• Volunteer receiving sporozoites via needle injection.

    Direct venous inoculation of Plasmodium falciparum sporozoites for controlled human malaria infection.

    Mordmüller et al., 2015 Malaria Journal

Overview

Despite considerable efforts during recent years to combat malaria, the disease remains a major threat to public health in tropical countries. The most severe clinical courses of malaria are due to infections with the protozoan species Plasmodium falciparum. The virulence of P. falciparum has been linked to the ability of infected red blood cells to adhere to a range of endothelial cell surface molecules expressed on blood vessel walls such as CD36 and ICAM-1. This so-called sequestration process allows the parasite to avoid spleen-dependent killing mechanisms. However, membrane proteins mediating sequestration are exposed to the host’s immune system and need to be varied in a long-lasting chronic infection by undergoing antigenic variation. For this reason, P. falciparum possesses several multicopy gene families coding for variant surface antigens, which are characterized by an extensive sequence polymorphism. The best known is the high molecular weight PfEMP1 family (P. falciparum erythrocyte membrane protein 1), which is encoded by 60 var genes per parasite genome. Each var gene encodes a similar, but not identical PfEMP1 version with particular receptor binding capacities. The expression switching between different var genes enables the parasite to change its immunological appearance and cytoadhesion capability during the course of infection. Accordingly, blocking the expression switch between different PfEMP1 variants exposed on the surface of infected erythrocytes would give the immune system a major advantage in fighting malaria infections. Additionally, disease-causing PfEMP1 variants or other virulence factors could be used for anti-disease interventions.    

Research Projects

Var gene expression in experimental human malaria infections

How the parasite coordinates its var gene expression in vivo is of tremendous interest and we are currently taking advantage of controlled human malaria infection (CHMI) studies to address this question. During CHMI studies either malaria-naïve or pre-exposed volunteers are infected with one lot of purified, cryopreserved NF54 or 7G8 sporozoites, the infectious mosquito stage of the parasite, provided by Sanaria, USA. Parasite-positive blood from the volunteers is immediately preserved for transcript profiling of the entire NF54/7G8 var gene repertoire either by quantitative real time PCR (qPCR) or RNA sequencing. For comparison, in vitro cultivated ‘pre-mosquito parasites’, gametocytes and sporozoites are also analysed. We aim to compare var gene expression patterns i) between different parasite stages, ii) between in vitro-cultivated parasites and those obtained from the volunteers, iii) between parasites recovered from malaria-naïve and semi-immune volunteers, iv) between in vivo samples obtained longitudinally during the course of volunteer infections, and v) between the two genetically different parasite strain used for CHMI studies. This analysis should allow us to answer if an intrinsic program of the parasite determines the expression of the major virulence factor PfEMP1 at the early onset of P. falciparum blood infections in malaria-naïve individuals, how this expression pattern is modulated by the host immunity and how the expression is controlled by the parasite.

Dot plots and pie charts showing the var gene expression patterns in the pre-mosquito parasites and those obtained from the volunteers.
Expression of var genes in parasites before and after transmission to the human host. The expression pattern changes dramatically indicating a reset of virulence gene expression upon transmission.

Virulence-associated gene expression patterns in natural human malaria infections

Mainly children under five years of age and pregnant women from malaria-endemic regions suffer from severe malaria, but adults from areas of lower endemicity and non-immune travelers are also vulnerable to severe disease. Although severe malaria manifests as three main overlapping syndromes in children (cerebral malaria, hyperlactatemia/acidosis and severe anemia), disease symptomatology also varies according to age with more multiorgan complications and a higher fatality rate in adults. The underlying factors responsible for the different disease syndromes in children or age-related differences seen in adults remain largely unknown. To better understand the biological processes involved in host-pathogen interactions we are analysing samples i) from a Ghanaian cohort of paediatric malaria patients with accurately defined phenotypes of the different severe malaria syndromes and asymptomatic controls or ii) from returning adult travellers with varying previous malaria exposure and different clinical manifestations. We use an RNA sequencing and analysis pipeline to uncover associations of parasites gene expression (including var genes) with the different malaria syndromes, disease severity and a naïve immune status.

Heat map showing expression diefferences of PfEMP1 domains
Differential expression of var gene domains in P. falciparum parasites from first-time infected and pre-exposed adult travelers.

