RESUMEN

American Tegumentary Leishmaniasis (ATL) is a disease of high severity and incidence in Brazil, in addition to being a worldwide concern in public health. Leishmania amazonensis is one of the etiological agents of ATL, and the inefficiency of control measures, associated with the high toxicity of the treatment and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present study proposes to elaborate a chimeric protein (rChiP), based on the fusion of multiple epitopes of CD4+/CD8+ T cells, identified in the immunoproteome of the parasites L. amazonensis and L. braziliensis. The designed chimeric protein was tested in the L. amazonensis murine model of infection using the following formulations: 25 µg of the rChiP in saline (rChiP group) and 25 µg of the rChiP plus 25 µg of MPLA-PHAD® (rChiP+MPLA group). After completing immunization, CD4+ and CD8+ T cells, stimulated with SLa-Antigen or rChiP, showed an increased production of nitric oxide and intracytoplasmic pro-inflammatory cytokines, in addition to the generation of central and effector memory T cells. rChiP and rChiP+MPLA formulations were able to promote an effective protection against L. amazonensis infection determined by a reduction in the development of skin lesions and lower parasitic burden. Reduction in the development of skin lesions and lower parasitic burden in the vaccinated groups were associated with an increase of nitrite, CD4+/CD8+IFN-γ+TNF-α+ and CD4+/CD8+CD44highCD62Lhigh/low T cells, IgGTotal, IgG2a, and lower rates of IgG1 and CD4+/CD8+IL-10+. This data suggests that proposed formulations could be considered potential tools to prevent ATL.

Asunto(s)

Adyuvantes Inmunológicos , Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos , Epítopos de Linfocito T , Memoria Inmunológica , Vacunas contra la Leishmaniasis , Leishmaniasis Cutánea , Animales , Leishmaniasis Cutánea/prevención & control , Leishmaniasis Cutánea/inmunología , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD4-Positivos/inmunología , Epítopos de Linfocito T/inmunología , Ratones , Vacunas contra la Leishmaniasis/inmunología , Femenino , Adyuvantes Inmunológicos/administración & dosificación , Ratones Endogámicos BALB C , Proteínas Recombinantes de Fusión/inmunología , Proteínas Recombinantes de Fusión/genética , Leishmania braziliensis/inmunología , Lípido A/análogos & derivados , Lípido A/inmunología , Anticuerpos Antiprotozoarios/inmunología , Citocinas/metabolismo , Citocinas/inmunología , Modelos Animales de Enfermedad , Antígenos de Protozoos/inmunología

RESUMEN

There are no approved vaccines yet for human visceral leishmaniasis (VL), the most severe form of the leishmaniasis clinical manifestations that is fatal in over 95 % of untreated cases. It is well-accepted that immunological changes during aging have deleterious impact on the efficacy of vaccines and response to infections. In this work, we compared the response of young and aged mice to intranasal vaccination with killed Leishmania amazonensis promastigote antigens (LaAg) that were then challenged with L. infantum infection, a species that causes visceral leishmaniasis. Intranasal vaccination with LaAg induced a similar reduction in parasitism and hepatosplenomegaly in both young and aged mice compared to their unvaccinated counterparts. Following infection, there was also a less prominent inflammatory profile particularly in the vaccinated aged group, with lower production of TNF-α and nitrite compared to the respective unvaccinated group. Interestingly, the LaAg intranasal vaccination promoted increased production of IFN-γ that was observed in both young- and aged vaccinated groups. Additionally, CD4+ and CD8+T cells from both vaccinated groups presented decreased expression of the inhibitory receptors PD-1 and KLRG1 compared to their unvaccinated controls. Interestingly, a strong positive correlation was observed between the expression of both inhibitory receptors PD-1 and KLRG1 and parasitism, which was more conspicuous in the unvaccinated-aged mice than in the others. Overall, this study helps define new strategies to improve vaccine effectiveness and provides a perspective for prophylactic alternatives against leishmaniasis.

