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Listeriolysin – a useful cytolysin
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News & Comment
George R. Gunn, III Christian Peters Yvonne Paterson* Dept of Microbiology, University of Pennsylvania, PA 19104, USA. *e-mail: [email protected] References 1 Dietrich, G. et al. (2001) From evil to good: a cytolysin in vaccine development. Trends Microbiol. 9, 23–28 2 Pan, Z-K. et al. (1995) A recombinant Listeria monocytogenes vaccine expressing a model tumour antigen protects mice against lethal tumour challenge and causes regression of established tumours. Nat. Med. 1, 471–477 3 Pan, Z-K. et al. (1995) Regression of established cancer mediated by the oral administration of a recombinant Listeria monocytogenes vaccine. Cancer Res. 55, 4776–4779 4 Decatur, A.L. and Portnoy, D.A. (2000) A PESTlike sequence in listeriolysin O essential for Listeria monocytogenes pathogenicity. Science 290, 992–995 5 Rechsteiner, M. and Rogers, S.W. (1996) PEST sequences and regulation by proteolysis. Trends Biochem. Sci. 21, 267–271 6 Rock, K.L. and Goldberg, A. (1999) Degradation of cell proteins and the generation of MHC class Ipresented peptides. Annu. Rev. Immunol. 17, 739–779
Listeriolysin – a useful cytolysin Response from Dietrich et al.
In their response to our recent review in Trends in Microbiology1, George Gunn, Christian Peters and Yvonne Paterson describe a recently discovered characteristic of listeriolysin, its PESTlike sequence, which targets proteins to the ubiquitin-proteosome pathway for protein degradation2. Peptides containing this sequence can therefore be used to enhance the efficacy of T-cell-dependent vaccines such as those against human papilloma virus (HPV) and influenza virus3,4. Previously, similar vaccination approaches based on ubiquitin conjugation to target antigens into the ubiquitin-proteasome degradation pathway for major histocompatibility complex (MHC) class I-restricted antigen processing and presentation have been successfully applied in some instances5,6, but without success in others7. Hence, the PEST-like sequence might add an attractive new facet to the capabilities of listeriolysin as a vaccine adjuvant.
TRENDS in Microbiology Vol.9 No.4 April 2001
Additionally, listeriolysin can induce signal transduction pathways in infected cells, leading to a strong pro-inflammatory response. Although these features make listeriolysin an extremely versatile vaccine adjuvant, they were not within the scope of our review, which concentrated on the capability of listeriolysin to provide a route for phagosomal antigens and vaccine formulations into the cytosol of antigen-presenting cells (APCs). It is beyond doubt that the hemolytic activity of listeriolysin is responsible for enhanced MHC class I-dependent processing and presentation of passenger antigens given or expressed separately1. The PEST-like sequence alone without the hemolytic activity of listeriolysin is insufficient for the elicitation of strong immune responses against listeriolysin itself or protection against L. monocytogenes8. We recently constructed a Salmonella strain secreting a point-mutated (Trp492Ala) version of listeriolysin, which still contains the full PEST-like sequence, although it is hemolytically inactive. Immunization of mice with Salmonellae secreting wildtype listeriolysin elicited stronger protection against L. monocytogenes than did bacteria secreting the hemolytically inactive form. Only the hemolytically active form had access to the cytosol of infected cells and hence to ubiquitindependent processing. These examples7,8 show that ubiquitin conjugation alone might be insufficient for efficient targeting of antigens into the ubiquitindegradation pathway. Other factors, such as accessibility to the cytosol of APCs, might be required to guarantee enhanced cellular immune responses. The PEST-like sequence, however, could be very important for the safety of listeriolysin as an adjuvant. The activity of listeriolysin is restricted to the acidic environment of the phagosome of APCs. Listeriolysin is not only inactive at cytosolic pH values, but is also degraded very rapidly in the cytosol, thereby leaving L. monocytogenes-infected cells intact. Decatur and Portnoy recently showed that this rapid processing and inactivation of listeriolysin is caused by the presence of the PEST-like sequence in listeriolysin2. When this PEST-like sequence is deleted, listeriolysin accumulates in the cytosol during infection, and the host cells are killed. Perfringolysin, which is also active at neutral pH and lacks the PEST-like
