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Exam #3 > Norma > Flashcards

Norma Flashcards

1
Q

What is a virus?

A
  • small (go through a filter)
  • small genome packaged as a nucleoprotein
  • a capsid holds in the nucleoprotein
  • may have an outer plasma membrane (envelope)
  • obligate parasites
  • classified by the disease they cause or the organ system they infect
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2
Q

List the symptoms that can lead to a differential containing a viral infection?

A
  • rash
  • fever (most viruses)
  • conjunctivitis
  • pharyngitis (especially respiratory viruses)
  • hepatitis
  • pneumonia
  • bronchiolitis
  • adenopathy
  • parotitis
  • meningoenecephalitis
  • arthritis
  • congenital or perinatal disorders
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3
Q

What are the categories and types used in the Baltimore classification for viral identification?

A
  • DNA viruses - Double stranded (ds) DNA, Single stranded (ss) DNA
  • RNA viruses - dsRNA, ssRNA(+), ssRNA(-)
  • Retro-transcribing viruses - ssRNA (RT), dsDNA (RT)
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4
Q

What is a serotype?

A
  • A subset of a species

- when immunity developed it will only be to that specific serotype

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5
Q

What is the classification of diagnosis used for?

A
  • to determine how to treat the disease

- to determine the best method of disinfection or prevention of infection

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6
Q

What determines virus classification?

A
  • disease produced
  • physical characteristics (structure, envelope)
  • Genome sequence is primary characteristic
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7
Q

What is the importance of the outer envelope?

A
  • developed during budding of the virion

- contains glycoproteins that interact with the receptors on the eukaryotic cells

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8
Q

What are the differences between RNA and DNA viruses in their speed of replication?

A
  • RNA viruses evolve rapidly but at a high error rate due to RNA-dependent-RNA-polymerase
  • DNA viruses evolve more slowly due to the need to be in the nucleus and use the host cells transcription enzymes but at a low error rate
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9
Q

What is often packaged within a virus particle?

A
  • nucleoprtein - protein and genome complex
  • polymerase (RNA/DNA dependent)
  • protease for further capsid breakdown and to cleave polycystronic mRNA
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10
Q

What are the typical shapes for capsids?

A
  • icosahedral and helical

- complex viruses

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11
Q

What is the epidemiology of viral infections

A
  • present on fomites
  • present on droplets - may be inhaled or contact fomites
  • present in body fluids
  • transmitted by vectors
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12
Q

What are some modes of transmission for viruses?

A
  • respiratory
  • fecal-oral
  • sexual transmission
  • direct contact
  • urine-associated transmission
  • parenteral transmission
  • vertical - mother to child
  • arthropod-borne transmission
  • zoonotic infections
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13
Q

What is tropism?

A
  • classifying a virus by the organ system that it infects and replicates in
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14
Q

What are the targets of antiviral therapy?

A
  • polymerases
  • viral proteases
  • viral capsids
  • immune activators (interferon beta)
  • immunoglobulin treatment (antiviral antibodies)
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15
Q

How does ssRNA (+) viruses replicate?

A
  • virus binds and enter cell and releases RNA
  • RNA is then translated (cells normal translation is stoped)
  • virion RNA then copied by RNA dependent RNA polymerase
  • both occur in the cytoplasm and then cause lysis of the cell
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16
Q

How does a DNA virus replicate?

A
  • virus binds and enters cell and releases viral DNA into the nucleus
  • transcription of the viral DNA by host’s enzymes
  • production of DNA rpeplication proteins and capsid proteins
  • viral DNA and viral proteins are packaged within a capsid and then bud off from the cell membrane
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17
Q

How does a retrovirus replicate?

A
  • virus binds and enters cell
  • reverse transcriptase make a cDNA copy of viral genome and releases cDNA into nucleus
  • viral DNA is then integrated into the host genome and replication of the cDNA and viral protein production occur
  • viral RNA and proteins are encapsulated and then bud off from the plasma membrane of the cell
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18
Q

What is the difference between primary infection site, secondary infection site and viremia?

A
  • Primary - site of first replication of virus
  • Secondary - pathogenic virus replication in secondary organs after viremia
  • Viremia - virus circulating in the blood stream
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19
Q

What is the difference between acute an chronic viral infection?

A
  • Acute - can be cleared by the body

- Chronic - isn’t cleared and virus remains within cell - dormant or persistent

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20
Q

What is meant by persistent viral infections?

A
  • infections that are not cleared after the acute period of infections and leads to chronic infection
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21
Q

What is meant by a latent viral infections?

A
  • infections that enter a dormant phase where the virus does not replicate but remains uncleared from the body
  • will have episodes of reactivation in which the virus replicates and causes symptoms
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22
Q

What are perinatal viral diseases?

A
  • infection before birth from the mother, at birth or from breast milk after birth
23
Q

What are some perinatal diseases caused by viral infections?

A
  • HIV - leads to AIDS
  • Parvovirus - miscarriage, hydrops fetalis
  • Rubella - hearing loss and other teratogenic effects
  • CMV - hearing loss and neurologic complications
  • Herpes simplex
  • HBV - leads to chronic infection but premature manifestations
  • Hep E - increased mortality of pregnant women
  • Enterovirus - multi-organ disease of neonates
24
Q

What are some connections between cancer and viruses?

