introduction to viruses

Question 1

what is viral tropism

Answer 1

limited to a single organ ,tissue ,specialized cell type or range of different organs tissues

Question 2

what factors define tropism

Answer 2

the viral glycoproteins (susceptibility)
presence of transcription factors
permissivity

Question 3

name the receptors of HIV

Answer 3

CD4,CCR5,CXCR4

Question 4

what are the cell types of HIV

Answer 4

T cells , macrophages

Question 5

what are the receptors for EBV

Answer 5

CR2

Question 6

What type of cells belong to EBV

Answer 6

B cells

Question 7

what is the receptor for influenza

Answer 7

silaic acid

Question 8

what is the receptor for the rhinovirus

Answer 8

ICAM-1

Question 9

what id the receptor for measles and HH46

Answer 9

CD46

Question 10

what are the steps to viral synthesis and replication

Answer 10

attachment 
penetration
uncoating 
macro molecular synthesis 
postranslational modification of proteins  
assembly of new virus particles 
release

Question 11

what are the early proteins responsible for

Answer 11

replication of nucleic acid

Question 12

what are the late proteins responsible for

Answer 12

formation of the viral capsomers such as structural proteins

Question 13

how are virions released

Answer 13

cell lysis

budding from plasma membrane

Question 14

growth of animal viruses -embryonated eggs

Answer 14

convenient and not expensive
viral suspension is injected into fluid of egg
viral growth detected by death of embryo
used for viral vaccines

Question 15

growth of animal viruses -living animals

Answer 15

mice ,rabbits ,guinea pig
expensive and ethically controversial
used in research

Question 16

growth of animal viruses -cell culture

Answer 16

homogeneous collection of cells
more convenient than egg or animal
virus infection leads to cytophatic effect and plaque formation

Question 17

primary cell culture

Answer 17

heterogeneous
closest to animal organs or tissue
challenging

Question 18

diploid cell strain

Answer 18

relatively homogeneous
further from animal
less hassle than primary cells

Question 19

continuous cell line

Answer 19

easy to maintain in a suspension or as a monolayer
furthest from primary source
most homogeneous tyoe

Question 20

name 4 physical methods of virus detection and quantification in order of most efficient to least

Answer 20

PCR ,Immunoassay ,hemagglutination ,electron microscopy

Question 21

when would we use the focus forming units

Answer 21

this technique is used to quantify viruses that do not cause any plaque forming units generation
florescently labeled antibodies against viral cell

Question 22

what does a defective virus need to infect a host

Answer 22

helper virus

Question 23

satellite virus

Answer 23

subgroup of defective viruses that require complementary function of completely unrelated helper virus

Question 24

what is the helper virus for hepatitis D virus (HDV)

Answer 24

Hepatitis B virus (HBV )

Question 25

viroids are only found in plants : TRUE or FALSE

Answer 25

TRUE

Question 26

How do viroids enter

Answer 26

through wounds or damaged surface

Question 27

how do viroids distribute

Answer 27

they distribute from cell to cell through plasmodesmata

Question 28

prions

Answer 28

transmissible spongiform encephalopathies ,they cause loss of motor control ;encephalitis ;widespread neuronal loss

Question 29

how can prions be acquired

Answer 29

infections;diet transfusipm heredity ;autosomal dominant mutation of PrP spontaneous

Question 30

how do prions function

Answer 30

the conversion from PrPc to PrPsc proceeds via chain reaction and the PrPsc proteins form filamentous aggregates that gradually damage neuronal tissue