Dissecting the gene expression, subcellular localization and function of small variant surface antigens

In addition to PfEMP1, which certainly mediates antigenic variation and endothelial receptor binding of P. falciparum, much less is known about the small variant surface antigens families RIFIN, STEVOR and PfMC-2TM. Interestingly, they members have been localized at different subcellular sites within the infected red blood cell and are, therefore, candidates for mediating several of the patho-physiological events during malaria disease. However, a better understanding of these small variant surface protein families is necessary and may reveal new targets for intervention. To get more insight in their function, we established analytical tools for analyzing parasites obtained from malaria patients, whose gene expression and protein localization is not influenced by prolonged in vitro-cultivation. We could already show that the gene expression of RIFIN- and STEVOR-encoding genes is enhanced in vivo and that proteins of both families contribute to the surface coat of the infected red blood cell. Currently, we are characterizing the gene expression, localization and functional role of small variant surface antigen in the invasive stage, the merozoite, as well as in other life cycle stages of the parasite.

Scheme of a trophozoites (top) and schizonts with developing merozoites (bottom) showing the localization of the small variant surface antigen families RIFIN, STEVOR and PfMC-2TM as dots within the infected erythrocyte.
Localization of the small variant surface antigens RIFIN, STEVOR and PfMC-2TM during asexual blood stage development. The subcellular localization depends on the parasite stage with a predominant association with the erythrocyte membrane during the trophozoite stage (top) and an localization within the newly formed merozoites during the schizont stage (bottom).

Publication Highlights

Laborgruppe Bachmann

Common virulence gene expression in adult first-time infected malaria patients and severe cases
Wichers JS, Tonkin-Hill G, Thye T, Krumkamp R, Kreuels B, Strauss J, von Thien H, Scholz JAMS, Smedegaard Hansson H, Weisel Jensen R, Turner L, Lorenz FR, Schöllhorn A, Bruchhaus I, Tannich E, Fendel R, Otto TD, Lavstsen T, Gilberger TW, Duffy MF, Bachmann A
elife. 2021 Apr 28;10:e69040. doi: 10.7554/eLife.69040.

Dissecting the gene expression, localization, membrane topology, and function of the Plasmodium falciparum STEVOR protein family
Wichers JS, Scholz JAM, Strauss J, Witt S, Lill A, Ehnhold LI, Neupert N, Liffner B, Lühken R, Petter M, Lorenzen S, Wilson DW, Löw C, Lavazec C, Bruchhaus I, Tannich E, Gilberger TW, Bachmann A
mBio. 2019 Jul 30;10(4):e01500-19. doi: 10.1128/mBio.01500-19.

Controlled human malaria infection with Plasmodium falciparum demonstrates impact of naturally acquired immunity on virulence gene expression
Bachmann A, Bruske E, Krumkamp R, Turner L, Wichers JS, Petter M, Held J, Duffy MF, Sim BKL, Hoffman SL, Kremsner PG, Lell B, Lavstsen T, Frank M, Mordmüller B, Tannich E
PLoS Pathog. 2019 Jul 11;15(7):e1007906. doi: 10.1371/journal.ppat.1007906.

Mosquito passage dramatically changes var gene expression in controlled human Plasmodium falciparum infections
Bachmann A, Petter M, Krumkamp R, Esen M, Held J, Scholz JAM, Li T, Sim BKL, Hoffman SL, Kremsner PG, Mordmüller B, Duffy MF, Tannich E
PLoS Pathog. 2016 Apr 12;12(4):e1005538. doi: 10.1371/journal.ppat.1005538.

All Publications

Laborgruppe Bachmann
2021

Common virulence gene expression in adult first-time infected malaria patients and severe cases
Wichers JS, Tonkin-Hill G, Thye T, Krumkamp R, Kreuels B, Strauss J, von Thien H, Scholz JAMS, Smedegaard Hansson H, Weisel Jensen R, Turner L, Lorenz FR, Schöllhorn A, Bruchhaus I, Tannich E, Fendel R, Otto TD, Lavstsen T, Gilberger TW, Duffy MF, Bachmann A
elife. 2021 Apr 28;10:e69040. doi: 10.7554/eLife.69040.

Identification of novel inner membrane complex and apical annuli proteins of the malaria parasite Plasmodium falciparum
Wichers JS, Wunderlich J, Heincke D, Pazicky S, Strauss J, Schmitt M, Kimmel J, Wilcke L, Scharf S, von Thien H, Burda PC, Spielmann T, Löw C, Filarsky M, Bachmann A, Gilberger TW
Cell Microbiol. 2021 Apr 8:e13341. doi: 10.1111/cmi.13341.

Laborgruppe Bachmann
2020

Adhesion between P. falciparum infected erythrocytes and human endothelial receptors follows alternative binding dynamics under flow and febrile conditions
Lubiana P, Bouws P, Roth LK, Dörpinghaus M, Rehn T, Brehmer J, Wichers JS, Bachmann A, Höhn K, Roeder T, Thye T, Gutsmann T, Burmester T, Bruchhaus I, Metwally NG
Sci Rep. 2020 Mar 11;10(1):4548. doi: 10.1038/s41598-020-61388-2.

