sm14 antigen plus adjuvant GLA(Financiadora de Estudos e Projetos)

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.

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.