Gallid herpesvirus 1

Gallid herpesvirus 1
Virus classification
Group:	Group I (dsDNA)
Order:	Herpesvirales
Family:	Herpesviridae
Subfamily:	Alphaherpesvirinae
Genus:	Iltovirus
Species:	Gallid herpesvirus 1 (GaHV-1)

Last updated April 03, 2019

Gallid herpesvirus 1 (GaHV-1) (also known as Avian herpesvirus 1) is a virus of the family Herpesviridae that causes avian infectious laryngotracheitis. It was originally recognized as a disease of chickens in the United States in 1926.^[1] The disease also occurs in pheasants.^[2]

A virus is a small infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.

Herpesviridae is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word herpein, referring to spreading cutaneous lesions, usually involving blisters, seen in flares of herpes simplex 1, herpes simplex 2 and herpes zoster (shingles). In 1971, the International Committee on the Taxonomy of Viruses (ICTV) established Herpesvirus as a genus with 23 viruses among four groups. Latent, recurring infections are typical of this group of viruses, though the family name does not refer to latency. Herpesviridae can cause latent or lytic infections.

The chicken is a type of domesticated fowl, a subspecies of the red junglefowl. It is one of the most common and widespread domestic animals, with a total population of more than 19 billion as of 2011. There are more chickens in the world than any other bird or domesticated fowl. Humans keep chickens primarily as a source of food and, less commonly, as pets. Originally raised for cockfighting or for special ceremonies, chickens were not kept for food until the Hellenistic period.

The disease is usually referred to as infectious laryngotracheitis or simply LT in the poultry industry. It is widely viewed as one of the most contagious viruses that affect the poultry industry. A confirmed case will usually result in the establishment of a quarantine zone around the farm. Inside this quarantine zone, poultry workers will avoid poultry farms to prevent the spread of the virus.

GaHV-1 is shed in respiratory secretions and transmitted by droplet inhalation or via fomites. A previously unexposed flock will develop cases for two to eight weeks following introduction. The incubation period is two to eight days.^[1]

A fomes or fomite is any inanimate object, that when contaminated with infectious agents, such as bacteria or viruses, can transfer disease to a new host.

Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent. In a typical infectious disease, incubation period signifies the period taken by the multiplying organism to reach a threshold necessary to produce symptoms in the host.

Clinical signs and diagnosis

Symptoms include coughing, sneezing, head shaking, lethargy, discharge from the eyes and nostrils (sometimes bloody), and difficulty breathing. The name comes from the severe inflammation of the larynx and trachea. A diphtheritic membrane may form in the trachea, causing obstruction.

The larynx, commonly called the voice box, is an organ in the top of the neck of tetrapods involved in breathing, producing sound, and protecting the trachea against food aspiration. The larynx houses the vocal folds, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The word larynx comes from a similar Ancient Greek word.

There may be problems in egg laying and the production of abnormal or thin-shelled eggs.

Mortality is typically less than 15 percent.^[2]

Histopathology, PCR, ELISA, immunofluorescent staining and viral isolation are all possible methods of diagnosis.

Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease. Specifically, in clinical medicine, histopathology refers to the examination of a biopsy or surgical specimen by a pathologist, after the specimen has been processed and histological sections have been placed onto glass slides. In contrast, cytopathology examines (1) free cells or (2) tissue micro-fragments.

The enzyme-linked immunosorbent assay (ELISA) is a commonly used analytical biochemistry assay, first described by Engvall and Perlmann in 1972. The assay uses a solid-phase enzyme immunoassay (EIA) to detect the presence of a ligand in a liquid sample using antibodies directed against the protein to be measured. The ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries.

Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows visualization of the distribution of the target molecule through the sample. The specific region an antibody recognizes on an antigen is called an epitope. There have been efforts in epitope mapping since many antibodies can bind the same epitope and levels of binding between antibodies that recognize the same epitope can vary. Additionally, the binding of the fluorophore to the antibody itself cannot interfere with the immunological specificity of the antibody or the binding capacity of its antigen. Immunofluorescence is a widely used example of immunostaining and is a specific example of immunohistochemistry. This technique primarily makes use of fluorophores to visualise the location of the antibodies.

