Cypovirus

Cypovirus is a genus of double-stranded RNA viruses in the family Reoviridae. These viruses primarily infect insects, particularly those in the order Lepidoptera (moths and butterflies), and are commonly known as cytoplasmic polyhedrosis viruses (CPVs).

Taxonomy and Structure:

Cypoviruses belong to the family Reoviridae, characterized by their non-enveloped, icosahedral capsid containing a segmented double-stranded RNA (dsRNA) genome. The genome of Cypoviruses typically consists of 10-12 segments of dsRNA, each encoding one or more viral proteins. The capsid is composed of multiple layers of proteins, providing structural integrity and protection for the viral genome.

Replication Cycle:

Cypoviruses replicate in the cytoplasm of infected insect cells. The virus enters the host cell through ingestion, typically by the insect consuming contaminated foliage. Once inside the cell, the viral genome is transcribed into messenger RNA (mRNA) by viral RNA-dependent RNA polymerase. The mRNA is then translated into viral proteins, which are involved in various aspects of the viral replication cycle. New viral particles are assembled in the cytoplasm and are occluded within polyhedral protein crystals, called polyhedra. These polyhedra are highly stable and protect the virus from environmental degradation.

Host Range and Pathology:

Cypoviruses are highly specific to their insect hosts, often infecting only a limited range of species or even specific tissues within the host. Infection typically occurs in the midgut epithelial cells, disrupting the digestive process and leading to symptoms such as stunted growth, reduced feeding, diarrhea, and ultimately death in some cases. The formation of polyhedra within the cytoplasm of infected cells is a hallmark of Cypovirus infection.

Ecological Significance and Applications:

Cypoviruses play a significant role in regulating insect populations in natural ecosystems. They can cause epizootics (disease outbreaks) in insect populations, leading to significant reductions in their numbers. Because of their host specificity and safety profile, some Cypoviruses have been explored as potential biopesticides for controlling insect pests in agriculture and forestry. However, their relatively slow speed of kill compared to chemical insecticides has limited their widespread adoption.

Disease Name:

The disease caused by Cypoviruses is typically referred to as cytoplasmic polyhedrosis.