Development of the Sm14/GLA-SE Schistosomiasis Vaccine Candidate: An Open, Non-Placebo-Controlled, Standardized-Dose Immunization Phase Ib Clinical Trial Targeting Healthy Young Women.

We report the successful closure of Phase I clinical trials, comprising Phases Ia and Ib, of the vaccine candidate against human schistosomiasis: the Schistosoma mansoni 14 kDa fatty acid-binding protein (Sm14) + glucopyranosyl lipid A in squalene emulsion (GLA-SE). Shown here are the results of Phase Ib, an open, non-placebo-controlled, standardized-dose immunization trial involving 10 healthy 18-49-year-old women. Fifty micrograms of the Sm14 protein plus 10 µg GLA-SE per dose was given intramuscularly thrice at 30-day intervals. Participants were assessed clinically, biochemically, and immunologically for up to 120 days. In preambular experiments involving vaccinated pregnant female rabbits, we did not find any toxicological features in either the offspring or mothers, and the vaccine induced adaptive immunity in the animals. In women, no adverse events were observed, and vaccination induced high titers of anti-Sm14 serum IgG antibody production. Vaccination also elicited robust cytokine responses, with increased TNFα, IFNγ, and IL-2 profiles in all vaccinees on days 90 and 120. The completion of Phase I clinical trials, which were performed to the highest standards set by Good Clinical Research Practice (GCP) standards, and preclinical data in pregnant rabbits enabled the vaccine candidate to proceed to Phase II clinical trials in endemic areas.

Correction: Tendler, M., et al. Current Status of the Sm14/GLA-SE Schistosomiasis Vaccine: Overcoming Barriers and Paradigms towards the First Anti-Parasitic Human(itarian) Vaccine. Trop. Med. Infect. Dis. 2018, 3, 121.

The authors wish to make the following correction to this paper [...].

Current Status of the Sm14/GLA-SE Schistosomiasis Vaccine: Overcoming Barriers and Paradigms towards the First Anti-Parasitic Human(itarian) Vaccine.

Schistosomiasis, a disease historically associated with poverty, lack of sanitation and social inequality, is a chronic, debilitating parasitic infection, affecting hundreds of millions of people in endemic countries. Although chemotherapy is capable of reducing morbidity in humans, rapid re-infection demonstrates that the impact of drug treatment on transmission control or disease elimination is marginal. In addition, despite more than two decades of well-executed control activities based on large-scale chemotherapy, the disease is expanding in many areas including Brazil. The development of the Sm14/GLA-SE schistosomiasis vaccine is an emblematic, open knowledge innovation that has successfully completed phase I and phase IIa clinical trials, with Phase II/III trials underway in the African continent, to be followed by further trials in Brazil. The discovery and experimental phases of the development of this vaccine gathered a robust collection of data that strongly supports the ongoing clinical phase. This paper reviews the development of the Sm14 vaccine, formulated with glucopyranosyl lipid A (GLA-SE), from the initial experimental developments to clinical trials including the current status of phase II studies.

Schistosomiasis vaccine candidate Sm14/GLA-SE: Phase 1 safety and immunogenicity clinical trial in healthy, male adults.

DESIGN: Safety and immunogenicity of a recombinant 14kDa, fatty acid-binding protein(FABP) from Schistosoma mansoni (rSm14) were evaluated through an open, non-placebo-controlled, dose-standardized trial, performed at a single research site. The vaccine was formulated with glucopyranosyl lipid A (GLA) adjuvant in an oil-in-water emulsion (SE) and investigated in 20 male volunteers from a non-endemic area for schistosomiasis in the state of Rio de Janeiro, Brazil. Fifty microgram rSm14 with 10 µg GLA-SE (rSm14/GLA-SE)/dose were given intramuscularly three times with 30-day intervals. Participants were assessed clinically, biochemically and immunologically for up to 120 days. METHODS: Participants were screened for inclusion by physical examination, haematology and blood chemistry; then followed to assess adverse events and immunogenicity. Sera were tested for IgG (total and isotypes) and IgE. T cell induction of cytokines IL-2, IL-5, IL-10, IFNγ and TNFα was assessed by Milliplex kit and flow cytometry. RESULTS: The investigational product showed high tolerability; some self-limited, mild adverse events were observed during and after vaccine administration. Significant increases in Sm14-specific total IgG, IgG1 and IgG3 were observed 30 days after the first vaccination with specific IgG2 and IgG4 after 60 days. An increase in IgE antibodies was not observed at any time point. The IgG response was augmented after the second dose and 88% of all vaccinated subjects had developed high anti-Sm14 IgG titres 90 days after the first injection. From day 60 and onwards, there was an increase in CD4(+) T cells producing single cytokines, particularly TNFα and IL-2, with no significant increase of multi-functional TH1 cells. CONCLUSION: Clinical trial data on tolerability and specific immune responses after vaccination of adult, male volunteers in a non-endemic area for schistosomiasis with rSm14/GLA-SE, support this product as a safe, strongly immunogenic vaccine against schistosomiasis paving the way for follow-up Phase 2 trials. Study registration ID: NCT01154049 at http://www.clinicaltrials.gov.

