Promising Technologies in the Field of Helminth Vaccines

Helminths contribute a larger global burden of disease than both malaria and tuberculosis. These eukaryotes have caused human infections since before our earliest recorded history (i.e.: earlier than 1200 B.C. for Schistosoma spp.). Despite the prevalence and importance of these infections, helminths are considered a neglected tropical disease for which there are no vaccines approved for human use. Similar to other parasites, helminths are complex organisms which employ a plethora of features such as: complex life cycles, chronic infections, and antigenic mimicry to name a few, making them difficult to target by conventional vaccine strategies. With novel vaccine strategies such as viral vectors and genetic elements, numerous constructs are being defined for a wide range of helminth parasites; however, it has yet to be discussed which of these approaches may be the most effective. With human trials being conducted, and a pipeline of potential anti-helminthic antigens, greater understanding of helminth vaccine-induced immunity is necessary for the development of potent vaccine platforms and their optimal design. This review outlines the conventional and the most promising approaches in clinical and preclinical helminth vaccinology.

Significance of pathogenicity factors in initiation of immune response in Helicobacter pylori infection

Helicobacter pylori is a unique microorganism capable of long-term colonization of the gastric mucosa, induction of the inflammatory process, antigenic mimicry and immune evasia. Flagella proteins, adhesins, invasive and aggressive enzymes, cytotoxin-associated protein, vacuolating cytotoxin can have a damaging effect on stomach epithelial cells. Recognition of molecular patterns of Helicobacter pylori by stomach cell receptors initiates activation of adapter proteins, protein kinases and transcription factors, leading to the production of proinflammatory cytokines, infiltration by neutrophilic granulocytes, absorption and killing of microorganisms by phagocytes with presentation of antigens to lymphocytes, while the activity and completeness of phagocytosis remain at a low level. Activation of CD8+-, CD16+- lymphocytes is accompanied by cytotoxic effect on both Helicobacter pylori and epithelial cells of the gastric mucosa. Weak immunogenicity of Helicobacter pylori antigens limits the production of anti-Helicobacter antibodies. Thus, activation of immune factors, in most cases, does not lead to complete elimination of the pathogen, but can aggravate the pathomorphological changes of the gastric epithelium.