This article was downloaded by: [University of Montana] On: 09 April 2015, At: 06:26 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Virulence Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/kvir20
Metamorphosis of Galleria mellonella research a
Helene C Eisenman a
Department of Natural Sciences; Baruch College and Graduate Center; The City University of New York; New York, NY USA Accepted author version posted online: 14 Jan 2015.
Click for updates To cite this article: Helene C Eisenman (2015) Metamorphosis of Galleria mellonella research , Virulence, 6:1, 1-2 To link to this article: http://dx.doi.org/10.1080/21505594.2014.998541
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
EDITORIAL Virulence 6:1, 1--2; January 2015; © 2015 Taylor & Francis Group, LLC
Metamorphosis of Galleria mellonella research Helene C Eisenman*
Downloaded by [University of Montana] at 06:26 09 April 2015
Department of Natural Sciences; Baruch College and Graduate Center; The City University of New York; New York, NY USA
Recently, non-vertebrate hosts, such as amoeba, nematodes, and insects have been explored as alternatives to rodents in infectious disease research.1,2 In particular, the popularity of the waxmoth Galleria mellonella as a model host has surged. A search of PubMed for articles with “Galleria mellonella” in the title or abstract reveals of list of over 1100 results. Of these, one quarter have been published within the last three years. The advantages of using G. mellonella larvae are numerous. Their use reduces the amount of vertebrate animals used in research, thereby alleviating some of the ethical problems associated with animal welfare. Moreover, they can be obtained easily and inexpensively and no special training, equipment or animal care facilities are required to maintain them.3 Much of the research with G. mellonella focuses on whether known virulence factors play a role in infection of the larvae. For example, clinical isolates from a Legionnaires’ disease outbreak in Edinburgh are able to infect G. mellonella and virulence in the larvae correlates with the type IV secretion system of the bacteria.4 In addition, clinical isolates of the yeast Candida albicans known to produce biofilms are associated with increased virulence in G. mellonella.5 Other research has studied antibiotic efficacy in the larvae. For example, ciprofloxacin reduces larval killing by extraintestinal pathogenic (ExPEC) Escherichia coli isolates.6 These studies demonstrate that G. mellonella is useful for studying virulence factors and antibiotic efficacy, but what about other aspects of pathogenesis? Considering the significant structural and physiological differences between humans and invertebrates, questions remain as to limits of using G. mellonella as a model
host. In the accompanying study, “Cryptococcus neoformans induces antimicrobial responses and behaves as a facultative intracellular pathogen in the non mammalian model Galleria mellonella,” Trevijano-Contador et al. address such questions by testing whether aspects of C. neoformans pathogenesis are replicated during infection of G. mellonella.7 Unlike vertebrates, G. mellonella has no adaptive immunity. The first line of defense in insects is the cuticle, a physical barrier rich in chitin that resists invasion. However if the cuticle is breached, other innate defenses are capable of providing protection from infection. Both cellular and humoral immune components can be found in the hemolymph of insects. The cellular immune responses include phagocytosis and encapsulation by hemocytes. Similar to mammalian phagocytes, hemocytes are capable of killing microbes by phagocytosis and oxidative killing. The humoral responses include a variety of secreted molecules with antimicrobial properties. Insects produce antimicrobial peptides capable of directly killing invading pathogens. Additionally, a phenoloxidase system defends against infection using melanin and melanin-intermediates to heal wounds and kill pathogens.8,9 Cryptococcus neoformans is a fungal pathogen known primarily to infect patients with poor immunity. Usually, infections result from the inhalation of spores or yeast into the lungs. The fungus may disseminate from the lungs to the central nervous system, leading to life-threatening meningoencephalitis. C. neoformans is capable of infecting various organisms besides mammals, such as amoeba, plants and insects, including G. mellonella.10-12 It is likely that many virulence attributes of C. neoformans are preserved across hosts. In one study, a
