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Pathogenic microbiology > Lecture 12 > Flashcards

Lecture 12 Flashcards

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Biology 101 flashcards
1
Q

what kind of virus causes influenza?

A

orthomyxoviruses that a family of RNA viruses that include influenza A, B, and C

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2
Q

what does the helically symmetric nucleocapsid of the influenza virus consist of?

A

a nucleoprotein and a multipartite genome of single stranded antisense RNA

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3
Q

what does the envelope that encloses the nucleocapsid of the virus consist of?

A

a lipid bilayer, two surface glycoproteins, a hemagglutinin (HA), and a neuraminidase (NA)

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4
Q

what does the HA protein do?

A

is it involved in attachment and membrane fusion in the endosome of the infected cell

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5
Q

what does the NA do?

A

its a glycoprotein located on the surface of the virus that cleaves the attachment between the hemagglutinin on the viral surface and the sialic acid receptor on the host cell membrane. this results in the release of the virion from the cell

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6
Q

how are influenza virus determined between A, B, and C?

A

by their internal antigens (M1 and NP proteins) that are the type specific proteins (type specific antigens)

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7
Q

what is the difference between the three strains of influenza?

A

type C is antigenetically stable

types A and B, the HA and NA antigens undergo genetic variation that is the basis for the emergence of new strains

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8
Q

what does being enveloped do for the influenza virus?

A

makes it readily inactivated by nonpolar solvents and by surface active agents

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9
Q

what are the 6 types of vaccines?

A
  1. live
  2. live attenuated
  3. killed inactivated
  4. toxoids
  5. cellular fraction
  6. recombinant
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10
Q

what are the 6 features of effective vaccines?

A
  1. safe
  2. protective
  3. gives sustained protection
  4. induces neutralizing antibody
  5. induces protective T cells
  6. practical considerations
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11
Q

what is the primary target for influenza viruses?

A

epithelial cells in the upper and lower respiratory tract

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12
Q

how does the influenza virus get into the nucleus?

A
  1. HA binds to sialic acid residues on glycoproteins or glycolipids on cell surface
  2. binding initiates uptake through receptor mediated endocytosis
  3. vesicles formed fuse with endosomes
  4. low pH inside endosomes triggers fusion reaction between viral envelope and endosome membrane
  5. low pH causes conformation change in HA this results in formation of a pore through which the virus is delivered in cytosol
  6. RNP complexes in cytosol are transported to nucleus
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13
Q

once inside the nucleus, what does the virus do?

A
  1. negative sense viral RNAs are transcribed to positive sense RNAs by the transcriptase carried with the RNPs
  2. negative sense viral RNAs serve as templates for production of positive sense RNA copies, which then direct synthesis of multiple new copies of negative sense viral RNAs
  3. these negative sense RNAs are transported back to the cells cytosol for assembly of new virus particles
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14
Q

once viral particles are transported into the nucleus what happens?

A
  1. synthesis of viral envelope proteins (HA, NA, and M2) in cytosol
  2. growing polypeptide chains are transported to the ER
  3. proteins are then glycosylated and folded into trimers and tetramers
  4. proteins are transported through golgi and finally to the plasma membrane
  5. Viral RNPs form and following a sequence of events virions bud from the host cell
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15
Q

Use diagram/picture on slide 15!

A

its a good review and has some extra facts

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16
Q

typically, what strains make up the flu shot?

A

2 influenza A strains and 1 influenza B

17
Q

who makes the final say about which flu vaccines are sold each year?

A

FDA

18
Q

what are some traits of inactivated viruses?

A
  1. example is salk polio virus treated with formaldehyde so that it cant reproduce in host
  2. use of the whole virus stimulates immunity to antigens in their natural conformation on the virus surface
19
Q

what are some traits of live, attenuated vaccines?

A
  1. example is MMR (measle, mumps, and rubella)
  2. generally more potent than killed ones
  3. made by the pathogen being grown in animals or tissue culture under conditions that make it less virulent
20
Q

what are subunit vaccines?

A
  1. they contain purified antigens rather than the whole organism
  2. not infectious
  3. can be safely given to immunosuppressed people and are less likely to induce immune reactions that cause side effects
21
Q

what are the disadvantages of subunit vaccines?

A
  1. may not retain their native conformation, so that antibodies produced against the subunit may not recognize the same protein on the pathogen surface
  2. isolated protein does not stimulate the immune system as well as the whole organism vaccine
22
Q

what is a recombinant vaccine?

A
  1. vaccine that in which genes for desired antigens are inserted into a vector, usually a virus, that has very low virulence
  2. techniques could be used to make safer attenuated pathogen vaccines
23
Q

how does the recombinant vaccine work?

A

vector expressing the antigen may be used as the vaccine, or the antigen may be purified and injected as a subunit vaccine

24
Q

what is special about the Hep B virus vaccine (HBV)?

A
  1. it is a recombinant subunit vaccine

2. it is much safer than using attenuated HBV

25
Q

how are recombinant HB vaccines made?

A
  1. combine HB antigen producing gene with plasmid DNA cut with restriction enzymes to form recombinant DNA
  2. introduce recombinant DNA into a yeast cell
  3. recombinant yeast cell multiplies and produces HB antigen in fermentation tank
  4. extraction and purification of HB vaccine
26
Q

what are some traits of DNA vaccines?

A
  1. new and still experimental
  2. genes for desired antigens are located and cloned
  3. both humoral and cellular immunity can be induced
27
Q

how do DNA vaccines work?

A
  1. DNA is coated onto minute metal projectiles and injected into the muscle of an animal
  2. injection is done using a gene gun
  3. some muscle cells transcribe and translate the pathogen DNA which stimulates immune system

Pathogenic microbiology (12 decks)

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