Week 139 - Influenza Flashcards
What is a Virion?
This is the complete virus particle as it exists outside of the cell.
What is the general structure of a virus?
- *• Nuclecapsid - **This is the genome and the capsid.
- Genome - Genetic information
- Capsid - Protein coat for the genome made of of capsomeres.
- *• Envelope - **Not always present, some viruses are ‘naked’.
- Lipid bilayer, formed from host cell.
- Protein and glycoprotein spikes.
How may the genetic material in a virus be stored?
The Genome
May be RNA or DNA
May be Single stranded or Double Stranded
May be +ve or -ve
What is the significance if a virus stores its genetic information in +ve stranded RNA?
It can be directly translated into a protein, whilst a -ve strand needs to be transcribed first.
What family of DNA viruses are single-stranded and enveloped? Give an example of this family and what it causes.
Parvoviridae
- Parvovirus B19 - Causes ‘slapped cheek syndrome’, (Erythema infectiosum).
What family of viruses does the Parvovirus B19 belong to? And what does it cause?
Parvoviridae family, Single-stranded, enveloped DNA virus.
Causes ‘slapped cheek’ syndrome (Erythema infectorium - A rash in children, dangerous during pregnancy and sickle cell.
Which three familys of viruses are Double stranded, DNA and enveloped?
- Hepadnaviridae
- Herpesviridae
- Poxviridae
How is the genetic information stored in the hepadnaviridae family of viruses? Give examples.
Double stranded, DNA, Enveloped.
• Hepatitis B
Hepatitis B belongs to which family of viruses?
Hepadnaviridae (Double stranded, DNA, Enveloped)
What are the qualities of the Herpesviridae family of viruses and give some examples.
Double stranded, DNA, Enveloped.
- Herpes simplex
- Herpes Zoster
- Cytomegalovirus
- Epstein-Barr virus
- Human Herpesvirus 6,7 +8.
What family of viruses does herpes simplex belong to? What does it cause?
Herpesviridae (Double stranded,DNA,Enveloped)
Oral and genital ulcers.
What family of viruses does herpes zoster belong to? What does it cause?
Herpesviridae (DNA, Double-stranded, Enveloped)
Chickenpox and Shingles.
What family of viruses does cytomegalovirus belong to? What does it cause?
Herpesviridae (DNA, Double-stranded, Enveloped)
CMV infections, normally affect salivary glands and is asymptomatic but can be life-threatening during pregnancy and immuno-suppression.
What family of viruses does the Epstein-Barr virus belong to? What does it cause?
Herpesviridae (Double-stranded, DNA, Enveloped)
Glandular fever.
What are the characteristics of the poxviridae family of viruses? Give examples.
Double-stranded, DNA, Enveloped
- Molluscum Contagiosum
- Variola/Vaccina
What family of viruses to Molluscum Contagiosum belong to? What does it cause?
Poxviridae (DNA, Double-stranded, Enveloped)
Molluscum Contagiosum - common in children.
What family does the Variola/Vaccina virus belong to? What does it cause?
Poxviridae (DNA, Double-stranded, Enveloped)
Smallpox/ cowpox.
Which 2 viruses are DNA, Double-stranded but non-eveloped?
- Adenovirus
- Papillomavirus
What are the characteristics of the Adenovirus and what does it cause?
DNA, Double Stranded, Non-enveloped.
• URTIs and Gastroenteritis
What are the characteristics of the Papillomavirus and what does it cause?
DNA, Double-stranded, Non-Enveloped
• Warts
What are the three virus families that are -ve single stranded RNA and Enveloped?
- Orthomyxoviridae
- Paramyxoviridae
- Rhabdoviridae
What are the characteristics of the Orthomyxoviridae family of viruses and give an example.
- RNA, -ve single-stranded, Enveloped.
- Influenza
What family of viruses does influenza belong to?
Orthromyxoviridae (RNA, -ve singlestranded, Enveloped)
What are the characteristics of the Paramyxoviridae family of viruses and give some examples.
RNA, -ve single-stranded, Enveloped
- Respiratory Synctial Virus
- Parainfluenza Virus
- Measles Virus
Mumps Virus
What family does the Respiratory Syncytial virus belong to? What does it cause?
Paramyxoviridae (RNA, -ve Single-stranded, Enveloped)
• RTIs, esp. Bronchiliotis
What family does the Parainfluenza virus belong to? What does it cause?
Paramyxoviridae (RNA, -ve Single-Stranded, Enveloped)
- RTIs esp. Croup
- URTIs causing barking cough
What family do the Measles and Mumps viruses belong to?
Paramyxoviridae (RNA, -ve Single-stranded, Enveloped)
What virus is a member of the Rhabdovirus family and what are the characteristics of the family?
Rabies
RNA, -ve single-stranded, enveloped.
Which three viral families are +ve RNA, single-stranded and non-enveloped?
