Vaccine candidates and animal models for Kala-azar

Abstract

Kala-azar or Visceral Leishmaniasis (VL) is a serious human disease in tropical regions and rapidly emerging as an opportunistic infection in HIV patients. The available treatment against VL is associated with toxicity and drug resistance. Even though the development of vaccines against VL is received limited attention. The only successful immunization strategy in humans has been leishmanization, which is based on the development of durable immunity after recovery from infection at a chosen site, usually the arm, with viable non attenuated parasites. The use of this technique has been restricted or abandoned entirely, due to safety concerns. Researchers have applied numerous approaches to develop safe vaccines against VL using live promastigotes administered at a low dose, drug-treated attenuated Leishmania, recombinant Leishmania expressing cytokines, live parasites with CpG oligodeoxynucleotide motifs, genetically attenuated vaccines and killed Leishmania parasites with and without adjuvant. The use of live attenuated Leishmania preparations as candidate vaccines is very promising because they most closely mimic the natural course of infection and may therefore elicit similar immune responses. Leishmania mutants such as Leishmania major dhfr-ts mutant, the biopterin transporter-deficient mutant, the L. mexicana double mutant lacking both the CPA and CPB cysteine peptidase genes, L. amazonensis porphyric and L. donovani calrecitin mutants was generated for vaccine purpose. While each of these studies was mainly experimental and indicated that there is some level of protection but not complete or long-lived protection, particularly at preclinical or clinical stages. A successful approach towards a vaccine involves the requirement of Th1 subset of CD4⁺ cells along with Th2, CD8⁺, and B cells. Thus, there is an urgent need for the development of new safe vaccine against VL which would be capable of enhancing antigen presentation and eliciting potent immune responses without risk of disease development in humans.

Keywords: Leishmania donovani, vaccine candidates, approaches, feasibility, animal model

Cite this Article

Awanish Kumar. Vaccine Candidates and Animal Models for Kala-Azar. Research and Reviews: Journal of Immunology (RRJoI). 2015; 5(1): 29–35p.