Open access peer-reviewed chapter

Vaccines for Visceral Leishmaniasis: Hopes and Hurdles

Written By

Eltahir Awad Gasim Khalil

Submitted: 06 October 2017 Reviewed: 11 February 2018 Published: 10 October 2018

DOI: 10.5772/intechopen.75184

From the Edited Volume

Leishmaniases as Re-emerging Diseases

Edited by Farhat Afrin and Hassan Hemeg

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The leishmaniases are vector-borne parasitic diseases with multiple disease phenotypes that range from self-healing cutaneous ulcers to disfiguring post-kala-azar dermal leishmaniasis and fatal visceral leishmaniasis (VL). Infected individuals can develop subclinical infections or overt disease. Current treatments are toxic and expensive. The only successful control measure is case detection and drug treatment. Resistance to anti-leishmanial drugs are increasing with few drugs in the pipeline. The Leishmania parasites are good candidates for vaccine development, with no change in its antigenic coat and extensive cross-reactivity between species. First-generation vaccines are safe, immunogenic with inconclusive efficiency. These vaccines presented the leishmanin skin test (LST) as a potentially good surrogate marker of immunogenicity/protection that can help in future vaccine studies. First-generation vaccines are the only leishmaniasis vaccines that progressed to phase III. Second-generation vaccines are safe and immunogenic, but none progressed to phase III. Third-generation vaccines recently entered human testing. Alternative approaches include in silico prediction of immunogenic Leishmania epitopes with in vitro immunogenicity testing. New adjuvants can help in the quest to develop efficacious leishmaniasis vaccines. Failure of second- and third-generation vaccines to reach phase III, rising drug resistance and continued VL pandemics make it a necessity to revisit first-generation vaccines.


  • visceral leishmaniasis
  • first/second/third-generation vaccines
  • adjuvants

1. Introduction

The leishmaniases are vector-borne, widely prevalent parasitic diseases that are transmitted by phlebotomine sand flies. The transmission is either zoonotic or anthroponotic. Together with malaria they constitute the most commonly prevalent neglected parasitic diseases. The leishmaniases are among the most commonly neglected tropical diseases. The parasite is a unicellular organism that leads to multiple disease phenotypes that range from benign self-healing cutaneous ulcers to a markedly disfiguring diffuse cutaneous/post-kala-azar dermal leishmaniasis and fatal visceral leishmaniasis (VL, kala-azar). Cutaneous leishmaniasis (CL) is caused by L. tropica, L. aethiopica, and L. major in the Old World and L. mexicana, L. guyanensis, L. amazonensis, and L. braziliensis in the New World. Visceral leishmaniasis is a fatal form of the leishmaniasis if not treated. VL is a major health problem and is caused by L. donovani and L. infantum that are particularity prevalent in East Africa, the Indian subcontinent, Mediterranean Basin, and Latin America [1, 2, 3, 4, 5, 6, 7, 8, 9]. The HIV pandemic aggravated further the leishmaniasis morbidity and mortality. Drug treatment with sodium stibogluconate/paromomycin, miltefosine, or liposomal amphotericin B is expensive and carries major risks of toxicities. Current control measures that include case detection, drug treatment, and insecticide-impregnated bed nets are failing as evidenced by repeated epidemics especially in East Africa. In addition, increasing drug resistance and geographical expansion of the leishmaniases due to global warming and wars make the search for vaccines for the leishmaniases a necessity [2, 10, 11, 12, 13, 14, 15].

1.1. Immunity against visceral leishmaniasis

Visceral leishmaniasis is characterized by immune suppression manifesting as pancytopenia and anergy to some antigens like Leishmania antigens and purified protein derivative (PPD). Following successful drug treatment, a state of immune reconstitution ensues which is characterized by a dermatosis affecting most Sudanese patients known as post-kala-azar dermal leishmaniasis (PKDL). Macrophages, CD4+ T cells, CD8+, NK cells, and dendritic cells are known to be involved in the immune responses against Leishmania infections. Infection with L. donovani parasite can follow two different scenarios: susceptible individuals develop overt disease with dissemination of Leishmania parasites through infected macrophages with secretion of IL-4 and IL-10, and nonspecific stimulation of B cells and secretion of large amounts of antileishmanial antibodies [Th2 immune response]. Alternatively, individuals can develop protective immune responses [subclinical infection] with secretion of parasite antigen-specific IFN-γ, TNF-α by stimulated CD4+ T cells [Th1 immune response], and conversion in the leishmanin skin test (LST). Eliciting an exact immune response is an important VL vaccine requirement that should simulate those induced by natural infection. An important feature of an efficacious Leishmania vaccine should be to induce a parasite-specific Th1 immune response with sufficient amounts of IFN-γ and LST reactivity that should last for life. Induction of antileishmanial antibodies by a vaccine should be taken against it, taking into consideration that patients with overt diseases secrete large amounts of non-neutralizing antibodies. These antibodies have been shown to facilitate the internalization of the Leishmania parasites into macrophages [2, 16, 17, 18, 19].