Development of the Brazilian Anti Schistosomiasis Vaccine Based on the Recombinant Fatty Acid Binding Protein Sm14 Plus GLA-SE Adjuvant.

Data herein reported and discussed refer to vaccination with the recombinant fatty acid binding protein (FABP) family member of the schistosomes, called Sm14. This antigen was discovered and developed under a Brazilian platform led by the Oswaldo Cruz Foundation, from the Health Ministry in Brazil, and was assessed for safety and immunogenicity in healthy volunteers. This paper reviews past and recent outcomes of developmental phases of the Sm14-based anti schistosomiasis vaccine addressed to, ultimately, impact transmission of the second most prevalent parasitic endemic disease worldwide.

Evaluation of local immune response to Fasciola hepatica experimental infection in the liver and hepatic lymph nodes of goats immunized with Sm14 vaccine antigen.

Protection against Fasciola hepatica in goats immunized with a synthetic recombinant antigen from Schistosoma mansoni fatty acid-binding protein 14 (rSm14) was investigated by assessing worm burdens, serum levels of hepatic enzymes, faecal egg count and hepatic damage, which was evaluated using gross and microscopic morphometric observation. The nature of the local immune response was assessed by examining the distribution of CD2+, CD4+, CD8+ and γ´+ T lymphocytes along with IgG+, IL-4+ and IFN-γ+ cells in the liver and hepatic lymph nodes (HLN). The goats used consisted of group 1 (unimmunized and uninfected), group 2 [infected control - immunized with Quillaia A (Quil A)] and group 3 (immunized with rSm14 in Quil A and infected), each containing seven animals. Immunization with rSm14 in Quil A adjuvant induced a reduction in gross hepatic lesions of 56.6% (p < 0.001) and reduced hepatic and HLN infiltration of CD2+, CD4+, CD8+ and γ´+ T lymphocytes as well as IL-4+ and IFN-γ+ cells (p < 0.05). This is the first report of caprine immunization against F. hepatica using a complete rSm14 molecule derived from S. mansoni. Immunization reduced hepatic damage and local inflammatory infiltration into the liver and HLN. However, considering that Quil A is not the preferential/first choice adjuvant for Sm14 immunization, further studies will be undertaken using the monophosphoryl lipid A-based family of adjuvants during clinical trials to facilitate anti-Fasciolavaccine development.

Evaluation of local immune response to Fasciola hepatica experimental infection in the liver and hepatic lymph nodes of goats immunized with Sm14 vaccine antigen

Protection against Fasciola hepatica in goats immunized with a synthetic recombinant antigen from Schistosoma mansoni fatty acid-binding protein 14 (rSm14) was investigated by assessing worm burdens, serum levels of hepatic enzymes, faecal egg count and hepatic damage, which was evaluated using gross and microscopic morphometric observation. The nature of the local immune response was assessed by examining the distribution of CD2+, CD4+, CD8+ and γ´+ T lymphocytes along with IgG+, IL-4+ and IFN-γ+ cells in the liver and hepatic lymph nodes (HLN). The goats used consisted of group 1 (unimmunized and uninfected), group 2 [infected control - immunized with Quillaia A (Quil A)] and group 3 (immunized with rSm14 in Quil A and infected), each containing seven animals. Immunization with rSm14 in Quil A adjuvant induced a reduction in gross hepatic lesions of 56.6 percent (p < 0.001) and reduced hepatic and HLN infiltration of CD2+, CD4+, CD8+ and γ´+ T lymphocytes as well as IL-4+ and IFN-γ+ cells (p < 0.05). This is the first report of caprine immunization against F. hepatica using a complete rSm14 molecule derived from S. mansoni. Immunization reduced hepatic damage and local inflammatory infiltration into the liver and HLN. However, considering that Quil A is not the preferential/first choice adjuvant for Sm14 immunization, further studies will be undertaken using the monophosphoryl lipid A-based family of adjuvants during clinical trials to facilitate anti-Fasciolavaccine development.

