micro

Question 1

Basis of Baltimore classification

Answer 1

genome, mode of replication

Question 2

Baltimore classification group

Answer 2

Class 1: ds DNA
Class 2: ss DNA
Class 3: ds RNA
Class 4: ss RNA pos sense
Class 5: ss RNA neg sense
Class 6: ss RNA pos sense w/ ds DNA (retrovirus)
Class 7: ds DNA w/ pos sense, part ss DNA w/ ss RNA (reversiviruses)

Question 3

Structure vs non-structure protein

Answer 3

SP: Make up viral structure, facilitate enter into cell
NSP: enzymes, codes for viral genome

Question 4

Typical structure of virus

Answer 4

nucleic acid inside a capsid subunit (naked) or further inside membrane with spikes

Question 5

replication life cycle of virus

Answer 5

1. attachment
2. Penetration
3. replication of viral genome
4. production of late viral proteins
5. assembly
6. release

Question 6

Cytopathic effect (CPE)

Answer 6

effect of virus replication oh host cells
used as a diagnostic tool

Question 7

how does viruses cause disease

Answer 7

1. replication within host cell leading to damage to cell directly
2. Host defenses lead to cell damage as it tries to clear virus
3. Rotavirus code for toxin proteins

Question 8

Cell lysis

Answer 8

early protein shutdown host macromolecules > Accumulation leads to inhibition of host cell and viral synthesis

Rounding up of cells due to lost of adherence proteins then lysis

Question 9

types of Cytopathic effect

Answer 9

Cell lysis
Syncytia
Inclusion bodies
Transformation

Question 10

Viral infection steps

Answer 10

1. invade host
2. replicate in cell
3. overcome/evade local defenses
4. spread to other cells and areas
5. replicate again
6. exit host to infected another host

Question 11

immune cells responsible for fighting viral infections

Answer 11

Cytotoxic T cells, which targets cells with virus antigenic marker on MHC class 1

Question 12

how does virus evade immune system

Answer 12

• viruses poorly immunogenic
• don’t display enough antigen on cell surface
• inactivate T and B cells as well as macrophages
• interfere with MHC
• antigen production to bind neutralizing antibodies
• mutation that changes antigenic protein of virus

Question 13

incubation time for rabies

Answer 13

28-140, Long

Question 14

what is RO

Answer 14

Reproduction number
ave number of secondary cases generated from the one primary case

Question 15

Viral symmetry

Answer 15

Icosahedral: all DNA animal viruses except poxvirus
Helical: ssRNA, need envelope
Complex

Question 16

Syncytia

Answer 16

plasma membrane fuse to form giant multinucleated cells

Question 17

inclusion bodies

Answer 17

bodies that appear in cells as result of viral infection (aggregation of mature viral particles)

Question 18

Transformation

Answer 18

cancerous or pre-cancerous like changes, breakdown of cellular regulation due to viral protein

Question 19

different types of infection

Answer 19

Acute non-persistent: self-limiting, most colds
Persistent: infection not terminated, HIV integrate into host DNA
Latent: some might never cause disease or have episodes, herpes

Question 20

Virus detection methods

Answer 20

Direct: microscope
virus isolation: cell culture
immunological: serology
molecular methods > PCR, microarray, sequencing

Question 21

Microscope method

Answer 21

electron: expensive, detect unknown virus
Light: histology section, poor sensitivity and specificity, indirect (changes in cell not the actual virus)

Question 22

Cell line type

Answer 22

Primary: taken from animal/human and grown, last around 50-70 passages due to shortening of telomere.

Continuous: cancer cell, no limit

Question 23

Hayflick limit

Answer 23

the number of times (about 50) that normal human embryonic cells can divide before they succumb to senescence

Question 24

viral serology

Answer 24

Indirect method, detect antibody produced
- can determine immune status, pre/post vaccine
-window period for IgM and IgG

Question 25

Nucleic acid detection

Answer 25

fast, sensitive, specific typing by sequencing
- need virus to be present (no past infection)

Question 25

PCR type

Answer 25

multiplex: multiple set of primers
nested: increase sensitivity and specificity but prone to contamination
reverse transcription: initial conversion of RNA to DNA (30mins)

Question 26

Cycle threshold

Answer 26

cycle when fluorescence becomes detectable
Hight CT = low amount of starting template
Low CT = high amount of starting template

Question 27

HPV family

Answer 27

Papillomaviridae

Question 28

HPV infectious cycle