1.2. Feasibility of vaccines for the leishmaniases

A vaccine against the Leishmania parasite is a real feasibility, because unlike the plasmodium and other parasites, Leishmania rarely changes its antigenic coat. Leishmania infections induce lifelong immunity with extensive cross-reactivity between different species of leishmania. Therefore, a single vaccine can be potentially effective against many forms of the leishmaniases. Although the exchange of genetic material between distant Leishmania strains [L. major and L. donovani] has recently been raised, this may have some implications for drug treatment, but not leishmaniasis vaccine development [20, 21].

1.3. Vaccine biomarkers of immunogenicity, susceptibility, and protection

The ability of vaccines to induce antibody production, Th1 (IFN-γ) or Th2 (IL-4, IL-10) immune response, can be objectively measured for phase II studies. Based on published data, we believe that the leishmanin skin test (LST) can be used as a surrogate marker for induction of cell-mediated immunity/protection against visceral leishmaniasis in phase II/III studies [22, 23, 24, 25].

1.4. The leishmanin skin test (LST)

LST is an in vivo skin test that marks Leishmania antigen-specific T-cell responses. The brand of LST reagent used in East Africa is an L. major suspension that is manufactured under GMP conditions in Pasteur Institute, Iran. The LST has been shown to be a potentially good diagnostic aide for the diagnosis of African visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) in all age groups in endemic areas. LST reactivity indicates sustained cell-mediated immunity, which is nonreactive in patients with VL and becomes reactive 6 months after cure. In addition, LST reactivity is a lifelong phenomenon [2, 11, 26]. Individuals with LST reactivity do not develop VL as was shown in a two decades follow-up period among the large numbers of LST reactive individuals in VL endemic areas in Sudan [2, 27] (Khalil et al., personal communication). Evaluation of LST reactivity in endemic areas in East Africa and India as reported previously included small sample size and did not specify the duration between cure and LST testing. Bern et al. [28] in Bangladesh demonstrated that the frequency of LST reactivity increased with increasing duration following cure using L. infantum antigen. The Bangladesh study mentioned loss of LST reactivity, but did not show any data about population movement that we specifically look at when evaluating LST reactivity from year to year. The questions of LST standardization, sensitivity, potency, stability of the Leishmania antigens, and longevity of the skin reaction were addressed satisfactory by Weigle and colleagues in 1991 [29]. Combination of different Leishmania strains can markedly improve the specificity of the LST as was shown previously [28, 29, 30, 31, 32]. In conclusion, different Leishmania strains in the LST reagent, the inadequate technique (subcutaneous rather than intradermal injection), and the time of test reading can greatly affect the outcome and interpretation of results of LST. LST is a potentially good surrogate marker of immunogenicity/protection that can be useful in future VL vaccine studies.


2. Leishmanization

Leishmanization is a true predecessor of leishmaniasis vaccines; the procedure was practiced in Central Asia and the Middle East for times deep in history. Although leishmanization is still practiced in some areas, it is considered unsafe and cannot be standardized. Recently, it has been used as a method of evaluation for candidate vaccines [33]. Leishmanization gave way to killed or live-attenuated first-generation Leishmania vaccines. Leishmanization like first-generation and third-generation vaccines that use genetically modified Leishmania parasites or use bacteria and viruses that carry Leishmania genes is daunted by the issue of standardization [34].


