged in both use cases was the need to identify new biomarkers that would allow for greater precision in program delivery. As LF diagnostic tests are rarely used for individual clinical diagnosis, it became apparent that reliance on population-based surveys for decision making requires consideration of test performance in the context of such surveys. In low prevalence settings, the number of false positive test results may lead to unnecessary continuation or resumption of MDA, thus wasting valuable resources and time. Therefore, highly specific diagnostic tools are paramount when used to measure low thresholds. The TPP process brought to the forefront the importance of linking use case, program platform and diagnostic performance characteristics when defining required criteria for diagnostic tools.

Kimberly Y Won, Katherine Gass, Marco Biamonte, Daniel Argaw Dagne, Camilla Ducker, Christopher Hanna, Achim Hoerauf, Patrick J Lammie, Sammy M Njenga, Rahmah Noordin, Kapa D Ramaiah, Reda Ramzy, Ronaldo G Carvalho Scholte, Anthony W Solomon, Ashley A Souza, Jordan Tappero, Emily Toubali, Gary J Weil, Steven A Williams, Jonathan D King. PLoS Negl Trop Dis 15(11): e0009968. https://doi.org/10.1371/journal.pntd.0009968

Long-read assembly and comparative evidence-based reanalysis of Cryptosporidium genome sequences reveals expanded transporter repertoire and duplication of entire chromosome ends including subtelomeric regions

Donna Huber on November 11, 2021

Cryptosporidiosis is a leading cause of waterborne diarrheal disease globally and an important contributor to mortality in infants and the immunosuppressed. Despite its importance, the Cryptosporidium community has only had access to a good, but incomplete, Cryptosporidium parvum IOWA reference genome sequence. Incomplete reference sequences hamper annotation, experimental design and interpretation. We have generated a new C. parvum IOWA genome assembly supported by PacBio and Oxford Nanopore long-read technologies and a new comparative and consistent genome annotation for three closely related species C. parvum, Cryptosporidium hominis and Cryptosporidium tyzzeri We made 1,926 C. parvum annotation updates based on experimental evidence. They include new transporters, ncRNAs, introns and altered gene structures. The new assembly and annotation revealed a complete Dnmt2 methylase ortholog. Comparative annotation between C. parvum, C. hominis and C. tyzzeri revealed that most “missing” orthologs are found suggesting that the biological differences between the species must result from gene copy number variation, differences in gene regulation and single nucleotide variants (SNVs). Using the new assembly and annotation as reference, 190 genes are identified as evolving under positive selection, including many not detected previously. The new C. parvum IOWA reference genome assembly is larger, gap free and lacks ambiguous bases. This chromosomal assembly recovers all 16 chromosome ends, 13 of which are contiguously assembled. The three remaining chromosome ends are provisionally placed. These ends represent duplication of entire chromosome ends including subtelomeric regions revealing a new level of genome plasticity that will both inform and impact future research.

Rodrigo P Baptista, Yiran Li, Adam Sateriale, Karen L Brooks, Alan Tracey, Mandy J Sanders, Brendan R E Ansell, Aaron R Jex, Garrett W Cooper, Ethan D Smith, Rui Xiao, Jennifer E Dumaine, Peter Georgeson, Bernard Pope, Matthew Berriman, Boris Striepen, James A Cotton, Jessica C Kissinger. Genome Res. 2021 Nov 11;gr.275325.121. doi: 10.1101/gr.275325.121.

Evolutionary genomics of APSE: a tailed phage that lysogenically converts the bacterium Hamiltonella defensa into a heritable protective symbiont of aphids

Donna Huber on November 10, 2021

Background: Most phages infect free-living bacteria but a few have been identified that infect heritable symbionts of insects or other eukaryotes. Heritable symbionts are usually specialized and isolated from other bacteria with little known about the origins of associated phages. Hamiltonella defensa is a heritable bacterial symbiont of aphids that is usually infected by a tailed, double-stranded DNA phage named APSE.

Methods: We conducted comparative genomic and phylogenetic studies to determine how APSE is related to other phages and prophages.

Results: Each APSE genome was organized into four modules and two predicted functional units. Gene content and order were near-fully conserved in modules 1 and 2, which encode predicted DNA metabolism genes, and module 4, which encodes predicted virion assembly genes. Gene content of module 3, which contains predicted toxin, holin and lysozyme genes differed among haplotypes. Comparisons to other sequenced phages suggested APSE genomes are mosaics with modules 1 and 2 sharing similarities with Bordetella-Bcep-Xylostella fastidiosa-like podoviruses, module 4 sharing similarities with P22-like podoviruses, and module 3 sharing no similarities with known phages. Comparisons to other sequenced bacterial genomes identified APSE-like elements in other heritable insect symbionts (Arsenophonus spp.) and enteric bacteria in the family Morganellaceae.

Conclusions: APSEs are most closely related to phage elements in the genus Arsenophonus and other bacteria in the Morganellaceae.

Bret M Boyd, Germain Chevignon, Vilas Patel, Kerry M Oliver, Michael R Strand. Virol J. 2021 Nov 10;18(1):219. doi: 10.1186/s12985-021-01685-y.

