Background Buruli ulcer is a severe human skin disease caused by Mycobacterium ulcerans. This disease is primarily diagnosed in West Africa with increasing incidence. Antimycobacterial drug therapy is relatively effective during the preulcerative stage of the disease, but surgical excision of lesions with skin grafting is often the ultimate treatment. The mode of transmission of this Mycobacterium species remains a matter of debate, and relevant interventions to prevent this disease lack (i) the proper understanding of the M. ulcerans life history traits in its natural aquatic ecosystem and (ii) immune signatures that could be correlates of protection. We previously set up a laboratory ecosystem with predatory aquatic insects of the family Naucoridae and laboratory mice and showed that (i) M. ulcerans-carrying aquatic insects can transmit the mycobacterium through bites and (ii) that their salivary glands are the only tissues hosting replicative M. ulcerans. Further investigation in natural settings revealed that 5%–10% of these aquatic insects captured in endemic areas have M. ulcerans–loaded salivary glands. In search of novel epidemiological features we noticed that individuals working close to aquatic environments inhabited by insect predators were less prone to developing Buruli ulcers than their relatives. Thus we set out to investigate whether those individuals might display any immune signatures of exposure to M. ulcerans-free insect predator bites, and whether those could correlate with protection. Methods and Findings We took a two-pronged approach in this study, first investigating whether the insect bites are protective in a mouse model, and subsequently looking for possibly protective immune signatures in humans. We found that, in contrast to control BALB/c mice, BALB/c mice exposed to Naucoris aquatic insect bites or sensitized to Naucoris salivary gland homogenates (SGHs) displayed no lesion at the site of inoculation of M. ulcerans coated with Naucoris SGH components. Then using human serum samples collected in a Buruli ulcer–endemic area (in the Republic of Benin, West Africa), we assayed sera collected from either ulcer-free individuals or patients with Buruli ulcers for the titre of IgGs that bind to insect predator SGH, focusing on those molecules otherwise shown to be retained by M. ulcerans colonies. IgG titres were lower in the Buruli ulcer patient group than in the ulcer-free group. Conclusions These data will help structure future investigations in Buruli ulcer–endemic areas, providing a rationale for research into human immune
Lagarrigue V, Portaels F, Meyers WM, Aguiar J (2000) [Buruli ulcer: Risk of bone involvement! Apropos of 33 cases observed in Benin.]. Med Trop (Mars) 60: 262–266.
[3]
George KM, Chatterjee D, Gunawardana G, Welty D, Hayman J, et al. (1999) Mycolactone: A polyketide toxin from required for virulence. Science 283: 854–857.
[4]
George KM, Pascopella L, Welty DM, Small PL (2000) A toxin, mycolactone, causes apoptosis in guinea pig ulcers and tissue culture cells. Infect Immun 68: 877–883.
[5]
Duker AA, Carranza EJ, Hale M (2004) Spatial dependency of Buruli ulcer prevalence on arsenic-enriched domains in Amansie West District, Ghana: Implications for arsenic mediation in infection. Int J Health Geogr 3: 19.
[6]
Johnson PD, Stinear T, Small PL, Pluschke G, Merritt RW, et al. (2005) Buruli ulcer ( infection): New insights, new hope for disease control. PLoS Med 2: e108.. doi:10.1371/journal.pmed.0020108.
[7]
Sizaire V, Nackers F, Comte E, Portaels F (2006) infection: Control, diagnosis, and treatment. Lancet Infect Dis 6: 288–296.
[8]
Portaels F, Aguiar J, Debacker M, Guedenon A, Steunou C, et al. (2004) BCG vaccination as prophylaxis against osteomyelitis in Buruli ulcer disease. Infect Immun 72: 62–65.
[9]
Nackers F, Dramaix M, Johnson RC, Zinsou C, Robert A, et al. (2006) BCG vaccine effectiveness against Buruli ulcer: A case-control study in Benin. Am J Trop Med Hyg 75: 768–774.
[10]
Etuaful S, Carbonnelle B, Grosset J, Lucas S, Horsfield C, et al. (2005) Efficacy of the combination rifampin-streptomycin in preventing growth of in early lesions of Buruli ulcer in humans. Antimicrob Agents Chemother 49: 3182–3186.
[11]
Debacker M, Zinsou C, Aguiar J, Meyers W, Portaels F (2002) disease (Buruli ulcer) following human bite. Lancet 360: 1830.
[12]
Debacker M, Zinsou C, Aguiar J, Meyers WM, Portaels F (2003) First case of disease (Buruli ulcer) following a human bite. Clin Infect Dis 36: 67–68.
[13]
Barker DJP (1973) Epidemiology of infection. Trans R Soc Trop Med Hyg 66: 867.
[14]
Barker DJP, Clancey JK, Morrow RH, Rao S (1970) Transmission of Buruli disease. Brit Med 4: 558.
[15]
Roberts B, Hirst R (1997) Immunomagnetic separation and PCR for detection of Mycobacterium ulcerans. J Clin Microbiol 35: 2709–2711.
[16]
Ross BC, Marino L, Oppedisano F, Edwards R, Robins-Browne RM, et al. (1997) Development of a PCR assay for rapid diagnosis of infection. J Clin Microbiol 35: 1696–1700.