A
  • Hep B,C - hepatocellular carcinoma, cholangiocarcinoma
  • HPV - cervical cancer and oropharyngeal cancer
  • Epstein-Barr virus - lymphoma
  • HHV8 - Karposi’s sarcoma, lymphoma
  • HTLV1 - T-cell lymphoma
25
Q

What are causes of epidemics of viral infections?

A
  • re-emerging viral infections
  • viruses new to human beings
  • new medical, cultural and agricultural practices results in new transmission
26
Q

What is the difference between indirect and direct testing?

A
  • indirect testing is a test for immune consequences of viral infections
  • direct testing is for the virus, viral protein or nucleic acid
27
Q

What are three presumptions of signs/symptoms and diagnostics of virology?

A
  • some presentations are definitive without testing
  • during outbreaks, pts with the same symptoms will have the same infections
  • some tests are too expensive or take to long
28
Q

What are some direct methods of viral infection detection?

A
  • culture live virus
  • electron microscopy for viral structures
  • antigen (protein fragments)
  • DNA/RNA genome
29
Q

What are some characteristics of culturing live virus?

A
  • expensive and time consuming
  • not always possible
  • usually type of virus is needed to be known
  • morphology can be examined
  • determine cytopathic effect
30
Q

What is the cytopathic effect?

A
  • when virus is within the cell the cell will die
31
Q

What are some characteristics of electron microscopy?

A
  • allows identification of the viral family but not serotype
32
Q

What is hemagglutination?

A
  • a quantification test

- adding virus and RBC and see if agglutination occurs and if so then the virus has that capability

33
Q

What are some characteristics of antigen detection?

A
  • uses a virus specific antibody
  • antibody on a well will bind to the viral antigen and then a second AB (with attached indicator) will bind to the antigen
  • amount of indicator within wells will show amount of viral antigen
34
Q

What are some characteristics of Direct Fluorescence Assay?

A
  • an antibody that has fluorescence attached is added to a specimen and when bound to the viral antigen the fluorescence will be visible
35
Q

What is the advantage of PCR and RT-PCR?

A
  • the procedure is extremely sensitive and specific
36
Q

What are some indirect methods of viral infection detection?

A
  • ELISA
  • Indirect immunofluorescence assay
  • detection of specific AB types (titer draws)
  • Western blot
37
Q

What are some examples of upper respiratory infection?

A
  • rhinitis
  • pharyngitis
  • sinusitis
  • laryngitis
38
Q

What are some examples of lower respiratory infections?

A
  • bronchitis
  • bronchiolitis
  • pneumonia
39
Q

What are some viral infections resulting in the common cold?

A
  • rhinovirus
  • coronaviruses
  • Respiratory syncytial virus (winter)
  • Adenovirus (summer)
  • Parainfluenza virus (winter)
40
Q

Discuss some childhood respiratory infections and their characteristics.

A
  • rhinovirus - associated with asthmatic episodes
  • parainfluenza virus - many types, seasonal
  • Respiratory syncytial virus - pneumonia
  • Metapneumovirus - LRI
  • Human herpes virus 6 - interstitial pneumonia
  • Enterovirus infections - summer cold
41
Q

What are the types of Parainfluenza virus?

A
  • HPIV-1,2 - childhood croup (fall)
  • HPIV-3 - spring and early summer
  • HPIV-4 - less common
42
Q

What are some common routes of transmission of respiratory viruses?

A
  • contact with secretions
  • contact with aerosolized microdroplets
  • hands to the eyes
  • inhalation
  • fomites
43
Q

What are three respiratory virus families?

A
  • Orthomyxoviruses - influenza
  • Paramyxoviruses - parainfluenza (mumps), morbillivirus (measles), respiratory syncytial virus, metapneumovirus
  • Adenoviruses
44
Q

What are the characteristics of RSV?

A
  • most common respiratory virus in infants
  • extreme pathogenic effect on reparatory epithelium
  • recovery is longer than bacterial infections
45
Q

What are the characteristics of Adenoviruses?

A
  • many serotypes
  • can cause myocarditis in children
  • cause conjunctivitis
46
Q

What are some characteristics of Orthomyxoviruses?

A
  • contain hemagglutinin proteins and neuraminidase proteins
  • contains 3 types A, B, C
  • negative strand genomic RNA
47
Q

Describe the subtypes of influenza viruses.

A
  • A - pandemic and seasonal - between humans and animals - LRI
  • B - seasonal - humans only - LRI
  • C - mild illness - URI
48
Q

What are the actions of the orthomyxovirus proteins?

A
  • Hemagglutinin - allows attachment

- Neuraminidase - allows release of newly made virus particles from cells

49
Q

What is the idea of antigenic drift?

A
  • mutations that occur during replication will lead to a drifting into new antigenic shapes
  • virus can escape the immune system
50
Q

What is the idea of antigenic shift?

A
  • genetic changes occur that allow a virus to jump from species to species
  • can occur with or without genetic mixing and may include an intermediate host
51
Q

What are pandemics?

A
  • caused when a virus enters the human population and spreads world wide
52
Q

What causes a pandemic?

A
  • a novel virus with little/no immunity
  • capability to replicate in humans
  • pathogenic and virulent in humans
  • capable of human to human transmission
53
Q

What is the difference between the vaccines and antivirals?

A
  • vaccines are the best prevention option but efficacy is dependent ton a correct match
  • antivirals are meant to stop the spread

Exam #3 (9 decks)

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