Our impasse in developing a malaria vaccine

Cellular and Molecular Life Sciences

Volumn 68, Issue 7, 2011, Pages 1105-1113

  Good, Michael F ^a  

^a GRIFFITH UNIVERSITY   (Australia)

Author keywords

Immune response; Malaria; Natural immunity; Vaccine

Indexed keywords

CIRCUMSPOROZOITE PROTEIN; EPITOPE; MALARIA VACCINE; MEROZOITE SURFACE PROTEIN 1;

ARTICLE; CELLULAR IMMUNITY; DRUG EFFICACY; DRUG TARGETING; GENETIC POLYMORPHISM; HUMAN; IMMUNOGENICITY; MALARIA; MALARIA CONTROL; NONHUMAN; PARASITE IMMUNITY; PLASMODIUM FALCIPARUM; VACCINATION; VACCINE PRODUCTION;

ANIMALS; ANTIBODIES; ANTIGENS, PROTOZOAN; EPITOPES; HUMANS; IMMUNITY, CELLULAR; MALARIA; MALARIA VACCINES; PLASMODIUM FALCIPARUM;

EID: 79953720559     PISSN: 1420682X     EISSN: 14209071     Source Type: Journal    
DOI: 10.1007/s00018-011-0634-5     Document Type: Article

References (60)

