An α-Gal-containing neoglycoprotein-based vaccine partially protects against murine cutaneous leishmaniasis caused by Leishmania major

Abstract

BackgroundProtozoan parasites from the genus Leishmania cause broad clinical manifestations known as leishmaniases, which affect millions of people worldwide. Cutaneous leishmaniasis (CL), caused by L. major, is one the most common forms of the disease in the Old World. There is no preventive or therapeutic human vaccine available for L. major CL, and existing drug treatments are expensive, have toxic side effects, and resistant parasite strains have been reported. Hence, further therapeutic interventions against the disease are necessary. Terminal, non-reducing, and linear α-galactopyranosyl (α-Gal) epitopes are abundantly found on the plasma membrane glycolipids of L. major known as glycoinositolphospholipids. The absence of these α-Gal epitopes in human cells makes these glycans highly immunogenic and thus potential targets for vaccine development against CL.Methodology/Principal findingsHere, we evaluated three neoglycoproteins (NGPs), containing synthetic α-Gal epitopes covalently attached to bovine serum albumin (BSA), as vaccine candidates against L. major, using α1,3-galactosyltransferase-knockout (α1,3GalT-KO) mice. These transgenic mice, similarly to humans, do not express nonreducing, linear α-Gal epitopes in their cells and are, therefore, capable of producing high levels of anti-α-Gal antibodies. We observed that Galα(1,6)Galβ-BSA (NGP5B), but not Galα(1,4)Galβ-BSA (NGP12B) or Galα(1,3)Galα-BSA (NGP17B), was able to significantly reduce the size of footpad lesions by 96% in comparison to control groups. Furthermore, we observed a robust humoral and cellular immune response with production of high levels of protective lytic anti-α-Gal antibodies and induction of Th1 cytokines.Conclusions/SignificanceWe propose that NGP5B is an attractive candidate for the study of potential synthetic α-Gal-neoglycoprotein-based vaccines against L. major infection.

Vaccination with Alpha-Gal Protects Against Mycobacterial Infection in the Zebrafish Model of Tuberculosis

“…The possibility of using the antibody-mediated immune response against α-Gal for the control of infectious diseases caused by pathogens with this modification on their surface in hosts such as humans, birds, and fishes that do not have the capacity to synthesize α-Gal was initially suggested by results in the malaria mouse model [15]. Then, results in leishmaniasis and Chagas disease further supported this possibility [18][19][20], leading to proposing the possibility of development of a single-antigen pan-vaccine for the control of major infectious diseases worldwide [11,16,17,30]. Pathogens causing infectious diseases with high incidence worldwide and with α-Gal modifications include Plasmodium, Mycobacterium, Leishmania, Trypanosoma, Anaplasma, Borrelia, and Aspergillus species and viruses such as human immunodeficiency virus (HIV), measles virus, vaccinia virus, paramyxovirus, vesicular stomatitis virus, Sindbis virus, and retroviruses [6,9,14,15,[17][18][19][20][21].…”

“…Within the conflict and cooperation that drove the evolution of tick-host-pathogen interactions [13], humans evolved by losing the capacity to synthesize α-Gal to increase the protective immune response against pathogens with this modification on their surface while increasing the risk to develop the AGS [6]. This evolutionary adaptation suggested the possibility of developing vaccines and other interventions to induce the anti-α-Gal IgM/IgG protective response against pathogen infection to prevent or control major infectious diseases worldwide [14][15][16][17][18][19][20].…”

“…Recently, the C57BL/6 α1,3-Galactosyltransferase-knockout (α1,3-GalT-KO) mouse animal model was used to study the antibody response to the carbohydrate α-Gal and its potential for the control of infectious diseases such as malaria, leishmaniasis, Chagas disease, granulocytic anaplasmosis, and influenza caused by pathogens with this modification on their surface and/or by enhancing the protective immune response against these pathogens [15][16][17][18][19][20][21][22]. The results showed protection against pathogen infection in response to α-Gal-containing vaccine formulations [15,[18][19][20][21][22]. However, the protective effect of the anti-α-Gal immune response for the control of tuberculosis caused by Mycobacterium spp.…”

Allergic Reactions and Immunity in Response to Tick Salivary Biogenic Substances and Red Meat Consumption in the Zebrafish Model

“…Recently, C57BL/6 α1,3-galactosyltransferase-knockout (α1,3-GalT-KO) mice that like humans do not synthesize α-Gal have been used as a model to characterize the percutaneous sensitization to α-Gal and Amblyomma sculptum tick saliva (Araujo et al, 2016) and the IgE-mediated immune response to cutaneous exposure to Amblyomma americanum tick proteins (Chandrasekhar et al, 2019). Additionally, this animal model has been used to study the antibody response to the carbohydrate α-Gal and its potential for the control of infectious diseases caused by pathogens with this modification on their surface (Yilmaz et al, 2014;Cabezas-Cruz et al, 2016;Iniguez et al, 2017;Moura et al, 2017;Portillo et al, 2019). In this context, various fish species constitute models for investigating human diseases (Schartl, 2014), and zebrafish (Danio rerio Hamilton 1822) is a relevant animal model for research in genetics, developmental biology, toxicology, oncology, immunology, and allergy (Huang et al, 2018).…”

Infection with Toxocara canis Inhibits the Production of IgE Antibodies to α-Gal in Humans: Towards a Conceptual Framework of the Hygiene Hypothesis?

“…Anti-α-Gal Abs, principally immunoglobulin (Ig)G, IgM, and IgA isotypes, are typically produced by healthy human individuals as an immunological response to continuous antigenic stimulation by gastrointestinal bacteria producing α-Gal on their outer surface [7]. Interestingly, the resulting IgG and IgM Abs were found to be protective against important microbial and parasitic infections [8][9][10][11]. However, hyperproduction of specific IgE Abs to α-Gal triggered by bites of ixodid ticks (Acari: Ixodidae) may lead to a delayed and potentially fatal anaphylactic reaction to mammalian meats (e.g., beef, pork, lamb) and other α-Gal-containing products [12,13].…”