Virus replication and cultivation of viruses -- L2

Question 1

What are the 7 stages of viral replication?

Answer 1

1) attachment
2) penetration
3) uncoating
4) synthesis
5) assembly
6) maturation
7) release

Question 2

viral proteins on the capsid or phospholipid envelope interact with specific receptors on the host cells surface -so virus attaches to the host cell happens at what stage of viral replication?

Answer 2

ATTACHMENT

Question 3

Is attachment reversible or irreversible?

Answer 3

reversible

Question 4

a virus can only infect the cells which have the correct receptor

Answer 4

attachment specificity

Question 5

binding specificity limits what?

Answer 5

the virus to only infecting certain cell types within their host

Question 6

determines cell type specificity happens at what stage of viral replication?

Answer 6

attachment

Question 7

Redundancy in ligand-receptor combinations happens at what stage of viral replication?

Answer 7

attachment

Question 8

the process of attachment to a specific receptor can result in conformational changes in viral capsid proteins and lipid envelope that results in the fusion of viral and cellular membrane happens at what stage of viral replication?

Answer 8

penetration

Question 9

The main step of penetration is crossing the ___?

Answer 9

plasma membrane

Question 10

Receptor-mediated endocytosis

Answer 10

penetration

Question 11

Fusion with Plasma membrane happens at what stage of viral replication?

Answer 11

penetration

Question 12

Direct penetration of a genome happens at what stage of viral replication?

Answer 12

penetration

Question 13

Is penetration reversible or irreversible?

Answer 13

irreversible once the viral particle penetrates into the cell it cannot come out

Question 14

the viral capsid is removed and degraded by viral enzymes or host enzymes releasing the viral genomic nucleic acid material inside the cell happens at what stage of viral replication

Answer 14

uncoating

Question 15

Viral DNA or RNA has to be released from the surrounding capsid happens at what stage of viral replication

Answer 15

uncoating

Question 16

The various sites that uncoating can happen at:

Answer 16

– At the cell surface
– Within a cytoplasm
– At a nuclear pore
– Within a nucleus

Question 17

TRUE OR FALSE: Uncoating can be complete or incomplete

Answer 17

TRUE

Question 18

a large amount of viral proteins and viral nucleic acid is produced inside the host cell happens at what stage of viral replication

Answer 18

Synthesis

Question 19

involves transcriptions or generation of positive messenger RNAs (mRNAs) from their genomes and the use of host ribosomes to translate the viral mRNA into viral proteins happens at what stage of viral replication

Answer 19

Synthesis

Question 20

Viral nucleic acid is packed into viral protein coat to form large number of viral particles happens at what stage of viral replication

Answer 20

Assembly

Question 21

the viral particles undergo structural changes in the protein coat until they become infectious happens at what stage of viral replication

Answer 21

Maturation

Question 22

All the infectious virions are released from the host cell via bursting of the host cell or budding (OR CELL LYSIS) of the host cell happens at what stage of viral replication

Answer 22

Release

Question 23

Viruses only replicate in ____ cells

Answer 23

living

Question 24

List examples of how we cultivate viruses:

Answer 24

– Experimental animals
– Avian embryos (in eggs)
– In vitro Cell culture
– In vitro Organ culture

Question 25

why are animals still used for virus research?

Answer 25

1) Animal models for viral pathogenesis and host immune responses 2) vaccine testing 3) production of reagents

Question 26

Are avian embryos still used for isolation of certain viruses and why?

Answer 26

Yes because they are bacteriologically sterile and Immunologically incompetent

Question 27

What 3 isolation viruses are used for research in avian embryos?

Answer 27

– Influenza virus – ILT – Poxviruses

Question 28

What are the 4 types of cell cultures:

Answer 28

1) primary cell cultures 2) secondary cell cultures 3) continuous cell lines 4) organ cultures

Question 29

What type of cell culture is prepared directly from tissues but difficult to establish, time consuming and expensive?

Answer 29

primary cell culture

Question 30

What type of cell culture are primary cells passaged in vitro for a limited number of passages?

Answer 30

secondary cell culture

Question 31

What type of cell cultures are specialized techniques that are rarely used?

Answer 31

Organ culture

Question 32

What type of cell culture is easy to work with, less susceptible to viral infections, and have immortal cell lines?

Answer 32

continuous cell lines

Question 33

What type of cell culture is used 99% of the time?

Answer 33

continuous cell lines

Question 34

Viruses posses the following characteristics: a. Viruses contain both DNA and RNA. b. The viral nucleic acids are enclosed within the nucleus inside the viral particle. c. The viral nucleic acids are used to generate viral mRNA within the host cell. d. Viruses contain ribosomes, which are released into the host cell and used for viral protein synthesis. e. All viruses can be cultured in vitro in the appropriate cell culture system.

Answer 34

c. The viral nucleic acids are used to generate viral mRNA within the host cell.

Question 35

non-specific binding of viral particle to the cell membrane – random initial virus-cell contact

Answer 35

Adsorption

Question 36

Which of these stages in the viral replication cycle is least likely to be targeted by antiviral drugs? a. Adsorption. b. Attachment. c. Uncoating d. Synthesis e. Release.

Answer 36

a. Adsorption.

Question 37

The main advantage of using virus isolation over the molecular based diagnostic assays such as PCR is that: a. Virus isolation is quicker than PCR. b. Virus isolation is cheaper than PCR. c. Virus isolation requires less sophisticated equiment and fewer skills than more advanced tests such as PCR. d. Unlike PCR, virus isolation demonstrates the presence of live virus in the sample. e. Unlike PCR, virus isolation provides immediate definitive identification of the virus, based upon the type of a cytopathic effect (CPE) produced in cell culture

Answer 37

d. Unlike PCR, virus isolation demonstrates the presence of live virus in the sample.

Question 38

# Choose the least correct statement regarding the attachment of the virus to the host cell: a. Attachment is necessary for viral entry into the cell. b. Attachment step is one of the important determinants for viral tissue tropism and host range. c. Attachment relies on specific binding between viral and host proteins. d. Attachment is immediately followed by penetration of the virus into the host cell. e. Attachment step cannot be blocked as viruses typically use a wide variety of host receptors for attachment and entry.

Answer 38

e. Attachment step cannot be blocked as viruses typically use a wide variety of host receptors for attachment and entry.