Antigenic variation is employed by a number of different protozoan parasites. Trypanosoma brucei (the model for study of protozoan antigenic variation) and Plasmodium falciparum are some of the most well studied examples of protozoan parasites that exhibit antigenic variation.ntigenic variation is the expression of various alternative forms of antigen on the cell surface. Whereas phase variation is the phenotypic switch that is usually reversible and is referred to as an ON-OFF switch.
NO: Amitriptyline is a tricyclic antidepressant for depression and some forms of anxiety, sometimes used for chronic pain or migraine. Xanax is a triazolobenzodiazepine or a benzodiazepine with an extra triazole ring structure. It is quite addicting and has a short half-life.
Amitriptyline is a popular antidepressant that's available only in generic form in the U.S. It used to be sold under the brand name Elavil. Amitriptyline is classified as a tricyclic antidepressant. For years, some doctors have considered it a front-line treatment for fibromyalgia and chronic fatigue syndrome (ME/CFS). However, this came about more from trial-and-error use than clinical studies.