sequence, is toxic to host cells. Mutant forms of perfringolysin, exhibiting either a lower pH-optimum9 or carrying the PESTlike sequence, leading to a decrease in protein half-life in the host-cell cytosol2, were non-toxic. Marking for rapid degradation by conjugation with the PEST-sequence could therefore provide a valuable strategy to enhance the general safety and reactogenicity of bacterial toxins used as vaccine adjuvants. Guido Dietrich* Ivaylo Gentschev Werner Goebel Dept of Microbiology, University of Würzburg, 97074 Würzburg, Germany. Jürgen Hess Stefan H.E. Kaufmann Max-Planck-Institute for Infection Biology, 10117 Berlin, Germany. *Present address: University of Wuerzburg, Institute for Hygiene and Microbiology, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany. e-mail: [email protected] References 1 Dietrich, G. et al. (2001) From evil to good: a cytolysin in vaccine development. Trends Microbiol. 9, 23–28 2 Decatur, A.L. and Portnoy, D.A. (2000) A PESTlike sequence in listeriolysin O essential for Listeria monocytogenes pathogenicity. Science 290, 992–995 3 Pan, Z.K. et al. (1995) A recombinant Listeria monocytogenes vaccine expressing a model tumour antigen protects mice against lethal tumour cell challenge and causes regression of established tumours. Nat. Med. 1, 471–477 4 Pan, Z.K. et al. (1999) Regression of established B16F10 melanoma with a recombinant Listeria monocytogenes vaccine. Cancer Res. 59, 5264–5269 5 Xiang, R. et al. (2000) An autologous oral DNA vaccine protects against murine melanoma. Proc. Natl. Acad. Sci. U. S. A. 97, 5492–5497 6 Delogu, G. et al. (2000) DNA vaccination against tuberculosis: expression of a ubiquitin-conjugated tuberculosis protein enhances antimycobacterial immunity. Infect. Immun. 68, 3097–3102 7 Fu, T.M. et al. (1998) Induction of MHC class Irestricted CTL response by DNA immunization with ubiquitin-influenza virus nucleoprotein fusion antigens. Vaccine 16, 1711–1717 8 Hess, J. et al. (2000) Secretion of different listeriolysin cognates by recombinant attenuated Salmonella typhimurium: superior efficacy of haemolytic over non-haemolytic constructs after oral vaccination. Microbes Infect. 2, 1799–1806 9 Jones, S. et al. (1996) Conversion of an extracellular cytolysin into a phagosome-specific lysin which supports the growth of an intracellular pathogen. Mol. Microbiol. 21, 1219–1225
http://tim.trends.com 0966-842X/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
News & Comment
George R. Gunn, III Christian Peters Yvonne Paterson* Dept of Microbiology, University of Pennsylvania, PA 19104, USA. *e-mail: [email protected] References 1 Dietrich, G. et al. (2001) From evil to good: a cytolysin in vaccine development. Trends Microbiol. 9, 23–28 2 Pan, Z-K. et al. (1995) A recombinant Listeria monocytogenes vaccine expressing a model tumour antigen protects mice against lethal tumour challenge and causes regression of established tumours. Nat. Med. 1, 471–477 3 Pan, Z-K. et al. (1995) Regression of established cancer mediated by the oral administration of a recombinant Listeria monocytogenes vaccine. Cancer Res. 55, 4776–4779 4 Decatur, A.L. and Portnoy, D.A. (2000) A PESTlike sequence in listeriolysin O essential for Listeria monocytogenes pathogenicity. Science 290, 992–995 5 Rechsteiner, M. and Rogers, S.W. (1996) PEST sequences and regulation by proteolysis. Trends Biochem. Sci. 21, 267–271 6 Rock, K.L. and Goldberg, A. (1999) Degradation of cell proteins and the generation of MHC class Ipresented peptides. Annu. Rev. Immunol. 17, 739–779
Listeriolysin – a useful cytolysin Response from Dietrich et al.
In their response to our recent review in Trends in Microbiology1, George Gunn, Christian Peters and Yvonne Paterson describe a recently discovered characteristic of listeriolysin, its PESTlike sequence, which targets proteins to the ubiquitin-proteosome pathway for protein degradation2. Peptides containing this sequence can therefore be used to enhance the efficacy of T-cell-dependent vaccines such as those against human papilloma virus (HPV) and influenza virus3,4. Previously, similar vaccination approaches based on ubiquitin conjugation to target antigens into the ubiquitin-proteasome degradation pathway for major histocompatibility complex (MHC) class I-restricted antigen processing and presentation have been successfully applied in some instances5,6, but without success in others7. Hence, the PEST-like sequence might add an attractive new facet to the capabilities of listeriolysin as a vaccine adjuvant.