Stringent selection of knobby Plasmodium falciparum-infected erythrocytes during cytoadhesion at febrile temperature
Dörpinghaus M, Fürstenwerth F, Roth LK, Bouws P, Rakotonirinalalao M, Jordan V, Sauer M, Rehn T, Pansegrau E, Höhn K, Mesén-Ramírez P, Bachmann A, Lorenzen S, Roeder T, Metwally NG, Bruchhaus I
Microorganisms. 2020 Jan 25;8(2):174. doi: 10.3390/microorganisms8020174.

Structural insights into PfARO and characterization of its interaction with PfAIP
Geiger M, Brown C, Wichers JS, Strauss J, Lill A, Thuenauer R, Liffner B, Wilcke L, Lemcke S, Heincke D, Pazicky S, Bachmann A, Löw C, Wilson DW, Filarsky M, Burda PC, Zhang K, Junop M, Gilberger TW
J Mol Biol. 2020 Feb 14;432(4):878-896. doi: 10.1016/j.jmb.2019.12.024.

Laborgruppe Bachmann
2019

Dissecting the gene expression, localization, membrane topology, and function of the Plasmodium falciparum STEVOR protein family
Wichers JS, Scholz JAM, Strauss J, Witt S, Lill A, Ehnhold LI, Neupert N, Liffner B, Lühken R, Petter M, Lorenzen S, Wilson DW, Löw C, Lavazec C, Bruchhaus I, Tannich E, Gilberger TW, Bachmann A
mBio. 2019 Jul 30;10(4):e01500-19. doi: 10.1128/mBio.01500-19.

Controlled human malaria infection with Plasmodium falciparum demonstrates impact of naturally acquired immunity on virulence gene expression
Bachmann A, Bruske E, Krumkamp R, Turner L, Wichers JS, Petter M, Held J, Duffy MF, Sim BKL, Hoffman SL, Kremsner PG, Lell B, Lavstsen T, Frank M, Mordmüller B, Tannich E
PLoS Pathog. 2019 Jul 11;15(7):e1007906. doi: 10.1371/journal.ppat.1007906.

Laborgruppe Bachmann
2018

Plasmodium falciparum gametocyte-infected erythrocytes do not adhere to human primary erythroblasts
Neveu G, Dupuy F, Ladli M, Barbieri D, Naissant B, Richard C, Martins RM, Lopez-Rubio JJ, Bachmann A, Verdier F, Lavazec C
Sci Rep. 2018 Dec 14;8(1):17886. doi: 10.1038/s41598-018-36148-y.

Laborgruppe Bachmann
2017

Characterisation of Plasmodium falciparum populations selected on the human endothelial receptors P-selectin, E-selectin, CD9 and CD151
Metwally NG, Tilly AK, Lubiana P, Roth LK, Dörpinghaus M, Lorenzen S, Schuldt K, Witt S, Bachmann A, Tidow H, Gutsmann T, Burmester T, Roeder T, Tannich E, Bruchhaus I
Sci Rep. 2017 Jun 22;7(1):4069. doi: 10.1038/s41598-017-04241-3.

Laborgruppe Bachmann
2016

Sporozoite route of infection influences in vitro var gene transcription of Plasmodium falciparum parasites from controlled human infections
Dimonte S, Bruske E, Hass J, Supan C, Salazar CL, Held J, Tschan S, Esen M, Flötenmeyer M, Koch I, Berger J, Bachmann A, Sim BKL, Hoffman SL, Kremsner PG, Mordmüller B, Frank M
J Infect Dis. 2016 Sep 15;214(6):884-94. doi: 10.1093/infdis/jiw225.

Plasmodium falciparum STEVOR phosphorylation regulates host erythrocyte deformability enabling malaria parasite transmission
Naissant B, Dupuy F, Duffier Y, Lorthiois A, Duez J, Scholz JAM, Buffet P, Merckx A, Bachmann A, Lavazec C
Blood. 2016 Jun 16;127(24):e42-53. doi: 10.1182/blood-2016-01-690776.

Mosquito passage dramatically changes var gene expression in controlled human Plasmodium falciparum infections
Bachmann A, Petter M, Krumkamp R, Esen M, Held J, Scholz JAM, Li T, Sim BKL, Hoffman SL, Kremsner PG, Mordmüller B, Duffy MF, Tannich E
PLoS Pathog. 2016 Apr 12;12(4):e1005538. doi: 10.1371/journal.ppat.1005538.

