Animal virus

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Animal viruses are viruses that infect animals. Viruses infect all cellular life and although viruses infect every animal, plant, fungus and protist species, each has its own specific range of viruses that often infect only that species. [1]

Contents

Vertebrates

The viruses of vertebrates are informally distinguished between those that primarily cause infections of humans and those that infect other animals. The two fields of study are called medical (or clinical) virology and veterinary virology respectively. [2] Although not the first viruses to be discovered and characterised, [3] those that cause infections of humans are the most studied. [4] Different viruses can infect all the organs and tissues of the body and the outcomes range from mild or no symptoms, to life-threatening diseases. [5] Humans cannot be infected by plant or insect viruses, but they are susceptible to infections with viruses from other vertebrates. These are called viral zoonoses or zoonotic infections. [6] Examples include, rabies, yellow fever and pappataci fever. [7]

The viruses that infect other vertebrates are related to those of humans and most families of viruses that cause human diseases are represented. [8] They are important pathogens of livestock and cause diseases such as foot-and-mouth disease and bluetongue. [9] Jersey and Guernsey breeds of cattle are particularly susceptible to pox viruses, with symptoms characterised by widespread, unsightly skin lesions. And most people have heard of myxomatosis, which is a fatal pox virus infection of rabbits: once infected they die within twelve days. [10] The virus was deliberately released in Australia in 1950, in an attempt to control the exponentially growing rabbit population. Rabbits had been brought to the continent in 1859 for sport, and having no natural predators, bred at an extraordinary rate. The infection killed 99.8 percent of rabbits, but by the late 1950s, Australian rabbits started to become immune to the virus and the population of rabbits increased, but never to the vast numbers seen before 1950. [11]

Rabbits around a waterhole during the myxomatosis trial at the site on Wardang Island, South Australia in 1938 Rabbits MyxomatosisTrial WardangIsland 1938.jpg
Rabbits around a waterhole during the myxomatosis trial at the site on Wardang Island, South Australia in 1938

Companion animals such as cats, dogs, and horses, if not vaccinated, can catch serious viral infections. Canine parvovirus 2 is caused by a small DNA virus, and infections are often fatal in pups. [12] The emergence of the parvovirus in the 1970s was the most significant in the history of infectious diseases. The disease spread rapidly across the world, and thousands of dogs died from the infection. [13] The virus originated in cats, the vector of feline panleukopenia, but a mutation that changed just two amino acids in the viral capsid protein VP2 [14] allowed it to cross the species barrier, and dogs, unlike cats, had no resistance to the disease. [15] Canine distemper virus is closely related to measles virus and is the most important viral disease of dogs. The disease (which was first described in 1760, by Edward Jenner, the pioneer of smallpox vaccination, is highly contagious, but is well controlled by vaccination. In the 1990s, thousands of African lions died from the infection, which they contracted from feral dogs and hyenas. [16]

Marine mammals are susceptible to viral infections. In 1988 and 2002, thousands of harbor seals were killed in Europe by the measles-like phocine distemper virus. [17] Large outbreaks of the disease were recorded among the seal populations of Lake Baikal and along the shores of the Baltic and North Sea. The infection resembled canine distemper; the animals died within two weeks of respiratory distress and many aborted pups were seen. [18] Many other viruses, including caliciviruses, herpesviruses, adenoviruses and parvoviruses, circulate in marine mammal populations. [19]

Fish too have their viruses. They are particularly prone to infections with rhabdoviruses, which are distinct from, but related to rabies virus. At least nine types of rhabdovirus cause economically important diseases in species including salmon, pike, perch, sea bass, carp and cod. The symptoms include anaemia, bleeding, lethargy and a mortality rate that is affected by the temperature of the water. In hatcheries the diseases are often controlled by increasing the temperature to 15–18 °C. [20] Like all vertebrates, fish suffer from herpes viruses. These ancient viruses have co-evolved with their hosts and are highly species-specific. [21] In fish, they cause cancerous tumours and non-cancerous growths called hyperplasia. [22]

