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Author: Donna Huber

Onchocerciasis: Target product profiles of in vitro diagnostics to support onchocerciasis elimination mapping and mass drug administration stopping decisions

Donna Huber on August 3, 2022

In June 2021, the World Health Organization (WHO), recognizing the need for new diagnostics to support the control and elimination of onchocerciasis, published the target product profiles (TPPs) of new tests that would support the two most immediate needs: (a) mapping onchocerciasis in areas of low prevalence and (b) deciding when to stop mass drug administration programs. In both instances, the test should ideally detect an antigen specific for live, adult O. volvulus female worms. The preferred format is a field-deployable rapid test. For mapping, the test needs to be ≥ 60% sensitive and ≥ 99.8% specific, while to support stopping decisions, the test must be ≥ 89% sensitive and ≥ 99.8% specific. The requirement for extremely high specificity is dictated by the need to detect with sufficient statistical confidence the low seroprevalence threshold set by WHO. Surveys designed to detect a 1-2% prevalence of a given biomarker, as is the case here, cannot tolerate more than 0.2% of false-positives. Otherwise, the background noise would drown out the signal. It is recognized that reaching and demonstrating such a stringent specificity criterion will be challenging, but test developers can expect to be assisted by national governments and implementing partners for adequately powered field validation.

Marco A. Biamonte ,Paul T. Cantey,Yaya I. Coulibaly,Katherine M. Gass,Louise C. Hamill,Christopher Hanna,Patrick J. Lammie,Joseph Kamgno,Thomas B. Nutman,David W. Oguttu,Dieudonné P. Sankara,Wilma A. Stolk,Thomas R. Unnasch. PLoS Negl Trop Dis. 2022 Aug 3;16(8):e0010682. doi: 10.1371/journal.pntd.0010682.

Oxygen-dependent regulation of E3(SCF)ubiquitin ligases and a Skp1-associated JmjD6 homolog in development of the social amoeba Dictyostelium

Donna Huber on August 3, 2022

E3-SCF (Skp1/cullin-1/F-box protein) polyubiquitin ligases activate the proteasomal degradation of over a thousand proteins, but the evolutionary diversification of the F-box protein (FBP) family of substrate receptor subunits has challenged their elucidation in protists. Here we expand the FBP candidate list in the social amoeba Dictyostelium and show that the Skp1 interactome is highly remodeled as cells transition from solitary growth to multicellular development. Importantly, a subset of candidate FBPs was less represented when the posttranslational hydroxylation and glycosylation of Skp1 was abrogated by deletion of the O2 -sensing Skp1 prolyl hydroxylase PhyA. A role for this Skp1 modification for SCF activity was indicated by partial rescue of development, which normally depends on high O2 and PhyA, of phyA -knockout cells by proteasomal inhibitors. Further examination of two FBPs, FbxwD and the Jumonji C protein JcdI, suggested that Skp1 was substituted by other factors in phyA-knockout cells. Although a double-knockout of jcdI and its paralog jcdH did not affect development, overexpression of JcdI increased its sensitivity to O2. JcdI, a non-heme dioxygenase shown to have physiological O2-dependence, is conserved across protists with its F-box and other domains, and related to the human oncogene JmjD6. Sensitization of JcdI-overexpression cells to O2 depended on its dioxygenase activity and other domains, but not its F-box, which may however be the mediator of its reduced levels in wild-type relative to Skp1 modification mutant cells. The findings suggest that activation of JcdI by O2 is tempered by homeostatic down-regulation via PhyA and association with Skp1.

Andrew W Boland, Elisabet Gas-Pascual, Braxton L Nottingham, Hanke van der Wel, M Osman Sheikh, Christopher M Schafer, Christopher M West. J Biol Chem. 2022 Aug 3;102305. doi: 10.1016/j.jbc.2022.102305.

Direct type I interferon signaling in hepatocytes controls malaria

Donna Huber on July 19, 2022

Malaria is a devastating disease impacting over half of the world’s population. Plasmodium parasites that cause malaria undergo obligatory development and replication in hepatocytes before infecting red blood cells and initiating clinical disease. While type I interferons (IFNs) are known to facilitate innate immune control to Plasmodium in the liver, how they do so has remained unresolved, precluding the manipulation of such responses to combat malaria. Utilizing transcriptomics, infection studies, and a transgenic Plasmodium strain that exports and traffics Cre recombinase, we show that direct type I IFN signaling in Plasmodium-infected hepatocytes is necessary to control malaria. We also show that the majority of infected hepatocytes naturally eliminate Plasmodium infection, revealing the potential existence of anti-malarial cell-autonomous immune responses in such hepatocytes. These discoveries challenge the existing paradigms in Plasmodium immunobiology and are expected to inspire anti-malarial drugs and vaccine strategies.

