Phasmaviridae

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Phasmaviridae
Kingdom:	Orthornavirae
Phylum:	Negarnaviricota
Class:	Ellioviricetes
Order:	Bunyavirales
Family:	Phasmaviridae

Phasmaviridae is a family of negative-sense single-stranded RNA viruses within the order Bunyavirales. This family includes viruses that primarily infect arthropods, such as mosquitoes and ticks. The name "Phasmaviridae" is derived from the Greek word "phasma," meaning "ghost," reflecting the often elusive nature of these viruses in terms of detection and study.

Structure

Phasmaviridae viruses are characterized by their spherical to pleomorphic shape, with an average diameter of 80-120 nm. The viral envelope is derived from the host cell membrane and contains glycoproteins that facilitate attachment and entry into host cells. The genome of Phasmaviridae is segmented, typically consisting of three segments: L (large), M (medium), and S (small), which encode the RNA-dependent RNA polymerase, glycoproteins, and nucleocapsid proteins, respectively.

Genome

The genome of Phasmaviridae is composed of negative-sense, single-stranded RNA. The L segment encodes the RNA-dependent RNA polymerase, which is essential for viral replication. The M segment encodes the glycoproteins, which are involved in host cell entry and immune evasion. The S segment encodes the nucleocapsid protein, which encapsidates the viral RNA and is crucial for the formation of the ribonucleoprotein complex.

Replication Cycle

The replication cycle of Phasmaviridae begins with the attachment of the virus to the host cell surface via interactions between viral glycoproteins and host cell receptors. Following entry into the host cell, the viral RNA is released into the cytoplasm, where the RNA-dependent RNA polymerase transcribes the negative-sense RNA into positive-sense mRNA. This mRNA is then translated into viral proteins by the host cell's ribosomes. The newly synthesized viral proteins and RNA are assembled into progeny virions, which bud from the host cell, acquiring their envelope in the process.

Pathogenesis

While many Phasmaviridae viruses are primarily associated with arthropods, some have been implicated in causing disease in vertebrates, including humans. The pathogenic potential of these viruses is often linked to their ability to evade the host immune response and establish persistent infections. Symptoms of infection can range from mild febrile illness to more severe conditions, depending on the specific virus and host factors.

Epidemiology

Phasmaviridae viruses are distributed worldwide, with a higher prevalence in tropical and subtropical regions where their arthropod hosts are abundant. The transmission of these viruses is primarily vector-borne, with mosquitoes and ticks serving as the main vectors. Understanding the ecology and epidemiology of Phasmaviridae is crucial for developing strategies to prevent and control outbreaks.

Research and Public Health

Research on Phasmaviridae is ongoing, with a focus on understanding the molecular mechanisms of viral replication, pathogenesis, and host interactions. Public health efforts aim to monitor and control the spread of these viruses, particularly in regions where they pose a significant threat to human and animal health.

Also see

• Bunyavirales
• Negative-sense single-stranded RNA virus
• Arthropod-borne virus
• Viral replication