Viruses

Question 1

what are some characteristics of viruses?

Answer 1

miniscule

acellular

have DNA or RNA

cause infection in humans, animals, plants, bacteria

no metabolic pathway

cause most diseases in industrialized world

neither grow nor respond to environment

obligate intracellular parasites (can’t reproduce independently)

no cytoplasmic membrane, organelles, cytoplasm

Question 2

examples of virus families & what they can cause

Answer 2

Paramyxoviridae - mumps

Coronaviridae - covid-19

Question 3

one virus particle

Answer 3

virion

Question 4

nucleic acid surrounded by protein coat

Answer 4

nucleocapsid

Question 5

how can viral genomes differ from one another?

Answer 5

DNA or RNA
linear or circular

one piece or segmented

Question 6

the capsid is made of __________

Answer 6

capsomeres

Question 7

what is the difference between naked & enveloped viruses?

Answer 7

enveloped have a phospholipid bilayer around their nucleocapid acquired from a host cell

naked do not

Question 8

are naked or enveloped viruses tougher?

Answer 8

naked

Question 9

do naked or enveloped viruses have more of an advantage inside the host?

Answer 9

enveloped

Question 10

what are an enveloped virus’s advantages?

Answer 10

hides it from immune system

can fuse with cell membrane to infect it

Question 11

what can damage an enveloped virus?

Answer 11

heat, freezing, pH change, chemical disinfectants, lipid solvents

Question 12

what do some viruses have that help them attach to host cells?

Answer 12

glycoprotein spikes

Question 13

3 virus shapes

Answer 13

icosahedral

helical

complex

Question 14

5 steps of animal virus replication

Answer 14

attachment

penetration & uncoating

synthesis of viral proteins & replication of genome

assembly

release

Question 15

viruses need __ receptors on a cell’s surface to attach

Answer 15

2

Question 16

how do enveloped vs naked viruses attach?

Answer 16

enveloped - spikes attach to cell’s receptors

naked - capsid attaches to cell’s receptors

Question 17

how do nakes vs enveloped viruses attach?

Answer 17

naked: capsid attaches to receptors on cell
enveloped: protein spikes attach to receptors on cell

Question 18

how do enveloped viruses penetrate cell?

Answer 18

fusion with cell membrane

endocytosis

Question 19

how do naked viruses penetrate cell?

Answer 19

direct penetration - genome directly through cell membrane

endocytosis

Question 20

explain uncoating

Answer 20

viral nucleic acids and enzymes are released from protein coat

RNA remains in cytoplasm, DNA goes to nucleus

Question 21

explain replication of DNA viruses

Answer 21

mostly occurs in nucleus

virus encodes its own enzymes - DNA polymerase

may embed themselves in host’s genome and become latent viruses/proviruses

Question 22

explain replication of RNA viruses

Answer 22

occurs in cytoplasm

uses viral enzyme replicase (same as RNA polymerase)

many mutations occur (lack of proofreading)

Question 23

explain reverse transcribing viruses

Answer 23

used by retroviruses

encodes enzyme reverse transcriptase

synthesizes DNA from a strand of RNA

also become proviruses/latent viruses

Question 24

examples of reverse transcribing viruses

Answer 24

HIV

HTLV

Question 25

examples of RNA viruses

Answer 25

influenza SARS-CoV-2

Question 26

examples of DNA viruses

Answer 26

herpes human papilloma virus

Question 27

explain assembly

Answer 27

virus particles assembled to form viruses

Question 28

what are the 2 types of release?

Answer 28

budding - used by enveloped viruses - triggers apoptosis lytic cycle - used by naked viruses - body's immune defenses may lyse infected cell

Question 29

what are the 2 types of viral infection?

Answer 29

acute - sudden onset, short duration persistent - lasts years to life

Question 30

what are 2 types of persistent infection, and examples?

Answer 30

chronic - continuous production of viral particles - Hepatitis B latent - viral genome remains silent in cell until triggered to reactivate - herpes

Question 31

pathogenesis of herpes

Answer 31

initially affects epithelial cells - slow-spreading skin lesions then infectsneurons - travels up neurons into specific ganglia

Question 32

viruses caus \_\_\_% of human cancers

Answer 32

20-25%

Question 33

what are oncogenes?

Answer 33

genes that can transform a cell into a tumor cell

Question 34

how can viruses cause cancer? (3 ways)

Answer 34

carry copies of oncogenes in their genomes promote oncogenes in host interfere with tumor repression

Question 35

6 examples of cancer-causing viruses and their cancers

Answer 35

human papillomavirus (HPV) - cancer of cervix, vulva, vagina, penis, anus, oropharynx hepatitis B - liver cancer hepatitis C - liver cancer Epstein-Barr - cancer of nasopharynx, Burkitt lymphoma herpesvirus type 8 - Kaposi sarcoma human t-lymphocyte virus (HTLV) - leukemia, lymphoma

Question 36

2 ways we can grow viruses

Answer 36

human cell culture embryonated chicken eggs

Question 37

common cold infects the...

Answer 37

upper respiratory tract

Question 38

common cold viruses

Answer 38

rhinoviruses coronaviruses adenoviruses

Question 39

pathogenesis of common cold

Answer 39

respiratory epithelial cell destruction

Question 40

common cold transmission & incubation

Answer 40

droplet, direct, indirect, airborne (maybe) 24-48hrs

Question 41

what is the biggest health concern with common colds?

Answer 41

secondary infections

Question 42

influenza infects...

Answer 42

upper & lower respiratory tract

Question 43

type of influenzavirus

Answer 43

A, B, C in humans

Question 44

influenza pathogenesis

Answer 44

destroys respiratory epithelium

Question 45

transmission & incubation of influenza

Answer 45

droplet, direct, indirect, airborne (likely) 48hrs

Question 46

antivirals for influenza work during _______ stages and include 2 drugs:

Answer 46

early stages Tamiflu Zofluza

Question 47

2 types of protein spikes on influenzaviruses

Answer 47

hemagglutinin neuraminidase

Question 48

this type of influenza caused the Spanish Flu and Swine Flu outbreaks

Answer 48

H1N1

Question 49

2 mechanisms by which influenzavirus mutates

Answer 49

antigenic drift - random mutations occuring in types A & B antigenic shift - mixture of genes from two strains of type A

Question 50

what can cause gastroenteritis?

Answer 50

norovirus rotavirus other microbes

Question 51

gastroenteritis transmission

Answer 51

fecal-oral

Question 52

gastroenteritis pathogenesis

Answer 52

destroys epithelium of small intestine interferes with secretion and absorption of fluid and nutrients

Question 53

What is R₀?

Answer 53

reproductive ratio how many people one person can infect

Question 54

What is S_I?

Answer 54

series interval period of time from first symptoms of person 1 to first symtoms of person 2

Question 55

which cells does SARS-CoV-2 target?

Answer 55

Type II pneumocytes

Question 56

what are signs and symptoms of Covid-19?

Answer 56

dyspnea (SOB, increased respiration rate) hypoxemia productive cough fever tachycardia systemic inflammatory response syndrome hypotension multisystem organ failure