Invertebrates

Honey bee infected with deformed wing virus Dwv honey bee.jpg
Honey bee infected with deformed wing virus

Arthropods is the largest group of animals and has shown to be a major reservoir of different viruses, both insect-specific viruses (ISV) and viruses that can infect both vertebrates and invertebrates, more known as arthropod-borne viruses (arboviruses). Insect-specific viruses are, as the name reveals, characterised by their incapacity to infect vertebrates. This can be assessed through, viral inoculation of mammalian, avian, or amphibian cell lines. [23] The first (ISV) was discovered over 40 years ago by Stollar and Thomas. [24] It was isolated from an Aedes aegypti cell culture where a large number of syncytia were observed and the virus was named cell fusing agent virus (CFAV). Further, when inoculated on different vertebrate cell lines no cytopathic effect (CPE) could be observed and the virus could not be re-isolated, suggesting that the virus must be insect-specific. [24]

Invertebrates do not produce antibodies by the lymphocyte-based adaptive immune system that is central to vertebrate immunity, but they are capable of effective immune responses. [25] Phagocytosis was first observed in invertebrates, [26] and this and other innate immune responses are important in immunity to viruses and other pathogens. The hemolymph of invertebrates contains many soluble defence molecules, such as hemocyanins, lectins, and proteins, which protect these animals against invaders. [27]

The health of the honey bee has been important to human societies for centuries. [28] Like all invertebrates, the honey bee (Apis mellifera) is susceptible to many viral infections, [29] and their numbers have dramatically declined around the world. [30] These bees often suffer infestations of varroa mites, which are vectors for deformed wing virus, [31] as a result, this virus has become one of the most widely distributed and contagious insect viruses on the planet. [32] The virus causes stunted wings and as a result, the infected bees are unable to leave the hive and forage for nectar. [31] Symptomatic bees have a severely reduced life-span of less than 48 hours and are often expelled from the hive by other bees. Bees are crucial to the survival of humans, along with producing honey, they pollinate plants that contribute up to one third of the food we eat, and their dramatic decline is a grave concern. [33]

Baculoviruses are among the best studied of the invertebrate viruses. They infect and kill several species of agricultural pests, [34] and as natural insecticides, they have been used to control insect populations in Brazil and Paraguay such as the velvet bean caterpillar (Anticarsia gemmatalis), a pest of soy beans. [35] Viruses are an attractive alternative to chemical pesticides because they are safe to other wildlife and leave no residues. [36]

Viruses can also change the behaviour of their insect hosts to their own advantage. A baculovirus of the gypsy moth (Lymantria dispar) makes their caterpillars climb to the tops of trees where they die. In doing so, they release a shower of millions of progeny viruses that go on to infect more caterpillars. [37]

Related Research Articles

<span class="mw-page-title-main">Canine distemper</span> Viral disease affecting some mammals

Canine distemper virus (CDV) is a viral disease that affects a wide variety of mammal families, including domestic and wild species of dogs, coyotes, foxes, pandas, wolves, ferrets, skunks, raccoons, and felines, as well as pinnipeds, some primates, and a variety of other species. CDV does not affect humans.

<i>Parvoviridae</i> Family of viruses

Parvoviruses are a family of animal viruses that constitute the family Parvoviridae. They have linear, single-stranded DNA (ssDNA) genomes that typically contain two genes encoding for a replication initiator protein, called NS1, and the protein the viral capsid is made of. The coding portion of the genome is flanked by telomeres at each end that form into hairpin loops that are important during replication. Parvovirus virions are small compared to most viruses, at 23–28 nanometers in diameter, and contain the genome enclosed in an icosahedral capsid that has a rugged surface.

<i>Paramyxoviridae</i> Family of viruses

Paramyxoviridae is a family of negative-strand RNA viruses in the order Mononegavirales. Vertebrates serve as natural hosts. Diseases associated with this family include measles, mumps, and respiratory tract infections. The family has four subfamilies, 17 genera, three of which are unassigned to a subfamily, and 78 species.