1. DJ Kemp RL Coppel AF Cowman RB Saint GV Brown RF Anders 1983 Expression of Plasmodium falciparum blood-stage antigens in Escherichia coli: detection with antibodies from immune humans Proc Natl Acad Sci USA 80 12 3787 3791 6304737 10.1073/pnas.80.12.3787 1:CAS:528:DyaL3sXlt1SnsbY%3D
2. J Ellis LS Ozaki RW Gwadz AH Cochrane V Nussenzweig RS Nussenzweig GN Godson 1983 Cloning and expression in E. Coli of the malarial sporozoite surface antigen gene from Plasmodium knowlesi Nature 302 536 538 6339949 10.1038/302536a0 1:CAS:528:DyaL3sXhvFaltbg%3D (Pubitemid 13111139)
3. CJ Sutherland N Tanomsing D Nolder M Oguike C Jennison S Pukrittayakamee C Dolecek TT Hien VE do Rosario AP Arez J Pinto P Michon AA Escalante F Nosten M Burke R Lee M Blaze TD Otto JW Barnwell A Pain J Williams NJ White NP Day G Snounou PJ Lockhart PL Chiodini M Imwong SD Polley 2010 Two nonrecombining sympatric forms of the human malaria parasite Plasmodium ovale occur globally J Infect Dis 201 10 1544q 1550q 10.1086/652240
4. K Baer C Klotz SHI Kappe T Schneider U Frevert 2007 Release of hepatic Plasmodium yoelii merozoites into the pulmonary microvasculature PLoS Pathog 3 11(e171) 1651 1688 1:CAS:528:DC%2BD2sXhsVOgu73F
5. K Marsh 1992 Malaria-a neglected disease? Parasitology 104 Supplimentary S53 S69 1589300 10.1017/S0031182000075247
6. LH Miller MF Good G Milon 1994 Malaria Pathogenesis Science 264 1878 1883 8009217 10.1126/science.8009217 1:STN:280:DyaK2c3nvVCruw%3D%3D (Pubitemid 24245626)
7. MC Kennedy J Wang Y Zhang AP Miles F Chitsaz A Saul CA Long LH Miller AW Stowers 2002 In vitro studies with recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1): production and activity of an AMA1 vaccine and generation of a multiallelic response Infect Immun 70 12 6948 6960 12438374 10.1128/IAI.70.12.6948-6960.2002 1:CAS:528:DC%2BD38XptVyhsrs%3D (Pubitemid 35387930)
8. MF Good D Pombo IA Quakyi EM Riley RA Houghten A Menon DW Alling JA Berzofsky LH Miller 1988 Human T-cell recognition of the circumsporozoite protein of Plasmodium falciparum: immunodominant T-cell domains map to the polymorphic regions of the molecule Proc Natl Acad Sci USA 85 4 1199 1203 2448793 10.1073/pnas.85.4.1199 1:CAS:528:DyaL1cXitVars78%3D (Pubitemid 18073976)
9. L Schofield J Villaquiran A Ferreira H Schellekens RS Nussenzweig V Nussenzweig 1987 Gamma-interferon, CD8 + T cells and antibodies required for immunity to malaria sporozoites Nature 330 664 666 3120015 10.1038/330664a0 1:CAS:528:DyaL1cXlsVaqtA%3D%3D (Pubitemid 18005584)
10. + T cells (cytotoxic/suppressors) are required for protection in mice immunized with malaria sporozoites Proc Natl Acad Sci USA 85 573 576 2963334 10.1073/pnas.85.2.573 1:STN:280:DyaL1c7isVyrsQ%3D%3D (Pubitemid 18059317)
11. Y Zevering C Khamboonruang MF Good 1994 Natural amino acid polymorphisms of the circumsporozoite protein of Plasmodium falciparum abrogate specific human CD4 + T cell responsiveness Eur J Immunol 24 1418 1425 7911423 10.1002/eji.1830240627 1:CAS:528:DyaK2MXhslKltg%3D%3D (Pubitemid 24169528)
12. WR Ballou SL Hoffman JA Sherwood MR Hollingdale FA Neva WT Hockmeyer DM Gordon I Schneider RA Wirtz J Young 1987 Safety and efficacy of a recombinant DNA Plasmodium falciparum sporozoite vaccine Lancet 329 8545 1277 1281 10.1016/S0140-6736(87)90540-X (Pubitemid 17072190)
13. S Casares T-D Brumeanu TL Richie 2010 The RTS,S malaria vaccine Vaccine 28 31 4880 4898 20553771 10.1016/j.vaccine.2010.05.033 1:CAS:528: DC%2BC3cXovFertLo%3D
14. DM Gordon TW McGovern U Krzych JC Cohen I Schneider R LaChance DG Heppner G Yuan M Hollingdale M Slaoui, et al. 1995 Safety, immunogenicity, and efficacy of a recombinantly produced Plasmodium falciparum circumsporozoite protein-hepatitis B surface antigen subunit vaccine J Infect Dis 171 6 1576 1585 7769295 1:CAS:528:DyaK2MXms1Sgs7o%3D