3. First-generation vaccines

First-generation vaccines as whole parasite killed/attenuated were tested in animals and humans for cutaneous and visceral leishmaniases. Human studies have to be commended despite raised points of standardization and licensure purposes. First-generation vaccines are less costly and easy to manufacture. In addition, first-generation vaccines are the only human prophylactic VL vaccines that went on to phase III. Khalil and colleagues conducted the first human phase III VL vaccine study that was followed by a number of extended phase II studies on vaccines against visceral leishmaniasis [27]. Although the vaccine was not efficaciously different from BCG, important conclusions came out of this study: firstly, the leishmanin skin test (LST) is a first potentially good surrogate marker for immunogenicity/protection in humans. Secondly, modulation of whole parasite vaccines with strong adjuvants like alum markedly improved the immunogenicity of whole parasite vaccine as shown in phase II/extended phase II studies. Lack of funds under the pretense of poor standardization and lack of licensure potentials prevented progression of alum-precipitated Leishmania vaccines to phase III [22, 23, 24, 25, 35, 36, 37].

The future of VL control is bleak based on frequent VL pandemics that kill thousands of people in developing countries, increasing drug resistance, lack of new antileishmanial drugs in the pipeline, and failure of second-generation vaccines to make it to phase III. In view of all the above and the current regulations that prohibit the wide use of whole parasites/antigen vaccines, standardization of whole parasite/antigens has to be addressed objectively.

Important points have to be highlighted when revisiting first-generation vaccines: the Vaccinia [smallpox] vacine which is the first vaccine that helped to eradicate small pox has been a whole virus. Furthermore, the control and near elimination of poliomyelitis is successful due to the blessing of an attenuated whole virus. Since the above vaccines are considered fit for human use, whole parasite vaccines have to be given a similar standing especially in the era of existing strong adjuvants. Furthermore, the success of immunochemotherapy of post-kala-azar dermal leishmaniasis using alum-precipitated autoclaved L. major vaccine further supports giving a second chance for first-generation VL vaccines. The inconclusive results that were obtained from first-generation vaccine meta-analysis and put it into disrepute are probably due to the fact that the analysis included studies for cutaneous as well as visceral diseases in the same basket. It has to be clearly stated that these disease phenotypes are different with different immune responses and different endpoints of evaluation of efficacy [12, 13, 23, 25, 27, 35, 36, 38, 39, 40, 41].


4. Second-generation vaccines

Second-generation vaccines are recombinant Leishmania antigens (single peptides/polypeptides) that are highly purified, amenable to standardization/large-scale production, reproducibility, and cost-effective production. Safety and immunogenicity have been assured in phase I and II studies. But, it is clear that strong adjuvants are needed for these subunit vaccines to be satisfactorily immunogenic. Recently, our group tried an alternative cheaper way where an in silico approach was employed to predict immunogenic epitopes/peptides of Leishmania parasite antigenic coat. The predicted peptides were manufactured commercially and tested in an in vitro whole blood system and were shown to be immunogenic [IFN-γ production; no IL-10 production]. It was concluded that these peptides can be taken further for prophylactic leishmanin vaccine development. Further studies are underway to combine these peptides with known and potential adjuvants to increase their immunogenicity [42, 43, 44, 45, 46, 47, 48, 49]. In conclusion, second-generation VL vaccines will succeed when the mechanisms by which macrophages select the most suitable epitopes to induce the appropriate immune response are known.


5. Third-generation vaccines

DNA vaccines came into existence with advances in molecular biology and biotechnology, and the injection of small circle of DNA encoding potentially immunogenic proteins became a reality [50]. A number of experimental third-generation vaccines have been studied with demonstrated immunogenicity and healing abilities. The first human study for a third-generation therapeutic vaccine for visceral leishmaniasis and PKDL was carried out on healthy volunteers in the United Kingdom using CHAd63-KH vaccine. The CHAd63-KH vaccine is a replication-defective simian adenovirus expressing a novel synthetic gene (KH) encoding two Leishmania proteins KMP-11 and HASPB. The vaccine was shown to be safe and immunogenic [51, 52, 53].


6. Adjuvants for Leishmania vaccines

A plethora of adjuvants, live organisms (BCG), cytokines, oligonucleotide (CpG), minerals and particulate lipids, and polymer-based adjuvants are under investigations for Leishmania vaccine. Although there is an urgent need for studies on adjuvants in disease-endemic areas, access to potent adjuvants is the main hurdle for investigators and researchers in leishmaniasis-endemic countries [54, 55, 56, 57, 58, 59, 60, 61].


