Virology

Question 1

variolation

Answer 1

early vaccination efforts against smallpox

transfer of puss from smallpox pustules to healthy individuals

Question 2

virus size

Answer 2

small - must use electron microscopy for almost all viruses

influenza is the largest and is the smallest size possible to see on light microscopy

Question 3

can viruses be filtered

Answer 3

yes, can pass through filters and be isolated from bacteria/other organisms

Question 4

are viruses intra or extracellular parasites

Answer 4

obligate intracellular

requires a host cell to replicate - can NOT undergo binary fission

Question 5

are viruses living

Answer 5

no
- can not metabolize
- can not respond on demand
- unable to grow without a host
- no functional ribosomes

Question 6

what kind of genome to viruses have

Answer 6

DNA or RNA

never both

Question 7

viroid

Answer 7

“naked” nucleic acids that encode the viral genome

Question 8

encapsidated virus

Answer 8

viroid + protein capsid

Question 9

capsid

Answer 9

protects the genome and binds to host cells

encoded by genome BUT proteins are produced by host cell apparatus

Question 10

capsid characteristics

Answer 10

• exists host cell by LYSING
• environmentally resistant
• spread via harsh/dry conditions (feces, oral, fomites, dust)

Question 11

enveloped virus

Answer 11

encapsidated virus + envelope

Question 12

envelope

Answer 12

protects the nucleocapsid and binds to the host cells

made of phospholipids, proteins, and glycoproteins

Question 13

envelope characteristics

Answer 13

• phospholipids come from budding off of host cell membrane
• virus embeds its own proteins into the phospholipid layers
• exit host cell by LYSING or BUDDING
• environmentally sensitive
• spread by wet environments (systemic, mucosa)

Question 14

types of viruses

Answer 14

1. dna vs rna
2. double vs single stranded
3. +/- sense (if single strand)

Question 15

central dogma

Answer 15

all genomes get transcribed into mRNA then translated into proteins

Question 16

what are the two ways of classifying viruses

Answer 16

1. antigenic relatedness
2. nucleic acid sequences

Question 17

antigenic relatedness

Answer 17

1. isolated virus gets inactivated to destroy infectivity but remain antigenicity –> forms viral antigen
2. viral antigen immunized into host
3. host forms antibodies
4. serial antibody dilutions performed against other viral antigens to determine relatedness

closely related viruses would bind more of the antibody than others

Question 18

nucleic acid sequencing

Answer 18

1. enveloped virus gets extracted to expose genome
2. genome gets purified to form naked nucleic acid genome
3. PCR used to amplify genome
4. compare to other viruses

Question 19

what is the nomenclature of viruses

Answer 19

family –> genus –> species –> genotype