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Flashcards in Replication of Virus Deck (48)
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1

what do normal cells transcribe DNA in the nucleus to?

positive single stranded mRNA

2

what must viruses produce in order to be recognized by cellular ribosomes

mRNA -- so it can be translated

3

examples of dsDNA viruses

polyoma, papilloma, adeno, herpes, pox

4

what is the promoter for polyomavirus

SV40

5

what are the different classes of virus according to the genome they carry

class I: dsDNA virus
class II: ssDNA virus
class III: dsRNA
class IV: + ssRNA virus
class V: -ssRNA virus
class VI: +ssRNA virus, RT
class VII: dsDNA virus, ssRNA intermediate, RT

6

how do class I: dsDNA virus make +mRNA

they use host CELLULAR ENZYMES to transcribe IE (immediate early) and/or Early (E) mRNA

7

what happens with the IE mRNA

they get transcribed to IE proteins --> transcribed to E-mRNA ---> translated to E-proteins

8

what are the functions of E-proteins

they replicate parental DNA and late (L) mRNA --> translate to L proteins ---> assemble into capsids

tend to have regulatory functions in general

9

what does the capsid do in dsDNA once it is formed

incorporate the viral DNA to make mature virus

10

what is the exception to the dsDNA mechanims

pox virus -- it enters the cell with all the machinery it needs and commands membrane to come to them then poke holes to get out of the cell

11

where are the capsid proteins for dsDNA virus from?

L (late) genes

12

example of a class II: ssDNA virus

parvovirus

13

where does replication of ssDNA virus occur and what happens with the strands of DNA

nucleus of actively dividing cells: go from a (-) strand to a template for a (+) strand

14

mechanism to form mRNA in ssDNA virus

ssDNA ---> dsDNA (using cellular enzymes)
dsDNA --> mRNA (using cellular enzymes)
mRNA --> viral proteins

15

what is the function of the viral protein

they make up capsids which surrounds viral DNA in progeny virus

16

are there immediate early and early protein produced in ssDNA viruses

nope

17

shape of parvovirus and are they enveloped or not

icosahedral and nah not enveloped

18

how are the viruses released in ssDNA viruses

via lysis of cell

19

what is the consequence of dsRNA not being able to function as an mRNA

Class III viruses must package an RNA polymerase to make mRNA after infection of host cell

(genomes segmented)

20

type of polymerase is used in dsRNA viruses

RNA dependent RNA polymerase

RNA dependent - because that is the type of genome it is reading
RNA polymerase - because that is the type of genome it is making

21

example of dsRNA virus

reovirus, birnavirus, rotavirus (member of reovirus)

22

mechanism of dsRNA virus when forming mRNA

dsRNA is transcribed to viral mRNA (v-mRNA) using a RNA dependent RNA polymerase

v-mRNA gets translated to structural and non structural proteins

23

what is an immature capsid in dsRNA virus and why is it formed so early

immature capsid are formed from the resulting viral proteins -- capsid formed early because dsRNA looks foreign to the body so for protection, it needs the immature capsid

RNA replication will be concurrent with the packaging of genome segments

24

what happens once mRNA is packaged into the immature capsid

mRNA (viral) is copied within the capsid to form more dsRNA so more mRNAs can be formed

25

what does rotavirus cause in young children and infants

acute gastroenteritis

26

where does replication of dsRNA occur

cytoplasm

27

example of +ssRNA virus

Picornavirus, togavirus, coronavirus, flaviviruses

28

why is a +ssRNA virus considered directly infectious

+ss vRNA can be infectious without viral proteins

the ends of the genome is modified 􏰁--> 5’ end - protein or methyl. nt cap and 3’ end by poly A

once modified, they look exactly like mRNA

29

what are the two types of +ssRNA virus

IVa +ssRNA and IVb +ssRNA

30

difference between the two types of +ssRNA virus

IVa: the infectious +ssRNA gets translated into one polyprotein which is then cleaved by proteases into multiple viral proteins

IVb: the infectious +ssRNA gets translated into several proteins