Matthias Frank

University of Tübingen | EKU Tübingen · Department of Tropical Medicine

Mycobacterium tuberculosis complex (MTBC) Lineage 3 (L3) strains are abundant in world regions with the highest tuberculosis burden. To investigate the population structure and the global diversity of this major lineage, we analyzed a dataset comprising 2682 L3 strains from 38 countries over 5 continents, by employing 24-loci mycobacterial interspe...

Background: The multicopy var gene family of Plasmodium falciparum is of crucial importance for pathogenesis and antigenic variation. So far only var2csa, the var gene responsible for placental malaria, was found to be highly conserved among all P. falciparum strains. Here, a new conserved 3D7 var gene (PF3D7_0617400) is identified in several fiel...

Background: The transcriptome of Plasmodium falciparum clinical isolates varies according to strain, mosquito bites, disease severity and clinical history. Therefore, it remains a challenge to directly interpret the parasite's transcriptomic information into a more general biological signature in a natural human malaria infection. These confoundin...

The pathogenesis of Plasmodium falciparum malaria is linked to the variant surface antigen PfEMP1, which mediates tethering of infected erythrocytes to the host endothelium and is encoded by approximately 60 var genes per parasite genome. Repeated episodes of malaria infection result in the gradual acquisition of protective antibodies against PfEMP...

Background Plasmodium falciparum exhibits a high degree of inter-isolate genetic diversity in its variant surface antigen (VSA) families: P. falciparum erythrocyte membrane protein 1, repetitive interspersed family (RIFIN) and subtelomeric variable open reading frame (STEVOR). The role of recombination for the generation of this diversity is a subj...

Background: Although thousands of clinical isolates of Plasmodium falciparum are being sequenced and analysed by short read technology, the data do not resolve the highly variable subtelomeric regions of the genomes that contain polymorphic gene families involved in immune evasion and pathogenesis. There is also no current standard definition of th...

Tuberculosis is a leading cause of illness and death in Congo. No data are available about the population structure and transmission dynamics of the Mycobacterium tuberculosis complex strains prevalent in this central Africa country. On the basis of single-nucleotide polymorphisms detected by whole-genome sequencing, we phylogenetically characteriz...

Single-nucleotide polymorphisms specific for the Congo type sublineage of Mycobacterium tuberculosis as determined by whole-genome sequencing; maximum-likelihood tree of the study population and 65 reference strains; and intralineage pairwise distance comparison of the Republic of the Congo study population.

Background Cameroon is a country where tuberculosis still remains a major public health problem. The aim of the present research was to evaluate the potential of molecular markers in predicting first-line drug resistance and to investigate the predominant genotypes representative of Mycobacterium tuberculosis strains in the Centre region of Cameroo...

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is considered to be the main variant surface antigen (VSA) of Plasmodium falciparum and is mainly localized on electron-dense knobs in the membrane of the infected erythrocyte. Switches in PfEMP1 expression provide the basis for antigenic variation and are thought to be critical for para...

MOA Clones (35 generations after cloning) transcribing T0_36 display surface signals from high to low. (A) Clone G2 exhibits the strongest transcription signal and has a medium MFI of 69.67. (B), (C) and (D): The clones C8, A1 and H6 transcribe T0_36 at identical strength, yet the surface signal for clone C8 and A1 is high (MFI of 243 and 258.33) a...

MOA clones (35 generations after cloning) show low transcription signals but high to low FACS signals. (A) The clone E1 displays the lowest transcription signal yet has a high surface recognition signal (MFI of 161.67). (B) and (D) The clones D11 and G9 both transcribe DBL D7_35 at low levels yet have medium and low surface reactivity respectively...

PfEMP1 knock-down in NF54 clone C2 is efficient and can be reversed by CD36 binding. (A) Removal of blasticidin and selection for CD36 binding evokes var gene activation and cytoadhesion and yields a positive signal in flow cytometry. (B) Knock-down of PfEMP1 efficiency shown by transcription profiling. There is no adhesion to the CD36 receptor (ri...

in vitro var gene transcription analysis of MOA parasites. Long term transcription profiling with gene specific primers for day 0 var transcripts in culture adapted MOA bulk parasites for a total of 150 generations of continued growth. Transcript d0_37 was the most abundant transcript in vitro. (A), (B) and (C) display var transcription after 30, 9...

