139 - Influenza

Question 0

name a single stranded enveloped DNA virus

Answer 0

parvovirus (parvoviradae family) - erythema infectiosum

Question 1

What is a viron made up from?

Answer 1

Nucleocapsid - genome in centre with genetic material, surrounded by a capsid (protein coat made up from capsomeres).
Sometimes have envelope - lipid bilayer made from host cell membrane with protein and glycoprotein spikes (for attachment, uptake and uncoating)

Question 2

name some double stranded enveloped DNA viruses

Answer 2

Hepadnaviridae (hepatitis B)
Herpesviridae - herpes simpex (oral & genital ulcers), varicella zoster (chicken pox & shingles), Cytomegalovirus (salivary glands), Epstein Barr (Glandular fever), Human Herpes virus 6&7 (roseola.
Poxviridae - molluscum contagiosum, variola/vaccinia (small pox & cow pox)

Question 3

name some double stranded non-enveloped DNA viruses

Answer 3

Adenovirus (URTI & gastroenteritis)

Papillomavirus (warts)

Question 4

name some -ve single stranded enveloped RNA viruses

Answer 4

Orthomyxoviridae (influenza)
Paramyxoviridae - Respiratory Syncytial Virus (bronchiloitis), Parainfluenza virus (croup), Measles virus, mumps virus (parotitis)
Rhabdoviridae (rabies)
Hepatitis D

Question 5

name some +ve single stranded non-enveloped RNA viruses

Answer 5

calciviridae (norovirus - gastroenteritis)
Picomviridae - poliovirus (poliomyelitis - damage of motor neurones), rhinovirus (common cold), coxsachie virus (hand foot and mouth)
Astroviridae - astrovirus (gastroenteritis)

Question 6

name some +ve single stranded enveloped RNA viruses

Answer 6

flaviviridae - dengue, yellow fever, hepatitis C
retroviridae - HIV
Togaviridae - Rubella

Question 7

name some double stranded non-enveloped RNA viruses

Answer 7

Reoviridae - rotavirus (gastroenteritis)

Question 8

what is the virus lifecycle?

Answer 8

attachment->penetration->uncoating->replication->assembly ->maturation->release

Question 9

what is a localised infection?

Answer 9

sites of entry, replication and shedding are the same. eg influenza

Question 10

what is a disseminated infection?

Answer 10

sites of entry, replication and shedding show variation. eg measles

Question 11

what is an acute infection?

Answer 11

rapid onset, short lived, non persistent

Question 12

what is a chronic infection?

Answer 12

persistent infection with symptoms

Question 13

what is a latent infection?

Answer 13

persistent infection without symptoms or spread. eg hsv

Question 14

what is a subclinical infection?

Answer 14

persistent infection without symptoms but may be transmitted. eg typhoid, hep B

Question 15

what is an insidious infection?

Answer 15

long incubation period before symptoms occur. eg prions (fatal)

Question 16

how do viruses cause damage to cells?

Answer 16

immune interactions - apoptosis induction by Tc cells and free radicals like NO & superoxide produced by phagocytes
direct mechanisms - take over cell machinery, cell lysis, DNA modification and Immunosupression

Question 17

what strategies do antivirals use?

Answer 17

Immunoglobulins target attachment
Amanitidine targets uncoating by lowering pH
Aciclovir (mimics guanosine- blocks DNA chain formation), Ganciclovir target replication
Oseltamivir targets release - inhibits neuraminidase