Asunto(s)

Leishmania infantum , Leishmania mexicana , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Leishmaniasis , Vacunas Antiprotozoos , Humanos , Animales , Ratones , Anciano , Leishmaniasis Visceral/prevención & control , Receptor de Muerte Celular Programada 1 , Antígenos de Protozoos , Ratones Endogámicos BALB C , Citocinas

RESUMEN

This report presents the 2022 epidemiological profile of the Region, as well as describes the analyses of the goals and main indicators of the Plan of Action to Strengthen the Surveillance and Control of Leishmaniasis in the Americas 2017-2022, which at the regional level, were not fully achieved, but when analyzed individually by country, significant progress has been made, demonstrating the commitment and effort of the Ministries of Health with regard to the disease surveillance, patient care and control. Within the framework of the approval of the PAHO's Disease Elimination Initiative, the WHO Roadmap for 2030, and the publication of the cross-cutting resolutions: a) Plan of Action on Entomology and Vector Control 2018-2023 and b) One Health: A Comprehensive Approach to Addressing Health Threats, the leishmaniasis Plan of Action for 2023-2030 was updated, discussed, and agreed upon with endemic countries, specialists, collaborators and partners. With this new Plan, it is expected to improve and strengthen surveillance and control actions to obtain better results, such as expand access and implementation of diagnostic methodologies, and treatment alternatives for affected people living in risk areas, also, execution of actions according to the risk stratification, reduction of vector contact, among others.

Asunto(s)

Leishmaniasis , Leishmaniasis Mucocutánea , Leishmaniasis Visceral , Leishmaniasis Cutánea , Vacunas contra la Leishmaniasis , Enfermedades Transmisibles , Enfermedades Desatendidas , Américas

RESUMEN

Vaccination with live attenuated Leishmania parasites such as centrin deleted Leishmania donovani (LdCen-/-) against visceral leishmaniasis has been reported extensively. The protection induced by LdCen-/- parasites was mediated by both CD4+ and CD8+ T cells. While the host immune mediators of protection are known, parasite determinants that affect the CD4+ and CD8+ T cell populations remain unknown. Parasite encoded inflammatory cytokine MIF has been shown to modulate the T cell differentiation characteristics by altering the inflammation induced apoptosis during contraction phase in experimental infections with Leishmania or Plasmodium. Neutralization of parasite encoded MIF either by antibodies or gene deletion conferred protection in Plasmodium and Leishmania studies. We investigated if the immunogenicity and protection induced by LdCen-/- parasites is affected by deleting MIF genes from this vaccine strain. Our results showed that LdCen-/-MIF-/- immunized group presented higher percentage of CD4+ and CD8+ central memory T cells, increased CD8+ T cell proliferation after challenge compared to LdCen-/- immunization. LdCen-/-MIF-/- immunized group presented elevated production of IFN-γ+ and TNF-α+ CD4+ T cells concomitant with a reduced parasite load in spleen and liver compared to LdCen-/-group following challenge with L. infantum. Our results demonstrate the role of parasite induced factors involved in protection and long-term immunity of vaccines against VL.

Asunto(s)

Leishmania donovani , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Parásitos , Animales , Ratones , Linfocitos T CD8-positivos , Leishmaniasis Visceral/parasitología , Leishmania donovani/genética , Linfocitos T CD4-Positivos , Ratones Endogámicos BALB C

RESUMEN

Vaccination against visceral leishmaniasis (VL) should be considered as a safe and effective measure to disease control; however, few vaccines are available against canine VL and there is no an approved human vaccine. In this context, in the present study, we evaluated the endonuclease III (ENDO) protein, which was recently showed to be antigenic for human disease, as a vaccine candidate against Leishmania infantum infection. The recombinant protein (rENDO) was administered in BALB/c mice alone or associated with saponin (rENDO/Sap) or micelles (rENDO/Mic) as adjuvants. Controls received saline, saponin or empty micelles. Results showed that both rENDO/Sap and rENDO/Mic compositions induced higher levels of IFN-γ, IL-12, TNF-α, and GM-CSF cytokines, besides nitrite and IgG2a isotype antibodies, before and after challenge infection, which were related to both CD4+ and CD8+ T cell subtypes. The immunological results contributed to significant reductions in the parasite load found in the spleens, livers, bone marrows and draining lymph nodes of the vaccinated animals. In general, mice immunized with rENDO/Mic presented a slightly higher Th1-type cellular and humoral immune response, as compared to those receiving rENDO/Sap. In addition, saponin caused a slight to moderate inflammatory edema in their vaccinated footpads, which was not observed when micelles were used with rENDO. In addition, a preliminary analysis showed that the recombinant protein was immunogenic to human cells cultures, since PBMCs from treated VL patients and healthy subjects showed higher lymphoproliferation and IFN-γ production in the culture supernatants. In conclusion, data suggest that rENDO could be considered as a candidate to be evaluated in future studies as vaccine to protect against VL.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Leishmaniasis , Saponinas , Humanos , Animales , Perros , Ratones , Micelas , Proteínas Recombinantes , Leishmaniasis/prevención & control , Adyuvantes Inmunológicos , Ratones Endogámicos BALB C , Antígenos de Protozoos

