isaviruses

Isaviruses are a genus of large, double-stranded DNA viruses belonging to the *Alphaherpesvirinae* subfamily within the *Herpesviridae* family. They primarily infect avian species, particularly birds such as chickens, turkeys, and other poultry, though some strains may also affect other avian hosts like ducks or pigeons. The genus name *Isoavirus* derives from the Greek word *isos*, meaning "equal," referencing the near-equal length of the two DNA strands in their genome.

The most well-known member of this genus is the *Gallid herpesvirus 2* (GaHV-2), commonly referred to as the **infectious laryngotracheitis virus (ILTV)**. ILTV is a significant pathogen in commercial poultry farming, causing respiratory infections characterized by inflammation of the larynx and trachea. Symptoms include coughing, gasping, nasal discharge, and hemorrhagic lesions in the respiratory tract. The virus spreads through direct contact with infected birds or contaminated environments, such as dust or equipment.

Isaviruses have a broad host range within birds but are generally species-specific. Transmission often occurs through aerosolized respiratory secretions or fomites. While most avian herpesviruses establish latent infections in sensory neurons, isaviruses tend to cause acute, often severe, clinical disease rather than chronic latency. Vaccination and biosecurity measures, such as quarantine and disinfection, are critical in managing outbreaks in commercial poultry operations.

The viral genome consists of approximately 150–160 kilobase pairs of linear, double-stranded DNA, encoding around 70–80 proteins. Like other herpesviruses, isaviruses possess a complex replication cycle, including phases of DNA synthesis, capsid assembly, and envelopment. Research into isaviruses focuses on understanding their pathogenesis, developing vaccines, and exploring their potential as model systems for studying herpesvirus biology.