Clinical Isolates of Trichomonas vaginalis Concurrently Infected by Strains of Up to Four Trichomonasvirus Species (Family Totiviridae)

Abstract

ABSTRACT Trichomonas vaginalis , which causes the most common nonviral sexually transmitted disease worldwide, is itself commonly infected by nonsegmented double-stranded RNA (dsRNA) viruses from the genus Trichomonasvirus , family Totiviridae . To date, cDNA sequences of one or more strains of each of three trichomonasvirus species have been reported, and gel electrophoresis showing several different dsRNA molecules obtained from a few T. vaginalis isolates has suggested that more than one virus strain might concurrently infect the same parasite cell. Here, we report the complete cDNA sequences of 3 trichomonasvirus strains, one from each of the 3 known species, infecting a single, agar-cloned clinical isolate of T. vaginalis , confirming the natural capacity for concurrent (in this case, triple) infections in this system. We furthermore report the complete cDNA sequences of 11 additional trichomonasvirus strains, from 4 other clinical isolates of T. vaginalis . These additional strains represent the three known trichomonasvirus species, as well as a newly identified fourth species. Moreover, 2 of these other T. vaginalis isolates are concurrently infected by strains of all 4 trichomonasvirus species (i.e., quadruple infections). In sum, the full-length cDNA sequences of these 14 new trichomonasviruses greatly expand the existing data set for members of this genus and substantiate our understanding of their genome organizations, protein-coding and replication signals, diversity, and phylogenetics. The complexity of this virus-host system is greater than has been previously well recognized and suggests a number of important questions relating to the pathogenesis and disease outcomes of T. vaginalis infections of the human genital mucosa.