mutant library was screened for decreased virulence in Caenorhabditis elegans and, for many of the candidates, reduced virulence was seen in both G. mellonella and mice.13 C. neoformans has several well-characterized virulence factors that contribute to its pathogenesis. One of the most studied virulence factors is the capsule, a polysaccharide layer surrounding the cell. The capsule is mainly composed of the polysaccharides glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), in addition to a small proportion of mannoproteins. The capsule is dynamic and can change in size and structure under different conditions, including during infection. One of the main functions of the capsule with regard to virulence is the protection of C. neoformans cells from phagocytosis by macrophages. Furthermore, GXM shed from cells during infection interferes with immune cell function.14,15 Similar to what is seen in mammals, capsule size increases during G. mellonella infection and increased capsule size in correlated with reduced phagocytosis by hemocytes.16 In the present study, the authors find that capsule and GXM have an effect on lytic activity of the larval hemolymph, a humoral immune response of G. mellonella. Furthermore, they observe that the antigenic properties of the capsule change upon infection.7 Together, these findings suggest that capsule dynamics are important in the pathogenesis of C. neoformans in G. mellonella, just as they are in mammalian hosts. Interaction of the C. neoformans with phagocytes is critical in the pathogenesis of cryptococcal infection of mammals, especially the ability of the fungus to disseminate through the host. Clinical isolates that exhibit a high level of phagocytosis by macrophages and intracellular replication in vitro are associated with death in humans.17
*Correspondence to: Helene C Eisenman; Email: [email protected] Submitted: 12/05/2014; Accepted: 12/10/2014 http://dx.doi.org/10.1080/21505594.2014.998541
www.tandfonline.com
Virulence
1
Downloaded by [University of Montana] at 06:26 09 April 2015
Upon phagocytosis by macrophages, the phagolysosome forms. After which, there are several possible outcomes. C. neoformans is capable of replication inside this compartment, leading to damage of the phagolysosome membrane, leaking of capsular polysaccharide into the cytoplasm and ultimately lysis of the host cell and release of fungal cells.18,19 Alternatively, non-lytic release may occur, a unique process of extrusion from macrophages. Within hours of phagocytosis, yeast cells may be expelled from the macrophages. After such events, both the yeast and the host cells are intact and able to reproduce. 20,21 Lastly, C. neoformans occasionally moves between macrophages by direct transfer of yeast between infected and uninfected cells.22, 23 The phenomena of intracellular replication, extrusion and direct transfer suggest a means by which C. neoformans can disseminate References 1. Glavis-Bloom J, Muhammed M, Mylonakis E. Of model hosts and man: Using Caenorhabditis elegans, Drosophila melanogaster and Galleria mellonella as model hosts for infectious disease research. Adv Exp Med Biol 2012; 710:11-7; PMID:22127881; http:// dx.doi.org/10.1007/978-1-4419-5638-5_2 2. Tosetti N, Croxatto A, Greub G. Amoebae as a tool to isolate new bacterial species, to discover new virulence factors and to study the host-pathogen interactions. Microb