F1 Domain of the Leishmania (Leishmania) donovani Nucleoside Hydrolase Promotes a Th1 Response in Leishmania (Leishmania) infantum Cured Patients and in Asymptomatic Individuals Living in an Endemic Area of Leishmaniasis

Abstract

The Leishmania (Leishmania) donovani nucleoside hydrolase NH36 is the main antigen of the Leishmune® vaccine and one of the promising candidates for vaccination against visceral leishmaniasis. The antigenicity of the N-terminal (F1), the central (F2), or the C-terminal recombinant domain (F3) of NH36 was evaluated using peripheral blood mononuclear cells (PBMC) from individuals infected with L. (L.) infantum from an endemic area of visceral leishmaniasis of Spain. Both NH36 and F1 domains significantly increased the PBMC proliferation stimulation index of cured patients and infected asymptomatic individuals compared to healthy controls. Moreover, F1 induced a 19% higher proliferative response than NH36 in asymptomatic exposed subjects. In addition, in patients cured from visceral leishmaniasis, proliferation in response to NH36 and F1 was accompanied by a significant increase of IFN-γ and TNF-α secretion, which was 42–43% higher, in response to F1 than to NH36. The interleukin 17 (IL-17) secretion was stronger in asymptomatic subjects, in response to F1, as well as in cured cutaneous leishmaniasis after NH36 stimulation. While no IL-10 secretion was determined by F1, a granzyme B increase was detected in supernatants from cured patients after stimulation with either NH36 or F1. These data demonstrate that F1 is the domain of NH36 that induces a recall cellular response in individuals with acquired resistance to the infection by L. (L.) infantum. In addition, F1 and NH36 discriminated the IgG3 humoral response in patients with active visceral leishmaniasis due to L. (L.) donovani (Ethiopia) and L. (L.) infantum (Spain) from that of endemic and non-endemic area controls. NH36 showed higher reactivity with sera from L. (L.) donovani-infected individuals, indicating species specificity. We conclude that the F1 domain, previously characterized as an inducer of the Th1 and Th17 responses in cured/exposed patients infected with L. (L.) infantum chagasi, may also be involved in the generation of a protective response against L. (L.) infantum and represents a potential vaccine candidate for the control of human leishmaniasis alone, or in combination with other HLA epitopes/antigens.

NH36 and F3 Antigen-Primed Dendritic Cells Show Preserved Migrating Capabilities and CCR7 Expression and F3 Is Effective in Immunotherapy of Visceral Leishmaniasis

“…NH36 is composed of 314 amino acids. The NH36 sequence is deposited in SWISS-PROT (accession code Q8WQX2), EMBL (AY007193), GenBank™ and DDJB (AAG02281.1) data bases ( 15 , 20 ). F3 is composed of the amino acids 199–314 of NH36.…”

“…F3 is composed of the amino acids 199–314 of NH36. The sequences of the NH36 and F3 were cloned in the pET28b plasmid system, expressed in E. coli Bl21DE3 cells and purified by affinity chromatography (Ni-NTA, Qiagen), as described before ( 15 , 20 ). The presence or absence of LPS was confirmed using the LAL QCL-1000 kit (Lonza).…”

“…NH36 is a promising vaccine antigen, which protects mice and dogs from VL infection ( 15 – 18 ). NH36 domains and epitopes are recognized by PBMC of subclinical and cured human patients from Brazil ( 19 ) and from Spain ( 20 ). F3 holds the most important NH36-epitopes for antibodies and MHC class II receptors of mice and induces a CD4 + T-cell-mediated protection against VL, correlated with an enhanced TNF-α and strong decrease of IL-10 secretion ( 15 , 21 ).…”

The Delay in the Licensing of Protozoal Vaccines: A Comparative History

“…Antigen-specific responses of IL-2 and TNF-α were generated in Balb/c and C57 Bl6 mice vaccinated against visceral and cutaneous leishmaniasis (140,(142)(143)(144) and in dogs treated against ZVL (148). In addition, the generation of Th1 and Th17 responses against the domains of NH36 was observed in human asymptomatic and cured L. (L.) infantum chagasi-infected subjects from Brazil (145) and L. (L.) infantum-infected individuals from Spain (149).…”

Substrate-source flexibility of an exponential-fed perfusion process to produce plasmid DNA for use as leishmaniasis vaccine

“…The development of a vaccine is currently perceived as the right approach to battle leishmaniasis and is considered a social priority [15]. In particular, a pDNA vaccine carrying the nucleoside hydrolase NH36 gene is a suitable candidate for this purpose [16,17].…”