15. ME Polhemus SA Remich BR Ogutu JN Waitumbi L Otieno S Apollo JF Cummings KE Kester CF Ockenhouse A Stewart O Ofori-Anyinam I Ramboer CP Cahill M Lievens M-C Dubois MA Demoitie A Leach J Cohen WR Ballou DG Heppner 2009 Evaluation of RTS,S/AS02A and RTS,S/AS01B in adults in a high malaria transmission area PLoS One 4 7 e6465 19649245 10.1371/journal.pone.0006465
16. KA Bojang PJ Milligan M Pinder L Vigneron A Alloueche KE Kester WR Ballou DJ Conway WH Reece P Gothard L Yamuah M Delchambre G Voss BM Greenwood A Hill KP McAdam N Tornieporth JD Cohen T Doherty RTS SMVTT 2001 Efficacy of RTS,S/AS02 malaria vaccine against Plasmodium falciparum infection in semi-immune adult men in The Gambia: a randomised trial Lancet 358 9727 1927 1934 11747915 10.1016/S0140-6736(01)06957-4 1:CAS:528:DC%2BD3MXpt1ahurk%3D (Pubitemid 34072872)
17. Kester KE, Cummings JF, Ofori-Anyinam O, Ockenhouse CF, Krzych U, Moris P, Schwenk R, Nielsen RA, Debebe Z, Pinelis E, Juompan J, Williams J, Dowler M, Stewart VA, Wirtz RA, Dubois M-C, Lievens M, Cohen J, Ballou WR, Gray Heppner D Jr, RTS,S Vaccine Evaluation Group (2009) Randomized, double-blind, Phase 2a trial of falciparum malaria vaccines RTS,S/AS01B and RTS,S/AS02A in malaria-naive adults: safety, efficacy, and immunologic associates of protection. J Infectious Diseases 200(3):337-346
18. I Sagara A Dicko RD Ellis MP Fay SI Diawara MH Assadou MS Sissoko M Kone AI Diallo R Saye MA Guindo O Kante MB Niambele K Miura GE Mullen M Pierce LB Martin A Dolo DA Diallo OK Doumbo LH Miller A Saul 2009 A randomized controlled Phase 2 trial of the blood stage AMA1-C1/alhydrogel malaria vaccine in children in Mali Vaccine 27 23 3090 3098 10.1016/j.vaccine.2009.03.014 19428923 10.1016/j.vaccine.2009.03.014 1:CAS:528:DC%2BD1MXltlaqu7Y%3D
19. A Ouattara J Mu S Takala-Harrison R Saye I Sagara A Dicko A Niangaly J Duan R Ellis L Miller X Su CV Plowe OK Doumbo 2010 Lack of allele-specific efficacy of a bivalent AMA1 malaria vaccine Malaria J 9 175 10.1186/1475-2875-9- 175
20. S Dutta JS Sullivan KK Grady JD Haynes J Komisar AH Batchelor L Soisson C Diggs DG Heppner DE Lanar WE Collins JW Barnwell 2009 High antibody titer against apical membrane antigen-1 is required to protect against malaria in the Aotus model PLoS One 4 12 e8138 19997632 10.1371/journal.pone.0008138
21. MA Thera OK Doumbo D Coulibaly MB Laurens AK Kone AB Guindo K Traore M Sissoko DA Diallo I Diarra B Kouriba M Daou A Dolo M Baby MS Sissoko I Sagara A Niangaly I Traore A Olotu O Godeaux A Leach M-C Dubois WR Ballou J Cohen D Darby Thompson T Dube L Soisson CL Diggs SL Takala KE Lyke B House D Lanar S Dutta DG Heppner CV Plowe 2010 Safety and immunogenicity of an AMA1 malaria vaccine in Malian children: results of a Phase 1 randomized controlled trial PLoS One 5 2 e9041 20140214 10.1371/journal.pone.0009041
22. AE Barry L Schultz CO Buckee JC Reeder 2009 Contrasting population structures of the genes encoding ten leading vaccine-candidate antigens of the human malaria parasite, Plasmodium falciparum PLoS ONE 4 12 e8497 10.1371/journal.pone.0008497 20041125 10.1371/journal.pone.0008497
23. J Duan J Mu MA Thera D Joy SL Kosakovsky Pond D Diemert CA Long H Zhou K Miura A Ouattara A Dolo OK Doumbo x Su l Miller 2008 Population structure of the genes encoding the polymorphic Plasmodium falciparum apical membrane antigen 1: implications for vaccine design Proc Natl Acad Sci USA 105 22 7857 7862 18515425 10.1073/pnas.0802328105 1:CAS:528:DC%2BD1cXnt1Sgs7s%3D (Pubitemid 351872728)