RESUMEN

The development of an immunogenic, effective, and safe vaccine is essential as an alternative for disease control. The present study aimed to evaluate the immunogenicity and efficacy potential of a polyepitope T-cell antigen candidate against visceral leishmaniasis in a murine model. BALB/c mice were immunized with three doses subcutaneously with Poly-T Leish alone or adjuvanted with Saponin plus Monophosphoryl lipid A, with 15-day intervals between doses, and challenged with 107 stationary-phase Leishmania infantum promastigotes via tail vein. Immunogenicity and parasitism in spleen and liver of immunized mice were evaluated 45 days post-challenge. Our results revealed that the immunization with Poly-T Leish and Poly-T Leish/SM increases the percentage of specific T (CD4+ and CD8+) lymphocytes proliferation in vitro after antigen-specific stimulation. Also, Poly-T Leish and Poly-T Leish/SM groups showed a high percentage of IFN-γ and TNF-α-producing T cells, meanwhile, the Poly-T Leish/SM group also showed an increased percentage of multifunctional T cells producing double and triple-positive (IFN-γ+TNF-α+IL-2+) cytokines. The immunization with Poly-T Leish or Poly-T Leish/SM stimulated a decreased IL-4 and IL-10 compared to the Saline and adjuvant group. Poly-T Leish/SM immunized mice exhibit a noteworthy reduction in the parasite burden (spleen and liver) through real-time PCR (96%). Moreover, we observed higher nitrite secretion in 120-hour stimulated-culture supernatant using Griess method. We demonstrated that the Poly-T Leish/SM candidate was potentially immunogenic, providing enhancement of protective immune mechanisms, and conferred protection reducing parasitism. Our candidate was considered potential against visceral leishmaniasis, and eventually, could be tested in phase I and II clinical trials in dogs.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Adyuvantes Inmunológicos/farmacología , Animales , Antígenos de Protozoos , Perros , Leishmaniasis Visceral/prevención & control , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Factor de Necrosis Tumoral alfa

RESUMEN

In recent years, several advances have been observed in vaccinology especially for neglected tropical diseases (NTDs). One of the tools employed is epitope prediction by immunoinformatic approaches that reduce the time and cost to develop a vaccine. In this scenario, immunoinformatics is being more often used to develop vaccines for NTDs, in particular visceral leishmaniasis (VL) which is proven not to have an effective vaccine yet. Based on that, in a previous study, two predicted T-cell multi-epitope chimera vaccines were experimentally validated in BALB/c mice to evaluate the immunogenicity, central and effector memory and protection against VL. Considering the results obtained in the mouse model, we assessed the immune response of these chimeras inMesocricetus auratushamster, which displays, experimentally, similar pathological status to human and dog VL disease. Our findings indicate that both chimeras lead to a dominant Th1 response profile, inducing a strong cellular response by increasing the production of IFN-γ and TNF-α cytokines associated with a decrease in IL-10. Also, the chimeras reduced the spleen parasite load and the weight a correlation between protector immunological mechanisms and consistent reduction of the parasitic load was observed. Our results demonstrate that both chimeras were immunogenic and corroborate with findings in the mouse model. Therefore, we reinforce the use of the hamster as a pre-clinical model in vaccination trials for canine and human VL and the importance of immunoinformatic to identify epitopes to design vaccines for this important neglected disease.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Células TH1 , Animales , Cricetinae , Perros , Humanos , Ratones , Adyuvantes Inmunológicos , Antígenos de Protozoos , Citocinas , Enfermedades de los Perros , Epítopos de Linfocito T , Leishmaniasis Visceral/prevención & control , Ratones Endogámicos BALB C , Bazo