<span class="mw-page-title-main">Fifth disease</span> Medical condition

Erythema infectiosum, fifth disease, or slapped cheek syndrome is one of several possible manifestations of infection by parvovirus B19. Fifth disease typically presents as a rash and is more common in children. While parvovirus B19 can affect humans of all ages, only two out of ten individuals will present with physical symptoms.

Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. Viruses have short generation times, and many—in particular RNA viruses—have relatively high mutation rates. Although most viral mutations confer no benefit and often even prove deleterious to viruses, the rapid rate of viral mutation combined with natural selection allows viruses to quickly adapt to changes in their host environment. In addition, because viruses typically produce many copies in an infected host, mutated genes can be passed on to many offspring quickly. Although the chance of mutations and evolution can change depending on the type of virus, viruses overall have high chances for mutations.

<span class="mw-page-title-main">Parvovirus B19</span> Human virus that infects RBC precursors

Human parvovirus B19, generally referred to as B19 virus(B19V),parvovirus B19 or sometimes erythrovirus B19, is a known human virus in the family Parvoviridae, genus Erythroparvovirus; it measures only 23–26 nm in diameter. Human parvovirus b19 is a below-species classification of Erythroparvovirus primate1. The name is derived from Latin parvum, meaning small, reflecting the fact that B19 ranks among the smallest DNA viruses. B19 virus is most known for causing disease in the pediatric population; however, it can also affect adults. It is the classic cause of the childhood rash called fifth disease or erythema infectiosum, or "slapped cheek syndrome". The name comes from it being the fifth in a list of historical classifications of common skin rash illnesses in children.

Viral pathogenesis is the study of the process and mechanisms by which viruses cause diseases in their target hosts, often at the cellular or molecular level. It is a specialized field of study in virology.

<i>Carnivore protoparvovirus 1</i> Species of parvovirus

Carnivore protoparvovirus 1 is a species of parvovirus that infects carnivorans. It causes a highly contagious disease in both dogs and cats separately. The disease is generally divided into two major genogroups: FPV containing the classical feline panleukopenia virus (FPLV), and CPV-2 containing the canine parvovirus type 2 (CPV-2) which appeared in the 1970s.

<span class="mw-page-title-main">Canine parvovirus</span> Contagious virus mainly affecting dogs

Canine parvovirus is a contagious virus mainly affecting dogs and wolves. CPV is highly contagious and is spread from dog to dog by direct or indirect contact with their feces. Vaccines can prevent this infection, but mortality can reach 91% in untreated cases. Treatment often involves veterinary hospitalization. Canine parvovirus often infects other mammals including foxes, wolves, cats, and skunks. Felines (cats) are also susceptible to panleukopenia, a different strain of parvovirus.

<span class="mw-page-title-main">Innate immune system</span> Immunity strategy in living beings

The innate immune system or nonspecific immune system is one of the two main immunity strategies in vertebrates. The innate immune system is an alternate defense strategy and is the dominant immune system response found in plants, fungi, prokaryotes, and invertebrates.

Infectious canine hepatitis (ICH) is an acute liver infection in dogs caused by Canine mastadenovirus A, formerly called Canine adenovirus 1 (CAV-1). Canine mastadenovirus A also causes disease in wolves, coyotes, and bears, and encephalitis in foxes. The virus is spread in the feces, urine, blood, saliva, and nasal discharge of infected dogs. It is contracted through the mouth or nose, where it replicates in the tonsils. The virus then infects the liver and kidneys. The incubation period is 4 to 9 days.

Porcine parvovirus (PPV), a virus in the species Ungulate protoparvovirus 1 of genus Protoparvovirus in the virus family Parvoviridae, causes reproductive failure of swine characterized by embryonic and fetal infection and death, usually in the absence of outward maternal clinical signs. The disease develops mainly when seronegative dams are exposed oronasally to the virus anytime during about the first half of gestation, and conceptuses are subsequently infected transplacentally before they become immunocompetent. There is no definitive evidence that infection of swine other than during gestation is of any clinical or economic significance. The virus is ubiquitous among swine throughout the world and is enzootic in most herds that have been tested. Diagnostic surveys have indicated that PPV is the major infectious cause of embryonic and fetal death. In addition to its direct causal role in reproductive failure, PPV can potentiate the effects of porcine circovirus type II (PCV2) infection in the clinical course of postweaning multisystemic wasting syndrome (PMWS).

