''Enterovirus E'' (formerly bovine enterovirus (BEV)) is a picornavirus of the genus '' Enterovirus''. The virus may also be referred to as enteric cytopathic bovine orphan virus (ECBO). It is endemic in cattle populations worldwide, and although normally fairly nonpathogenic, it can cause reproductive, respiratory, or enteric disease – particularly when the animal is concurrently infected with another pathogen. The virus is spread horizontally by either the oral-fecal route or by the respiratory route. Viral shedding may occur for several months after initial infection. The virus has not been shown to transmit from animals to humans.

Virology

Structure and genome

In common with other picornaviruses, the capsid of BEV is composed of 60 copies of each of four structural proteins, VP1, VP2, VP3 and VP4, in icosahedral symmetry, at about 27 nm in diameter, and enclosing a single stranded positive sense RNA genome of about 7,500 bases. The capsid is not enveloped and roughly spherical with an outer radius of 159 Ångströms and an inner radius of 107 Å. The outer surface of BEV is smoother than the closely related

poliovirus A poliovirus, the causative agent of polio (also known as poliomyelitis), is a serotype of the species ''Enterovirus C'', in the family of ''Picornaviridae''. There are three poliovirus serotypes: types 1, 2, and 3. Poliovirus is composed of an ...

due to the truncation of surface protein loops in BEV. It is also smoother than the related human

rhinovirus The rhinovirus (from the grc, ῥίς, rhis "nose", , romanized: "of the nose", and the la, vīrus) is the most common viral infectious agent in humans and is the predominant cause of the common cold. Rhinovirus infection proliferates in tem ...

due to the extension of a surface loop in BEV. The three antigenic sites of BEV all occur on a surface ridge at the junction between VP1, VP2, and VP3. BEV has a crater-like depression at the icosahedral 5-fold axis which descends into a cylindrical hole of 10 Å in diameter which runs almost to the inner surface of the capsid. A hydrophobic pocket contained within VP1 contains a myristic acid molecule, the removal of which appears to be a prerequisite for virus uncoating.

Replication

To replicate, BEV must attach to the host cell surface receptor, penetrate into the cell cytoplasm, and the genome must be uncoated. The host cell surface receptor for BEV has yet to be identified, but is sensitive to neuraminidase.

Genetic variability

BEVs were originally classified into seven serotypes, but are now accepted as falling into two serotypes, 1 and 2, which are further classified into subtypes. BEV strain VG-5-27 of serotype 1, subtype 1, is the most extensively studied. The tissue tropism of serotype 1 is extremely broad, including human, sheep, horse, dog, camel, and other mammalian hosts. BEV-like sequences have even been reported in shellfish from water contaminated with bovine faeces. Serotype 2 viruses are only found in domestic cattle.

Signs and symptoms

Most cattle show no clinical signs when infected with the virus. However

abortion Abortion is the termination of a pregnancy by removal or expulsion of an embryo or fetus. An abortion that occurs without intervention is known as a miscarriage or "spontaneous abortion"; these occur in approximately 30% to 40% of pregn ...

stillbirth Stillbirth is typically defined as fetal death at or after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. A stillbirth can result in the feeling of guilt or grief in the mother. The term ...

infertility Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...

, and neonatal mortality can occur following infection of the reproductive tract. Enteric signs include

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

and weight loss, and respiratory infection can produce a mucoid nasal discharge.

Diagnosis

As clinical signs are fairly nonspecific and bovine enterovirus is ubiquitous in cattle populations, other causes of disease must be ruled out before diagnosing enterovirus as the cause of disease.

Electron microscopy An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...

PCR PCR or pcr may refer to: Science * Phosphocreatine, a phosphorylated creatine molecule * Principal component regression, a statistical technique Medicine * Polymerase chain reaction ** COVID-19 testing, often performed using the polymerase chain r ...

complement fixation The complement fixation test is an immunological medical test that can be used to detect the presence of either specific antibody or specific antigen in a patient's serum, based on whether complement fixation occurs. It was widely used to diagnos ...

, antibody fluorescence, neutralization test, and

haemagglutination Hemagglutination, or haemagglutination, is a specific form of agglutination that involves red blood cells (RBCs). It has two common uses in the laboratory: blood typing and the quantification of virus dilutions in a haemagglutination assay. Blood ...

can be used to identify the virus in tissues or secretions.

Treatment and control

Treatment is symptomatic. Appropriate isolation and hygiene measures should be employed to minimise the spread of disease during an outbreak.

Research

The virus has been investigated for its antitumor capabilities, as it is capable of replicating within breast cancer cell lines and producing a

cytopathic effect Cytopathic effect or cytopathogenic effect (abbreviated CPE) refers to structural changes in host cells that are caused by viral invasion. The infecting virus causes lysis of the host cell or when the cell dies without lysis due to an inability to ...

in human

monocyte Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and conventional dendritic cells. As a part of the vertebrate innate immune system monocytes also inf ...