Biology subjects

Nibert, M. L.

Publications and source records attributed to Nibert, M. L..

4 recordsLinked to original sources

bioRxiv2024

Differential Drug Susceptibility Across Trichomonasvirus Species Allows for Generation of Varied Isogenic Clones of Trichomonas vaginalis

Trichomonas vaginalis (Tvag) is a sexually transmitted human pathogen that is commonly infected with strains of one or more of five known species of Trichomonas vaginalis viruses (TVVs), members of genus Trichomonasvirus. TVVs are thought not to have an extracellular phase to their lifecycle and instead to be transmitted vertically from mother to daughter cells. As a result, generation of isogenic virus-positive and virus-negative sets of Tvag clones has been a major barrier to study interactions between TVVs and their host. Nucleoside analog 2-C-methylcytidine (2CMC) has been recently reported to clear trichomonads of infections with TVV1, TVV2, and TVV3. We used 2CMC to treat a panel of Tvag isolates that collectively harbor at least one representative strain of each TVV species and thereby provided evidence that infections with TVV4 and TVV5 can also be cleared by 2CMC. Furthermore, our results suggest a newly identified difference in drug susceptibility between TVV species. We took advantage of these susceptibility difference to generate isogenic sets of Tvag clones harboring different combinations of the five TVV species. These results provide both new insight into differences between these species and new avenues for generating tools to study the potential roles of TVVs in Tvag biology.

microbiology↗

bioRxiv2023

Transcriptome mining of RNA viruses (family Totiviridae) in Eimeria necatrix and Eimeria stiedai

Coccidian protozoa from the genus Eimeria are widespread parasites of vertebrates, causing serious disease (coccidiosis) and economic loss most notably in poultry. Several species of Eimeria are themselves infected with small RNA viruses assigned to the family Totiviridae. In this study, the sequences of two such viruses were newly determined, one of which represents the first complete protein-coding sequence of a virus from E. necatrix, an important pathogen of chickens, and the other of which is from E. stiedai, an important pathogen of rabbits. Sequence features of the newly identified viruses, compared with those of ones reported previously, provide several insights. Phylogenetic analyses suggest that these eimerian viruses constitute a well-demarcated clade, probably deserving of recognition as a distinct genus.

microbiology↗

bioRxiv2021

Discovery of a new species of trichomonasvirus in the human parasite Trichomonas vaginalis using transcriptome mining

Trichomonas vaginalis is the most common nonviral cause of sexually transmitted infections globally, with an estimated quarter of a billion people infected around the world. Infection by the protozoan parasite results in the clinical syndrome trichomoniasis, which manifests as an inflammatory syndrome with acute and chronic consequences. Half or more of these parasites are themselves infected with one or more dsRNA viruses which can exacerbate the inflammatory disease. Four distinct viruses have been found in T. vaginalis to date, Trichomonas vaginalis virus 1 through 4 (or TVVs). Despite the global prevalence of these viruses, few coding-complete genome sequences have been determined. We conducted viral sequence mining in publicly available transcriptomes across 60 RNA-seq datasets representing 13 distinct T. vaginalis isolates. We assembled sequences for 27 new trichomonasvirus strains across all known TVV species, with 17 of these assemblies representing coding-complete genomes. Using a strategy of de novo sequence assembly followed by taxonomic classification, we discovered a fifth species of TVV that we term Trichomonas vaginalis virus 5 (TVV5). Six strains of TVV5 were assembled, including two coding-complete genomes. These TVV5 sequences exhibit high sequence identity to each other, but low identity to any strains of TVV1-4. Phylogenetic analysis corroborates the species-level designation. These results substantially increase the number of coding-complete TVV genome sequences and demonstrate the utility of mining publicly available transcriptomes for the discovery of RNA viruses in a critical human pathogen.

microbiology↗

bioRxiv2019

A Novel Taxon of RNA Viruses Endemic to Planarian Flatworms

The phylum Platyhelminthes is composed of both parasitic and non-parasitic flatworms. While the parasitic species have drawn attention for their wide effects on human and livestock heath, free-living flatworms, such as freshwater planarians, have become molecular models of regeneration and stem cell biology in the laboratory. However, one aspect of planarian biology that remains understudied is the relationship between host and any endemic viruses. Here we used searches of multiple transcriptomes from Schmidtea mediterranea asexual strain CIW4 and detected a novel, double-stranded RNA (dsRNA) virus, named S. mediterranea tricladivirus (SmedTV), which represents a distinct taxon (proposed new genus) within a larger taxon of monosegmented dsRNA viruses of diverse hosts. Experimental evidence for SmedTV in S. mediterranea CIW4 was obtained through whole-mount in situ hybridization (WISH). SmedTV "expression" (detected by both sense and anti-sense probes) was discrete yet variable from worm to worm and cell type to cell type, suggesting a persistent infection. Single-cell RNA sequencing (scRNAseq) further supported that SmedTV expression was low in stem cells, but substantially higher in multiple, though not all, differentiated tissues, with notable neural enrichment. Interestingly, knockdown of SmedTV by RNA-interference resulted in a "cure" of SmedTV after 10 RNAi doses, and expression remained undetectable by WISH even after 90 days. Due to being able to evade host defenses and the endogenous RNAi pathway, we believe SmedTV represents a novel animal model to study host-virus evolution. Statement of significancePlanarians are freshwater flatworms and emerging models to study the molecular mechanisms of adult stem cell and regenerative biology. However, they also live in aquatic environments with high amounts of viruses, bacteria, fungi, and protist pathogens. How the planarian immune system copes with all of these is largely unknown and only 2 types of virus have been described. Here we find a novel dsRNA virus, endemic to multiple types of flatworms. We show that it is a persistent infection, and likely transmits from stem cell to differentiated cell in the planarian, while avoiding endogenous RNA-interference machinery and mechanisms used to suppress viruses. We present this as a new model to study host-virus defense and evolution.

microbiology↗