DBL specific primers for amplification of DBLs from DNA of days 0, 7 and 28. Sequence D0H21 was identified by DBL cloning on all three days and was used as a control for primer design. All chimeric DBL sequences and the corresponding primers can be supplied by the authors’ upon request. (DOCX)

Gene specific PCR primer pairs for E5 var sequences. Primer pairs were designed based on the hypervariable regions of the E5 specific DBLs. (DOCX)

MOA serum surface recognition of the laboratory strain NF54-C2 is increased after CD36 receptor binding. (A) The copy number is shown at the y-axis. The adhesion phenotype (bound trophozoites per 50 C32 cell nuclei) is depicted on the right and also the flow cytometry dot plot, where iRBCs (right lower corner) are not recognized by the antibodies o...

var gene specific PCR primer set for MOA culture adapted field isolates and in vivo var transcripts. Forward and reverse sequences for the 36 var loci were designed based on the corresponding DBLα sequences. MOA clone names are indicated by capital letters. Day0 in vivo MOA transcripts are indicated by the prefix d0. DBL T0_36 is the same as DBL D7...

Transcription strength of the dominant DBLs in all 19 MOA clones and the MOA bulk culture. (DOCX)

Both routine and research tuberculosis laboratory capacity urgently need to be expanded in large parts of sub-Saharan Africa. In 2009, the “Centre de Recherches Médicales de Lambaréné” (CERMEL), took a strategic decision to expand its activities by building tuberculosis (TB) laboratory capacity to address research questions and to improve routine d...

Generalist and specialist species differ in the breadth of their ecological niches. Little is known about the niche width of obligate human pathogens. Here we analyzed a global collection of Mycobacterium tuberculosis lineage 4 clinical isolates, the most geographically widespread cause of human tuberculosis. We show that lineage 4 comprises global...

Early mortality after initiation of antiretroviral therapy (ART) occurs in 9-39% of patients in sub-Saharan Africa. A significant proportion of deaths are attributable to tuberculosis (TB). Low baseline CD4 T-cell count and low body mass index (BMI) are strongly associated with early mortality. We hypothesized that initiation of ART concurrent with...

Despite overall global progress in tuberculosis (TB) control, TB remains one of the deadliest communicable diseases. This study prospectively assessed TB epidemiology in Lambaréné, Gabon, a Central African country ranking 10th in terms of TB incidence rate in the 2014 World Health Organization TB report. In Lambaréné, between 2012 and 2013, 201 adu...

Background. Antigenic variation in Plasmodium falciparum is mediated by the multi-copy var gene family. Each parasite possesses about 60 var genes and switching between active var loci results in antigenic variation. Here, the effect of mosquito and host passage on in vitro var gene transcription is investigated. Methods. 30 malaria naïve individu...

Anamnese und klinischer Befund: Ein 13-jähriges Mädchen stellte sich 6 Monate nach Rückkehr von einer Afrika-Rundreise aufgrund von Fieberschüben in unserer tropenmedizinischen Ambulanz vor. Sie berichtete über ca. alle 48 Stunden auftretende, plötzliche Fieberepisoden mit anschließender Erschöpfung. Während der 6 Monate zurück liegenden Afrika-Rei...

Clonorchiasis is a cholangiopathy caused by foodborne trematode parasites, also known as liver flukes. Clonorchiasis is endemic in a wide geographical area extending from Eastern Europe to Southeast Asia. Infested hosts may remain asymptomatic for decades and consequently their liver can become available as a graft. To date, 20 liver transplantatio...

Seit 2011 wurde weltweit bei uber 100 Besuchern der Insel Tioman, Malaysia, die Verdachtsdiagnose einer muskularen Sarkozystose gemeldet, einer bislang nur sporadisch beobachteten parasitaren Erkrankung. Ursachlich ist vermutlich Sarcocystis nesbitti. Ausbruchsursache sowie Therapie sind unklar. Die Diagnosesicherung erfordert den mikroskopischen Z...

In the Republic in Congo, the national algorithm for the diagnosis of pulmonary tuberculosis (TB) relies on Ziehl-Neelsen (ZN) sputum smear microscopy, chest X-ray radiography (CXR) and clinical symptoms. Microscopy positive pulmonary TB (MPT+) is defined as symptoms of TB and a positive ZN smear. Microscopy negative pulmonary TB (MPT-) is defined...

Background In the 1990s, resistance rates of 15% for streptomycin-resistance and 0.6% for multidrug-resistance (MDR) were reported from the Central Region of Cameroon. This work assesses drug resistant tuberculosis in this region 12 years after reorganization of the National Tuberculosis Control Program (NTCP). Methods This cross-sectional study w...

Background The potential of genetic testing to rapidly diagnose drug resistance has lead to the development of new diagnostic assays. However, prior to implementation in a given setting, the association of specific mutations with specific drug resistance phenotypes should be evaluated. The purpose of this study was to evaluate molecular markers in...

Background: Since 2011, about 100 travellers to the island of Tioman, Malaysia, have been diagnosed worldwide with suspected muscular sarcocystosis, a previously only sporadically observed parasitic disease. Source of infection and therapy remain unclear. Final diagnosis requires microscopic identification of cysts in muscle biopsies. The study ob...