Pathog 2014; PMID:25088032; DOI: S08824010(14)00106-5 [pii] 3. Mylonakis E. Galleria mellonella and the study of fungal pathogenesis: Making the case for another genetically tractable model host. Mycopathologia 2008; 165:1-3; PMID:18060516; http://dx.doi.org/10.1007/ s11046-007-9082-z 4. McAdam PR, Vander Broek CW, Lindsay DS, Ward MJ, Hanson MF, Gillies M, Watson M, Stevens JM, Edwards GF, Fitzgerald J. Gene flow in environmental Legionella pneumophila leads to genetic and pathogenic heterogeneity within a legionnaires inverted question mark disease outbreak. Genome Biol 2014; 15:504; PMID:25370747; DOI: s13059-014-0504-1 [pii] 5. Borghi E, Romagnoli S, Fuchs BB, Cirasola D, Perdoni F, Tosi D, Braidotti P, Bulfamante G, Morace G, Mylonakis E. Correlation between Candida albicans biofilm formation and invasion of the invertebrate host Galleria mellonella. Future Microbiol 2014; 9:163-73; PMID:2457 1071; http://dx.doi.org/10.2217/fmb.13.159 [doi] 6. Williamson DA, Mills G, Johnson JR, Porter S, Wiles S. In vivo correlates of molecularly inferred virulence among extraintestinal pathogenic Escherichia coli (ExPEC) in the wax moth Galleria mellonella model system. Virulence 2014; 5:388-93; PMID:24518442; http://dx.doi.org/10.4161/viru.27912 [doi] 7. Trevijano-Contador N, Herrero-Fernandez I, GarciaBarbazan I, Scorzoni L, Rueda C, Rossi SA, GarciaRodas R, Zaragoza O. Cryptococcus neoformans induces antimicrobial responses and behaves as a facultative intracellular pathogen in the non mammalian model Galleria mellonella. Virulence 2015; 6(1):66-74; http:// dx.doi.org/10.4161/21505594.2014.986412 8. Cerenius L, Soderhall K. The prophenoloxidase-activating system in invertebrates. Immunol Rev 2004; 198:116-26; PMID:15199959
2
through the human body. According to this “Trojan Horse” hypothesis, fungal cells can use phagocytic cells as a place to hide from direct attack by the immune system and be transported through the body and across the blood-brain-barrier.24 Trevijano-Contador et al. recapitulate two important aspects of the interaction of C. neoformans with macrophages in G. mellonella hemocytes. First, C. neoformans cells are observed to replicate inside hemocytes. Second, fungal cells may be released non-lytically from G. mellonella hemocytes.7 Interestingly, extrusion of C. neoformans has also been observed in amoeba 25 and Drosophila cell culture.26 The discovery of intracellular replication and extrusion in G. mellonella hemocytes as well suggests evolutionarily conserved mechanisms govern these interactions. It is interesting to consider the purpose of
these phenomena in “alternative” hosts like amoeba and insects where dissemination through the bloodstream or across a blood-brain-barrier does not occur. Such questions remain to be addressed in future studies. The present study shows that G. mellonella research can be expanded beyond identification of virulence factors to more detailed aspects of pathogenesis. This further validates the usefulness of nontraditional models and of G. mellonella in particular. It is fascinating that multiple aspects of C. neoformans pathogenesis are preserved among hosts as different as mammals and insects. Furthermore, the research underscores the idea that virulence is a product of ancient evolutionary interactions that predate the interaction of C. neoformans with mammals.
9. Kavanagh K, Reeves EP. Exploiting the potential of insects for in vivo pathogenicity testing of microbial pathogens. FEMS Microbiol Rev 2004; 28:101-12; PMID:14975532; http://dx.doi.org/10.1016/j.femsre. 