7. Conclusion

Failure of second- and third-generation vaccines to reach phase III, rising drug resistance, and continued devastating VL pandemics make it a necessity to study further first-generation vaccines.


  1. 1. Pearson RD, Sousa AQ. Clinical spectrum of Leishmaniasis. Clinical Infectious Diseases. 1996;22:1-13
  2. 2. Zijlstra EE, El-Hassan AM. Leishmaniasis in Sudan. Visceral leishmaniasis. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2001;95(Suppl 1):S27-S58
  3. 3. Sacks D, Kamhawi S. Molecular aspects of parasite-vector and vector–host interactions in leishmaniasis. Annual Review of Microbiology. 2001;55:453-483
  4. 4. Alvar J, Canavate C, Molina R, Moreno J, Nieto J. Canine leishmaniasis. Advances in Parasitology. 2004;57:1-88
  5. 5. Desjeux P. Leishmaniasis: Current situation and new perspectives. Comparative Immunology, Microbiology and Infectious Diseases. 2004;27:305-318
  6. 6. Chappuis F, Sundar S, Hailu A, Ghalib H, Rijal S, Peeling RW, et al. Visceral leishmaniasis: What are the needs for diagnosis, treatment and control? Nature Reviews. Microbiology. 2007;5:873-882
  7. 7. Reithinger R, Dujardin JC, Louzir H, Pirmez C, Alexander B, Brooker S. Cutaneous leishmaniasis. The Lancet Infectious Diseases. 2007;7:581-596
  8. 8. Postigo JA. Leishmaniasis in the World Health Organization Eastern Mediterranean Region. International Journal of Antimicrobial Agents. 2010;36(Suppl 1):S62-S65
  9. 9. Alvar J, Velez ID, Bern C, Herrero M, Desjeux P, Cano J, et al. Leishmaniasis worldwide and global estimates of its incidence. PLoS One. 2012;7:e35671
  10. 10. Khalil EAG, Musa AM, Elgawi SH, Meshasha A, Gamar Eldawla I, Elhassan MO, Eljaleel KA, Younis BM, Elfaki MEE, El-Hassan AM. Revival of a leishmaniasis focus in White Nile state, Sudan. Annals of Tropical Medicine & Parasitology 2008;102(1):79-80
  11. 11. Krolewiecki AJ, Almazan MC, Quipildor M, Juarez M, Gil JF, Espinosa M, Canabire M, Cajal SP. Reappraisal of Leishmanin Skin Test (LST) in the management of American Cutaneous Leishmaniasis: A retrospective analysis from a reference center in Argentina. PLoS Neglected Tropical Diseases. 2017;11(10):e0005980. DOI: 10.1371/journal.pntd.0005980
  12. 12. Musa AM, Noazin S, Khalil EAG, Modabber F. Immunological stimulation for the treatment of leishmaniasis: A modality worthy of serious consideration. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2010;104(1):1-2
  13. 13. Sundar S, Singh A. What steps can be taken to counter the increasing failure of miltefosine to treat visceral leishmaniasis? Expert Review of Anti-Infective Therapy. 2013;11:117-119
  14. 14. Lindoso JAL, Cunha MA, Queiroz IT. Moreira. Leishmaniasis–HIV coinfection: Current challenges. HIV/AIDS (Auckland, N.Z.). 2016;8:147-156. Published online 2016 Oct 7. DOI: 10.2147/HIV.S93789
  15. 15. Kimutai R, Musa AM, Njoroge S, Omollo R, Alves F, Hailu A, et al. Safety and effectiveness of sodium stibogluconate and paromomycin combination for the treatment of visceral Leishmaniasis in eastern Africa: Results from a Pharmacovigilance Programme. Clinical Drug Investigation. 2017;37:259-272
  16. 16. Carvalho EM, Bacellar O, Barral A, Badaro R, Johnson WD. Antigen-specific immunosuppression in visceral leishmaniasis is cell mediated. The Journal of Clinical Investigation. 1989;83(3):860-864. DOI: 10.1172/JCI113969
  17. 17. Rodrigues V, da Silva JS, Campos-Neto A. Transforming growth factor β and immunosuppression in experimental visceral Leishmaniasis. Infection and Immunity. 1998;66(3):1233-1236