TRENDS in Microbiology Vol.9 No.4 April 2001
Additionally, listeriolysin can induce signal transduction pathways in infected cells, leading to a strong pro-inflammatory response. Although these features make listeriolysin an extremely versatile vaccine adjuvant, they were not within the scope of our review, which concentrated on the capability of listeriolysin to provide a route for phagosomal antigens and vaccine formulations into the cytosol of antigen-presenting cells (APCs). It is beyond doubt that the hemolytic activity of listeriolysin is responsible for enhanced MHC class I-dependent processing and presentation of passenger antigens given or expressed separately1. The PEST-like sequence alone without the hemolytic activity of listeriolysin is insufficient for the elicitation of strong immune responses against listeriolysin itself or protection against L. monocytogenes8. We recently constructed a Salmonella strain secreting a point-mutated (Trp492Ala) version of listeriolysin, which still contains the full PEST-like sequence, although it is hemolytically inactive. Immunization of mice with Salmonellae secreting wildtype listeriolysin elicited stronger protection against L. monocytogenes than did bacteria secreting the hemolytically inactive form. Only the hemolytically active form had access to the cytosol of infected cells and hence to ubiquitindependent processing. These examples7,8 show that ubiquitin conjugation alone might be insufficient for efficient targeting of antigens into the ubiquitindegradation pathway. Other factors, such as accessibility to the cytosol of APCs, might be required to guarantee enhanced cellular immune responses. The PEST-like sequence, however, could be very important for the safety of listeriolysin as an adjuvant. The activity of listeriolysin is restricted to the acidic environment of the phagosome of APCs. Listeriolysin is not only inactive at cytosolic pH values, but is also degraded very rapidly in the cytosol, thereby leaving L. monocytogenes-infected cells intact. Decatur and Portnoy recently showed that this rapid processing and inactivation of listeriolysin is caused by the presence of the PEST-like sequence in listeriolysin2. When this PEST-like sequence is deleted, listeriolysin accumulates in the cytosol during infection, and the host cells are killed. Perfringolysin, which is also active at neutral pH and lacks the PEST-like
sequence, is toxic to host cells. Mutant forms of perfringolysin, exhibiting either a lower pH-optimum9 or carrying the PESTlike sequence, leading to a decrease in protein half-life in the host-cell cytosol2, were non-toxic. Marking for rapid degradation by conjugation with the PEST-sequence could therefore provide a valuable strategy to enhance the general safety and reactogenicity of bacterial toxins used as vaccine adjuvants. Guido Dietrich* Ivaylo Gentschev Werner Goebel Dept of Microbiology, University of Würzburg, 97074 Würzburg, Germany. Jürgen Hess Stefan H.E. Kaufmann Max-Planck-Institute for Infection Biology, 10117 Berlin, Germany. *Present address: University of Wuerzburg, Institute for Hygiene and Microbiology, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany. e-mail: [email protected] References 1 Dietrich, G. et al. (2001) From evil to good: a cytolysin in vaccine development. Trends Microbiol. 9, 23–28 2 Decatur, A.L. and Portnoy, D.A. (2000) A PESTlike sequence in listeriolysin O essential for Listeria monocytogenes pathogenicity. Science 290, 992–995 3 Pan, Z.K. et al. (1995) A recombinant Listeria monocytogenes vaccine expressing a model tumour antigen protects mice against lethal tumour cell challenge and causes regression of established tumours. Nat. Med. 1, 471–477 4 Pan, Z.K. et al. (1999) Regression of established B16F10 melanoma with a recombinant Listeria monocytogenes vaccine. Cancer Res. 59, 5264–5269 5 Xiang, R. et al. (2000) An autologous oral DNA vaccine protects against murine melanoma. Proc. Natl. Acad. Sci. U. S. A. 97, 5492–5497 6 Delogu, G. et al. (2000) DNA vaccination against tuberculosis: expression of a ubiquitin-conjugated tuberculosis protein enhances antimycobacterial immunity. Infect. Immun. 68, 3097–3102 7 Fu, T.M. et al. (1998) Induction of MHC class Irestricted CTL response by DNA immunization with ubiquitin-influenza virus nucleoprotein fusion antigens. Vaccine 16, 1711–1717 8 Hess, J. et al. (2000) Secretion of different listeriolysin cognates by recombinant attenuated Salmonella typhimurium: superior efficacy of haemolytic over non-haemolytic constructs after oral vaccination. Microbes Infect. 2, 1799–1806 9 Jones, S. et al. (1996) Conversion of an extracellular cytolysin into a phagosome-specific lysin which supports the growth of an intracellular pathogen. Mol. Microbiol. 21, 1219–1225
http://tim.trends.com 0966-842X/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.