Double-stranded RNA viruses

Overview

Rotavirus, a double-stranded RNA virus

Double-stranded RNA viruses are a diverse group of viruses that have a genome composed of double-stranded RNA. These viruses are known to infect a wide range of hosts, including humans, animals, plants, and fungi. The double-stranded RNA genome is a unique feature that distinguishes these viruses from other types of RNA viruses, which typically have single-stranded RNA genomes.

Structure

The structure of double-stranded RNA viruses is characterized by a segmented genome, which is enclosed within a protein shell known as a capsid. The capsid provides protection to the viral RNA and plays a crucial role in the virus's ability to infect host cells. Some double-stranded RNA viruses, such as rotavirus, have a triple-layered capsid that enhances their stability and infectivity.

Replication

Replication of double-stranded RNA viruses occurs in the cytoplasm of the host cell. The viral RNA-dependent RNA polymerase is responsible for synthesizing new RNA strands using the double-stranded RNA as a template. This process involves the transcription of the double-stranded RNA into messenger RNA (mRNA), which is then translated into viral proteins by the host's ribosomes.

Pathogenesis

Double-stranded RNA viruses are associated with a variety of diseases in their hosts. For example, rotavirus is a leading cause of severe gastroenteritis in young children worldwide. The infection is characterized by symptoms such as diarrhea, vomiting, and fever. The virus primarily targets the cells of the small intestine, leading to inflammation and impaired absorption of nutrients.

Immune Response

The host immune system recognizes double-stranded RNA as a pathogen-associated molecular pattern (PAMP), triggering an innate immune response. This response includes the production of interferons and the activation of natural killer cells and other immune cells. The adaptive immune response is also activated, leading to the production of specific antibodies that target the virus.

Classification

Double-stranded RNA viruses are classified into several families, including:

• Reoviridae: This family includes rotavirus, which is a major cause of viral gastroenteritis.
• Birnaviridae: Known for infecting fish and birds.
• Totiviridae: Infects fungi and protozoa.

Related pages

• RNA virus
• Viral replication
• Viral pathogenesis
• Immune response to viruses