2003.09.002 10. Apidianakis Y, Rahme LG, Heitman J, Ausubel FM, Calderwood SB, Mylonakis E. Challenge of drosophila melanogaster with Cryptococcus neoformans and role of the innate immune response. Eukaryot Cell 2004; 3:413-9; PMID:15075271 11. Steenbergen JN, Shuman HA, Casadevall A. Cryptococcus neoformans interactions with amoebae suggest an explanation for its virulence and intracellular pathogenic strategy in macrophages. Proc Natl Acad Sci U S A 2001; 98:15245-50; PMID:11742090; http://dx. doi.org/10.1073/pnas.261418798 12. Xue C, Tada Y, Dong X, Heitman J. The human fungal pathogen Cryptococcus can complete its sexual cycle during a pathogenic association with plants. Cell Host Microbe 2007; 1:263-73; PMID:18005707; http://dx. doi.org/10.1016/j.chom.2007.05.005 13. Desalermos A, Tan X, Rajamuthiah R, Arvanitis M, Wang Y, Li D, Kourkoumpetis TK, Fuchs BB, Mylonakis E. A multi-host approach for the systematic analysis of virulence factors in Cryptococcus neoformans. J Infect Dis 2014; PMID:25114160; DOI: jiu441 [pii] 14. O’Meara TR, Alspaugh JA. The Cryptococcus neoformans capsule: A sword and a shield. Clin Microbiol Rev 2012; 25:387-408; PMID:22763631; http://dx. doi.org/10.1128/CMR.00001-12 [doi] 15. Vecchiarelli A, Pericolini E, Gabrielli E, Kenno S, Perito S, Cenci E, Monari C. Elucidating the immunological function of the Cryptococcus neoformans capsule. Future Microbiol 2013; 8:1107-16; PMID:24020739; http://dx.doi.org/10.2217/fmb.13.84 [doi] 16. Garcia-Rodas R, Casadevall A, Rodriguez-Tudela JL, Cuenca-Estrella M, Zaragoza O. Cryptococcus neoformans capsular enlargement and cellular gigantism during Galleria mellonella infection. PLoS One 2011; 6: e24485; PMID:21915338; http://dx.doi.org/10.1371/ journal.pone.0024485 17. Alanio A, Desnos-Ollivier M, Dromer F. Dynamics of Cryptococcus neoformans -macrophage interactions reveal that fungal background influences outcome during cryptococcal meningoencephalitis in humans.
MBio 2011; 2:Print 2011; PMID:21828220; http:// dx.doi.org/10.1128/mBio.00158-11 [doi] Tucker SC, Casadevall A. Replication of Cryptococcus neoformans in macrophages is accompanied by phagosomal permeabilization and accumulation of vesicles containing polysaccharide in the cytoplasm. Proc Natl Acad Sci U S A 2002; 99:3165-70; PMID:11880650; http://dx.doi.org/10.1073/pnas.052702799 [doi] Feldmesser M, Kress Y, Novikoff P, Casadevall A. Cryptococcus neoformans is a facultative intracellular pathogen in murine pulmonary infection. Infect Immun 2000; 68:4225-37; PMID:10858240 Alvarez M, Casadevall A. Phagosome extrusion and host-cell survival after Cryptococcus neoformans phagocytosis by macrophages. Curr Biol 2006; 16:2161-5; http://dx.doi.org/10.1016/j.cub.2006.09.061 Ma H, Croudace JE, Lammas DA, May RC. Expulsion of live pathogenic yeast by macrophages. Current Biology 2006; 16:2156-60; http://dx.doi.org/10.1016/j. cub.2006.09.032 Alvarez M, Casadevall A. Cell-to-cell spread and massive vacuole formation after Cryptococcus neoformans infection of murine macrophages. BMC Immunol 2007; 8:16; PMID:17705844; DOI: 1471-2172-8-16 [pii] Ma H, Croudace JE, Lammas DA, May RC. Direct cellto-cell spread of a pathogenic yeast. BMC Immunol 2007; 8:15; PMID:17705831; DOI: 1471-2172-8-15 [pii] Charlier C, Nielsen K, Daou S, Brigitte M, Chretien F, Dromer F. Evidence of a role for monocytes in dissemination and brain invasion by Cryptococcus neoformans. Infect Immun 2009; 77:120-7; PMID:18936186; http://dx.doi.org/10.1128/IAI.01065-08 [doi] Chrisman CJ, Alvarez M, Casadevall A. Phagocytosis of Cryptococcus neoformans by, and nonlytic exocytosis from, Acanthamoeba castellanii. Appl Environ Microbiol 2010; 76:6056-62; PMID:20675457; http://dx. doi.org/10.1128/AEM.00812-10 [doi] Qin QM, Luo J, Lin X, Pei J, Li L, Ficht TA, de Figueiredo P. Functional analysis of host factors that mediate the intracellular lifestyle of Cryptococcus neoformans. PLoS Pathog 2011; 7:e1002078; PMID:21698225; http://dx.doi.org/10.1371/journal.ppat.1002078 [doi]
Virulence
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Volume 6 Issue 1
Virulence Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/kvir20
Metamorphosis of Galleria mellonella research a
Helene C Eisenman a
Department of Natural Sciences; Baruch College and Graduate Center; The City University of New York; New York, NY USA Accepted author version posted online: 14 Jan 2015.