- Calciviridae
- Picomviridae
- Astroviridae
What are the characteristics of the Calciviridae family of viruses? Give examples.
RNA, +ve single-stranded, non-enveloped.
• Norovirus
What family does the norovirus belong to?
Calciviridae
RNA, +ve Single-stranded, Non-enveloped
What are the characteristics of the Picomviridae virus? Give examples.
RNA, +ve single-stranded, non-enveloped.
- Poliovirus
- Rhinovirus
- Coxsachie virus
What family does the poliovirus belong to? What does it cause?
Picomviridae (RNA, +ve Single-stranded, Non-enveloped)
• Poliomyelitis - Motorneurone damage and parlysis.
What family does the Rhinovirus belong to? What does it cause?
Picomviridae (RNA, +ve single-stranded, Non-enveloped)
• Common cold
What family does the Coxsachie virus belong to? What does it cause?
Picomviridae (RNA, +ve Single-stranded, Non-enveloped)
- Hand, Foot and mouth in children.
- Gastroenteritis.
What are the characteristics of the astroviridae family? Give examples.
RNA, +ve Single-stranded, Non-enveloped.
• Astrovirus
What family does the astrovirus belong to? What does it cause?
Astroviridae (RNA, +ve Single-stranded, Non-enveloped)
Gastroenteritis
Which three viral families are RNA, +ve single-stranded, Enveloped?
- Flaviviridae
- Retroviridae
- Togaviridae
What are the charactistics of the Flaviviridae family? Give examples.
RNA, +ve Single-Stranded, Enveloped
• Dengue, West Nile, Yellow, Hepatitis C
What are the characterisitics of the Retroviridae family? Give an example.
RNA, +ve Single-stranded, Enveloped
• HIV
What are the characteristics of the Togaviridae family of viruses? Give examples.
RNA, +ve Single-stranded, Enveloped
• Rubella virus
Which family of viruses is Double-stranded RNA, Non-enveloped? Give examples.
Reoviridae
• Rotavirus
Which family does the Rotavirus belong to? What does it cause?
Reoviridae (RNA, Double-stranded, Non-Enveloped)
Gastroenteritis
What are the six stages of viral replication?
1)
What are the two mechanisms for the attachment stage of viral replication?
- Attachment structures on virion surface - Glycoproteins, caspid proteins.
- Host Receptor Molecules - A virus might mimic a host hormones etc.
What are the three mechanisms for the penetration stage of viral replication?
1) Receptor mediated endocytosis
2) Membrane fusion
3) Viral translocation
What occurs during the uncoating stage of viral replication?
Capsid is disasembled in order to expose the genome.
What are the stages in genome replication and protein production in **DNA **viruses?
- Early protein production
- Viral DNA production
- Late protein production
- Nucleocapsid assembly
What are the two major problems that **RNA **viruses face during genomic replication and protein synthesis?
1) The vRNA cannot be copied directly by host machinary.
2) Each molecule of vRNA can only be translated into one protein.
vRNA cannot be copied by the host machinary. How do viruses resolve this problem?
- Have their own RNA-polymerase
- Have their own RNA-transciptase
- Contain a gene to produce RNA-polymerase (can only occur in +ve strands)
How are non-enveloped viruses released from the cell?
Can only occur through cell lysis.
What is disseminated infection?
This refers to a viral infection where the site of entry, site of replication and site of shedding are not all the same.
E.g. Measles
What is a latent infection?
This is a persistant infection without symptoms and without spread.
What is a subclinical viral infection?
This is a persistant infection without symptoms but it may be transmitted.
What is an insidiour infection?
This a viral infection with a long incubation period before symptoms appear.
What is the broad strategy of an antiviral?
They interfere with the viral replication cycle.
- Attachment
- Uncoating
- Replication
- Release
How does Amatidine work as a anti-viral?
It targets uncoating, by blocking H+ channels which reduce the pH to prevent the virus from uncoating.
Aciclovir: An antiviral, how does it work? Side-effects? Used on?
Metabolised by viral enzyme to become activated and then terminates DNA chain by mimicking Guanine but not allowing next base to bind.
- Side-effects are minimal as only becomes active in infected cells.
- Hepes simplex and Varicella Zoster
Which drug is used to treat herpes simplex and varicella zoster?
Aciclovir
Glanciclovir: An antiviral, mechanism? Side-effects? Indications?
Same mechanism as Aciclovir, it causes DNA termination due to mimicking guanine. However, it works in all cells, does not need to be activated by virus.
- Side-effects: Widespread and unpleasant, particulary affects red blood cell production.
- Used in CMV and very dangerous infections.
What are Oseltamivir and Zantamivir?
Antivirals, Oseltamivir is tablet whilst Zantamivir is inhaled.
- Used against influenza in high-risk patients or during pandemics.
- Inhibits neuraminidase an enzyme required for the release of virals.
