Protozoal Viruses

Abstract

This chapter presents a review of literature of protozoal viruses, along with an overview of the viruses of Entamoeba histolytica . One of the earliest references to the presence of virus-like structures in protozoa appears to be reported in 1960, when a small array of virus-like particles (VLPs) in a single section of a trophozoite of a simian strain (NRS) of E. histolytica cultivated in association with a mixed bacterial flora was found. VLPs have been described in malaria parasites, amebo-flagellate Hraegleria gruberi, and Leishwzania hertigi . Although there are no reports of viral agents or VLPs in Paramecium aurelia , however, phage-like bodies in kappa— one of the endosymbionts of this protozoan—are intimately associated with the overall economy of the paramecium host. E. histolytica produces icosahedral viruses and lysis in one or more susceptible amebal hosts. Several physical, chemical, and biological properties of E. histolytica are also discussed in the chapter. An examination of sectioned and negatively stained particles indicates that the virus is icosahedral in morphology because it presents profiles compatible with it having 5-, 3-, and 2-fold axes of rotational symmetry.