[17]
Uganda Buruli Group (1971) Epidemiology of infection at Kinyara, Uganda. Trans Soc Trop Med Hyg 65: 763–775.
[18]
Ross BC, Johnson PD, Oppedisano F, Marino L, Sievers A, et al. (1997) Detection of in environmental samples during an outbreak of ulcerative disease. Appl Environ Microbiol 63: 4135–4138.
[19]
Portaels F, Chemlal K, Elsen P, Johnson PD, Hayman JA, et al. (2001) in wild animals. Rev Sci Tech 20: 252–264.
[20]
Portaels F, Fonteyne P-A, Meyers WM (1999) Insects in transmission of mycobacterium ulcerans infection. Lancet 353: 986.
[21]
Marsollier L, Aubry J, Coutanceau E, Andre JP, Small PL, et al. (2005) Colonization of the salivary glands of by requires host plasmatocytes and a macrolide toxin, mycolactone. Cell Microbiol 7: 935–943.
[22]
Marsollier L, Robert R, Aubry J, Saint Andre JP, Kouakou H, et al. (2002) Aquatic insects as a vector for . Appl Environ Microbiol 68: 4623–4628.
[23]
Marsollier L, Severin T, Aubry J, Merritt RW, Saint Andre JP, et al. (2004) Aquatic snails, passive hosts of . Appl Environ Microbiol 70: 6296–6298.
[24]
Marsollier L, Andre JP, Frigui W, Reysset G, Milon G, et al. (2006) Early trafficking events of within . Cell Microbiol. Epub 24 August 2006. 10.1111/j.1462-5822.2006.00790.x.
[25]
Eddyani M, Ofori-Adjei D, Teugels G, De Weirdt D, Boakye D, et al. (2004) Potential role for fish in transmission of disease (Buruli ulcer): An environmental study. Appl Environ Microbiol 70: 5679–5681.
[26]
Ribeiro J, Francischetti I (2003) Role of arthropod saliva in blood feeding: Sialome and post-sialome perspective. Annu Rev Entomol 48: 73–88.
[27]
Gomes RB, Brodskyn C, de Oliveira CI, Costa J, Miranda JC, et al. (2002) Seroconversion against saliva concurrent with the development of anti- delayed-type hypersensitivity. J Infect Dis 186: 1530–1534.
[28]
Oliveira F, Kamhawi S, Seitz AE, Pham VM, Guigal PM, et al. (2006) From transcriptome to immunome: Identification of DTH inducing proteins from a salivary gland cDNA library. Vaccine 24: 374–390.
[29]
Belkaid Y, Valenzuela JG, Kamhawi S, Rowton E, Sacks DL, et al. (2000) Delayed-type hypersensitivity to sand fly bite: An adaptive response induced by the fly? Proc Natl Acad Sci U S A 97: 6704–6709.
[30]
Valenzuela JG, Belkaid Y, Garfield MK, Mendez S, Kamhawi S, et al. (2001) Toward a defined anti-Leishmania vaccine targeting vector antigens: Characterization of a protective salivary protein. J Exp Med 194: 331–342.
[31]
Marsollier L, Honore N, Legras P, Manceau AL, Kouakou H, et al. (2003) Isolation of three strains resistant to rifampin after experimental chemotherapy of mice. Antimicrob Agents Chemother 47: 1228–1232.
[32]
Tanghe A, Content J, Van Vooren JP, Portaels F, Huygen K (2001) Protective efficacy of a DNA vaccine encoding antigen 85A from BCG against Buruli ulcer. Infect Immun 69: 5403–5411.
[33]
Andersen P, Doherty TM (2005) The success and failure of BCG—Implications for a novel tuberculosis vaccine. Nat Rev Microbiol 3: 656–662.
[34]
Morris RV, Shoemaker CB, David JR, Lanzaro GC, Titus RG (2001) Sandfly maxadilan exacerbates infection with and vaccinating against it protects against infection. J Immunol 167: 5226–5230.
[35]
Burke G, Wikel SK, Spielman A, Telford SR, McKay K, et al. (2005) Hypersensitivity to ticks and Lyme disease risk. Emerg Infect Dis 11: 36–41.
[36]
Titus RG, Bishop JV, Mejia JS (2006) The immunomodulatory factors of arthropod saliva and the potential for these factors to serve as vaccine targets to prevent pathogen transmission. Parasite Immunol 28: 131–141.
[37]
Kamhawi S, Belkaid Y, Modi G, Rowton E, Sacks D (2000) Protection against cutaneous leishmaniasis resulting from bites of uninfected sand flies. Science 290: 1351–1354.
[38]
Belkaid Y, Kamhawi S, Modi G, Valenzuela J, Noben-Trauth N, et al. (1998) Development of a natural model of cutaneous leishmaniasis: Powerful effects of vector saliva and saliva preexposure on the long-term outcome of infection in the mouse ear dermis. J Exp Med 188: 1941–1953.
[39]
Davies DG, Parsek MR, Pearson JP, Iglewski BH, Costerton JW, et al. (1998) The involvement of cell-to-cell signals in the development of a bacterial biofilm. Science 280: 295–298.