Treatment and control

A vaccine is available (ATCvet code: QI01AD08 ( WHO )), but it does not prevent latent infections. It can be used during an outbreak to decrease morbidity and deaths.

Biosecurity measure including quarantine, isolation and disinfection are very important in controlling the spread of an outbreak.

Biosecurity has multiple meanings and is defined differently according to various disciplines. The original definition of biosecurity started out as a set of preventive measures designed to reduce the risk of transmission of infectious diseases in crops and livestock, quarantined pests, invasive alien species, and living modified organisms. The emerging nature of biosecurity threats means that small scale risks blow up rapidly, thus an effective policy becomes a challenge for there are limitations on time and resources available for analysing threats and estimating the likelihood of their occurrence.

A quarantine is used to separate and restrict the movement of people; it is a restraint upon the activities or communication of persons or the transport of goods designed to prevent the spread of disease or pests,' for a certain period of time. This is often used in connection to disease and illness, such as those who may possibly have been exposed to a communicable disease, but do not have a confirmed medical diagnosis. The term is often erroneously used to mean medical isolation, which is "to separate ill persons who have a communicable disease from those who are healthy," and refers to patients whose diagnosis has been confirmed.

In health care facilities, isolation represents one of several measures that can be taken to implement infection control: the prevention of contagious diseases from being spread from a patient to other patients, health care workers, and visitors, or from outsiders to a particular patient. Various forms of isolation exist, in some of which contact procedures are modified, and others in which the patient is kept away from all others. In a system devised, and periodically revised, by the U.S. Centers for Disease Control and Prevention (CDC), various levels of patient isolation comprise application of one or more formally described "precaution".

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Alphaherpesvirinae is a subfamily of Herpesviridae, primarily distinguished by reproducing more quickly than other subfamilies of Herpesviridae. In animal virology the most important herpesviruses belong to the Alphaherpesvirinae. Pseudorabies virus is the causative agent of Aujeszky's disease in pigs and bovine herpesvirus 1 is the causative agent of bovine infectious rhinotracheitis and pustular vulvovaginitis. Mammals serve as natural hosts. There are currently 37 species in this subfamily, divided among 5 genera. Diseases associated with this subfamily include: HHV-1 and HHV-2: skin vesicles or mucosal ulcers, rarely encephalitis and meningitis, HHV-3: chickenpox (varicella) and shingles, gaHV-2: Marek's disease.

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H5N2 is a subtype of the species Influenzavirus A. The subtype infects a wide variety of birds, including chickens, ducks, turkeys, falcons, and ostriches. Affected birds usually do not appear ill, and the disease is often mild as avian influenza viral subtypes go. Some variants of the subtype are much more pathogenic than others, and outbreaks of "high-path" H5N2 result in the culling of thousands of birds in poultry farms from time to time. It appears that people who work with birds can be infected by the virus, but suffer hardly any noticeable health effects. Even people exposed to the highly pathogenic H5N2 variety that killed ostrich chicks in South Africa only seem to have developed conjunctivitis, or a perhaps a mild respiratory illness. There is no evidence of human-to-human spread of H5N2. In November 12, 2005 it was reported that a falcon was found to have H5N2.

Bovine herpesvirus 1 (BoHV-1) is a virus of the family Herpesviridae and the subfamily Alphaherpesvirinae, known to cause several diseases worldwide in cattle, including rhinotracheitis, vaginitis, balanoposthitis, abortion, conjunctivitis, and enteritis. BoHV-1 is also a contributing factor in shipping fever, also known as bovine respiratory disease (BRD). It is spread horizontally through sexual contact, artificial insemination, and aerosol transmission and it may also be transmitted vertically across the placenta. BoHV-1 can cause both clinical and subclinical infections, depending on the virulence of the strain. Although these symptoms are mainly non-life-threatening it is an economically important disease as infection may cause a drop in production and affect trade restrictions. Like other herpesviruses, BoHV-1 causes a lifelong latent infection and sporadic shedding of the virus. The sciatic nerve and trigeminal nerve are the sites of latency. A reactivated latent carrier is normally the source of infection in a herd. The clinical signs displayed are dependent on the virulence of the strain. There is a vaccine available which reduces the severity and incidence of disease. Some countries in Europe have successfully eradicated the disease by applying a strict culling policy.

