Associate Professor Thomas Kurt Proft
- 1991: MSc in Biology, University of Heidelberg, Germany
- 1995: PhD (Dr. rer.nat.) in Molecular Microbiology, Center for Molecular Biology Heidelberg, University of Heidelberg, Germany
- 1995-2001: Research Fellow, University of Auckland
- 2001-2007: Senior Research Fellow, University of Auckland
- 2004-2008: Hercus Senior Research Fellow (HRC New Zealand)
- 2007-2011: Senior Lecturer in Microbiology and Infectious Diseases, University of Auckland
Research | Current
Streptococcus pyogenes, or group A streptococcus (GAS) can cause a variety of diseases ranging from pharyngitis and tonsillitis to severe invasive diseases, such as bacteremia, septic scarlet fever, necrotizing fasciitis (“flesh eating disease”) and streptococcal toxic shock syndrome (STSS). Streptococcal sequela, which include glomerulonephritis and acute rheumatic fever are often complications of streptococcal infection and this remains a significant problem in developed countries. GAS infections, including skin and soft tissue infections, are believed to account for >10 million cases each year in the U.S. alone. In 2002, the Centers for Disease Control and Prevention estimated that there were 9000 cases of invasive GAS disease (3.2/100,000 population) and 1200 GAS-associated deaths in the U.S. Acute rheumatic fever (ARF) continues to produce significant cardiac morbidity and mortality in young people in the developing world, where it remains the leading cause of acquired heart disease. Streptococcal infections affect New Zealanders of all ethnicities. However, ethnic inequalities exist in morbidity and mortality resulting from GAS infection. Māori and Pacific Islanders have disproportionally high hospital admissions for streptococcal skin diseases, necrotising fasciitis, and acute rheumatic fever. Our research focuses on virulence factors produced by GAS, in particular superantigens and cell wall-anchored virulence factors, such as pili, and the development of a vaccine against GAS.
Streptococcus pyogenes nuclease (SpnA) and streptococcus 5'-nucleotidase (S5nA)
SpnA is a cell wall-anchored nuclease that cleaves ssDNA, dsDNA and RNA. We have shown that SpnA is able to degrade neutrophil extracellular traps (NETs) to evade the host immune response. Our work focuses on further biochemical and structural characterisation of this enzyme and investigate its potential as a vaccine target and diagnostic tool. S5nA is a cell wall-anchored nucleotidase that converts nucleotides into nucleosides and inorganic phosphate. Of particular interest is the hydrolysis of AMP and dAMP into the immunomodulatory components adenosine and deoxyadenosine, respectively. Our current research focuses on the biochemical and structural characterisation of S5nA, in particular a possible synergy with SpnA to generate the macrophage-toxic dAdo from degraded NETs.
A pilus-based vaccine against GAS
In 2016, 137 people were hospitalised with rheumatic fever in New Zealand. Globally, about 30 million people are thought to be affected by rheumatic heart disease. No safe and efficacious vaccine against GAS is currently available.
We aim to develop vaccines against GAS based on the streptococcal pili, hair-like appendages protruding from the surface of the bacteria. At least 6 different pilus types are found in various GAS strains and there is also some degree of antigenic variation between pilus proteins within the same pilus types. We are following two main strategies to develop a vaccine:
- GASPEL – group A streptococcus pilus expressed on Lactococcus lactis. In this approach, we express the complete pilus structure (backbone pilin, tip adhesin and cell wall linker protein) on the surface of the food-grade bacterium L. lactis. We have shown that mice immunised intranasally with L. lactis expressing the FCT-3 type pilus (M18/T18 strain) or the FCT-4 type pilus (M28/T28 strain) generated functional antibodies that were protective in bactericidal assays. Furthermore, the vaccine provided type-specific protection of mice in a nasopharyngeal infection model.
- TeeVax – a multivalent T antigen domain vaccine. Sequence analysis of the tee gene (encoding the pilus backbone pilin aka T antigen) in >100 clinical GAS isolates revealed limited antigenic variation with 18 clades and 3 subclades. We have generated 3 recombinant proteins, each containing protein domains from 6 different T antigens. Rabbits immunised with the 3 fusion proteins generated highly cross-reactive antibodies that recognised GAS strains from all known T serotypes.
PilVax – a novel peptide delivery platform for the development of mucosal vaccines
Peptide vaccines are an attractive strategy to engineer the induction of highly targeted immune responses and avoid potentially allergenic and/or reactogenic protein regions. However, peptides by themselves are often unstable and poorly immunogenic, necessitating the need for an adjuvant and a specialised delivery system. We have developed a novel peptide delivery platform (PilVax) that allows the presentation of a stabilised and highly amplified peptide as part of the group A streptococcus serotype M1 pilus structure (PilM1) on the surface of the non-pathogenic bacterium Lactococcus lactis. To show proof of concept, we have successfully inserted the model peptide Ova324-339 into 3 different loop regions of the backbone protein Spy0128, which resulted in the assembly of the pilus containing large numbers of peptide on the surface of L. lactis. Intranasal immunisation of mice with L. lactis PilM1-Ova generated measurable Ova-specific systemic and mucosal responses (IgA and IgG). Furthermore, we show that multiple peptides can be inserted into the PilVax platform and that peptides can also be incorporated into structurally similar, but antigenically different pilus structures. PilVax may be useful as a cost-effective platform for the development of peptide-vaccines against a variety of important human pathogens.