24. S Takala D Coulibaly MA Thera AH Batchelor MP Cummings AA Escalante A Ouattara K Traore A Niangaly AA Djimde OK Doumbo CV Plowe 2009 Extreme polymorphism in a vaccine antigen and risk of clinical malaria: implications for vaccine development Sci Transl Med 1 2 1 10 2ra5
25. E Remarque B Faber C Kocken A Thomas 2008 A diversity-covering approach to immunization with Plasmodium falciparum apical membrane antigen 1 induces broader allelic recognition and growth inhibition responses in rabbits Infect Immun 76 June 2006 2070
26. F al-Yaman B Genton KJ Kramer SP Chang GS Hui M Baisor MP Alpers 1996 Assessment of the role of naturally acquired antibody levels to Plasmodium falciparum merozoite surface protein-1 in protecting Papua New Guinean children from malaria morbidity Am J Trop Med Hyg 54 5 443 448 8644896 1:STN:280:DyaK283ktVWntQ%3D%3D (Pubitemid 26162236)
27. S Singh MC Kennedy CA Long AJ Saul LH Miller AW Stowers 2003 Biochemical and immunological characterization of bacterially expressed and refolded Plasmodium falciparum 42 kDa C-terminal merozoite surface protein 1 Infect Immun 71 12 6766 6774 14638762 10.1128/IAI.71.12.6766-6774.2003 1:CAS:528: DC%2BD3sXpsFGnsLc%3D (Pubitemid 37475304)
28. S Singh K Miura H Zhou O Muratova B Keegan A Miles LB Martin AJ Saul LH Miller CA Long 2006 Immunity to recombinant Plasmodium falciparum merozoite surface protein 1 (MSP1): protection in Aotus nancymai monkeys strongly correlates with anti-MSP1 antibody titer and in vitro parasite-inhibitory activity Infect Immun 74 8 4573 4580 16861644 10.1128/IAI.01679-05 1:CAS:528:DC%2BD28XnvFWqsrg%3D (Pubitemid 44157244)
29. BR Ogutu OJ Apollo D McKinney W Okoth J Siangla F Dubovsky K Tucker JN Waitumbi C Diggs J Wittes E Malkin A Leach LA Soisson JB Milman L Otieno CA Holland M Polhemus SA Remich CF Ockenhouse J Cohen WR Ballou SK Martin E Angov VA Stewart JA Lyon DG Heppner MR Withers 2009 Blood stage malaria vaccine eliciting high antigen-specific antibody concentrations confers no protection to young children in western Kenya PLoS One 4 3 4708 10.1371/journal.pone.0004708 10.1371/journal.pone.0004708
30. MN Wykes YH Zhou XQ Liu MF Good 2005 Plasmodium yoelii can ablate vaccine-induced long-term protection in mice J Immunol 175 4 2510 2516 16081823 1:CAS:528:DC%2BD2MXntVSqsrc%3D (Pubitemid 41113862)
31. GE Weiss PD Crompton S Li LA Walsh S Moir B Traore K Kayentao A Ongoiba OK Doumbo SK Pierce 2009 Atypical memory B cells are greatly expanded in individuals living in a malaria-endemic area J Immunol 183 3 2176 2182 10.4049/jimmunol.0901297 19592645 10.4049/jimmunol.0901297 1:CAS:528: DC%2BD1MXoslCrtrY%3D
32. C Hirunpetcharat JH Tian DC Kaslow N Van Rooijen S Kumar JA Berzofsky LH Miller MF Good 1997 Complete protective immunity induced in mice by immunization with the 19 kDa carboxyl-terminal fragment of the merozoite surface protein-1 (MSP1[19]) of Plasmodium yoelii expressed in Saccharomyces cerevisiae: correlation of protection with antigen-specific antibody titer, but not with effector CD4 + T cells J Immunol 159 3400 3411 9317139 1:CAS:528: DyaK2sXmtlOhs74%3D (Pubitemid 127482099)
33. JL Grun WP Weidanz 1983 Antibody-independent immunity to reinfection malaria in B-cell-deficient mice Infect Immun 41 3 1197 1204 6350181 1:STN:280:DyaL3s3ovFGqtw%3D%3D (Pubitemid 13048597)
34. DA Brake CA Long WP Weidanz 1988 Adoptive protection against Plasmodium chabaudi adami malaria in athymic nude mice by a cloned T cell line J Immunol 140 6 1989 1993 3126238 1:STN:280:DyaL1c7lsVGitg%3D%3D
35. AW Taylor-Robinson RS Phillips A Severn S Moncada FY Liew 1993 The role of TH1 and TH2 cells in a rodent malaria infection Science 260 5116 1931 1934 8100366 10.1126/science.8100366 1:CAS:528:DyaK3sXmtVWltbo%3D (Pubitemid 23258272)
