The establishment of giardiasis, a disease caused by the protozoan parasite Giardia lamblia, starts with the adhesion of trophozoites to the surface of host intestinal epithelial cells. Trophozoites then replicate and colonize the gastrointestinal tract, eliciting multiple biological responses in their hosts. The interactions between the host organism and parasite can be evaluated by a variety of in vivo and in vitro means. Proper detection and treatment of giardiasis require a thorough understanding of the molecular mechanisms of the disease course from the onset of infection through establishment of chronic disease. This article reviews a collection of recent studies to provide an overview of the advances that have been made over the past 5 years (2015–2020) in establishing a stronger understanding of the molecular basis of Giardia-host interactions, with a particular emphasis on the use of in vitro techniques. The outcome of pathogen-host association produced several effector mechanisms critical to parasite survival/replication and to control of infection by the host. These included differential gene expression, regulation of the intestinal barrier function (expression/location of tight junction proteins, mucus turnover, cell apoptosis), and alterations of GIT microbial community. Understanding of giardiasis has progressed rapidly through the use of in vitro means of experimentation during the period from 2015 to 2020. The discovery of new molecular networks in Giardia-host interactions from both perspectives contributed to a more comprehensive understanding of giardiasis.