The transcriptome of Balamuthia mandrillaris trophozoites for structure-guided drug design

Donna Huber on November 4, 2021

Balamuthia mandrillaris, a pathogenic free-living amoeba, causes cutaneous skin lesions as well as granulomatous amoebic encephalitis, a ‘brain-eating’ disease. As with the other known pathogenic free-living amoebas (Naegleria fowleri and Acanthamoeba species), drug discovery efforts to combat Balamuthia infections of the central nervous system are sparse; few targets have been validated or characterized at the molecular level, and little is known about the biochemical pathways necessary for parasite survival. Current treatments of encephalitis due to B. mandrillaris lack efficacy, leading to case fatality rates above 90%. Using our recently published methodology to discover potential drugs against pathogenic amoebas, we screened a collection of 85 compounds with known antiparasitic activity and identified 59 compounds that impacted the growth of Balamuthia trophozoites at concentrations below 220 µM. Since there is no fully annotated genome or proteome of B. mandrillaris, we sequenced and assembled its transcriptome from a high-throughput RNA-sequencing (RNA-Seq) experiment and located the coding sequences of the genes potentially targeted by the growth inhibitors from our compound screens. We determined the sequence of 17 of these target genes and obtained expression clones for 15 that we validated by direct sequencing. These will be used in the future in combination with the identified hits in structure guided drug discovery campaigns to develop new approaches for the treatment of Balamuthia infections.

Isabelle Q Phan, Christopher A Rice, Justin Craig, Rooksana E Noorai, Jacquelyn R McDonald, Sandhya Subramanian, Logan Tillery, Lynn K Barrett, Vijay Shankar, James C Morris, Wesley C Van Voorhis, Dennis E Kyle, Peter J Myler. Sci Rep. 2021 Nov 4;11(1):21664. doi: 10.1038/s41598-021-99903-8.

The Histidine Ammonia Lyase of Trypanosoma cruzi Is Involved in Acidocalcisome Alkalinization and Is Essential for Survival under Starvation Conditions

Donna Huber on November 2, 2021

Trypanosoma cruzi, the agent of Chagas disease, accumulates polyphosphate (polyP) and Ca2+ inside acidocalcisomes. The alkalinization of this organelle stimulates polyP hydrolysis and Ca2+ release. Here, we report that histidine ammonia lyase (HAL), an enzyme that catalyzes histidine deamination with production of ammonia (NH3) and urocanate, is responsible for acidocalcisome alkalinization. Histidine addition to live parasites expressing HAL fused to the pH-sensitive emission biosensor green fluorescent protein (GFP) variant pHluorin induced alkalinization of acidocalcisomes. PolyP decreased HAL activity of epimastigote lysates or the recombinant protein but did not cause its polyphosphorylation, as determined by the lack of HAL electrophoretic shift on NuPAGE gels using both in vitro and in vivo conditions. We demonstrate that HAL binds strongly to polyP and localizes to the acidocalcisomes and cytosol of the parasite. Four lysine residues localized in the HAL C-terminal region are instrumental for its polyP binding, its inhibition by polyP, its function inside acidocalcisomes, and parasite survival under starvation conditions. Expression of HAL in yeast deficient in polyP degradation decreased cell fitness. This effect was enhanced by histidine and decreased when the lysine-rich C-terminal region was deleted. In conclusion, this study highlights a mechanism for stimulation of acidocalcisome alkalinization linked to amino acid metabolism.

IMPORTANCE Trypanosoma cruzi is the etiologic agent of Chagas disease and is characterized by the presence of acidocalcisomes, organelles rich in phosphate and calcium. Release of these molecules, which are necessary for growth and cell signaling, is induced by alkalinization, but a physiological mechanism for acidocalcisome alkalinization was unknown. In this work, we demonstrate that a histidine ammonia lyase localizes to acidocalcisomes and is responsible for their alkalinization.

Brian S Mantilla, Cristina Azevedo, Paul W Denny, Adolfo Saiardi, Roberto Docampo. mBio. 2021 Nov 2;e0198121. doi: 10.1128/mBio.01981-21.

Expeditious recruitment of circulating memory CD8 T cells to the liver facilitates control of malaria

Donna Huber on November 2, 2021

Circulating memory CD8 T cell trafficking and protective capacity during liver-stage malaria infection remains undefined. We find that effector memory CD8 T cells (Tem) infiltrate the liver within 6 hours after malarial or bacterial infections and mediate pathogen clearance. Tem recruitment coincides with rapid transcriptional upregulation of inflammatory genes in Plasmodium-infected livers. Recruitment requires CD8 T cell-intrinsic LFA-1 expression and the presence of liver phagocytes. Rapid Tem liver infiltration is distinct from recruitment to other non-lymphoid tissues in that it occurs both in the absence of liver tissue resident memory “sensing-and-alarm” function and ∼42 hours earlier than in lung infection by influenza virus. These data demonstrate relevance for Tem in protection against malaria and provide generalizable mechanistic insights germane to control of liver infections.

Mitchell N Lefebvre, Fionna A Surette, Scott M Anthony, Rahul Vijay, Isaac J Jensen, Lecia L Pewe, Lisa S Hancox, Natalija Van Braeckel-Budimir, Stephanie van de Wall, Stina L Urban, Madison R Mix, Samarcith P Kurup, Vladimir P Badovinac, Noah S Butler, John T Harty. Cell Rep. 2021 Nov 2;37(5):109956. doi: 10.1016/j.celrep.2021.109956.