36. FH Amante MF Good 1997 Prolonged Th1-like response generated by a Plasmodium yoelii-specific T cell clone allows complete clearance of infection in reconstituted mice Parasite Immunol 19 111 126 9106817 10.1046/j.1365-3024. 1997.d01-187.x 1:CAS:528:DyaK2sXislWqurw%3D (Pubitemid 27138285)
37. M Elloso H van der Heyde J vande Waa D Manning W Weidanz 1994 Inhibition of Plasmodium falciparum in vitro by human gamma delta T cells J Immunol 153 3 1187 1194 8027548 1:CAS:528:DyaK2cXlsFGltr0%3D
38. DJ Pombo G Lawrence C Hirunpetcharat C Rzepczyk M Bryden N Cloonan K Anderson Y Mahakunkijcharoen LB Martin D Wilson S Elliott S Elliott DP Eisen JB Weinberg A Saul MF Good 2002 Immunity to malaria after administration of ultra-low doses of red cells infected with Plasmodium falciparum Lancet 360 9333 610 617 12241933 10.1016/S0140-6736(02)09784-2 (Pubitemid 35232195)
39. T Imai J Shen B Chou X Duan L Tu K Tetsutani C Moriya H Ishida S Hamano C Shimokawa H Hisaeda K Himeno 2010 Involvement of CD8 + T cells in protective immunity against murine blood-stage infection with Plasmodium yoelii 17XL strain Eur J Immunol 40 4 1053 1061 10.1002/eji.200939525 20101613 10.1002/eji.200939525 1:CAS:528:DC%2BC3cXkvFChsbs%3D
40. L Favila-Castillo A Monroy-Ostria E Kobayashi C Hirunpetcharat N Kamada MF Good 1996 Protection of rats against malaria by a transplanted immune spleen Parasite Immunol 18 7 325 331 9229385 10.1046/j.1365-3024.1996.d01-117.x 1:STN:280:DyaK2szntlemtA%3D%3D (Pubitemid 26266453)
41. SJ Meding SC Cheng B Simon-Haarhaus J Langhorne 1990 Role of gamma interferon during infection with Plasmodium chabaudi Infect Immun 58 11 3671 3678 1977706 1:CAS:528:DyaK3cXmt12gtb4%3D (Pubitemid 20353368)
42. T Yoneto T Yoshimoto CR Wang Y Takahama M Tsuji S Waki H Nariuchi 1999 Gamma interferon production is critical for protective immunity to infection with blood-stage Plasmodium berghei XAT but neither no production nor NK cell activation is critical Infect Immun 67 2349 2356 10225894 1:CAS:528: DyaK1MXivFWiu7k%3D (Pubitemid 29200492)
43. MC D'Ombrain LJ Robinson DI Stanisic J Taraika N Bernard P Michon I Mueller L Schofield 2008 Association of early interferon-gamma production with immunity to clinical malaria: a longitudinal study among Papua New Guinean children Clin Infect Dis 47 11 1380 1387 10.1086/592971 18947328 10.1086/592971
44. JY Le Hesran N Fievet J Thioulouse P Personne B Maubert S M'Bidias D Etye'ale M Cot P Deloron 2006 Development of cellular immune responses to Plasmodium falciparum blood stage antigens from birth to 36 months of age in Cameroon Acta Trop 98 3 261 269 10.1016/j.actatropica.2006.05.010 16820138 10.1016/j.actatropica.2006.05.010 1:CAS:528:DC%2BD28Xnt1yksbk%3D (Pubitemid 44088383)
45. A Toure-Balde JL Sarthou G Aribot P Michel JF Trape C Rogier C Roussilhon 1996 Plasmodium falciparum induces apoptosis in human mononuclear cells Infect Immun 64 3 744 750 8641776 1:CAS:528:DyaK28Xht12lsL8%3D (Pubitemid 26065543)
46. K Kemp BD Akanmori L Hvlid 2001 West African donors have high percentages of activated cytokine producing T cells that are prone to apoptosis Clin Exp Immunol 126 1 69 75 11678901 10.1046/j.1365-2249.2001.01657.x 1:STN:280:DC%2BD3Mrntlagsg%3D%3D (Pubitemid 32989494)
47. H Xu J Wipasa H Yan M Zeng MO Makobongo FD Finkelman A Kelso MF Good 2002 The mechanism and significance of deletion of parasite-specific CD4(+) T cells in malaria infection J Exp Med 195 7 881 892 11927632 10.1084/jem.20011174 1:CAS:528:DC%2BD38Xis1Oltbg%3D (Pubitemid 34286759)
48. MO Makobongo G Riding H Xu C Hirunpetcharat D Keough J de Jersey P Willadsen MF Good 2003 The purine salvage enzyme hypoxanthine guanine xanthine phosphoribosyl transferase is a major target antigen for cell-mediated immunity to malaria Proc Natl Acad Sci USA 100 5 2628 2633 12594331 10.1073/pnas. 0337629100 1:CAS:528:DC%2BD3sXitVaisbo%3D (Pubitemid 36297549)