Stability improvement of the fatty acid binding protein Sm14 from S. mansoni by Cys replacement: structural and functional characterization of a vaccine candidate.

The Schistosoma mansoni fatty acid binding protein (FABP), Sm14, is a vaccine candidate against, S. mansoni and F. hepatica. Previously, we demonstrated the importance of a correct fold to achieve protection in immunized animals after cercariae challenge [[10]. C.R.R. Ramos, R.C.R. Figueredo, T.A. Pertinhez, M.M. Vilar, A.L.T.O. Nascimento, M. Tendler, I. Raw, A. Spisni, P.L. Ho, Gene structure and M20T polymorphism of the Schistosoma mansoni Sm14 fatty acid-binding protein: structural, functional and immunoprotection analysis. J. Biol. Chem. 278 (2003) 12745-12751.]. Here we show that the reduction of vaccine efficacy over time is due to protein dimerization and subsequent aggregation. We produced the mutants Sm14-M20(C62S) and Sm14-M20(C62V) that, as expected, did not dimerize in SDS-PAGE. Molecular dynamics calculations and unfolding experiments highlighted a higher structural stability of these mutants with respect to the wild-type. In addition, we found that the mutated proteins, after thermal denaturation, refolded to their active native molecular architecture as proved by the recovery of the fatty acid binding ability. Sm14-M20(C62V) turned out to be the more stable form over time, providing the basis to determine the first 3D solution structure of a Sm14 protein in its apo-form. Overall, Sm14-M20(C62V) possesses an improved structural stability over time, an essential feature to preserve its immunization capability and, in experimentally immunized animals, it exhibits a protection effect against S. mansoni cercariae infections comparable to the one obtained with the wild-type protein. These facts indicate this protein as a good lead molecule for large-scale production and for developing an effective Sm14 based anti-helminthes vaccine.

The biotechnology-value chain: development of Sm14 as a schistosomiasis vaccine.

In the 1990s, WHO/TDR created a product development program and initiated collaborations with other major international donors to promote rapid vaccine development and other tools for the control of endemic diseases. This "push strategy" was chosen to achieve effective research projects fostering innovation in the context of rapid product development. In the field of vaccine development, the aim was to bring forth ways and means to immunize against the most important human parasite diseases. Although the malaria vaccine projects scored initial successes it has been difficult to move forward decidedly. With regard to schistosomiasis, more than 10 important antigens with strong potential as vaccines candidates emerged from the several 100 scientific projects supported by international donor agencies and national research programs over the last few decades. Among those still seriously pursued, the Fatty Acid-Binding Protein (FABP)-14 kDa Schistosoma mansoni (Sm14) antigen stands out, both due to its steady progress towards field trials and because it represents the sole vaccine candidate to emerge from an endemic country. Work has now progressed to the scale-up level and an industrial production process has successfully been put in place. The very special feature of Sm14 is its strong immunological reactivity with an antigen shared between two different important parasites, which give this vaccine candidate the potential to be used against more than one infection. It has been demonstrated that it has effect not only against S. mansoni in humans but also against Fasciola hepatica, a parasite that causes disease in cattle and sheep leading to annual losses over 3 $US billion to the food industry worldwide. The Sm14 patents, granted to Oswaldo Cruz Foundation (FIOCRUZ), a Brazilian scientific institution directly linked to the Brazilian Ministry of Health, have been licensed to a private company which has the intention to lead the Sm14 project to success, both in the veterinary and in the human field. The objective is to provide economic performance by fostering scientific and economic progress and thus reach the global market. Sm14 is at present at the stage of planning clinical trials under a private-public partnership (PPP) initiative in collaboration with FIOCRUZ which has recently received significant financial support from FINEP, a public Brazilian Financial Agency.

Mycobacterial codon optimization of the gene encoding the Sm14 antigen of Schistosoma mansoni in recombinant Mycobacterium bovis Bacille Calmette-Guérin enhances protein expression but not protection against cercarial challenge in mice.

A mycobacterial codon-optimized gene encoding the Sm14 antigen of Schistosoma mansoni was generated using oligonucleotide assembly. This synthetic gene enhanced approximately fourfold the protein expression level in recombinant Mycobacterium bovis Bacille Calmette-Guérin (rBCG) when compared to that obtained using the native gene in the same expression vector. Immunization of mice with rBCG expressing Sm14 via the synthetic gene induced specific cellular Th1-predominant immune responses, as determined by interferon-gamma production of Sm14-stimulated splenocytes, which were comparable to those recorded in animals immunized with an rBCG strain expressing the native gene. Administration of a single dose of the rBCG-Sm14 construct carrying the synthetic gene conferred protection against cercarial challenge in outbred Swiss mice, at a level equivalent to those provided by either a single dose of rBCG expressing the native gene or three doses of Escherichia coli-derived recombinant Sm14. Our data demonstrated that despite improving the level of antigen expression, the codon optimization strategy did not result in enhanced immunity or protection against cercarial S. mansoni challenge.

