Viruses and Prions

These flashcards cover key concepts related to viruses and prions, including their structures, classifications, diseases, and prevention methods.

What are viruses primarily composed of?

Viruses are primarily composed of genetic material (either DNA or RNA) and a protein coat.

What is the typical size range of most viruses?

The size range of most viruses is between 10 to 100 nm.

What type of genetic material can viruses contain?

Viruses can contain either DNA or RNA, but never both.

What is the protein shell surrounding the nucleic acid in a virus called?

The protein shell is called the capsid.

What is the entire virus particle, including the capsid and genetic material, referred to as?

The entire virus particle is called the virion.

Where does the lipid envelope of some viruses derive from?

The lipid envelope is derived from the host cell membrane.

What type of symmetry is observed in herpesviruses?

Herpesviruses exhibit icosahedral symmetry.

What symmetry do most mammalian RNA viruses exhibit?

Most mammalian RNA viruses exhibit helical symmetry.

What occurs during the attachment step of viral replication?

The virus binds to specific receptors on the host cell.

What does viral uncoating refer to?

Viral uncoating refers to the removal of the lipid envelope and capsid, releasing viral nucleic acid.

What are the proteins on the surface of enveloped viruses called?

The proteins are called peplomers or spikes.

What types of genomes may viral genomes consist of?

Viral genomes may consist of single-stranded DNA, double-stranded RNA, segmented RNA molecules, or combinations thereof.

What factor dictates the minimum number of proteins encoded by a viral genome?

The concept of genetic economy dictates the minimum number of proteins.

What is a pathognomic character of Measles infection in the mouth?

Koplik's spots are a pathognomic character of Measles infection.

Influenza viruses belong to which family?

Influenza viruses belong to the Orthomyxoviridae family.

What is rhinovirus a common cause of?

Rhinovirus is a common cause of the common cold.

What period is defined by no detectable infectious virions in an infected cell?

This period is called the eclipse period.

Where does viral assembly for most enveloped viruses occur?

Viral assembly occurs in the plasma membrane, cell nucleus, or cytoplasm.

How do enveloped viruses typically release from the host cell?

Enveloped viruses typically release by budding.

What are prions primarily composed of?

Prions are primarily composed of protein.

What is the native form of prion protein?

The native form of prion protein is PrP^C.

What structural change is associated with the abnormal prion protein?

The abnormal prion protein exhibits a change to an insoluble beta-sheet structure.

Which disease is caused by prions in humans?

Kuru, Creutzfeldt-Jakob disease (CJD), and variant CJD (vCJD) are all caused by prions.

What is variant CJD (vCJD) primarily linked to?

Variant CJD is primarily linked to the consumption of infected animal tissues.

What sterilization method is recommended for prion-contaminated surgical instruments?

Sterilization in a vacuum autoclave for 18 minutes at 134°C is recommended.

What is the primary method to prevent prion diseases?

The primary method is avoiding the consumption of suspect food, especially neural tissues.

Which animal is primarily affected by the prion disease scrapie?

Sheep are primarily affected by the prion disease scrapie.

What was Kuru historically associated with?

Kuru was historically associated with the consumption of human brain tissue.

How does variant Creutzfeldt-Jakob Disease differ from classic CJD?

Variant CJD affects younger patients more frequently.

What characterizes fatal familial insomnia?

Fatal familial insomnia is characterized by progressive insomnia and circadian rhythm disruption.

What factors are used to classify viruses into families?

Factors include presence or absence of an envelope, type of nucleic acid, and symmetry of the nucleocapsid.

Which of the following is a DNA virus?

Herpes simplex virus (HSV) is a DNA virus.

What makes RNA viruses unique?

RNA viruses can have segmented genomes.

What enzyme is found in retroviruses?

Reverse transcriptase is an enzyme found in retroviruses.

What enzyme is responsible for uncoating and early replication in some DNA viruses?

Various enzymes, specific to the virus, are responsible for uncoating and early replication.

What is the primary route of transmission for rhinoviruses?

The primary route of transmission for rhinoviruses is airborne respiratory droplets.

How do orthomyxoviruses and paramyxoviruses attach to host cells?

They attach to host cells via hemagglutinin binding to host glycoproteins or glycolipids.

What is the latent period in a viral infection also known as?

The latent period is also referred to as the eclipse phase.

Which virus is known to replicate in the nucleus of the host cell?

HIV is known to replicate in the nucleus of the host cell.

Which virus can take years to produce symptoms after infection?

HIV can take years to produce symptoms after infection.

What do viral surface proteins often act as?

Viral surface proteins often act as antigenic determinants.

Why do prion proteins resist destruction?

They resist destruction because they form insoluble beta-sheets.

How do viroids differ from viruses?

Viroids consist solely of RNA and do not have a capsid.

Which statement is NOT true about prions?

Prions do not contain DNA.

What should dental instruments used on patients with suspected CJD undergo?

They should be incinerated or sterilized with specific protocols.

What should ideally happen with dental procedures on patients with known prion diseases?

They should ideally be performed with disposable instruments.

What is the incubation period for prion diseases?

The incubation period can last up to 50 years.

What does the term 'spongiform' refer to in prion diseases?

It refers to the sponge-like vacuolation of brain cells.

What is the proteinaceous infectious agent causing scrapie called?

The proteinaceous infectious agent causing scrapie is called a prion.

Which virus family includes measles and mumps?

The Paramyxoviridae family includes measles and mumps.