Laborgruppe Bachmann
2015

Type of in vitro cultivation influences cytoadhesion, knob structure, protein localization and transcriptome profile of Plasmodium falciparum
Tilly AK, Thiede J, Metwally NG, Lubiana P, Bachmann A, Roeder T, Rockliffe N, Lorenzen S, Tannich E, Gutsmann T, Bruchhaus I
Sci Rep. 2015 Nov 16;5:16766. doi: 10.1038/srep16766.

A comparative study of the localization and membrane topology of members of the RIFIN, STEVOR and PfMC-2TM protein families in Plasmodium falciparum-infected erythrocytes
Bachmann A, Scholz JAM, Janßen M, Klinkert MQ, Tannich E, Bruchhaus I, Petter M
Malar J. 2015 Jul 16;14:274. doi: 10.1186/s12936-015-0784-2.

Laborgruppe Bachmann
2014

Evidence of promiscuous endothelial binding by Plasmodium falciparum-infected erythrocytes
Esser C, Bachmann A, Kuhn D, Schuldt K, Förster B, Thiel M, May J, Koch-Nolte F, Yáñez-Mó M, Sánchez-Madrid F, Schinkel AH, Jalkanen S, Craig AG, Bruchhaus I, Horstmann RD
Cell Microbiol. 2014 May;16(5):701-8. doi: 10.1111/cmi.12270.

Laborgruppe Bachmann
2012

Temporal expression and localization patterns of variant surface antigens in clinical Plasmodium falciparum isolates during erythrocyte schizogony
Bachmann A, Petter M, Tilly AK, Biller L, Uliczka KA, Duffy MF, Tannich E, Bruchhaus I
PLoS One. 2012;7(11):e49540. doi: 10.1371/journal.pone.0049540.

Laborgruppe Bachmann
2011

Highly co-ordinated var gene expression and switching in clinical Plasmodium falciparum isolates from non-immune malaria patients
Bachmann A, Predehl S, May J, Harder S, Burchard GD, Gilberger TW, Tannich E, Bruchhaus I
Cell Microbiol. 2011 Sep;13(9):1397-409. doi: 10.1111/j.1462-5822.2011.01629.x.

Laborgruppe Bachmann
2010

The essentials of protein import in the degenerate mitochondrium of Entamoeba histolytica
Dolezal P, Dagley MJ, Kono M, Wolynec PP, Likic VA, Foo JH, Sedinova M, Tachezy J, Bachmann A, Bruchhaus I, Lithgow T
PLoS Pathog. 2010 Mar 19;6(3):e1000812. doi: 10.1371/journal.ppat.1000812.

Laborgruppe Bachmann
2009

Absence of erythrocyte sequestration and lack of multicopy gene family expression in Plasmodium falciparum from a splenectomized malaria patient
Bachmann A, Esser C, Petter M, Predehl S, von Kalckreuth V, Schmiedel S, Bruchhaus I, Tannich E
PLoS One. 2009 Oct 14;4(10):e7459. doi: 10.1371/journal.pone.0007459.

Laborgruppe Bachmann
2008

Characterization of a conserved rhoptry-associated leucine zipper-like protein in the malaria parasite Plasmodium falciparum
Haase S, Cabrera A, Langer C, Treeck M, Struck N, Herrmann S, Jansen PW, Bruchhaus I, Bachmann A, Dias S, Cowman AF, Stunnenberg HG, Spielmann T, Gilberger TW
Infect Immun. 2008 Mar;76(3):879-87. doi: 10.1128/IAI.00144-07.

An Entamoeba cysteine peptidase specifically expressed during encystations
Ebert F, Bachmann A, Nakada-Tsukui K, Hennings I, Drescher B, Nozaki T, Tannich E, Bruchhaus I
Parasitol Int. 2008 Dec;57(4):521-4. doi: 10.1016/j.parint.2008.07.002.

Alumni

Doctoral Thesis

Jan Stephan Wichers (2017 – 2020) : Localization, function and expression dynamics of virulence-associated multigene families of Plasmodium falciparum

Judith Anna Marie Scholz (2013 – 2016) : Genexpression, Lokalisation und funktionelle Untersuchung der variablen Oberflächenproteinfamilie STEVOR des Malariaerregers Plasmodium falciparum (WELCH, 1897)

Contact

Dr. rer. nat. Anna Bachmann

Phone: +49 40 42818-439
Fax: +49 40 42818-512
E-Mail: bachmann@bnitm.de


Technical staff

Heidrun von Thien (+49) 40 4218-241

PhD/MD students

Yannick Daniel Höppner (+49) 40 4218-241
Julia Mareike Ruge (+49) 40 4218-241