Biophotonic imaging of GAS
We have developed a plasmid-based system for the bioluminescence labeling of GAS and related species with firefly luciferase and Lux. Expression of the reporter genes from a plasmid results in strong bioluminescence signals with detection limits of around 50 cfu on a plate reader. The introduction of a toxin-antitoxin cassette into the plasmid ensures segregational stability in the absence of an antibiotic making this system ideal for animal infection studies. Furthermore, the plasmid can easily be introduced in any GAS strain and we already have labelled more than 70 clinical isolates.
Current lab members:
Dr Jacelyn Loh: Senior Research Fellow and Heart Foundation Research Fellow
Dr Catherine Tsai: Research Fellow
Mrs Adrina Khemlani: Research Technician
Ms Kar Yan Soh: PhD student
Mr Sam Blanchett: PhD student
Ms. Haniyeh Aghababa: PhD student
Mr. Tiger Aspell: PhD student
Teaching | Current
MEDSCI 202: Microbiology and Immunology (Course Director)
MEDSCI 203: Mechanisms of Disease
NURSING 201: Microbiology and Immunology
MEDSCI 301: Molecular Basis of Disease
MEDSCI 314: Immunology
BIOSCI 349: Biomedical Microbiology
MBChB 321: Blood, Immunity and Infection
MEDSCI 705: Infection, Immunity and Disease
- Young Investigator Travel Award, Japanese Society for Immunology (2000)
- Early Career Research Excellence Award, University of Auckland (2001)
- Invitrogen Life Sciences Young Investigator Award (2004)
- HRC Sir Charles Hercus Research Fellowship (2004-2008)
Areas of expertise
Group A Streptococcus
Bacterial Immune Evasion
Group A Streptococcus vaccine
Faculty Board of Research (FMHS) (2003-2018)
Research Committee (Dept. of Molecular Medicine & Pathology)
Editorial Board - Biotechnology Letters, PLoS One
Selected publications and creative works (Research Outputs)
- Soh, K. Y., Loh, J. M. S., & Proft, T. (2018). Orthologues of Streptococcus pyogenes nuclease A (SpnA) and Streptococcal 5'-nucleotidase A (S5nA) found in Streptococcus iniae. Journal of biochemistry, 164 (2), 165-171. 10.1093/jb/mvy039
Other University of Auckland co-authors: Jacelyn Loh
- Hanson-Manful, P., Whitcombe, A. L., Young, P. G., Atatoa Carr, P. E., Bell, A., Didsbury, A., ... Moreland, N. J. (2018). The novel Group A Streptococcus antigen SpnA combined with bead-based immunoassay technology improves streptococcal serology for the diagnosis of acute rheumatic fever. Journal of Infection, 76 (4), 361-368. 10.1016/j.jinf.2017.12.008
Other University of Auckland co-authors: Paul Young, Edwin Mitchell, Rod Dunbar, Nikki Moreland, Alicia Didsbury
- Wagachchi, D., Tsai, J.-Y. C., Chalmers, C., Blanchett, S., Loh, J. M. S., & Proft, T. (2018). PilVax - a novel peptide delivery platform for the development of mucosal vaccines. Scientific Reports, 8, 1-12. 10.1038/s41598-018-20863-7.
Other University of Auckland co-authors: Catherine Tsai, Sam Blanchett, Jacelyn Loh
- Loh, J., Tsai, J.-Y., & Proft, T. (2017). The ability of Group A streptococcus to adhere to immortalized human skin versus throat cell lines does not reflect their predicted tissue tropism. Clinical Microbiology and Infection, 23 (9), 677.e1-677.e3. 10.1016/j.cmi.2017.03.011
Other University of Auckland co-authors: Jacelyn Loh, Catherine Tsai
- Loh, J. M., Lorenz, N., Tsai, C. J.-Y., Khemlani, A. H. J., & Proft, T. (2017). Mucosal vaccination with pili from Group A Streptococcus expressed on Lactococcus lactis generates protective immune responses. Scientific Reports, 710.1038/s41598-017-07602-0
Other University of Auckland co-authors: Jacelyn Loh, Catherine Tsai, Natalie Lorenz
- Lorenz, N., Loh, J. M. S., Moreland, N. J., & Proft, T. (2017). Development of a high-throughput opsonophagocytic assay for the determination of functional antibody activity against Streptococcus pyogenes using bioluminescence. Journal of Microbiological Methods, 134, 58-61. 10.1016/j.mimet.2017.01.010
Other University of Auckland co-authors: Jacelyn Loh, Nikki Moreland, Natalie Lorenz
- Chalmers, C., Khemlani, A. H. J., Sohn, C. R., Loh, J. M. S., Tsai, C. J.-Y., & Proft, T. (2017). Streptococcus pyogenes nuclease A (SpnA) mediated virulence does not exclusively depend on nuclease activity. Journal of Microbiology, Immunology and Infection10.1016/j.jmii.2017.09.006
Other University of Auckland co-authors: Jacelyn Loh, Catherine Tsai
- Tsai, J.-Y. C., Loh, J. M. S., Clow, F., Lorenz, N., & Proft, T. (2017). The Group A Streptococcus serotype M2 pilus plays a role in host cell adhesion and immune evasion. Molecular Microbiology, 103 (2), 282-298. 10.1111/mmi.13556
Other University of Auckland co-authors: Natalie Lorenz, Catherine Tsai, Jacelyn Loh