Camila Marques-da-Silva, Kristen Peissig, Michael P Walker, Justine Shiau, Carson Bowers, Dennis E Kyle, Rahul Vijay, Scott E Lindner, Samarchith P Kurup. Cell Rep. 2022 Jul 19;40(3):111098. doi: 10.1016/j.celrep.2022.111098.

In the News: Christopher Rice quoted in news stories on Naegleria fowleri

Donna Huber on July 18, 2022

Assistant Research Scientist Christopher Rice is quoted in news stories about the brain-eating amoeba Naegleria fowleri

Swimming in freshwater? Here’s what to know about the rare brain-eating Naegleria fowleri. (USA Today)

Iowa lake beach temporarily closed after swimmer contracts rare brain-eating amoeba infection (Daily News)

Missouri swimmer infected with rare brain-eating amoeba, likely from lake in Iowa (CBS News)

Swimmer at Lake of Three Fires State Park infected with brain-eating amoeba (The Gazette)

Man Infected With a Brain-Eating Amoeba While Swimming in Iowa Lake (Now This News)

 

A Krüppel-like factor is required for development and regeneration of germline and yolk cells from somatic stem cells in planarians

Donna Huber on July 15, 2022

Fig 8. Germ cell niche factor ophis is required to sustain yolk cell production/vitellogenesis.
(A–C) Maximum intensity projections of confocal sections showing FISH of LamA (A), klf4l (B), and MX1 (C) (green) in the ventral posterior region of sexually mature control versus ophis RNAi animals. Dashed line denotes planarian boundary. N = 3 to 5 experiments, n = 7 to 26 planarians. (A) ophis RNAi results in a dramatic loss of the LamA+ cells throughout the vitellaria. Note that LamA expression is only visible in the branched gut in ophis RNAi planarians. (B, C) ophis RNAi results in a reduction of klf4l+ yolk cell progenitors and MX1+ differentiated yolk cells. (A–C) Nuclei are counterstained with DAPI (gray). Scale bars, 200 μm. (D) Model depicting similarities shared between gonads (where gametogenesis occurs) and vitellaria (where yolk cell production occurs). klf4l+/nanos+/piwi-1+ presumptive GSCs in testes and ovaries divide and give rise to klf4l–/nanos+/piwi-1+ progeny. These germ cells are supported by ophis+ somatic gonadal niche cells. Vitellaria are comprised of klf4l+/nanos+/piwi-1+ “germ cell–like” yolk progenitors that are mitotically competent, sustain yolk cell production, and are supported by ophishigh support cells. FISH, fluorescent RNA in situ hybridization; klf4l, klf4-like; RNAi, RNA interference.

Abstract

Sexually reproducing animals segregate their germline from their soma. In addition to gamete-producing gonads, planarian and parasitic flatworm reproduction relies on yolk cell-generating accessory reproductive organs (vitellaria) supporting development of yolkless oocytes. Despite the importance of vitellaria for flatworm reproduction (and parasite transmission), little is known about this unique evolutionary innovation. Here, we examine reproductive system development in the planarian Schmidtea mediterranea, in which pluripotent stem cells generate both somatic and germ cell lineages. We show that a homolog of the pluripotency factor Klf4 is expressed in primordial germ cells (PGCs), presumptive germline stem cells (GSCs), and yolk cell progenitors. Knockdown of this klf4-like (klf4l) gene results in animals that fail to specify or maintain germ cells; surprisingly, they also fail to maintain yolk cells. We find that yolk cells display germ cell-like attributes and that vitellaria are structurally analogous to gonads. In addition to identifying a new proliferative cell population in planarians (yolk cell progenitors) and defining its niche, our work provides evidence supporting the hypothesis that flatworm germ cells and yolk cells share a common evolutionary origin.

Melanie Issigonis, Akshada B Redkar, Tania Rozario, Umair W Khan, Rosa Mejia-Sanchez, Sylvain W Lapan, Peter W Reddien, Phillip A Newmark. PLoS Biol. 2022 Jul 15;20(7):e3001472. doi: 10.1371/journal.pbio.3001472.

