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

Category: publications

Direct type I interferon signaling in hepatocytes controls malaria

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.

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

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.


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.

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

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

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

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.

Disruption of Toxoplasma gondii-Induced Host Cell DNA Replication Is Dependent on Contact Inhibition and Host Cell Type

The protozoan Toxoplasma gondii is a highly successful obligate intracellular parasite that, upon invasion of its host cell, releases an array of host-modulating protein effectors to counter host defenses and further its own replication and dissemination. Early studies investigating the impact of T. gondii infection on host cell function revealed that this parasite can force normally quiescent cells to activate their cell cycle program. Prior reports by two independent groups identified the dense granule protein effector HCE1/TEEGR as being solely responsible for driving host cell transcriptional changes through its direct interaction with the cyclin E regulatory complex DP1 and associated transcription factors. Our group independently identified HCE1/TEEGR through the presence of distinct repeated regions found in a number of host nuclear targeted parasite effectors and verified its central role in initiating host cell cycle changes. Additionally, we report here the time-resolved kinetics of host cell cycle transition in response to HCE1/TEEGR, using the fluorescence ubiquitination cell cycle indicator reporter line (FUCCI), and reveal the existence of a block in S-phase progression and host DNA synthesis in several cell lines commonly used in the study of T. gondii. Importantly, we have observed that this S-phase block is not due to additional dense granule effectors but rather is dependent on the host cell line background and contact inhibition status of the host monolayer in vitro. This work highlights intriguing differences in the host response to reprogramming by the parasite and raises interesting questions regarding how parasite effectors differentially manipulate the host cell depending on the in vitro or in vivo context.

IMPORTANCE Toxoplasma gondii chronically infects approximately one-third of the global population and can produce severe pathology in immunologically immature or compromised individuals. During infection, this parasite releases numerous host-targeted effector proteins that can dramatically alter the expression of a variety of host genes. A better understanding of parasite effectors and their host targets has the potential to not only provide ways to control infection but also inform us about our own basic biology. One host pathway that has been known to be altered by T. gondii infection is the cell cycle, and prior reports have identified a parasite effector, known as HCE1/TEEGR, as being responsible. In this report, we further our understanding of the kinetics of cell cycle transition induced by this effector and show that the capacity of HCE1/TEEGR to induce host cell DNA synthesis is dependent on both the cell type and the status of contact inhibition.

Edwin Pierre-Louis, Menna G Etheridge, Rodrigo de Paula Baptista, Asis Khan, Nathan M Chasen, Ronald D Etheridge. mSphere. 2022 May 19;e0016022. doi: 10.1128/msphere.00160-22.

Review of 2022 WHO guidelines on the control and elimination of schistosomiasis

Schistosomiasis is a helminthiasis infecting approximately 250 million people worldwide. In 2001, the World Health Assembly (WHA) 54.19 resolution defined a new global strategy for control of schistosomiasis through preventive chemotherapy programmes. This resolution culminated in the 2006 WHO guidelines that recommended empirical treatment by mass drug administration with praziquantel, predominately to school-aged children in endemic settings at regular intervals. Since then, school-based and community-based preventive chemotherapy programmes have been scaled-up, reducing schistosomiasis-associated morbidity. Over the past 15 years, new scientific evidence-combined with a more ambitious goal of eliminating schistosomiasis and an increase in the global donated supply of praziquantel-has highlighted the need to update public health guidance worldwide. In February, 2022, WHO published new guidelines with six recommendations to update the global public health strategy against schistosomiasis, including expansion of preventive chemotherapy eligibility from the predominant group of school-aged children to all age groups (2 years and older), lowering the prevalence threshold for annual preventive chemotherapy, and increasing the frequency of treatment. This Review, written by the 2018-2022 Schistosomiasis Guidelines Development Group and its international partners, presents a summary of the new WHO guideline recommendations for schistosomiasis along with their historical context, supporting evidence, implications for public health implementation, and future research needs.

Nathan C Lo, Fernando Schemelzer Moraes Bezerra, Daniel G Colley, Fiona M Fleming, Mamoun Homeida, Narcis Kabatereine, Fatma M Kabole, Charles H King, Margaret A Mafe, Nicholas Midzi, Francisca Mutapi, Joseph R Mwanga, Reda M R Ramzy, Fadjar Satrija, J Russell Stothard, Mamadou Souncalo Traoré, Joanne P Webster, Jürg Utzinger, Xiao-Nong Zhou, Anthony Danso-Appiah, Paolo Eusebi, Eric S Loker, Charles O Obonyo, Reginald Quansah, Song Liang, Michel Vaillant, M Hassan Murad, Paul Hagan, Amadou Garba. Lancet Infect Dis. 2022 May 17;S1473-3099(22)00221-3. doi: 10.1016/S1473-3099(22)00221-3.