Sm14 of Schistosoma mansoni in fusion with tetanus toxin fragment C induces immunoprotection against tetanus and schistosomiasis in mice.

We have constructed vectors that permit the expression in Escherichia coli of Schistosoma mansoni fatty acid-binding protein 14 (Sm14) in fusion with the nontoxic, but highly immunogenic, tetanus toxin fragment C (TTFC). The recombinant six-His-tagged proteins were purified by nickel affinity chromatography and used in immunization and challenge assays. Animals inoculated with TTFC in fusion with or coadministered with Sm14 showed high levels of tetanus toxin antibodies, while animals inoculated with Sm14 in fusion with or coadministered with TTFC showed high levels of Sm14 antibodies. In both cases, there were no changes in the type of immune response (Th2) obtained with the fusion proteins compared to those obtained with the nonfused proteins. Mice immunized with the recombinant proteins (TTFC in fusion with or coadministered with Sm14) survived the challenge with tetanus toxin and did not show any symptoms of the disease. Control animals inoculated with either phosphate-buffered saline (PBS) or Sm14 died with severe symptoms of tetanus after 24 h. Mice immunized with the recombinant proteins (Sm14 in fusion with or coadministered with TTFC) showed a 50% reduction in worm burden when they were challenged with S. mansoni cercariae, while control animals inoculated with either PBS or TTFC were not protected. The results show that the expression of other antigens in fusion at the carboxy terminus of TTFC is feasible for the development of a multivalent recombinant vaccine.

rDNA-RFLP identification of Candida species in immunocompromised and seriously diseased patients.

PCR was used to amplify a targeted region of the ribosomal DNA of 76 Candida spp. isolates from immunocompromised and seriously diseased patients. Thirty-seven strains isolated from different anatomical sites of 11 patients infected with HIV (Vitória, ES, Brazil), 26 isolates from patients under treatment at Odilon Behrens Hospital and 13 isolates from skin and urine samples from São Marcos Clinical Analysis Laboratory (Belo Horizonte, Brazil) were scored. Fragments of rDNA were amplified using primer pairs ITS1-ITS4, for the amplification of ITS1 and ITS2 regions, including the gene for the 5.8 s subunit. Amplification resulted in fragments ranging in size from 350 to 950 bp. Amplicons were digested with eight restriction enzymes. A pattern of species-specificity among the different medically important Candida species could be identified following restriction digestion of the PCR products. Candida albicans was the species most frequently observed, except for the group of newborns under treatment at the Odilon Behrens Hospital and for the isolates from the clinical analysis laboratory. C. parapsilosis was the species most frequently observed in these two groups.

Genetic variability analysis among clinical Candida spp. isolates using random amplified polymorphic DNA.

The patterns of genetic variation of samples of Candida spp. isolated from patients infected with human immunodeficiency virus in Vitória, state of Espírito Santo, Brazil, were examined. Thirty-seven strains were isolated from different anatomical sites obtained from different infection episodes of 11 patients infected with the human immunodeficiency virus (HIV). These samples were subjected to randomly amplified polymorphic DNA (RAPD) analysis using 9 different primers. Reproducible and complex DNA banding patterns were obtained. The experiments indicated evidence of dynamic process of yeast colonization in HIV-infected patients, and also that certain primers are efficient in the identification of species of the Candida genus. Thus, we conclude that RAPD analysis may be useful in providing genotypic characters for Candida species typing in epidemiological investigations, and also for the rapid identification of pathogenic fungi.

Recombinant Mycobacterium bovis BCG expressing the Sm14 antigen of Schistosoma mansoni protects mice from cercarial challenge.

The Sm14 antigen of Schistosoma mansoni was cloned and expressed in Mycobacterium bovis BCG as a fusion with the Mycobacterium fortuitum beta-lactamase protein under the control of its promoter, pBlaF*; the protein was localized in the bacterial cell wall. The rBCG-Sm14 strain was shown to be relatively stable in cultured murine and bovine monocytes in terms of infectivity, bacterial persistence, and plasmid stability. The immunization of mice with rBCG-Sm14 showed no induction of anti-Sm14 antibodies; however, splenocytes of immunized mice released increased levels of gamma interferon upon stimulation with recombinant Sm14 (rSm14), indicating an induction of a Th1-predominant cellular response against Sm14. Mice immunized with one or two doses of rBCG-Sm14 and challenged with live S. mansoni cercaria showed a 48% reduction in worm burden, which was comparable to that obtained by immunization with three doses of rSm14 purified from Escherichia coli. The data presented here further enhance the status of Sm14 as a promising candidate antigen for the control of schistosomiasis and indicate that a one-dose regimen of rBCG-Sm14 could be considered a convenient means to overcome many of the practical problems associated with the successful implementation of a multiple-dose vaccine schedule in developing countries.