Click for updates To cite this article: Helene C Eisenman (2015) Metamorphosis of Galleria mellonella research , Virulence, 6:1, 1-2 To link to this article: http://dx.doi.org/10.1080/21505594.2014.998541
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
EDITORIAL Virulence 6:1, 1--2; January 2015; © 2015 Taylor & Francis Group, LLC
Metamorphosis of Galleria mellonella research Helene C Eisenman*
Downloaded by [University of Montana] at 06:26 09 April 2015
Department of Natural Sciences; Baruch College and Graduate Center; The City University of New York; New York, NY USA
Recently, non-vertebrate hosts, such as amoeba, nematodes, and insects have been explored as alternatives to rodents in infectious disease research.1,2 In particular, the popularity of the waxmoth Galleria mellonella as a model host has surged. A search of PubMed for articles with “Galleria mellonella” in the title or abstract reveals of list of over 1100 results. Of these, one quarter have been published within the last three years. The advantages of using G. mellonella larvae are numerous. Their use reduces the amount of vertebrate animals used in research, thereby alleviating some of the ethical problems associated with animal welfare. Moreover, they can be obtained easily and inexpensively and no special training, equipment or animal care facilities are required to maintain them.3 Much of the research with G. mellonella focuses on whether known virulence factors play a role in infection of the larvae. For example, clinical isolates from a Legionnaires’ disease outbreak in Edinburgh are able to infect G. mellonella and virulence in the larvae correlates with the type IV secretion system of the bacteria.4 In addition, clinical isolates of the yeast Candida albicans known to produce biofilms are associated with increased virulence in G. mellonella.5 Other research has studied antibiotic efficacy in the larvae. For example, ciprofloxacin reduces larval killing by extraintestinal pathogenic (ExPEC) Escherichia coli isolates.6 These studies demonstrate that G. mellonella is useful for studying virulence factors and antibiotic efficacy, but what about other aspects of pathogenesis? Considering the significant structural and physiological differences between humans and invertebrates, questions remain as to limits of using G. mellonella as a model
host. In the accompanying study, “Cryptococcus neoformans induces antimicrobial responses and behaves as a facultative intracellular pathogen in the non mammalian model Galleria mellonella,” Trevijano-Contador et al. address such questions by testing whether aspects of C. neoformans pathogenesis are replicated during infection of G. mellonella.7 Unlike vertebrates, G. mellonella has no adaptive immunity. The first line of defense in insects is the cuticle, a physical barrier rich in chitin that resists invasion. However if the cuticle is breached, other innate defenses are capable of providing protection from infection. Both cellular and humoral immune components can be found in the hemolymph of insects. The cellular immune responses include phagocytosis and encapsulation by hemocytes. Similar to mammalian phagocytes, hemocytes are capable of killing microbes by phagocytosis and oxidative killing. The humoral responses include a variety of secreted molecules with antimicrobial properties. Insects produce antimicrobial peptides capable of directly killing invading pathogens. Additionally, a phenoloxidase system defends against infection using melanin and melanin-intermediates to heal wounds and kill pathogens.8,9 Cryptococcus neoformans is a fungal pathogen known primarily to infect patients with poor immunity. Usually, infections result from the inhalation of spores or yeast into the lungs. The fungus may disseminate from the lungs to the central nervous system, leading to life-threatening meningoencephalitis. C. neoformans is capable of infecting various organisms besides mammals, such as amoeba, plants and insects, including G. mellonella.10-12 It is likely that many virulence attributes of C. neoformans are preserved across hosts. In one study, a