<i>Feline calicivirus</i> Species of virus

Feline calicivirus (FCV) is a virus of the family Caliciviridae that causes disease in cats. It is one of the two important viral causes of respiratory infection in cats, the other being Felid alphaherpesvirus 1. FCV can be isolated from about 50% of cats with upper respiratory infections. Cheetahs are the other species of the family Felidae known to become infected naturally.

Carnivore bocaparvovirus 1, formerly Canine minute virus is a species of Bocaparvovirus of the family Parvoviridae that infects dogs. It is similar to bovine parvovirus in its protein structure and DNA. A virus causing respiratory disease in humans has been called human bocavirus due to its similarity to these viruses. Canine minute virus was originally discovered in Germany in 1967 in military dogs, although it was originally thought to not cause disease. Dogs and puppies are infected orally, and the virus is spread transplacentally to the fetuses. Symptoms are seen most commonly between the ages of one to three weeks and include severe diarrhea, difficulty breathing, and anorexia. In severe cases, illness can be fatal.

<i>Deformed wing virus</i> Species of virus

Deformed wing virus (DWV) is an RNA virus, one of 22 known viruses affecting honey bees. While most commonly infecting the honey bee, Apis mellifera, it has also been documented in other bee species, like Bombus terrestris, thus, indicating it may have a wider host specificity than previously anticipated. The virus was first isolated from a sample of symptomatic honeybees from Japan in the early 1980s and is currently distributed worldwide. It is found also in pollen baskets and commercially reared bumblebees. Its main vector in A. mellifera is the Varroa mite. It is named after what is usually the most obvious deformity it induces in the development of a honeybee pupa, which is shrunken and deformed wings, but other developmental deformities are often present.

<span class="mw-page-title-main">Veterinary virology</span> Study of viruses affecting animals

Veterinary virology is the study of viruses in non-human animals. It is an important branch of veterinary medicine.

<span class="mw-page-title-main">Introduction to viruses</span> Non-technical introduction to viruses

A virus is a tiny infectious agent that reproduces inside the cells of living hosts. When infected, the host cell is forced to rapidly produce thousands of identical copies of the original virus. Unlike most living things, viruses do not have cells that divide; new viruses assemble in the infected host cell. But unlike simpler infectious agents like prions, they contain genes, which allow them to mutate and evolve. Over 4,800 species of viruses have been described in detail out of the millions in the environment. Their origin is unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria.

<span class="mw-page-title-main">Virus</span> Infectious agent that replicates in cells

A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, more than 11,000 of the millions of virus species have been described in detail. The study of viruses is known as virology, a subspeciality of microbiology.

DA2PP is a multivalent vaccine for dogs that protects against the viruses indicated by the alphanumeric characters forming the abbreviation: D for canine distemper, A2 for canine adenovirus type 2, which offers cross-protection to canine adenovirus type 1, the first P for canine parvovirus, and the second P for parainfluenza. Because infectious canine hepatitis is another name for canine adenovirus type 1, an H is sometimes used instead of A. In DA2PPC, the C indicates canine coronavirus. This is not considered a core vaccination and is therefore often excluded from the abbreviation.

Chronic bee paralysis virus (CBPV) commonly affects adult Apis mellifera honey bees and causes a chronic paralysis that can easily spread to other members of a colony. Bees infected with CBPV begin to show symptoms after 5 days and die a few days after. Chronic bee paralysis virus infection is a factor that can contribute to or cause the sudden collapse of honeybee colonies. Since honeybees serve a vital role in ecological resilience, it is important to understand factors and diseases that threaten them.

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