  18. 18. Mohamed SN, Khalil EAG, Musa AM, Younis BM, Omer SA, Sharief AH, EL-Hassan AM. Anti-Leishmania donovani antibodies enhance promastigotes internalization into host macrophage. Journal of Microbiology and Antimicrobials. 2012;4(7):110-114. Available online: DOI: 10.5897/JMA11.047
  19. 19. Khalil EAG, Khidir SA, Musa AM, Musa BY, Elfaki MEE, Elkadaru AMY, Zijlstra EE, Mohamed El-Hassan AM. Post kala-azar dermal leishmaniasis: A paradigm of paradoxical immune reconstitution syndrome in non-HIV/AIDS patients. Journal of Tropical Medicine. 2013. 7 p. Article ID 275253.
  20. 20. Hailu A, Musa A, Wasunna M, Balasegaram M, Yifru S, Mengistu G, et al. Geographical variation in the response of visceral leishmaniasis to paromomycin in East Africa: A multicentre, open-label, randomized trial. PLoS Neglected Tropical Diseases. 2010;4(10):e709
  21. 21. Hassabelgawi SH, Musa AM, Khalil EAG, Abebe T, Younis BM, Mona EEE, AM EL-H, Hailu A, Bart A. Probable genetic hybrids between Leishmania species in Sudanese isolates. Journal of Microbiology and Antimicrobials. 2011;3(6):142-145
  22. 22. Khalil EAG, El Hassan AM, Zijlstra EE, Mukhtar MM, Ghalib HW, Musa B, Ibrahim ME, Kamil AA, Elsheikh M, Babiker A, Modabber F. Autoclaved Leishmania major vaccine for prevention of visceral leishmaniasis: A randomised, double-blind, BCG-controlled trial in Sudan. Lancet. 2000;356(9241):1565-1569
  23. 23. Kamil AA, Khalil EAG, Musa AM, Modabber F, Mukhtar MM, Ibrahim ME, Zijlstra EE, Sacks D, Smith PG, Zicker F, Elhassan AM. Alum-precipitated autoclaved L. major plus BCG, a candidate vaccine for visceral leishmaniasis: Safety, skin delayed hypersensitivity response and dose finding in healthy volunteers. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2003;97(3):365-368
  24. 24. EAG K, Ayed NB, Musa AM, Ibrahim ME, Mukhtar MM, Zijlstra EE, Elhassan IM, Smith PG, Kieny PM, Ghalib HW, Zicker F, Modabber F, Elhassan AM. Dichotomy of protective cellular immune responses to human visceral leishmaniasis. Clinical and Experimental Immunology. 2005;140:349-353
  25. 25. Khalil EAG, Musa AM, Modabber F, El-Hassan AM. Safety & immunogenicity of a candidate vaccine for visceral leishmaniasis (alum-precipitated autoclaved L. major +BCG) in children: An extended phase II study. Annals of Tropical Paediatrics. 2006;26(4):357-361
  26. 26. Manzur A, Ul Bari A. Sensitivity of leishmanin skin test in patients of acute cutaneous leishmaniasis. Dermatol Online Journal. 2006;12(4):2
  27. 27. Melby PC. Vaccination against cutaneous leishmaniasis: Current status. American Journal of Clinical Dermatology. 2002;3(8):557-570
  28. 28. Khalil EAG, Elhassan AM, Zisltra EE, Mukhtar MM, Ibrahim ME, et al. Safety & immunogenicity of an autoclaved L. major vaccine. East African Medical Journal. 2000;77(9):468-470
  29. 29. Bern C, Amann J, Haque R, Chowdhury R, Ali M, Kurkjian KM, Vaz L, Wagatsuma Y, Breiman RF, Secor WE, Maguire JH. Loss of leishmanin skin test antigen sensitivity and potency in a longitudinal study of visceral leishmaniasis in Bangladesh. The American Journal of Tropical Medicine and Hygiene. 2006;75(4):744-748
  30. 30. Weigle KA, Valderrama L, Arias AL, Santrich C, Saravia NG. Leishmanin skin test standardization and evaluation of safety, dose, storage, longevity of reaction and sensitization. The American Journal of Tropical Medicine and Hygiene. 1991;44(3):260-271