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Equid alphaherpesvirus 3, formerly Equine herpesvirus 3 (EHV-3), is a virus of the family Herpesviridae that affects horses. It causes a disease known as equine coital exanthema. The disease is spread through direct and sexual contact and possibly through flies carrying infected vaginal discharge. EHV-3 has an incubation period of as little as two days. Signs of the disease include pustules and ulcerations of the vagina, penis, prepuce, and perineum. Lesions may also be seen on the lips and teats. Usually the only symptom seen is a decreased libido in stallions. The lesions heal within two weeks. As with other herpes viruses, the virus remains latent in the host for life. Carrier animals can sometimes be identified by spots of pigment loss on black skin in the genital region. EHV-3 is best prevented by taking note of present clinical signs and keeping infected horses isolated and breeding stock from sexual contact with other horses. Antibiotic ointments should be used on the lesions to prevent secondary bacterial infections and hasten the healing process. It is also important to use disposable gloves and instruments in veterinary exams as the virus can be spread by using contaminated equipment.

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Feline viral rhinotracheitis (FVR) is an upper respiratory or pulmonary infection of cats caused by Felid alphaherpesvirus 1, of the family Herpesviridae. It is also commonly referred to as feline influenza, feline coryza, and feline pneumonia but, as these terms describe other very distinct collections of respiratory symptoms, they are misnomers for the condition. Viral respiratory diseases in cats can be serious, especially in catteries and kennels. Causing one-half of the respiratory diseases in cats, FVR is the most important of these diseases and is found worldwide. The other important cause of feline respiratory disease is feline calicivirus.

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Iltovirus is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Alphaherpesvirinae. Birds, galliform birds, psittacine birds, chickens, turkeys, and quail serve as natural hosts. There are currently only two species in this genus including the type species Gallid herpesvirus 1. Diseases associated with this genus include: acute respiratory diseases: gaHV-1: infectious laryngotracheitis; psHV-1: Pacheco's disease.

Channel Catfish virus is a member of the Alloherpesviridae family that causes disease in catfish. Infection with Channel catfish viral disease (CCVD) can cause significant economic loss in channel catfish farms.

Pacheco's disease is an acute and often lethal infectious disease in psittacine birds. The disease is caused by a species of herpesvirus, Psittacid alphaherpesvirus 1 (PsHV-1), which consists of four genotypes. Birds which do not succumb to Pacheco's disease after infection with the virus become asymptomatic carriers that act as reservoirs of the infection. These persistently infected birds, often Macaws, Amazon parrots and some species of conures, shed the virus in feces and in respiratory and oral secretions. Outbreaks can occur when stress causes healthy birds who carry the virus to shed it. Birds generally become infected after ingesting the virus in contaminated material, and show signs of the disease within several weeks.

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References

1 2 Fenner, Frank J.; Gibbs, E. Paul J.; Murphy, Frederick A.; Rott, Rudolph; Studdert, Michael J.; White, David O. (1993). Veterinary Virology (2nd ed.). Academic Press, Inc. ISBN 0-12-253056-X.
1 2 Carter, G.R.; Flores, E.F.; Wise, D.J. (2006). "Herpesviridae". A Concise Review of Veterinary Virology. Retrieved 2006-06-10.

External links

Avian Infectious Laryngotracheitis, expert reviewed and published by WikiVet, accessed 07/10/2011
Virus Pathogen Database and Analysis Resource (ViPR): Herpesviridae

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[Fenner_1993-1] 1 2 Fenner, Frank J.; Gibbs, E. Paul J.; Murphy, Frederick A.; Rott, Rudolph; Studdert, Michael J.; White, David O. (1993). Veterinary Virology (2nd ed.). Academic Press, Inc. ISBN 0-12-253056-X.

[Carter-2] 1 2 Carter, G.R.; Flores, E.F.; Wise, D.J. (2006). "Herpesviridae". A Concise Review of Veterinary Virology. Retrieved 2006-06-10.