In silico study to predict promiscuous peptides for immunodiagnosis of cystic echinococcosis.

Background: Cystic echinococcosis (CE), caused by Echinococcus granulosus, is a major zoonotic disease that causes significant human morbidity and mortality. This cosmopolitan disease is difficult to diagnose, treat, and control. So far, crude extracts of hydatid cyst fluid containing antigen B or antigen 5 have been used as the primary antigenic source for its immunodiagnosis. The main issue is that it reacts with sera from people infected with other helminths. There is currently no standard, specific, or sensitive test for disease diagnosis, and no human vaccine has been reported.

Aims and objectives: Considering the need for efficient immunization and/or immunodiagnosis, six E. granulosus antigens, antigen 5, antigen B, heat shock proteins such as Hsp-8 and Hsp-90, phosphoenolpyruvate carboxykinase, and tetraspanin-1, were chosen.

Materials and methods: Using various in silico tools, T cell and B cell epitopes (promiscuous peptides) were predicted by targeting antigen 5, antigen B, heat shock proteins such as Hsp-8 and Hsp-90, phosphoenolpyruvate carboxykinase, and tetraspanin-1.

Results: There are twelve promiscuous peptides with overlapping human leukocyte antigen (HLA) class-I, class-II, and conformational B cell epitopes. Such immunodominant peptides could be useful as subunit vaccines. Furthermore, six peptides specific for E. granulosus were also discovered, which may prove to be important markers in the diagnosis of CE, potentially preventing misdiagnosis and mismanagement.

Conclusion: These epitopes may be the most important vaccine targets in E. granulosus because they have the most promiscuous peptides and B cell epitopes, as well as the highest affinity for different alleles, as determined by docking scores. However, additional research using in vitro and in vivo models is undertaken.