Genetic variability analysis among clinical Candida spp. isolates using random amplified polymorphic DNA

The patterns of genetic variation of samples of Candida spp. isolated from patients infected with human immunodeficiency virus in Vitória, state of Espírito Santo, Brazil, were examined. Thirty-seven strains were isolated from different anatomical sites obtained from different infection episodes of 11 patients infected with the human immunodeficiency virus (HIV). These samples were subjected to randomly amplified polymorphic DNA (RAPD) analysis using 9 different primers. Reproducible and complex DNA banding patterns were obtained. The experiments indicated evidence of dynamic process of yeast colonization in HIV-infected patients, and also that certain primers are efficient in the identification of species of the Candida genus. Thus, we conclude that RAPD analysis may be useful in providing genotypic characters for Candida species typing in epidemiological investigations, and also for the rapid identification of pathogenic fungi.

An experimental bivalent peptide vaccine against schistosomiasis and fascioliasis.

With a view to producing peptides capable of inducing a protective immune response against Schistosoma mansoni and Fasciola hepatica, the sequence and structure of the protective antigens Sm14 and Fh15 were analyzed. Their C-termini showed a high level of sequence conservation which, together with models for their three-dimensional structures, aided in peptide selection. Vaccination trials in Swiss mice challenged with S. mansoni cercaria or F. hepatica metacercaria showed that peptides which included the sequences VTVGDVTA or EKNSESKLTQ were capable of inducing levels of protection equivalent to the recombinant form of Sm14. These peptides may represent an alternative to r-Sm14 for the development of a bivalent anti-helminth vaccine.

Vaccination against Fasciola hepatica infection using a Schistosoma mansoni defined recombinant antigen, Sm14.

Fasciola hepatica is the causative agent of fasciolosis in many areas in America, Europe, Africa, Asia and Australia. There is an urgent need for improved methods to control the parasite's transmission. We describe the use of an experimental vaccine based on a recombinant antigen cloned from another parasite, Schistosoma mansoni (Sm14), that induces high levels of cross protection in mice against both S. mansoni and F. hepatica. Sheep and mice vaccinated with Sm14 were significantly protected against challenge infection with metacercariae of Fasciola hepatica and were completely free of the histopathological hepatic damage related to liver fluke infection. The vaccine will provide a valuable new tool to aid in transmission control of this economically important disease.

Gene structure and M20T polymorphism of the Schistosoma mansoni Sm14 fatty acid-binding protein. Molecular, functioanl, and immunoprotection analysis.

The Schistosoma mansoni Sm14 antigen belongs to the fatty acid-binding protein family and is considered a vaccine candidate against at least two parasite worms, Fasciola hepatica and S. mansoni. Here the genomic sequence and the polymorphism of Sm14 have been characterized for the first time. We found that the conserved methionine at position 20 is polymorphic, being exchangeable with threonine (M20T). To evaluate the function of the amino acid residue at this position, we have also constructed the mutant Sm14-A20 besides the two native isoforms (Sm14-M20 and Sm14-T20). The three purified recombinant His(6)-tagged Sm14 proteins (rSm14-M20, rSm14-T20, and rSm14-A20) present a predominant beta-barrel structure as shown by CD spectroscopy. Thermal and urea unfolding studies evidenced a higher structural stability of rSm14-M20 over the other forms (rSm14-M20>rSm14-T20>rSm14-A20). All of the Sm14 proteins were able to bind 11-(dansylamino)undecanoic acid (DAUDA) without substantial difference in the binding affinity. However, rSm14-M20 exhibited a higher affinity for natural fatty acids than the rSm14-T20 and rSm14-A20 proteins as judged by competitive experiments against DAUDA (rSm14-M20>rSm14-T20>rSm14-A20). The rSm14-M20 or rSm14-T20 isoforms but not the rSm14-A20 mutant was able to induce significant protection against S. mansoni cercariae challenge in immunized mice. The level of protection efficacy correlates with the extent of structure stability of the recombinant Sm14 isoforms and mutant.