Virus Nomenclature and Structures Lecture 1

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Questions and Answers

Which of the following factors is NOT a basis for virus classification?

Transmission method

Type of host

City of origin

Type of nucleic acid (correct)

What characteristic is used to describe whether a virus genome is segmented or non-segmented?

Type of host

Infectious process

Genome structure (correct)

Transmission vector

Why is recognizing the genome type of a virus important?

It influences diagnosis and treatment. (correct)

It predicts the transmission rate.

It helps in naming the virus.

It determines the virus's size.

Which type of virus belongs to the category of diseases transmitted by vectors?

Mosquito-borne viruses Signup and view all the answers

What aspect of a virus does virion size describe?

Physical dimensions Signup and view all the answers

Which of the following is NOT a classification criteria for viruses based on their evolutionary nomenclature?

Symptoms caused Signup and view all the answers

What does the term 'icosahedral capsid' refer to in the context of virology?

The shape of the protein shell surrounding the virus Signup and view all the answers

Which statement correctly describes a characteristic of the double-stranded genome?

It can be RNA or DNA. Signup and view all the answers

Which of the following viruses is classified based on the location where it was first reported?

Nipah virus Signup and view all the answers

What is the primary reason for classifying viruses by their transmission method?

To provide a basis for public health interventions Signup and view all the answers

What is the taxonomic suffix for the order of viruses?

-virales Signup and view all the answers

Which family of viruses does the genus Morbilivirus belong to?

Paramyxoviridae Signup and view all the answers

What characteristic is essential for membership of a virus species?

No single characteristic is essential. Signup and view all the answers

Which virus is known to be associated with the genus Coronavirus?

Severe acute respiratory syndrome virus (SARS-CoV) Signup and view all the answers

What is the taxonomic suffix for the family of viruses?

-viridae Signup and view all the answers

What is the possible state of a virion regarding its structure?

Naked or enveloped Signup and view all the answers

In which subfamily is the Paramyxovirus classified?

Paramyxovirinae Signup and view all the answers

What does the taxonomic suffix '-virinae' indicate?

It categorizes the subfamily of viruses. Signup and view all the answers

Which of the following is NOT a genus of the viral taxonomy mentioned?

Mumps virus Signup and view all the answers

What does the term 'nucleic acid' refer to in the context of viruses?

The genetic material present in the virus. Signup and view all the answers

Which virus classification involves single-stranded RNA with negative polarity?

(-) sense ssRNA viruses Signup and view all the answers

What is a characteristic feature of dsDNA viruses according to the Baltimore classification?

They include poxvirus and herpes virus. Signup and view all the answers

Which statement correctly describes ssDNA viruses?

They are notably represented by parvovirus. Signup and view all the answers

In what way do RNA reverse transcribing viruses operate?

They replicate via RNA to DNA conversion. Signup and view all the answers

Which virus from the Baltimore classification is associated with dsRNA?

Rotavirus Signup and view all the answers

Which of these viruses is categorized under the (-) sense ssRNA classification?

Rabies virus Signup and view all the answers

Which classification is not present in the Baltimore classification system?

soRNA viruses Signup and view all the answers

What defines the replication strategy of dsRNA viruses?

They have a segmented genome. Signup and view all the answers

Which virus is most likely to induce a strong inflammatory response in the host?

HIV Signup and view all the answers

Which of the following best describes ssRNA viruses?

They are translated directly into proteins. Signup and view all the answers

What type of genome structure is primarily associated with HBV?

Double-stranded DNA with RNA intermediate Signup and view all the answers

What role do structural proteins of a virus typically serve?

They facilitate virus attachment to host cells. Signup and view all the answers

How do virions differ in their survival outside host cells?

Survival duration varies depending on the virus. Signup and view all the answers

Non-structural proteins are primarily synthesized in which context?

They are encoded by viral genes but only made in infected cells. Signup and view all the answers

What is one of the primary functions of the viral genome's 5' methylated cap?

It helps initiate translation in the host cell. Signup and view all the answers

Which components do virions typically carry?

Genomes, capsids, and proteins Signup and view all the answers

What is the role of repeat sequences found in viral RNA genomes?

They serve as enhancers or origins of replication. Signup and view all the answers

What is NOT a characteristic of virions?

They can replicate independently of host cells. Signup and view all the answers

What is the function of proteases that are classified as non-structural proteins?

They assist in protein modification and maturation. Signup and view all the answers

What is a significant feature of genomic RNA that acts as mRNA for translation in the host?

It includes a 5' methylated cap and a 3' polyadenosine tail. Signup and view all the answers

Study Notes

Lecture 1: Virus Nomenclature and Structures

Learning outcomes: Students will be able to categorize viruses and describe their structures and functions.

General Nomenclature of Viruses

Virus classification is based on:
- Host type (e.g., human, avian)
- Disease type (e.g., measles, influenza)
- Transmission method (vector-borne, non-vector-borne)
- Geographical location of initial outbreak

Evolution of Virus Nomenclature

Based on virus particle characteristics:
- Genome type (DNA or RNA; single or double stranded)
- Genome segmentation (segmented or non-segmented)
- Capsid shape (helical or icosahedral)
- Virion size
- Presence or absence of an envelope

International Committee on Taxonomy of Viruses

Viruses are categorized by order, family, subfamily, genus, and species.
This is used to organize knowledge about diverse viruses with similar or shared traits

Baltimore Classification of Viruses

Based on genome type (DNA or RNA; plus or minus strand) and replication strategies
Categorizes viruses into 7 classes.

The Baltimore Classification System

7 categories of viruses based on their genetic makeup and replication.
Example virus types included: DNA viruses, RNA viruses, single or double stranded.

Virions

Outside host cells, viruses survive as virions.
Virions are infectious—how long they survive outside host cells depends on the virus
Virions carry genomes, capsids, and lipid or protein envelopes (some have both)

Virus Genomes

Viral RNA genomes can act as mRNA.
They can have repeat sequences at the ends that serve various functions (e.g., promoters, enhancers, origins of replication).

Virus Proteins

Structural proteins: Components of virions; protect the viral genome, attach to host cells, and fuse viral envelopes with host membranes during replication.
Non-structural proteins: Encoded by viral genes and synthesized in infected cells. These carry out functions such as enzymes, transcription factors, and interfering with the host's immune response

Virus Proteins: Capsids

Major function: Protecting the viral genome
Other functions include reorganization and attachment to host cells, and releasing the genome into the cell.
Capsid+genome = nucleocapsid
Capsids are usually helical or icosahedral

Virion Membranes

Derived from host cell membranes.
Mostly animal viruses have envelopes. Influenza and herpesviruses are examples
Enveloped virions carry integral membrane proteins (glycoproteins) which typically play roles in attachment and fusion with host cell membranes.

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Description

This quiz covers the fundamentals of virus nomenclature and their structural characteristics. Students will learn how to classify viruses based on various criteria, including host types, diseases, and transmission methods. Additionally, the evolution of virus nomenclature and the Baltimore Classification will be discussed.