Fagbami named 2022 Burroughs Wellcome Fund PDEP Fellow

Donna Huber on July 13, 2022

postdoctoral fellow Lola Fagbami
UGA’s Lọla Fagbami, winner of a Burroughs Wellcome Fund 2022 Postdoctoral Diversity Enrichment Program fellowship, is a native of Lagos, Nigeria, who relocated to the United States with her family in the late 1990s. She is passionate about expanding scientific literacy through outreach and mentoring as well as refuting chemophobia—the fear of or aversion to chemicals and chemistry. (Photo by Lauren Corcino)

Lọla Fagbami, a postdoctoral research associate at UGA, has been awarded a Burroughs Wellcome Fund 2022 Postdoctoral Diversity Enrichment Program fellowship.

Fagbami, UGA’s first PDEP Fellow, conducts research on the human malaria parasite Plasmodium falciparum at the Center for Tropical and Emerging Global Diseases. She works with Vasant Muralidharan, associate professor of cellular biology in the Franklin College of Arts and Sciences, who nominated her for the award.

“Dr. Fagbami has excellent training in metabolomics, mass spectrometry and Plasmodium drug discovery. Her exceptional work as a graduate student has shown how human malaria-causing parasites use metabolic adaptation to induce antimalarial drug resistance. Dr. Fagbami is a fearless, highly intelligent, accomplished and outstanding scientist who will be a leader in our field,” Muralidharan wrote in his nomination letter.

“Her research project addresses a major gap in the field that has enormous implications for malaria elimination and eradication efforts,” he added.

The PDEP award provides $60,000 over three years to support career-development activities for historically excluded minority postdoctoral fellows pursuing academic careers in biomedical or medical research, according to the Burroughs Wellcome Fund.

“This award is an investment in me as a scientist and leader and will help advance my career to the next level,” Fagbami said. “I am excited to join the extraordinary community of PDEP scholars and also connect with program alumni who have successfully made the transition to research independence.”

Fagbami earned a B.S. in chemistry at Emory University, an M.B.S. and an M.P.H. in health policy at Rutgers University, and a Ph.D. in chemical biology at Harvard University.

Quantitative 3D Imaging of Trypanosoma cruzi-Infected Cells, Dormant Amastigotes, and T Cells in Intact Clarified Organs

Donna Huber on June 23, 2022

Chagas disease is a neglected pathology that affects millions of people worldwide, mainly in Latin America. The Chagas disease agent, Trypanosoma cruzi (T. cruzi), is an obligate intracellular parasite with a diverse biology that infects several mammalian species, including humans, causing cardiac and digestive pathologies. Reliable detection of T. cruzi in vivo infections has long been needed to understand Chagas disease’s complex biology and accurately evaluate the outcome of treatment regimens. The current protocol demonstrates an integrated pipeline for automated quantification of T. cruzi-infected cells in 3D-reconstructed, cleared organs. Light-sheet fluorescent microscopy allows for accurately visualizing and quantifying of actively proliferating and dormant T. cruzi parasites and immune effector cells in whole organs or tissues. Also, the CUBIC-HistoVision pipeline to obtain uniform labeling of cleared organs with antibodies and nuclear stains was successfully adopted. Tissue clearing coupled with 3D immunostaining provides an unbiased approach to comprehensively evaluate drug treatment protocols, improve the understanding of the cellular organization of T. cruzi-infected tissues, and is expected to advance discoveries related to anti-T. cruzi immune responses, tissue damage, and repair in Chagas disease.

Fernando Sanchez-Valdez, Ángel M Padilla, Juan M Bustamante, Caleb W D Hawkins, Rick L Tarleton. J Vis Exp. 2022 Jun 23;(184). doi: 10.3791/63919.

