Alphatetraviridae

1. Alphatetraviridae

The Alphatetraviridae is a family of viruses that primarily infect insects, particularly Lepidoptera (moths and butterflies). This family is part of the order Permutotetravirales. Members of this family are characterized by their non-enveloped, icosahedral capsids and their single-stranded, positive-sense RNA genomes.

Structure

Alphatetraviridae viruses have a simple structure. They are non-enveloped, meaning they lack a lipid membrane surrounding their capsid. The capsid itself is icosahedral, typically about 40 nm in diameter. The genome of Alphatetraviridae is composed of a single molecule of positive-sense RNA, which is approximately 5.5 to 6.5 kilobases in length.

Genome

The genome of Alphatetraviridae viruses encodes several proteins, including a RNA-dependent RNA polymerase necessary for replication, and structural proteins that form the capsid. The genome organization is relatively simple, with overlapping open reading frames that are translated into polyproteins, which are subsequently cleaved into functional viral proteins.

Replication Cycle

The replication cycle of Alphatetraviridae begins with the virus attaching to the host cell surface and entering the cell. Once inside, the viral RNA is released into the cytoplasm, where it serves as a template for translation of viral proteins. The RNA-dependent RNA polymerase replicates the viral genome, producing new RNA molecules that are packaged into newly formed capsids. The mature virions are then released from the host cell, often causing cell lysis.

Host Range and Pathogenicity

Alphatetraviridae primarily infects insects, with a strong preference for species within the order Lepidoptera. These viruses are not known to infect vertebrates, including humans, and are generally not considered pathogenic to non-target organisms. However, they can cause significant disease in their insect hosts, which can be utilized in biological control strategies against pest species.

Applications

Due to their specificity for insect hosts, Alphatetraviridae viruses have been studied for their potential use in biological pest control. They offer an environmentally friendly alternative to chemical pesticides, targeting specific pest species without harming beneficial insects or other wildlife.

Also see

• Lepidoptera
• RNA virus
• Biological pest control
• Virus classification