Chapter 13 Viruses

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Microbiology
Chapter 13
updated 3 years ago by Shaianne09
Grade levels:
College: Third year
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1

General Characteristics of Viruses

  • small size (nm)
  • acellular/noncellular
  • single type of nucleic acid (DNA or RNA)
  • protein coat
  • obligate intracellular parasites
2

Viral Structure

- virion: fully developed virus particle, infections

- nucleic acid

* DNA or RNA

* single-stranded or double stranded (ssDNA, dsDNA, ssRNA, dsRNA)

* linear, circular & segmented

3

Viral Structure: Capsid

  • protein nucleic acid
  • made of capsomeres
  • may have spikes
4

Viral Structure: Enzymes

- use host cell machinery

* drugs that interfere with viral reproduction also disrupt host cell function

- some package their own (viral) enzymes

* we can target these with drugs

5

Viral Structure: Envelope

- naked non-envelope

- enveloped viruses

* phospholipid membrane around capsid

* from host plasma or nuclear membrane

* must stay moist during spread from host to host

6

Viral Structure: Envelope

- viral & host specific proteins/carbs

* adsorption/attachment sites (bind host receptor)

~ naked viruses

~ enveloped viruses

* determine host range

* example: influenza & HIV

7

Attachment

...

8

Hemagglutination

...

9

Antigenic Drift

  • only RNA viruses can go through this
10

Classification

  • nucleic acid
  • size & shape
  • +/- envelope
  • strategy for replication
11

Virus Taxonomy

  • 6 orders -virales
  • 87 families -viridae
  • 19 subfamilies -
  • 248 genera -virus
12

Growth of Viruses

...

13

Virus Plaques

...

14

Viral Multiplication

...

15

Lytic Cycle

...

16

Comparison of Bacterial & Animal Virus Replication

...

17

Virus Entry

...

18

Animal Viral Biosynthesis: DNA Genomes

...

19

Animal Viral Biosynthesis: RNA Genomes

...

20

Release By Budding or Lysis

...

21

Influenza Virus

...

22

Antigenic Shift

...

23

Retrovirus: HIV Virion Structure

...

24

HIV Lifecycle

...

25

HIV Activation

...

26

Inhibition of HIV

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