mutant library was screened for decreased virulence in Caenorhabditis elegans and, for many of the candidates, reduced virulence was seen in both G. mellonella and mice.13 C. neoformans has several well-characterized virulence factors that contribute to its pathogenesis. One of the most studied virulence factors is the capsule, a polysaccharide layer surrounding the cell. The capsule is mainly composed of the polysaccharides glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), in addition to a small proportion of mannoproteins. The capsule is dynamic and can change in size and structure under different conditions, including during infection. One of the main functions of the capsule with regard to virulence is the protection of C. neoformans cells from phagocytosis by macrophages. Furthermore, GXM shed from cells during infection interferes with immune cell function.14,15 Similar to what is seen in mammals, capsule size increases during G. mellonella infection and increased capsule size in correlated with reduced phagocytosis by hemocytes.16 In the present study, the authors find that capsule and GXM have an effect on lytic activity of the larval hemolymph, a humoral immune response of G. mellonella. Furthermore, they observe that the antigenic properties of the capsule change upon infection.7 Together, these findings suggest that capsule dynamics are important in the pathogenesis of C. neoformans in G. mellonella, just as they are in mammalian hosts. Interaction of the C. neoformans with phagocytes is critical in the pathogenesis of cryptococcal infection of mammals, especially the ability of the fungus to disseminate through the host. Clinical isolates that exhibit a high level of phagocytosis by macrophages and intracellular replication in vitro are associated with death in humans.17
*Correspondence to: Helene C Eisenman; Email: [email protected] Submitted: 12/05/2014; Accepted: 12/10/2014 http://dx.doi.org/10.1080/21505594.2014.998541
www.tandfonline.com
Virulence
1
Downloaded by [University of Montana] at 06:26 09 April 2015
Upon phagocytosis by macrophages, the phagolysosome forms. After which, there are several possible outcomes. C. neoformans is capable of replication inside this compartment, leading to damage of the phagolysosome membrane, leaking of capsular polysaccharide into the cytoplasm and ultimately lysis of the host cell and release of fungal cells.18,19 Alternatively, non-lytic release may occur, a unique process of extrusion from macrophages. Within hours of phagocytosis, yeast cells may be expelled from the macrophages. After such events, both the yeast and the host cells are intact and able to reproduce. 20,21 Lastly, C. neoformans occasionally moves between macrophages by direct transfer of yeast between infected and uninfected cells.22, 23 The phenomena of intracellular replication, extrusion and direct transfer suggest a means by which C. neoformans can disseminate References 1. Glavis-Bloom J, Muhammed M, Mylonakis E. Of model hosts and man: Using Caenorhabditis elegans, Drosophila melanogaster and Galleria mellonella as model hosts for infectious disease research. Adv Exp Med Biol 2012; 710:11-7; PMID:22127881; http:// dx.doi.org/10.1007/978-1-4419-5638-5_2 2. Tosetti N, Croxatto A, Greub G. Amoebae as a tool to isolate new bacterial species, to discover new virulence factors and to study the host-pathogen interactions. Microb Pathog 2014; PMID:25088032; DOI: S08824010(14)00106-5 [pii] 3. Mylonakis E. Galleria mellonella and the study of fungal pathogenesis: Making the case for another genetically tractable model host. Mycopathologia 2008; 165:1-3; PMID:18060516; http://dx.doi.org/10.1007/ s11046-007-9082-z 4. McAdam PR, Vander Broek CW, Lindsay DS, Ward MJ, Hanson MF, Gillies M, Watson M, Stevens JM, Edwards GF, Fitzgerald J. Gene flow in environmental Legionella pneumophila leads to genetic and pathogenic heterogeneity within a legionnaires inverted question mark disease outbreak. Genome Biol 2014; 15:504; PMID:25370747; DOI: s13059-014-0504-1 [pii] 5. Borghi E, Romagnoli S, Fuchs BB, Cirasola D, Perdoni F, Tosi D, Braidotti P, Bulfamante G, Morace G, Mylonakis E. Correlation between Candida albicans biofilm formation and invasion of the invertebrate host Galleria mellonella. Future Microbiol 2014; 9:163-73; PMID:2457 1071; http://dx.doi.org/10.2217/fmb.13.159 [doi] 6. Williamson DA, Mills G, Johnson JR, Porter S, Wiles S. In vivo correlates of molecularly inferred virulence among extraintestinal pathogenic Escherichia coli (ExPEC) in the wax moth Galleria mellonella model system. Virulence 2014; 5:388-93; PMID:24518442; http://dx.doi.org/10.4161/viru.27912 [doi] 7. Trevijano-Contador N, Herrero-Fernandez I, GarciaBarbazan I, Scorzoni L, Rueda C, Rossi SA, GarciaRodas R, Zaragoza O. Cryptococcus neoformans induces antimicrobial responses and behaves as a facultative intracellular pathogen in the non mammalian model Galleria mellonella. Virulence 2015; 6(1):66-74; http:// dx.doi.org/10.4161/21505594.2014.986412 8. Cerenius L, Soderhall K. The prophenoloxidase-activating system in invertebrates. Immunol Rev 2004; 198:116-26; PMID:15199959
2
through the human body. According to this “Trojan Horse” hypothesis, fungal cells can use phagocytic cells as a place to hide from direct attack by the immune system and be transported through the body and across the blood-brain-barrier.24 Trevijano-Contador et al. recapitulate two important aspects of the interaction of C. neoformans with macrophages in G. mellonella hemocytes. First, C. neoformans cells are observed to replicate inside hemocytes. Second, fungal cells may be released non-lytically from G. mellonella hemocytes.7 Interestingly, extrusion of C. neoformans has also been observed in amoeba 25 and Drosophila cell culture.26 The discovery of intracellular replication and extrusion in G. mellonella hemocytes as well suggests evolutionarily conserved mechanisms govern these interactions. It is interesting to consider the purpose of
these phenomena in “alternative” hosts like amoeba and insects where dissemination through the bloodstream or across a blood-brain-barrier does not occur. Such questions remain to be addressed in future studies. The present study shows that G. mellonella research can be expanded beyond identification of virulence factors to more detailed aspects of pathogenesis. This further validates the usefulness of nontraditional models and of G. mellonella in particular. It is fascinating that multiple aspects of C. neoformans pathogenesis are preserved among hosts as different as mammals and insects. Furthermore, the research underscores the idea that virulence is a product of ancient evolutionary interactions that predate the interaction of C. neoformans with mammals.
