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Mpharm 1 COPY > PH1123 - viruses > Flashcards

PH1123 - viruses Flashcards

1
Q

what are examples of airborne viruses? (6)

A
  • chicken pox
  • influenza
  • measles
  • mumps
  • rubella
  • smallpox
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2
Q

what are examples of food and water viruses? (3)

A
  • viral gastroenteritis (norovirus)
  • hepititis A and E
  • poliomyelitis
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3
Q

what are examples of direct contact viruses? (6)

A
  • AIDS (HIV)
  • cold sores
  • genital herpes
  • human papillomavirus (cervial cancer)
  • leukaemia (retrovirus)
  • hepatitis B and C
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4
Q

what are viruses? (6)

A
  • acellular (non cells)
  • carriers of genetic materia (DNA or RNA but not both)
  • required a host for replication
  • obligatory intracellular parasite
  • cause diseases
  • difficult to treat
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5
Q

what is the viral envelope? (2)

A
  • surrounds the viral capsid

- in some but not all viruses

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6
Q

where is the viral envelope derived from?

A
  • portions of the host cell membranes (phospholipids and proteins) during viral replication
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7
Q

what are enveloped viruses susceptible to? (2)

A
  • desiccation (low survival in the environment)

- physical and chemical challenges

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8
Q

what does the viral envelope contain and what is its responsibility? (3)

A
  • contains host proteins but also virus encoded proteins
  • responsible for viral entry into the host cell
  • recognition of host cell receptor and initiation of entry by fusion or endocytosis
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9
Q

what is budding?

A
  • viral exits from cell
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10
Q

what is a viral capsid?

A
  • virus building block-proteins that are assembled to form a tight shell
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11
Q

what lodges inside the capsid for protection?

A
  • nucleic acid genomes
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12
Q

what is a capsomere?

A
  • individual proteins fit together to form a building block
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13
Q

what does the capsid denote?

A
  • the protein shell that encloses the nucleic acid
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14
Q

what is the viral genome in a virus? (3)

A
  • either RNA or DNA (single or double stranded)
  • circular and linear
  • dictates viral genome expression; translation
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15
Q

what is the viral tegument (viral matrix)?

A
  • cluster of proteins that lines the space between the envelope and nucleocapsid of all herpesviruses
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16
Q

what does viral tegument aid? (2)

A
  • viral DNA replication

- evasion of the immune system (inhibition of signalling in the immune system and activation of interferons)

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17
Q

what are on the surface of the viral envelopes and its purpose? (2)

A
  • glycoproteins (virus encoded) on the surface of envelope or protruding from the capsid
  • serves to identify and bind to receptor sites on hosts membrane
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18
Q

what are the groups that viruses are split into based on the baltimore classification? (5)

A
  • group I; double stranded DNA
  • group II; single stranded DNA
  • group III; double stranded RNA
  • group IV and V; single stranded RNA
  • group VI; double stranded DNA
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19
Q

what do adenoviruses cause?

A
  • upper respiratory tract infections
20
Q

what do poxviruses cause? (2)

A
  • variola; small pox virus

- vaccinia; derived from cowpox virus and immunise against small pox

21
Q

what do herpes viruses cause? (3)

A
  • herpes simplex virus 1; cold sores
  • herpes simplex virus 2; genital herpes
  • cytomegalovirus; affects unborn babies during pregnancy, people who work with children, immunocompromised patients, organ transplant recipients
22
Q

what are the symptoms of parvoviruses? (4)

A
  • low-grade fever
  • headache
  • rash and cold-like symptoms
  • red rash in face particularly cheeks
23
Q

what group are reteroviruses in and example? (2)

A
  • group VI; single stranded RNA

- eg HIV

24
Q

what are retroviruses and hepadnaviruses?

A
  • they are reverse transcriptase viruses as there is a RNA intermediate before viral proteins can be manufactured
25
Q

what are reverse transcriptases?

A
  • enzymes encoded in retroviruses viral genome
  • the enzyme is responsible for transcription of the viral RNA to produce a dsDNA that can be inserted into the host genome
26
Q

what is antigenic shift?