RESUMEN

Tegumentary leishmaniasis (TL) is a disease of high severity and incidence in Brazil, and Leishmania braziliensis is its main etiological agent. The inefficiency of control measures, such as high toxicity and costs of current treatments and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present work developed a gene encoding multiple T-cell (CD4+/CD8+) epitope, derived from conserved proteins found in Leishmania species and associated with TL, to generate a chimeric protein (rMEP/TL) and compose a vaccine formulation. For this, six T-cell epitopes were selected by immunoinformatics approaches from proteins present in the amastigote stage and associated with host-parasite interactions. The following formulations were then tested in an L. braziliensis murine infection model: rMEP/TL in saline or associated with MPLA-PHAD®. Our data revealed that, after immunization (three doses; 14-day intervals) and subsequent challenging, rMEP/TL and rMEP/TL + MPLA-vaccinated mice showed an increased production of key immunological biomarkers of protection, such as IgG2a, IgG2a/IgG1, NO, CD4+, and CD8+ T-cells with IFN-γ and TNF-α production, associated with a reduction in CD4+IL-10+ and CD8+IL-10+ T-cells. Vaccines also induced the development of central (CD44highCD62Lhigh) and effector (CD44highCD62Llow) memory of CD4+ and CD8+ T-cells. These findings, associated with the observation of lower rates of parasite burdens in the vaccinated groups, when compared to the control groups, suggest that immunization with rMEP/TL and, preferably, associated with an adjuvant, may be considered an effective tool to prevent TL. KEY POINTS: • Rational design approaches for vaccine development. • Central and effector memory of CD4+ and CD8+ T-cells. • Vaccine comprised of rMEP/TL plus MPLA as an effective tool to prevent TL.

Asunto(s)

Vacunas contra la Leishmaniasis , Leishmaniasis , Animales , Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos , Epítopos de Linfocito T/genética , Inmunoglobulina G , Interleucina-10/metabolismo , Leishmaniasis/prevención & control , Vacunas contra la Leishmaniasis/genética , Ratones , Ratones Endogámicos BALB C

RESUMEN

Treatment against visceral leishmaniasis (VL) presents problems by the toxicity of drugs, high cost and/or emergence of resistant strains. The diagnosis is hampered by variable sensitivity and/or specificity of tests. In this context, prophylactic vaccination could represent a control measure against disease. In this study, the protective efficacy of Leishmania LiHyC protein was evaluated in a murine model against Leishmania infantum infection. LiHyC was used as recombinant protein (rLiHyC) associated with saponin (rLiHyC/S) or Poloxamer 407-based polymeric micelles (rLiHyC/M) to immunize mice. Animals received also saline, saponin or empty micelles as controls. The immunogenicity was evaluated before and after the challenge, and results showed that vaccination with rLiHyC/S or rLiHyC/M induced the production of high levels of interferon-gamma (IFN-γ), interleukin (IL)-12 and granulocyte-macrophage colony-stimulating factor in cell culture supernatants, as well as higher IFN-γ expression evaluated by RT-qPCR and involvement from CD4+ and CD8+ T-cell subtypes producing IFN-γ, tumor necrosis factor-α and IL-2. A positive lymphoproliferative response was also found in cell cultures from vaccinated animals, besides high levels of rLiHyC- and parasite-specific nitrite and IgG2a antibodies. Immunological assays correlated with significant reductions in the parasite load in the spleens, livers, bone marrows and draining lymph nodes from vaccinated mice, when compared to values found in the controls. The micellar composition showed slightly better immunological and parasitological data, as compared to rLiHyC/S. Results suggest that rLiHyC associated with adjuvants could be considered for future studies as a vaccine candidate against VL.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Saponinas , Animales , Antígenos de Protozoos , Interferón gamma , Interleucina-12 , Ratones , Ratones Endogámicos BALB C , Micelas , Proteínas Recombinantes

