Multipartite virus genomes are composed of several segments, each packaged in a distinct viral particle. Although this puzzling genome architecture is found in ∼17% of known viral species, its distribution among hosts or among distinct types of genome-composing nucleic acid remains poorly understood. No convincing advantage of multipartitism has been identified, yet the maintenance of genomic integrity appears problematic. Here we review recent studies shedding light on these issues. Multipartite viruses rapidly modify the copy number of each segment/gene from one host species to another, a putative benefit if host switches are common. One multipartite virus functions in a multicellular way: The segments do not all need to be present in the same cell and can functionally complement across cells, maintaining genome integrity within hosts. The genomic integrity maintenance during host-to-host transmission needs further elucidation. These features challenge several virology foundations and could apply to other multicomponent viral systems.
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http://dx.doi.org/10.1146/annurev-virology-010220-063346 | DOI Listing |
bioRxiv
December 2024
DOE Joint Genome Institute, Berkeley, California, USA.
Microbial eukaryotes (aka protists) are known for their important roles in nutrient cycling across different ecosystems. However, the composition and function of protist-associated microbiomes remains largely elusive. Here, we employ cultivation-independent single-cell isolation and genome-resolved metagenomics to provide detailed insights into underexplored microbiomes and viromes of over 100 currently uncultivable ciliates and amoebae isolated from diverse environments.
View Article and Find Full Text PDFJ Virol
December 2024
DISTAL-Plant Pathology, University of Bologna, Bologna, Italy.
Unlabelled: The beet necrotic yellow vein virus (BNYVV) is a multipartite virus with the highest number (up to five) of genomic segments among RNA viruses. Classified as a soil-borne virus, it is persistently transmitted by the protozoan . Previous studies have demonstrated that the relative frequency of the BNYVV genomic RNAs was modified depending on the host plant as well as the infected organ, resulting in distinct stoichiometric ratios between the viral RNAs.
View Article and Find Full Text PDFVirus Evol
November 2024
Department of Plant Protection, Instituto de Ciencias Agrarias, ICA-CSIC,Calle Serrano 115 DPDO, Madrid, 28006, Spain.
Viruses in the include monopartite and bipartite genomes, suggesting the possibility to study members of this family to experimentally address evolutionary transitions resulting in multipartitism. Torradoviruses are bipartite members of the family characterized by a genus-specific 5' open reading frame, named P21, encoded by RNA2. Here, in a study originally intended to verify if P21 can function , we attempted to provide P21 from a third P21-expressing construct under control of the 35S promoter and containing the 5'- and 3'-untranslated regions (UTRs) of wild-type (WT) RNA2.
View Article and Find Full Text PDFEcoSal Plus
December 2024
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
Bacteriophage λ is a paradigm in the field of gene regulation and one of the best-understood systems in genetic regulatory biology. A so-called Genetic Switch determines the mechanisms by which λ transitions to its dual lifestyles-lytic or lysogenic. When λ initiates the lysogenic lifestyle, the phage-encoded CI repressor binds cooperatively to multi-partite operators in a defined pattern that autoregulates repression of phage lytic promoters as well as activation of the lysogenic promoter.
View Article and Find Full Text PDFViruses
October 2024
Julius Kühn Institute (JKI)-Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11-12, 38104 Brunswick, Germany.
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