Mindivirales

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Mindivirales
Kingdom:	Riboviria
Phylum:
Class:
Order:	Mindivirales
Family:	'

Mindivirales is an order of positive-sense single-stranded RNA viruses that primarily infect fungi, plants, and protists. This order is part of the realm Riboviria, which encompasses all RNA viruses that replicate via an RNA-dependent RNA polymerase. The name "Mindivirales" is derived from the Latin "mindi," meaning "small," reflecting the typically small genome sizes of these viruses.

Characteristics

Mindivirales viruses are characterized by their simple genome organization and lack of a capsid in some families. They possess a single-stranded RNA genome that is positive-sense, meaning it can be directly translated into proteins by the host cell's ribosomes. The genome size of Mindivirales viruses ranges from approximately 2.3 to 4.5 kilobases.

Genome and Replication

The genome of Mindivirales viruses encodes a limited number of proteins, primarily those necessary for replication. The key enzyme encoded is the RNA-dependent RNA polymerase (RdRp), which is essential for the replication of the viral RNA genome. In some families, such as Narnaviridae, the genome consists of a single open reading frame (ORF) that encodes the RdRp.

Replication occurs in the cytoplasm of the host cell. The positive-sense RNA genome is directly translated into viral proteins, including the RdRp, which then synthesizes a complementary negative-sense RNA strand. This strand serves as a template for the production of new positive-sense RNA genomes.

Host Range and Transmission

Mindivirales viruses have a diverse host range, including fungi, plants, and protists. They are often transmitted vertically through host cell division or horizontally through cell-to-cell contact. In plants, transmission can also occur via insect vectors or through mechanical damage to plant tissues.

Taxonomy

The order Mindivirales is divided into three families:

• Marnaviridae: This family includes viruses that primarily infect marine protists. They have a relatively simple genome structure and are important in marine ecosystems.

• Mitoviridae: Members of this family are known to infect fungi. They are unique in that they lack a capsid and exist as naked RNA molecules within the host cell.

• Narnaviridae: This family includes viruses that infect fungi and plants. They have the simplest genome organization, often consisting of a single ORF encoding the RdRp.

Research and Importance

Mindivirales viruses are of interest to researchers due to their simple genome structure and unique replication mechanisms. They provide insights into the evolution of RNA viruses and the interactions between viruses and their hosts. Additionally, some Mindivirales viruses have potential applications in biotechnology and agriculture, such as the development of viral vectors for gene delivery or the use of viruses as biological control agents.

Also see

• Riboviria
• RNA virus
• Virus classification
• Viral replication