  31. 31. Hailu A, Berhe N, Ali A, Gemetchu T. Use of Leishmania major derived leishmanin for skin test surveys of visceral leishmaniasis in Ethiopia. East African Medical Journal. 1997;74(1):41-45
  32. 32. Satti I, El-Hassan AM, Khalil EAG, Akuffo H. The effect of repeated leishmanin skin testing on the immune responses to Leishmania antigen in healthy volunteers. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2002;96:565-567
  33. 33. Gidwani K, Rai M, Chakravarty J, Boelaert M, Sundar S. Evaluation of leishmanin skin test in Indian visceral leishmaniasis. The American Journal of Tropical Medicine and Hygiene. 2009;80(4):566-567
  34. 34. Khamesipour A, Dowlati Y, Asilian A, Hashemi-Fesharki R, Javadi A, Noazin S, Modabber F. Leishmanization: Use of an old method for evaluation of candidate vaccines against leishmaniasis. Vaccine. 2005;25(28):3642-3648
  35. 35. Leishmanization. In: Mehlhorn H, editor. Encyclopedia of Parasitology. Berlin, Heidelberg: Springer; 2008
  36. 36. Musa AM, Khalil EAG, Ismail A, Elhassan IM, Fesharki H, Khamesipour A, Modabber F, Zijlstra EE, El-Hassan AM. Safety, immunogenicity and possible efficacy of immunochemotherapy of persistent post kala-azar dermal leishmaniasis (PKDL). Sudanese Journal of Dermatology. 2005;3:62-72
  37. 37. Musa AM, Khalil EAG, Mahgoub FA, Hassab Elgawi SH, Modabber F, Elkadaru AMY, Aboud MH, Noazin S, Ghalib HW, El-Hassan AM. Immunochemotherapy of persistent post kala-azar dermal leishmaniasis: A novel approach of treatment. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2008;102(1):58-63 Epub 2007 Oct 25
  38. 38. Musa AM, Younis B, Fadlalla A, Royce C, Balasegaram M, Wasunna M, et al. Paromomycin for the treatment of visceral leishmaniasis in Sudan: A randomized, open-label, dose-finding study. PLoS Neglected Tropical Diseases. 2010b;4(10):e855
  39. 39. Satti IN, Osman HY, Daifalla NS, Younis SA, Khalil EAG, Zijlstra EE, El Hassan AM, Ghalib HW. Immunogenicity and safety of autoclaved Leishmania major plus BCG vaccine in healthy Sudanese volunteers. Vaccine. 2001;19(15-16):2100-2106
  40. 40. Noazin S, Khamesipour A, Moulton LH, Tanner M, Nasseri K, Modabber F, Sharifi I, Khalil EAG, Velez Bernal ID, Antunes CMF, Smith PG. Efficacy of killed whole-parasite vaccines in the prevention of leishmaniasis: Meta-analysis. Vaccine. 2009;27:4747-4753. DOI: 10.1016/j. Vaccine. 2009.05.084
  41. 41. Noazin S, Modabber F, Khamesipour A, Smith PG, Moulton LH, Nasseri K, Sharifi I, Khalil EA, Bernal ID, Antunes CM, Kieny MP, Tanner M. First generation leishmaniasis vaccines: A review of field efficacy trials. Vaccine. 2008;26:6759-6767 Epub 2008 Oct 23
  42. 42. Chakravarty J, Kumar S, Trivedi S, Rai V, Singh A, Ashman J, et al. Vaccine. 2011;29:3531-3537
  43. 43. Nagill R, Kaur S. Vaccine candidates for leishmaniasis: A review. International Immunopharmacology. 2011;11(10):1464-1488. DOI: 10.1016/j.intimp.2011.05.008
  44. 44. Sundar S, Piazza F. A clinical trial to evaluate the safety and immunogenicity of the LEISH-F1+MPL-SE vaccine for use in the prevention of visceral leishmaniasis. Vaccine. 2011;29(19):3531-3537. DOI: 10.1016/j.vaccine.2011.02.096
  45. 45. Elfaki ME, Khalil EAG, De Groot AS, Musa AM, Gutiérrez Núñez A, Younis BM, Salih KA, El-Hassan AM. Immunogenicity and immune modulatory effects of in silico predicted L. donovani candidate peptide vaccines. Human Vaccines & Immunotherapeutics. 2012;8(12):1769-1774. [Epub ahead of print]