A case of Plasmodium knowlesi and HIV co-infection is reported in a German traveller returning from Thailand. The 54 year-old patient presented to the Institute of Tropical Medicine in Tübingen with a 11-day history of daily fever and chills. Initial microscopic evaluation of Giemsa-stained thin blood smears was suggestive of a mixed infection with...

Anamnese und klinischer Befund: Ein 57-jähriger Patient präsentierte sich ca. einen Monat nach Rückkehr von einer Costa-Rica-Reise mit zunehmender Leistungsminderung, Hauteffloreszenzen und Gelenkbeschwerden in der internistischen Notfallaufnahme. Nach Ausschluss häufiger Tropenerkrankungen wurde eine empirische antibiotische Therapie eingeleitet,...

The present study investigates the genetic diversity among Mycobacterium tuberculosis complex circulating in the Centre region of Cameroon and analyzes the relationship between genotypes and drug resistance patterns. Spoligotyping was performed by PCR-amplification followed by the reverse hybridization of 298 cultured specimens. Spoligotypes patter...

History and admission findings: We report on a 57-year-old patient presenting with progressive malaise, joint pain and skin rashes one month after visiting Costa Rica. After exclusion of common tropical diseases empiric antibiotic therapy was initiated, however, the patient's symptoms did not improve. Investigations: CT scan of the chest demonst...

Primers and conditions for microsatellite PCR amplification. Table of primer sequences and PCR cycling conditions employed for microsatellite analysis

Chloroquine resistance (CR) decreased after the removal of chloroquine from national treatment guidelines in Malawi, Kenia and Tanzania. In this investigation the prevalence of the chloroquine resistance (CQR) conferring mutant pfcrt allele and its associated chromosomal haplotype were determined before and after the change in Gabonese national tre...

Antigenic variation of Plasmodium falciparum is mediated by a mutually exclusive expression mechanism that limits expression to an individual member of the multicopy var gene family. This process determines the antigenic and adhesive phenotype of the infected red blood cell. Previously, we showed that var gene switching is influenced by chromosomal...

Physical contact is important for the interaction between animal cells, but it can represent a major challenge for protists like malaria parasites. Recently, novel filamentous cell-cell contacts have been identified in different types of eukaryotic cells and termed nanotubes due to their morphological appearance. Nanotubes represent small dynamic m...

Antigenic variation in Plasmodium falciparum malaria is mediated by the multicopy var gene gene family. Each parasite carries approximately 60 different var genes. A system of mutually exclusive expression ensures that only one gene is expressed in each individual cell. This ensures that only 1 of the 60 variants is exposed to the immune system. Sw...

The human malaria parasite Plasmodium falciparum utilises a mechanism of antigenic variation to avoid the antibody response of its human host and thereby generates a long-term, persistent infection. This process predominantly results from systematic changes in expression of the primary erythrocyte surface antigen, a parasite-produced protein called...

A fundamental yet poorly understood aspect of gene regulation in eukaryotic organisms is the mechanisms that control allelic exclusion and mutually exclusive gene expression. In the malaria parasite Plasmodium falciparum, this process regulates expression of the var gene family--a large, hypervariable repertoire of genes that are responsible for th...

Antigenic variation in Plasmodium falciparum malaria is mediated by transcriptional switches between different members of the multicopy var gene family. Each var gene encodes a member of a group of heterogeneous surface proteins collectively referred to as PfEMP1. Mutually exclusive expression ensures that an individual parasite only transcribes a...

During its red blood cell stage, the malaria parasite Plasmodium falciparum can switch its variant surface proteins (P. falciparum erythrocyte membrane protein 1) to evade the host immune response. The var gene family encodes P. falciparum erythrocyte membrane protein 1, different versions of which have unique binding specificities to various human...

The var gene family of the human malaria parasite Plasmodium falciparum remains a topic of intense research focus due to the key role these antigen-encoding genes play in the ability of parasites to cause disease and avoid the human immune response. In recent years, as molecular tools for investigating the mechanisms that coordinate var gene expres...

The human malaria parasite, Plasmodium falciparum, maintains a persistent infection altering the proteins expressed on the surface of the infected red blood cells, thus avoiding the host immune response. The primary surface antigen, a protein called PfEMP1, is encoded by a multicopy gene family called var. Each individual parasite only expresses a...

The primary virulence determinant of Plasmodium falciparum malaria parasite-infected cells is a family of heterogeneous surface receptors collectively referred to as PfEMP1. These proteins are encoded by a large, polymorphic gene family called var. The family contains approximately 60 individual genes, which are subject to strict, mutually exclusiv...

Antigenic variation in Plasmodium falciparum malaria is mediated by transcriptional switches between different members of the multicopy var gene family. Each var gene encodes a member of a group of heterogeneous surface proteins collectively referred to as PfEMP1. Mutually exclusive expression ensures that an individual parasite only transcribes a...