RESUMEN

Vaccination against visceral leishmaniasis (VL) should be considered as a control measure to protect against disease, and amastigote-specific proteins could help to develop such vaccines, since this parasite form is in contact with the host immune system during the active disease. In this study, a Leishmania amastigote-specific protein, LiHyG, was evaluated as recombinant protein (rLiHyG) as vaccine candidate against Leishmania infantum infection in BALB/c mice. The protein was associated with saponin (rLiHyG/Sap) or Poloxamer 407-based polymeric micelles (rLiHyG/Mic) as adjuvants, and animals receiving saline, saponin or micelle as controls. Immunological and parasitological analyses were performed before (n = 8 per group; as primary endpoint) and after (n = 8 per group; as secondary endpoint) infection. Results showed that, in both endpoints, rLiHyG/Sap and rLiHyG/Mic induced higher levels of IFN-γ, IL-12 and GM-CSF in spleen cell cultures from vaccinated animals, besides elevated presence of IgG2a isotype antibodies. Decreased hepatotoxicity and 'positive lymphoproliferative response were also found after challenge. Such findings reflected in significantly lower levels of parasite load found in their spleens, livers, bone marrows and draining lymph nodes. In conclusion, rLiHyG associated with Th1-type adjuvant could be considered for future studies as vaccine candidate to protect against VL.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Leishmaniasis , Saponinas , Adyuvantes Inmunológicos , Animales , Antígenos de Protozoos/genética , Leishmaniasis/prevención & control , Leishmaniasis Visceral/parasitología , Ratones , Ratones Endogámicos BALB C , Proteínas Recombinantes/genética

RESUMEN

The control of human visceral leishmaniasis (VL) is hard since there are no vaccines available as well as the treatment is hampered by toxicity and resistant parasites. Furthermore, as human, and canine VL causes immunosuppression, the combination of drugs with immunostimulatory agents is interesting to upregulate the immunity, reducing side-effects, improving treatment approaches against disease. Herein, we assessed the immunochemotherapy using miltefosine along with a vaccine formulated by Leishmania braziliensis antigens + saponin + monophosphoryl lipid-A (LBSapMPL) in L. infantum-infected hamsters. Two months after infection, the animals received treatments, and after 15 days they were evaluated for the treatment effect. The potential anti-Leishmania effect of miltefosine + LBSapMPL-vaccine was revealed by a specific immune response activation reflecting in control of spleen parasitism using half the miltefosine treatment time. The treated animals also showed an increase of total and T-CD4 splenocytes producing IFN-γ and TNF-α and a decrease of interleukin-10 and anti-Leishmania circulating IgG. In addition, it was demonstrated that the control of spleen parasitism is related to the generation of a protective Th1 immune response. Hence, due to the combinatorial action of miltefosine with LBSapMPL-vaccine in immunostimulating and controlling parasitism, this immunochemotherapy protocol can be an important alternative option against canine and human VL.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Animales , Antígenos de Protozoos , Cricetinae , Perros , Inmunidad , Leishmaniasis Visceral/tratamiento farmacológico , Leishmaniasis Visceral/prevención & control , Ratones , Ratones Endogámicos BALB C , Fosforilcolina/análogos & derivados , Bazo/parasitología

RESUMEN

Visceral leishmaniasis (VL) is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. Systemic VL is fatal if untreated and there are no prophylactic human vaccines available. Several studies suggest that Th1 cell-mediated immunity plays a major role in protecting against VL. In this chapter we describe a method for designing recombinant chimera vaccines in silico based on the prediction of T cell epitopes within protein antigens identified as potential protective immunogens. Development of a recombinant chimera protein (RCP) vaccine using T cell epitope peptides identified from four Leishmania proteins is used as an exemplar of this method.

