biology

Gyrovirus

Gyrovirus is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Gyrovirus rather than just read about it. In short: Gyrovirus is a genus of viruses, in the family Anelloviridae. Until 2011, chicken anemia virus was the only gyrovirus identified, but since then gyroviruses have also been identified in humans.

Key takeaways

Gyrovirus belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Gyrovirus to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gyrovirus from memory before moving on to harder problems.

Reference excerpt

Gyrovirus is a genus of viruses, in the family Anelloviridae. Until 2011, chicken anemia virus was the only gyrovirus identified, but since then gyroviruses have also been identified in humans. Diseases associated with this genus include: chicken infectious anemia, which is associated with depletion of cortical thymocytes and erythroblastoid cells.

Taxonomy The genus contains the following species:

Structure Gyroviruses have an average size of 19 to 27 nanometers. They are nonenveloped and have an icosahedral capsid with T=1 symmetry. The unique, single protein, trumpet-shaped capsomeres of Gyrovirus are arranged into 12 pentomers yielding a capsid 60 units in size. The genome is circular, non-segmented, and 2290–2320 nucleotides long.

Genome

The Gyrovirus genome consists of negative sense, single-stranded, circular, DNA. The genome is relatively small at 2,300 nucleotides. and contains three overlapping open reading frames that code for only three known proteins.

Proteins The Gyrovirus genome codes for a single polysistronic mRNA that subsequently codes for three proteins, VP1, VP2, and VP3. VP1 is the 51kd capsid protein; in addition to its structural function, it also contains motifs for rolling circle replication in the C-terminal region. VP2 is a 23kd nonstructural protein with phosphatase activity. Virions with mutations in SP2 are still replication competent; however, their cytopathic effects were highly attenuated. VP3, also called apoptin, is a 13kd protein that has been shown to independently induce apoptosis in chicken cells. Apoptin is also being researched for its ability to induce apoptosis in human tumor cells.

Replication strategy Viral replication is nuclear. Entry into the host cell is achieved by penetration into the host cell. Upon entering the host cell, the virus converts from single stranded to double stranded, circular DNA using host cell machinery. The circular dsDNA is then used as a template for transcription and for replication via a rolling circle mechanism similar to phiX174. DNA-templated transcription, with some alternative splicing mechanism is the method of transcription. The virus exits the host cell by nuclear egress, and nuclear pore export. Birds serve as the natural host. Transmission routes are fecal-oral, parental, egg transmission, and respiratory.

Chicken anemia virus Chicken anemia virus (CAV) was, until 2011, the only member of genus Gyrovirus identified. It causes disease worldwide in areas where chickens are produced. CAV causes severe anemia, hemorrhaging, and depletion of lymphoid tissue through the destruction of bone marrow erythroblastoid cells. The disease affects mainly young chicks not protected by maternal antibodies. Age resistance to disease begins at about one week, but can be overcome however by coinfection with immunosuppressive diseases, such as bursal disease virus, Marek’s disease, and others. A second virus in this genus—Avian gyrovirus 2—has been described. The viral genome shares ~40% of its sequence with Chicken anemia virus (CAV). The genome is 2383 nucleotides long and has three partially overlapping open reading frames encoding the proteins VP1, VP2 and VP3. These proteins share 38.8%, 40.3%, and 32.2% amino acid identities between their homologs in the CAV. Two species have been described from humans—human gyrovirus and human gyrovirus 3. Human gyrovirus 1 appears to be the same virus as avian gyrovirus 2. A fourth gyrovirus—gyrovirus 4 (GyV4)—has been isolated from human stool and chicken meat.

Literature

External links Viralzone: Gyrovirus ICTV

Worked examples

Example 1 — a first encounter with Gyrovirus

Start with the simplest possible case. Write down what Gyrovirus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Gyrovirus before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Gyrovirus ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Gyrovirus

In research: Gyrovirus appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Gyrovirus in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Gyrovirus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anelloviridae, Virus genera, so understanding it makes those chapters shorter.
In everyday life: Look for Gyrovirus outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Gyrovirus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gyrovirus means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Gyrovirus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gyrovirus in simple terms?

Gyrovirus is a genus of viruses, in the family Anelloviridae. Until 2011, chicken anemia virus was the only gyrovirus identified, but since then gyroviruses have also been identified in humans.

Why does Gyrovirus matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Gyrovirus?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Gyrovirus.