Plasmodium knowlesi Cytoadhesion Involves SICA Variant Proteins

Donna Huber on June 23, 2022

Plasmodium knowlesi poses a health threat throughout Southeast Asian communities and currently causes most cases of malaria in Malaysia. This zoonotic parasite species has been studied in Macaca mulatta (rhesus monkeys) as a model for severe malarial infections, chronicity, and antigenic variation. The phenomenon of Plasmodium antigenic variation was first recognized during rhesus monkey infections. Plasmodium-encoded variant proteins were first discovered in this species and found to be expressed at the surface of infected erythrocytes, and then named the Schizont-Infected Cell Agglutination (SICA) antigens. SICA expression was shown to be spleen dependent, as SICA expression is lost after P. knowlesi is passaged in splenectomized rhesus. Here we present data from longitudinal P. knowlesi infections in rhesus with the most comprehensive analysis to date of clinical parameters and infected red blood cell sequestration in the vasculature of tissues from 22 organs. Based on the histopathological analysis of 22 tissue types from 11 rhesus monkeys, we show a comparative distribution of parasitized erythrocytes and the degree of margination of the infected erythrocytes with the endothelium. Interestingly, there was a significantly higher burden of parasites in the gastrointestinal tissues, and extensive margination of the parasites along the endothelium, which may help explain gastrointestinal symptoms frequently reported by patients with P. knowlesi malarial infections. Moreover, this margination was not observed in splenectomized rhesus that were infected with parasites not expressing the SICA proteins. This work provides data that directly supports the view that a subpopulation of P. knowlesi parasites cytoadheres and sequesters, likely via SICA variant antigens acting as ligands. This process is akin to the cytoadhesive function of the related variant antigen proteins, namely Erythrocyte Membrane Protein-1, expressed by Plasmodium falciparum.

Mariko S Peterson, Chester J Joyner, Stacey A Lapp, Jessica A Brady, Jennifer S Wood, Monica Cabrera-Mora, Celia L Saney, Luis L Fonseca, Wayne T Cheng, Jianlin Jiang, Stephanie R Soderberg, Mustafa V Nural, Allison Hankus, Deepa Machiah, Ebru Karpuzoglu, Jeremy D DeBarry, Rabindra Tirouvanziam, Jessica C Kissinger, Alberto Moreno, Sanjeev Gumber, Eberhard O Voit, Juan B Gutierrez, Regina Joice Cordy, Mary R Galinski. Front Cell Infect Microbiol. 2022 Jun 23;12:888496. doi: 10.3389/fcimb.2022.888496. eCollection 2022.

Multiplex Serology for Measurement of IgG Antibodies Against Eleven Infectious Diseases in a National Serosurvey: Haiti 2014-2015

Donna Huber on June 9, 2022

Background: Integrated surveillance for multiple diseases can be an efficient use of resources and advantageous for national public health programs. Detection of IgG antibodies typically indicates previous exposure to a pathogen but can potentially also serve to assess active infection status. Serological multiplex bead assays have recently been developed to simultaneously evaluate exposure to multiple antigenic targets. Haiti is an island nation in the Caribbean region with multiple endemic infectious diseases, many of which have a paucity of data for population-level prevalence or exposure.

Methods: A nationwide serosurvey occurred in Haiti from December 2014 to February 2015. Filter paper blood samples (n = 4,438) were collected from participants in 117 locations and assayed for IgG antibodies on a multiplex bead assay containing 15 different antigens from 11 pathogens: Plasmodium falciparum, Toxoplasma gondii, lymphatic filariasis roundworms, Strongyloides stercoralis, chikungunya virus, dengue virus, Chlamydia trachomatis, Treponema pallidum, enterotoxigenic Escherichia coli, Entamoeba histolytica, and Cryptosporidium parvum.

Results: Different proportions of the Haiti study population were IgG seropositive to the different targets, with antigens from T. gondii, C. parvum, dengue virus, chikungunya virus, and C. trachomatis showing the highest rates of seroprevalence. Antibody responses to T. pallidum and lymphatic filariasis were the lowest, with <5% of all samples IgG seropositive to antigens from these pathogens. Clear trends of increasing seropositivity and IgG levels with age were seen for all antigens except those from chikungunya virus and E. histolytica. Parametric models were able to estimate the rate of seroconversion and IgG acquisition per year for residents of Haiti.

Conclusions: Multiplex serological assays can provide a wealth of information about population exposure to different infectious diseases. This current Haitian study included IgG targets for arboviral, parasitic, and bacterial infectious diseases representing multiple different modes of host transmission. Some of these infectious diseases had a paucity or complete absence of published serological studies in Haiti. Clear trends of disease burden with respect to age and location in Haiti can be used by national programs and partners for follow-up studies, resource allocation, and intervention planning.

YuYen Chan, Diana Martin, Kimberly E Mace, Samuel E Jean, Gillian Stresman, Chris Drakeley, Michelle A Chang, Jean F Lemoine, Venkatachalam Udhayakumar, Patrick J Lammie, Jeffrey W Priest, Eric William Rogier. Front Public Health. 2022 Jun 9;10:897013. doi: 10.3389/fpubh.2022.897013. eCollection 2022.