49. SR Elliott RD Kuns MF Good 2005 Heterologous immunity in the absence of variant-specific antibodies after exposure to subpatent infection with blood-stage malaria Infect Immun 73 4 2478 2485 15784594 10.1128/IAI.73.4.2478- 2485.2005 1:CAS:528:DC%2BD2MXjtFyns7s%3D (Pubitemid 40470851)
50. M Roestenberg M McCall J Hopman J Wiersma AJ Luty GJ van Gemert M van de Vegte-Bolmer B van Schaijk K Teelen T Arens L Spaarman Q de Mast W Roeffen G Snounou L Renia A van der Ven CC Hermsen R Sauerwein 2009 Protection against a malaria challenge by sporozoite inoculation N Engl J Med 361 5 468 477 10.1056/NEJMoa0805832 19641203 10.1056/NEJMoa0805832 1:CAS:528: DC%2BD1MXpt1CrsLY%3D
51. SL Hoffman LM Goh TC Luke I Schneider TP Le DL Doolan J Sacci P de la Vega M Dowler C Paul DM Gordon JA Stoute LW Church M Sedegah DG Heppner WR Ballou TL Richie 2002 Protection of humans against malaria by immunization with radiation-attenuated Plasmodium falciparum sporozoites J Infect Dis 185 8 1155 1164 11930326 10.1086/339409 (Pubitemid 34297774)
52. RS Nussenzweig J Vanderberg H Most C Orton 1967 Protective Immunity produced by the injection of x-irradiated sporozoites of Plasmodium berghei Nature 216 5111 160 162 6057225 10.1038/216160a0 1:STN:280: DyaF1c%2FksVaqsA%3D%3D
53. TC Luke SL Hoffman 2003 Rationale and plans for developing a non-replicating, metabolically active, radiation-attenuated Plasmodium falciparum sporozoite vaccine J Exp Biol 206 21 3803 3808 14506215 10.1242/jeb.00644 (Pubitemid 37365462)
54. SL Hoffman PF Billingsley E James A Richman M Loyevsky T Li S Chakravarty A Gunasekera R Chattopadhyay M Li R Stafford A Ahumada JE Epstein M Sedegah S Reyes TL Richie KE Lyke R Edelman MB Laurens CV Plowe BK Sim 2010 Development of a metabolically active, non-replicating sporozoite vaccine to prevent Plasmodium falciparum malaria Hum Vaccin 6 1 97 106 19946222 10.4161/hv.6.1.10396 1:CAS:528:DC%2BC3cXotVyns74%3D
55. AM Vaughan R Wang SH Kappe 2010 Genetically engineered, attenuated whole-cell vaccine approaches for malaria Hum Vaccin 6 1 107 113 19838068 10.4161/hv.6.1.9654 1:CAS:528:DC%2BC3cXotVyns78%3D
56. LA Purcell KA Wong SK Yanow M Lee TW Spithill A Rodriguez 2008 Chemically attenuated Plasmodium sporozoites induce specific immune responses, sterile immunity and cross-protection against heterologous challenge Vaccine 26 38 4880 4884 10.1016/j.vaccine.2008.07.017 18672017 10.1016/j.vaccine.2008.07.017 1:CAS:528:DC%2BD1cXhtVKnt73J
57. P Gueirard J Taveres S Thiberge F Bernex T Ishino G Milon B Franke-Fayard CJ Janse R Menard R Amino 2010 Development of the malaria parasite in the skin of the mammalian host Proc Natl Acad Sci USA 107 18640 18645 20921402 10.1073/pnas.1009346107 1:CAS:528:DC%2BC3cXhtl2mtbvF
58. D Lys Guilbride P Gawlinski PDL Guilbride 2010 Why functional pre-erythrocytic and bloodstage malaria vaccines fail: a meta-analysis of fully protective immunizations and novel immunological model PLoS One 5 5 e10685 20502667 10.1371/journal.pone.0010685
59. A Pinzon-Charry V McPhun V Kienzle C Hirunpetcharat C Engwerda J McCarthy MF Good 2010 Low doses of killed parasite in CpG elicit vigorous CD4 + T cell responses against blood-stage malaria in mice J Clin Invest 120 8 2967 2978 10.1172/JCI39222 20628205 10.1172/JCI39222 1:CAS:528:DC%2BC3cXhtVaiurzN
60. C Guinovart JJ Aponte J Sacarlal P Aide A Leach Q Bassat E Macete C Dobano M Lievens C Loucq WR Ballou J Cohen PL Alonso 2009 Insights into long-lasting protection induced by RTS,S/AS02A malaria vaccine: further results from a Phase IIb trial in Mozambican children PLoS One 4 4 e5165 10.1371/journal.pone.0005165 19365567 10.1371/journal.pone.0005165