Infectious pancreatic necrosis virus

Virus that causes disease in fish

Infectious pancreatic necrosis virus (IPNV) is a highly contagious virus that affects fish, particularly salmonids such as salmon and trout. It is a member of the genus Aquabirnavirus within the family Birnaviridae. The virus is known for causing infectious pancreatic necrosis (IPN), a disease that can lead to significant mortality in young fish.

Virology

Structure of Infectious Pancreatic Necrosis Virus

IPNV is a non-enveloped virus with a double-stranded RNA genome. The genome is segmented into two parts, designated as segment A and segment B. Segment A encodes for the viral polyprotein, which is processed into several structural and non-structural proteins, including the major capsid protein VP2. Segment B encodes for the RNA-dependent RNA polymerase, VP1.

The virus has an icosahedral capsid with a diameter of approximately 60 nm. The capsid is composed primarily of the VP2 protein, which is responsible for the antigenic properties of the virus. The VP3 protein is associated with the inner surface of the capsid and plays a role in genome packaging.

Pathogenesis

IPNV primarily affects young fish, causing high mortality rates in fry and fingerlings. The virus targets the pancreas, liver, and digestive tract, leading to necrosis of pancreatic tissue and other organs. Infected fish may exhibit symptoms such as abdominal distension, exophthalmia (bulging eyes), and darkening of the skin.

The disease is transmitted horizontally through water and can also be spread by asymptomatic carrier fish. Vertical transmission from parent to offspring is also possible, particularly through infected eggs.

Epidemiology

Infectious pancreatic necrosis is a global concern in aquaculture, affecting both freshwater and marine environments. The virus is highly stable in the environment, which contributes to its widespread distribution. Outbreaks are more common in hatcheries and fish farms where fish are kept at high densities.

Life cycle of Birnaviruses

Prevention and Control

Control of IPNV involves strict biosecurity measures, including disinfection of equipment and facilities, and the use of pathogen-free water sources. Vaccination is available and can provide protection against the virus. Selective breeding for resistant fish strains is also being explored as a long-term strategy to reduce the impact of the virus.

Related pages

• Infectious pancreatic necrosis
• Birnaviridae
• Aquabirnavirus
• Salmonid