Schistosoma mansonicercarial elastase (SmCE): differences in immunogenic properties of native and recombinant forms

Abstract

The Schistosoma mansoni cercarial elastase (SmCE) has previously been shown to be poorly immunogenic in mice. However, a minority of mice were able to produce antibodies against SmCE after multiple immunizations with crude preparations containing the enzyme. These mice were partially protected against challenge infections of S. mansoni. In the present study, we show that in contrast to the poor immunogenicity of the enzymatically active native form of SmCE derived from a crude preparation (cercarial transformation fluid), immunization of CBA/Ca mice with two enzymatically inactive forms, namely purified native SmCE or a recombinant SmCE fused to recombinant Schistosoma japonicum glutathione S-transferase (rSmCE-SjGST), after adsorption onto aluminum hydroxide adjuvant, induced specific anti-SmCE immunoglobulin G (IgG) in all mice within 2 weeks of the second immunization. The IgG antibody response to rSmCESjGST was mainly of the IgG1 subclass. These results suggest that inactive forms of the antigen could be used to obtain the optimum immunogenic effects as a vaccine candidate against schistosomiasis. Mice immunized with the rSmCESjGST on alum had smaller mean worm burdens and lower tissue egg counts when compared with adjuvant aloneand recombinant SjGST-injected controls. The native SmCE was antigenically cross-reactive with homologous enzymes of Schistosoma haematobium and Schistosoma margrebowiei.

Molecular characterization of a Trichinella spiralis elastase-1 and its potential as a diagnostic antigen for trichinellosis

“…Elastases are the trypsin-like proteins belonging to the family of serine proteases, they can degrade host's various macromolecular substances such as keratin, laminin, type IV collagen, fibronectin and elastin [64]. The elastases are involved in larva invasion, molting and digestion, and may exert a major action for parasite invasion [65,66].…”

Protective immunity in mice vaccinated with a novel elastase-1 significantly decreases Trichinella spiralis fecundity and infection

“…Elastase is a trypsin-like serine protease that can hydrolyze the host's diverse tissue components (e.g., fibronectin, laminin, type IV collagen, elastin). The elastases participate in parasite penetration, molting and digestion and may play a major role in worm intrusion of hosts [62]. In our previous study, TsE was cloned, expressed and identified, and it was likely a novel target molecule for preventive vaccines against T. spiralis infection.…”

Immune responses in mice vaccinated with a DNA vaccine expressing a new elastase from Trichinella spiralis

“…Elastases belong to a trypsin-like serine protease which has the ability to hydrolyse various tissue components, such as fibronectin, laminin, collagen and elastin. The elastases are involved in the parasite invasion and digestion, and might a crucial role act in worm invasion (El-Faham et al 2017). In a previous study, the TsE was cloned and expressed in Escherichia coli, and the rTsE might be a novel target molecule for anti-T. spiralis vaccines (Hu et al 2020).…”