9. Kavanagh K, Reeves EP. Exploiting the potential of insects for in vivo pathogenicity testing of microbial pathogens. FEMS Microbiol Rev 2004; 28:101-12; PMID:14975532; http://dx.doi.org/10.1016/j.femsre. 2003.09.002 10. Apidianakis Y, Rahme LG, Heitman J, Ausubel FM, Calderwood SB, Mylonakis E. Challenge of drosophila melanogaster with Cryptococcus neoformans and role of the innate immune response. Eukaryot Cell 2004; 3:413-9; PMID:15075271 11. Steenbergen JN, Shuman HA, Casadevall A. Cryptococcus neoformans interactions with amoebae suggest an explanation for its virulence and intracellular pathogenic strategy in macrophages. Proc Natl Acad Sci U S A 2001; 98:15245-50; PMID:11742090; http://dx. doi.org/10.1073/pnas.261418798 12. Xue C, Tada Y, Dong X, Heitman J. The human fungal pathogen Cryptococcus can complete its sexual cycle during a pathogenic association with plants. Cell Host Microbe 2007; 1:263-73; PMID:18005707; http://dx. doi.org/10.1016/j.chom.2007.05.005 13. Desalermos A, Tan X, Rajamuthiah R, Arvanitis M, Wang Y, Li D, Kourkoumpetis TK, Fuchs BB, Mylonakis E. A multi-host approach for the systematic analysis of virulence factors in Cryptococcus neoformans. J Infect Dis 2014; PMID:25114160; DOI: jiu441 [pii] 14. O’Meara TR, Alspaugh JA. The Cryptococcus neoformans capsule: A sword and a shield. Clin Microbiol Rev 2012; 25:387-408; PMID:22763631; http://dx. doi.org/10.1128/CMR.00001-12 [doi] 15. Vecchiarelli A, Pericolini E, Gabrielli E, Kenno S, Perito S, Cenci E, Monari C. Elucidating the immunological function of the Cryptococcus neoformans capsule. Future Microbiol 2013; 8:1107-16; PMID:24020739; http://dx.doi.org/10.2217/fmb.13.84 [doi] 16. Garcia-Rodas R, Casadevall A, Rodriguez-Tudela JL, Cuenca-Estrella M, Zaragoza O. Cryptococcus neoformans capsular enlargement and cellular gigantism during Galleria mellonella infection. PLoS One 2011; 6: e24485; PMID:21915338; http://dx.doi.org/10.1371/ journal.pone.0024485 17. Alanio A, Desnos-Ollivier M, Dromer F. Dynamics of Cryptococcus neoformans -macrophage interactions reveal that fungal background influences outcome during cryptococcal meningoencephalitis in humans.
MBio 2011; 2:Print 2011; PMID:21828220; http:// dx.doi.org/10.1128/mBio.00158-11 [doi] Tucker SC, Casadevall A. Replication of Cryptococcus neoformans in macrophages is accompanied by phagosomal permeabilization and accumulation of vesicles containing polysaccharide in the cytoplasm. Proc Natl Acad Sci U S A 2002; 99:3165-70; PMID:11880650; http://dx.doi.org/10.1073/pnas.052702799 [doi] Feldmesser M, Kress Y, Novikoff P, Casadevall A. Cryptococcus neoformans is a facultative intracellular pathogen in murine pulmonary infection. Infect Immun 2000; 68:4225-37; PMID:10858240 Alvarez M, Casadevall A. Phagosome extrusion and host-cell survival after Cryptococcus neoformans phagocytosis by macrophages. Curr Biol 2006; 16:2161-5; http://dx.doi.org/10.1016/j.cub.2006.09.061 Ma H, Croudace JE, Lammas DA, May RC. Expulsion of live pathogenic yeast by macrophages. Current Biology 2006; 16:2156-60; http://dx.doi.org/10.1016/j. cub.2006.09.032 Alvarez M, Casadevall A. Cell-to-cell spread and massive vacuole formation after Cryptococcus neoformans infection of murine macrophages. BMC Immunol 2007; 8:16; PMID:17705844; DOI: 1471-2172-8-16 [pii] Ma H, Croudace JE, Lammas DA, May RC. Direct cellto-cell spread of a pathogenic yeast. BMC Immunol 2007; 8:15; PMID:17705831; DOI: 1471-2172-8-15 [pii] Charlier C, Nielsen K, Daou S, Brigitte M, Chretien F, Dromer F. Evidence of a role for monocytes in dissemination and brain invasion by Cryptococcus neoformans. Infect Immun 2009; 77:120-7; PMID:18936186; http://dx.doi.org/10.1128/IAI.01065-08 [doi] Chrisman CJ, Alvarez M, Casadevall A. Phagocytosis of Cryptococcus neoformans by, and nonlytic exocytosis from, Acanthamoeba castellanii. Appl Environ Microbiol 2010; 76:6056-62; PMID:20675457; http://dx. doi.org/10.1128/AEM.00812-10 [doi] Qin QM, Luo J, Lin X, Pei J, Li L, Ficht TA, de Figueiredo P. Functional analysis of host factors that mediate the intracellular lifestyle of Cryptococcus neoformans. PLoS Pathog 2011; 7:e1002078; PMID:21698225; http://dx.doi.org/10.1371/journal.ppat.1002078 [doi]
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Volume 6 Issue 1