Small and intermediate size structural RNAs in the unicellular parasite Cryptosporidium parvum as revealed by sRNA-seq and comparative genomics

Small and intermediate-size noncoding RNAs (sRNAs and is-ncRNAs) have been shown to play important regulatory roles in the development of several eukaryotic organisms. However, they have not been thoroughly explored in Cryptosporidium parvum, an obligate zoonotic protist parasite responsible for the diarrhoeal disease cryptosporidiosis. Using Illumina sequencing of a small RNA library, a systematic identification of novel small and is-ncRNAs was performed in C. parvum excysted sporozoites. A total of 79 novel is-ncRNA candidates, including antisense, intergenic and intronic is-ncRNAs, were identified, including 7 new small nucleolar RNAs (snoRNAs). Expression of select novel is-ncRNAs was confirmed by RT-PCR. Phylogenetic conservation was analysed using covariance models (CMs) in related Cryptosporidium and apicomplexan parasite genome sequences. A potential new type of small ncRNA derived from tRNA fragments was observed. Overall, a deep profiling analysis of novel is-ncRNAs in C. parvum and related species revealed structural features and conservation of these novel is-ncRNAs. Covariance models can be used to detect is-ncRNA genes in other closely related parasites. These findings provide important new sequences for additional functional characterization of novel is-ncRNAs in the protist pathogen C. parvum.

Yiran Li, Rodrigo P Baptista, Xiaohan Mei, Jessica C Kissinger. Microb Genom. 2022 May;8(5). doi: 10.1099/mgen.0.000821

Polymorphic Molecular Signatures in Variable Regions of the Plasmodium falciparum var2csa DBL3x Domain Are Associated with Virulence in Placental Malaria

The Plasmodium falciparum protein VAR2CSA allows infected erythrocytes to accumulate within the placenta, inducing pathology and poor birth outcomes. Multiple exposures to placental malaria (PM) induce partial immunity against VAR2CSA, making it a promising vaccine candidate. However, the extent to which VAR2CSA genetic diversity contributes to immune evasion and virulence remains poorly understood. The deep sequencing of the var2csa DBL3X domain in placental blood from forty-nine primigravid and multigravid women living in malaria-endemic western Kenya revealed numerous unique sequences within individuals in association with chronic PM but not gravidity. Additional analysis unveiled four distinct sequence types that were variably present in mixed proportions amongst the study population. An analysis of the abundance of each of these sequence types revealed that one was inversely related to infant gestational age, another was inversely related to placental parasitemia, and a third was associated with chronic PM. The categorization of women according to the type to which their dominant sequence belonged resulted in the segregation of types as a function of gravidity: two types predominated in multigravidae whereas the other two predominated in primigravidae. The univariate logistic regression analysis of sequence type dominance further revealed that gravidity, maternal age, placental parasitemia, and hemozoin burden (within maternal leukocytes), reported a lack of antimalarial drug use, and infant gestational age and birth weight influenced the odds of membership in one or more of these sequence predominance groups. Cumulatively, these results show that unique var2csa sequences differentially appear in women with different PM exposure histories and segregate to types independently associated with maternal factors, infection parameters, and birth outcomes. The association of some var2csa sequence types with indicators of pathogenesis should motivate vaccine efforts to further identify and target VAR2CSA epitopes associated with maternal morbidity and poor birth outcomes.

Eldin Talundzic, Stephen Scott, Simon O Owino, David S Campo, Naomi W Lucchi, Venkatachalam Udhayakumar, Julie M Moore, David S Peterson. Pathogens. 2022 Apr 28;11(5):520. doi: 10.3390/pathogens11050520

Essential Bromodomain Tc BDF2 as a Drug Target against Chagas Disease

Trypanosoma cruzi is a unicellular parasite that causes Chagas disease, which is endemic in the American continent but also worldwide, distributed by migratory movements. A striking feature of trypanosomatids is the polycistronic transcription associated with post-transcriptional mechanisms that regulate the levels of translatable mRNA. In this context, epigenetic regulatory mechanisms have been revealed to be of great importance, since they are the only ones that would control the access of RNA polymerases to chromatin. Bromodomains are epigenetic protein readers that recognize and specifically bind to acetylated lysine residues, mostly at histone proteins. There are seven coding sequences for BD-containing proteins in trypanosomatids, named TcBDF1 to TcBDF7, and a putative new protein containing a bromodomain was recently described. Using the Tet-regulated overexpression plasmid pTcINDEX-GW and CRISPR/Cas9 genome editing, we were able to demonstrate the essentiality of TcBDF2 in T. cruzi. This bromodomain is located in the nucleus, through a bipartite nuclear localization signal. TcBDF2 was shown to be important for host cell invasion, amastigote replication, and differentiation from amastigotes to trypomastigotes. Overexpression of TcBDF2 diminished epimastigote replication. Also, some processes involved in pathogenesis were altered in these parasites, such as infection of mammalian cells, replication of amastigotes, and the number of trypomastigotes released from host cells. In in vitro studies, TcBDF2 was also able to bind inhibitors showing a specificity profile different from that of the previously characterized TcBDF3. These results point to TcBDF2 as a druggable target against T. cruzi.

Alejandro Pezza, Luis E Tavernelli, Victoria L Alonso, Virginia Perdomo, Raquel Gabarro, Rab Prinjha, Elvio Rodríguez Araya, Inmaculada Rioja, Roberto Docampo, Felix Calderón, Julio Martin, Esteban Serra. ACS Infect Dis. 2022 Apr 28. doi: 10.1021/acsinfecdis.2c00057.