Asunto(s)

Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Humanos , Antígenos de Protozoos/genética , Epítopos de Linfocito T , Leishmania/genética , Leishmaniasis Visceral/prevención & control , Péptidos , Proteínas Protozoarias/genética , Linfocitos T , Vacunas Sintéticas/genética

RESUMEN

Leishmaniases are neglected diseases caused by Leishmania parasites and affect millions of people worldwide. The induction of protective immunity against infection by some species of Leishmania has stimulated the development of vaccine candidates against the disease. In this chapter we describe protocols for immunizing mice with a recombinant chimera vaccine containing selected epitopes that specifically stimulate a Th1-type immune response. We describe protocols for challenging mice with live Leishmania parasite and for measuring parameters of the immune response to vaccination and parasite infection, including the production of cytokines, nitric oxide, and IgG antibodies, and the contribution of CD4+ and CD8+ T cells. We also provide protocols for isolating mouse organs for cell culture and for quantifying parasite loads in unvaccinated control animals and in vaccine-protected animals. These protocols can form the basis of immunological studies of candidate Leishmania vaccines in the mouse, as a step toward further vaccine development for human use.

Asunto(s)

Leishmania , Vacunas contra la Leishmaniasis , Leishmaniasis , Animales , Linfocitos T CD8-positivos/inmunología , Citocinas , Leishmaniasis/prevención & control , Leishmaniasis Visceral , Ratones , Ratones Endogámicos BALB C , Proteínas Protozoarias , Desarrollo de Vacunas , Vacunas Sintéticas

RESUMEN

This report presents a detailed analysis of 2021 data on leishmaniases in the Region of the Americas and includes a series of infographics with specific data on cutaneous and mucosal leishmaniasis in endemic countries. In addition, it describes the trend of cutaneous and visceral leishmaniasis in the period 2001-2021 and includes partial analyses of the goals of the Plan of Action to strengthen the surveillance and control of leishmaniases in the Americas 2017-2022. Preliminary analyses of targets and indicators show that, at the regional level, the goals were not achieved. However, progress has been made towards the goals of reducing the incidence of visceral leishmaniasis and reducing cases of cutaneous leishmaniasis in children under 10 years of age. On the other hand, if the country targets are analyzed, several met or made progress towards the targets compared to the baseline, demonstrating the commitment and effort of the Ministries of Health to improving the quality of surveillance, care and control of the disease.

Asunto(s)

Leishmaniasis , Leishmaniasis Mucocutánea , Leishmaniasis Visceral , Leishmaniasis Cutánea , Vacunas contra la Leishmaniasis , Enfermedades Transmisibles , Enfermedades Desatendidas , COVID-19

RESUMEN

The Pan American Health Organization (PAHO) continues to support endemic countries in order to achieve the objectives of controlling and eliminating leishmaniasis as a public health problem in the Region, in accordance with the PAHO Disease Elimination Initiative: A Policy for an Integrated Sustainable Approach to Communicable Diseases in the Americas, the World Health Organization (WHO) Roadmap for Neglected Tropical Diseases for 2021 to 2030 and the Plan of Action to Strengthen Leishmaniasis Surveillance and Control in the Americas 2017-2022. PAHO has provided support to endemic countries and together with them has implemented initiatives aimed at promoting prevention, surveillance, and control actions, with the aim of reducing morbidity, mortality and severe forms of the disease through access to early diagnosis, appropriate treatment, and the reduction of contact between people and leishmaniasis vectors. This report presents a detailed analysis of cutaneous, mucosal, and visceral leishmaniasis data in the Region of the Americas for 2020 and includes a series of infographics with specific data on cutaneous and mucosal leishmaniasis in endemic countries. As a result of the COVID-19 pandemic, active search activities, early detection and treatment of cases, as well as other field activities, have been reduced. Among the challenges facing the Region, we highlight the need for countries to resume activities and move forward with the diagnosis and treatment of cases of the different clinical forms of the disease. Furthermore, it is necessary to identify strategies for the follow-up and monitoring of cases, in order to achieve the targets of treating at least 90% of patients diagnosed with cutaneous and mucosal leishmaniasis, as well as reducing the lethality of visceral leishmaniasis to less than 50% in the Region.