  46. 46. Elfaki MEE, De Groot AS, Gutierrez AH, Younis BM, Tassone R, Terry F, Musa AM, Elhassan AM, Khalil EAG. In silico prediction of immunogenic T cell epitopes of Leishmania donovani GP63 protein: An alternative approach for anti-parasite vaccine development. Jacobs Journal of Vaccines and Vaccination. 2015;1(2):008
  47. 47. Coler RN, Duthie MS, Hofmeyer KA, Guderian J, Jayashankar L, Vergara J, et al. From mouse to man: Safety, immunogenicity and efficacy of a candidate leishmaniasis vaccine LEISH-F3+GLA-SE. Clinical & Translational Immunology. 2015;4(4):e35. DOI: 10.1038/cti.2015.6. eCollection 2015 Apr
  48. 48. Saeed WSE, Khalil EAG. Immune response modifying effects of bee venom protein [melittin]/autoclaved L. donovani complex in CD1 mice: The search for new vaccine adjuvants. Journal of Vaccines and Vaccination. 2017;8:372. ISSN: 2157-7560. DOI: 10.4172/2157-7560.1000372
  49. 49. Saeed WSE, Khalil EAG. Toxic effects and safety of bee venom protein [Melittin] in mice: Search for natural vaccine adjuvants. Journal of Natural Products and Resources. 2017b;3(1):111-114 ISSN: 2455-0299
  50. 50. Dunning N. Leishmania vaccines: From leishmanization to the era of DNA technology. Bioscience Horizons. 2009;2(1):73-82. DOI: 10.1093/biohorizons/hzp004
  51. 51. Ghaffarifar F, Jorjani O, Sharifi Z, Dalimi A, Hassan ZM, Tabatabaie F, et al. Enhancement of immune response induced by DNA vaccine cocktail expressing complete LACK and TSA genes against Leishmania major. APMIS. 2013;121(4):290-298. DOI: 10.1111/j.1600-0463.2012.02968.x Epub 2012 Sep 18
  52. 52. Soto M, Corvo L, Garde E, Ramírez L, Iniesta V, Bonay P. Coadministration of the three antigenic leishmania infantum poly (A) binding proteins as a DNA vaccine induces protection against leishmania major infection in BALB/c mice. PLOS Neglected Tropical Diseases. 2015;9(5):e0003751. DOI: 10.1371/journal.pntd.0003751. eCollection 2015 May
  53. 53. Osman M, Mistry A, Keding A, Gabe R, Cook E, Forrester S, et al. PLOS Neglected Tropical Diseases. A third generation vaccine for human visceral leishmaniasis and post kala azar dermal leishmaniasis: First-in-human trial of ChAd63-KH. 2017;11(5):e0005527. DOI: 10.1371/journal.pntd.0005527. eCollection 2017 May
  54. 54. Gurunathan S, Prussin C, Sacks DL, et al. Vaccine requirements for sustained cellular immunity to an intracellular parasitic infection. Nature Medicine. 1998;4:1409-1415
  55. 55. Campos-Neto A. Anti-leishmania vaccine. In: Farrell JP, editor. Leishmania: World Class Parasites. Vol. 4. Boston, MA: Springer; 2002. pp. 169-190
  56. 56. Vajdy M, Srivastava I, Polo J, Donnelly J, O’Hagan D, Singh M. Mucosal adjuvants and delivery systems for protein-, DNA- and RNA-based vaccines. Immunology & Cell Biology. 2004;82:617-627
  57. 57. Garçon N, Chomez P, Van Mechelen M. GlaxoSmithKline adjuvant systems in vaccines: Concepts, achievements and perspectives. Expert Review of Vaccines. 2007;6:723-739
  58. 58. Palatnik-de-Sousa CB. Vaccines for leishmaniasis in the fore coming 25 years. Vaccine. 2008;26:1709-1724
  59. 59. Reed SG, Bertholet S, Coler RN, Fierde M. New horizons in adjuvants for vaccine development. Trends in Immunology. 2009;30:23-32
  60. 60. Badiee A, Shargh VH, Khamesipour A, Jaafari MR. Micro/nanoparticle adjuvants for antileishmanial vaccines: Present and future trends. Vaccine. 2013;31:735-749
  61. 61. Higgins SC, Mills KH. TLR, NLR agonists, and other immune modulators as infectious disease vaccine adjuvants. Current Infectious Disease Reports. 2010;12:4-12

Written By

Eltahir Awad Gasim Khalil

Submitted: 06 October 2017 Reviewed: 11 February 2018 Published: 10 October 2018