Pathogenesis, Immune Response and Vaccine Development in Amoebiasis

Abstract

Worldwide, approximately fifty million cases of invasive E histolytica disease occur each year and resulting in more than 100,000 deaths. It is the second leading cause of mortality due to a protozoan parasitic infection after malaria. Entamoeba histolytica infection is associated with considerable morbidity and mortality in the form of intestinal and extra-intestinal amoebiasis especially in developing countries. Recent molecular studies have conclusively proved that there are morphologically similar species of Entamoeba. Of these, Entamoeba histolytica is pathogenic and invasive, where as E. dispar and E. moshkovskii are non-pathogenic and non-invasive. There is a degree of controversy about pathogenic potential of E. dispar and E. moshkovskii. The extraordinary phagocytic activity of Entamoeba histolytica trophozoites has been accepted as one of the virulence mechanisms responsible for their invasive capacity. The genetic, environmental and nutritional factors may influence the host susceptibility to amoebiasis. The parasite has a number of virulence factors and evasive mechanisms to counter immunity of host. Trophozoites secrete proteases enzymes to degrade extracellular matrix to invade the intestinal layers. A safe and effective vaccine for amoebiasis could drastically reduce morbidity and mortality. Studies indicate vaccines directed against Gal-lectin as the most promising and effective. Immunity that generates a strong intestinal humoral antibody IgA response would prevent the parasite colonization and subsequent intestinal invasion. Immunity to reinfection caused by heterologous species would be a challenge in vaccine production. Although some of the vaccines are tested in animal models, there is a need for clinical trials to prove its efficiency in humans. At present, in the absence of safe and effective vaccine, other control and prevention measures take prime spot.

Keywords: Entamoeba histolytica, amoebiasis, amoebic liver abscess, immunity, dysentery, immune response, vaccine, pathogenesis, Entamoeba dispar, Gal-lectin

Cite this Article

Durgadas Govind Naik. Pathogenesis, immune response and vaccine development in amoebiasis. Research and Reviews: Journal of Immunology. 2015; 5(3): 30–35p.