A
  • process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains
27
Q

what does antigenic shift cause? (4)

A
  • small changes/mutations happen continually over time
  • produces new virus strains that may not be recognised by the body’s immune system
  • difficult to immunise/vaccinate for long term protection
  • hybrid strain causing a pandemic
28
Q

where does the herpes simplex virus infect?

A
  • epithelial cells in the mucosal surface
29
Q

how do herpes simplex viruses replicate and spread on epithelial cells? (2)

A
  • productive replication

- production of progeny virions which spread to infect additional epithelial cells

30
Q

how does reactivation in the neuronal cell body occur for herpes simplex virus? (4)

A
  • initiation of viral lytic gene expression
  • newly formed capsids are transported to the axonal termini
  • infectious virus is release from the axon and infects the epithelial cell
  • resulting in recurrent infection and virus shedding
31
Q

what happens during the replication of HIV? (7)

A
  • fusion of HIV to the host cell surface
  • HIV RNA, reverse transcriptase, integrase and other viral proteins enter the host cell
  • viral DNA is formed by reverse transcription
  • viral DNA is transported across the nucleus and integrates into the host DNA
  • new viral RNA is used as genomic RNA and to make viral proteins
  • new viral RNA and proteins move to the cell surface and a new, immature HIV forms
  • the virus matures by protease releasing individual HIV proteins
32
Q

what is a plaque assay? (4)

A
  • grow a lawn of host cells on dish
  • add virus
  • virus replicate and lyse host cells
  • viral plaques; cytopathic effect
33
Q

what is the HI test? (4)

A
  • haemagglutinin inhibition assay (influenza)
  • measure how well antibodies bind to and thus inactivate influenza viruses
  • RBCs in a solution will sink to the bottom of the assay well and form a red dot at the bottom
  • when an influenza virus is added to the RBC solution, the virus’ haemagglutinin surface proteins bind to multiple RBC and keep RBCs suspended
34
Q

what is ELISA and what is it used for? (2)

A
  • enzyme-linked immunosorbent assay

- uses antibodies and changes colour to identify a substance

35
Q

what are the principles of ELISA? (5)

A
  • antigen on solid phase of ELISA (specific viral protein)
  • antibody in patients’ serum
  • anti-human antibody with an enzyme conjugate
  • enzyme acts on the substrate which changes colour
  • detection system to identify the colour produced
36
Q

what is AZT?

A
  • nucleoside analogue that resembles the nucleotides that are the building blocks of DNA
37
Q

what happens when AZT is used to build DNA? (3)

A
  • it prevents any more from being made and blocks further extension of the growing DNA chain
  • it ‘accidently’ inserts a molecules of zidovudine rather than a nucleoside
  • this terminated the DNA chain
38
Q

what does NNRTI stand for?

A
  • non-nucleoside reverse transcriptase inhibitors
39
Q

what are viral proteinase (protease)?

A
  • an enzyme that cleaves peptide/polypeptide/protein chains to functional proteins (mature virus)
40
Q

what is viral integrase?

A
  • an enzyme that allows for the transfer of HIV cDNA to cellular DNA
41
Q

what are fusion inhibitors?

A
  • an enzymes that prevents HIV envelope fusion
42
Q

what are neuraminidase inhibitors?

A
  • prevents the release of the virons (slow progression of infection)
43
Q

What is the viral genome?

A

either DNA or RNA but never both, can be circular or linear.

44
Q

How do retroviruses work and how can they be treated?

A

They transcribe their DNA into RNA and then transcript back into DNA before it is inserted into the host DNA. HIV is an example and reverse transcriptase has been used to treat this type of retrovirus.

45
Q

Briefly describe how the influenza virus replicates?

A

The virus binds to the host cell and becomes an endosome via endocytosis. In this vesicle ion channels uncoat the virus and its degrades. The RNA is then imported into the nucleus where its mRNA is synthesied. This mRNA leaves the nucleus and meets a ribosome where the viral proteins are synthesised, these proteins then move to the surface of the cell where they are implanted into the plasma membrane, this process is called budding. The virus is then released with a coating made from the host cell.

46
Q

Why does the flu virus change every year?

A

Antigenic drift, a process where one or more different strains of virus combine to form a new subtype with different surface antigens.

Mpharm 1 COPY (59 decks)

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