Asunto(s)

Leishmaniasis , Leishmaniasis Mucocutánea , Leishmaniasis Visceral , Leishmaniasis Cutánea , Vacunas contra la Leishmaniasis , Enfermedades Transmisibles , Enfermedades Desatendidas , Enfermedades Endémicas , Vigilancia en Desastres , Morbilidad , Mortalidad , COVID-19 , Pandemias

RESUMEN

Dogs are the main reservoir of Leishmania infantum in endemic regions. Canine leishmaniasis, caused by L. infantum, can progress to a chronic disease resulting in death. Vaccines have been developed with a certain degree of success. The pathogenesis of this disease is not completely understood, especially in previously vaccinated dogs. We herein described clinical data, parasite load, serum levels of cytokines, and the reservoir potential in vdogs vaccinated with the fucose-mannose ligand (FML)/QuilA saponin vaccine (Leishmune™) naturally infected (Vi) and compared to vaccinated not infected dogs (Vn). Thirty-four dogs from private owners were divided into two groups: vaccinated/infected and vaccinated/uninfected. Clinical evaluation, hematological and biochemical parameters, and serum levels of cytokines were measured by conventional methods. The parasite burden in the bone marrow was measured by quantitative real-time PCR, and the transmissibility of parasites to sand flies was assessed by xenodiagnosis. Clinical, biochemical, and hematological parameters of vaccinated infected dogs were mostly normal. Vi dogs developed mild disease with low clinical scores. Serum levels of IL-10 were higher in Vi dogs, and a strong correlation was observed in IL-4 levels and the A/G ratio in Vi dogs. These results suggest a role of TH2 response in Vi dogs, although more data is needed to better understand the disease in vaccinated dogs.

Asunto(s)

Citocinas/sangre , Lectinas/inmunología , Leishmania infantum/inmunología , Vacunas contra la Leishmaniasis/inmunología , Leishmaniasis Visceral/parasitología , Leishmaniasis Visceral/veterinaria , Vacunación , Animales , Perros , Femenino , Interleucina-4/sangre , Leishmaniasis Visceral/sangre , Leishmaniasis Visceral/patología , Masculino

RESUMEN

In Brazil, canine visceral leishmaniasis is an important public health problem due to its alarming growth. The high prevalence of infected dogs reinforces the need for a vaccine for use in prophylactic vaccination campaigns. In the present study, we evaluate the immunogenicity and protection of the best dose of Chimera A selected through the screening of cytokines production important in disease. BALB/c mice were vaccinated subcutaneously with three doses and challenged intravenously with 1 × 107L. infantum promastigotes. Spleen samples were collected to assess the intracellular cytokine profile production, T cell proliferation and parasite load. At first, three different doses of Chimera A (5 µg, 10 µg and 20 µg) were evaluated through the production of IFN-γ and IL-10 cytokines. Since the dose of 20 µg showed the best results, it was chosen to continue the study. Secondarily, Chimera A at dose of 20 µg was formulated with Saponin plus Monophosphoryl lipid A. Vaccination with Chimera A alone and formulated with SM adjuvant system was able to increase the percentage of the proliferation of specific T lymphocytes and stimulated a Th1 response with increased levels of IFN-γ, TNF-α and IL-2, and decreased of IL-4 and IL-10. The vaccine efficacy through real-time PCR demonstrated a reduction in the splenic parasite load in animals that received Chimera A formulated with the SM adjuvant system (92%). Additionally, we observed increased levels of nitric oxide in stimulated-culture supernatants. The Chimera A formulated with the SM adjuvant system was potentially immunogenic, being able to induce immunoprotective mechanisms and reduce parasite load. Therefore, the use of T-cell multi-epitope vaccine is promising against visceral leishmaniasis.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Leishmaniasis Visceral , Adyuvantes Inmunológicos , Animales , Antígenos de Protozoos , Brasil , Citocinas , Perros , Leishmaniasis Visceral/prevención & control , Ratones , Ratones Endogámicos BALB C

RESUMEN

Aim: Current treatments for leishmaniases are not satisfactory, thus alternatives are needed. We searched for clinical trials with immunotherapeutic approaches for patients with leishmaniasis. Materials & methods: Out of 205 articles, 24 clinical trials were selected, and eight submitted to meta-analysis. Results: A reduction in healing time was observed in patients with tegumentary leishmaniasis treated with pentavalent antimony plus granulocyte-macrophage colony-stimulating factor, and therapeutic vaccines. Overall meta-analysis indicated that immunotherapy associated with the standard chemotherapy generated a significantly reduced risk of treatment failure than the pentavalent antimony alone (p = 0.03). Conclusion: Our review confirmed the efficacy of immunotherapies for the treatment of cutaneous and visceral leishmaniasis and highlighted the importance of clinical trials using immunotherapies for leishmaniases.

Asunto(s)

Antiprotozoarios/uso terapéutico , Inmunoterapia/métodos , Leishmaniasis/terapia , Humanos , Vacunas contra la Leishmaniasis/uso terapéutico

RESUMEN

Leishmaniasis is a disease caused by an intracellular protozoan parasite of the genus Leishmania. Current treatments for leishmaniasis are long, toxic, and expensive and are not available in some endemic regions. Attempts to develop an effective vaccine are feasible, but no vaccine is in active clinical use. In this study, the LmxMBA gene of Leishmania mexicana was selected as a possible vaccine candidate using the reverse vaccinology approach, and the prophylactic effect generated by DNA vaccination with this gene in a murine model of cutaneous leishmaniasis was evaluated. The results showed that prophylactic vaccination with pVAX1::LmxMBA significantly reduced the size of the lesion and the parasitic load on the footpad, compared to the control groups. At a histological level, a smaller number of parasites were evident in the dermis, as well as the absence of connective tissue damage. Mice immunized with plasmid pVAX1::LmxMBA induced immunity characterized by an increase in the IgG2a/IgG1 > 1 ratio and a higher rate of lymphocyte proliferation. In this study, immunization with the plasmid promoted an improvement in the macroscopic and microscopic clinical manifestations of the experimental infection by L. mexicana, with a T helper 1 response characterized by an IgG2a/IgG1 > 1 ratio and high lymphoproliferative response. These findings support immunization with the plasmid pVAX1::LmxMBA as a preventive strategy against cutaneous infection of L. mexicana.

Asunto(s)

Fosfatasa Ácida/genética , Leishmania mexicana/fisiología , Vacunas contra la Leishmaniasis/inmunología , Leishmaniasis Cutánea/inmunología , Proteínas Protozoarias/genética , Piel/patología , Células TH1/inmunología , Animales , Anticuerpos Antiprotozoarios/sangre , Modelos Animales de Enfermedad , Femenino , Humanos , Inmunoglobulina G/sangre , Leishmaniasis Cutánea/prevención & control , Ratones , Ratones Endogámicos BALB C , Carga de Parásitos , Vacunación , Vacunas de ADN

RESUMEN

Treatment for visceral leishmaniasis (VL) is hampered mainly by the toxicity and/or high cost of antileishmanial drugs. What is more, variability on sensitivity and/or specificity of diagnostic tests hinders effective disease management. In this context, prophylactic vaccination should be considered as a strategy to prevent disease. In the present study, immunogenicity of the Leishmania eukaryotic Elongation Factor-1 beta (EF1b) protein, classified as a Leishmania virulence factor, was evaluated in vitro and in vivo and tested, for the first time, as a vaccine candidate against Leishmania infantum infection. The antigen was administered as DNA vaccine or as recombinant protein (rEF1b) delivered in saponin. BALB/c mice immunization with a DNA plasmid and recombinant protein plus saponin induced development of specific Th1-type immunity, characterized by high levels of IFN-γ, IL-12, GM-CSF, both T cell subtypes and antileishmanial IgG2a isotype antibodies, before and after infection. This immunological response to the vaccines was corroborated further by parasitological analysis of the vaccinated and then challenged mice, which showed significant reductions in the parasite load in their liver, spleen, bone marrow and draining lymph nodes, when compared to the controls. Vaccination using rEF1b/saponin induced a more robust Th1 response and parasitological protection when compared to the DNA vaccine. Furthermore, in vitro analysis of lymphoproliferation, IFN-γ and IL-10 levels in human PBMC cultures showed as well development of a specific Th1-type response. In conclusion, data suggest that EF1b could be a promising vaccine candidate to protect against L. infantum infection.

Asunto(s)

Leishmania infantum , Vacunas contra la Leishmaniasis , Animales , Antígenos de Protozoos/genética , Leucocitos Mononucleares , Ratones , Ratones Endogámicos BALB C , Factores de Elongación de Péptidos