Intro To Virology

Front 1

What is the capsid and what is it made of?

Back 1

Protein coat that surrounds the viral genome composed of repeating protein aggregates (capsomeres) and other proteins such as glycoproteins for host recognition and/or enzymatic function

Front 2

True/False.

Capsid is stable and resistant to environmental factors such as drying, detergents, etc.

Back 2

True

Front 3

ds DNA viruses

Back 3

most pathogenic DNA viruses are dsDNA
Typically transcribed/translated in the host nucleus *EXCEPT poxviruses

Front 4

ss DNA viruses

Back 4

translated in dsDNA in host cell prior to trxn/trsln

Front 5

partially dsDNA

Back 5

ssDNA regions are filled in before the genome enters the host cell nucleus
ex. hepadnaviruses (HepB)

Front 6

dsRNA

Back 6

Transcribed to + ssRNA and - ssRNA

(+RNA acts as mRNA)

Front 7

+ssRNA

Back 7

Can be translated directly into protein
--> like mRNA

Front 8

-ssRNA

Back 8

Serves as a template for +RNAs or DNA

Front 9

Ambisense ssRNA

Back 9

Has + and - sense regions on the same strand

Front 10

What are integral capsid proteins?

Back 10

proteins used for host recognition or enzymatic function
*NOT capsid proteins

Front 11

What are encapsidated proteins?

Back 11

Nucleic-acid binding proteins

ex. polymerases

Front 12

Non-enveloped OR enveloped are more resistant to heat, acids, drying, etc.?

Back 12

Non-enveloped

Front 13

Where is the envelope derived from for enveloped viruses?

Back 13

Derived from the host cell membrane, typically during exit from the host cell

Front 14

What are matrix proteins?

Back 14

Structural protein between the envelope and capsid that links them together.

Front 15

Why are enveloped viruses more susceptible to inactivation by environmental factors?

Back 15

The lipid envelope is readily disrupted and requires moisture; wihout the envelope the virus loses ability to recognize its host and loses the components required for infecting cells.

Front 16

ALL negative ssRNA viruses are ___.

Back 16

Enveloped

Front 17

Type and subtype are determined by ___.
Strain is determined by ___.

Back 17

Type = Serological characteristics;

Strian = patient/investigator, place isolated or # of an isolate

Front 18

Name the enveloped DNA viruses.

Back 18

Pox
Herpes
Hepadna

Front 19

Pox and Herpes have ____ genome.
Hepadna has ____ genome.

Back 19

ds Linear

ds Circular

Front 20

Name the naked DNA viruses.

Back 20

Polyoma
Papilloma
Adeno
Parvo

Front 21

Polyoma and Papilloma have ___ genome.
Adeno has ____ genome.
Parvo has ____ genome.

Back 21

ds Circular

ds Linear

ss Linear

Front 22

Name the naked +ssRNa viruses.

Back 22

Picorna
Calici

Front 23

Name the enveloped +ssRNA

Back 23

Toga
Flavi
Corona

Front 24

Name the enveloped -ssRNA viruses.

Back 24

Rhabdo
Filo
Orthomyxo*
Paramyxo
Bunya*
Arena*

*Segmented genome
**ALL -ssRNA are enveloped!

Front 25

Name the dsRNA viruses.

Back 25

Reo

(double capsid - naked; segmented genome)

Front 26

Name the +RNA diploid viruses.

Back 26

Retro

(enveloped)

Front 27

What are the basic steps of viral replication?

Back 27

1. Recognition & attachment
2. Penetration
3. Trxn/Trsln
4. Replication of viral genome
5. Assembly of virion and cell exit

Front 28

Recognition and attachment

Back 28

Viral surface proteins interact with specific host-cell receptor(s)

Front 29

Penetration
-enveloped
-naked

Back 29

Energy-dependent process to gain entry into cell cytoplasm
-most enveloped = fuse their membranes to deliver nucleocapsid or genome directly
-most naked = enter by receptor-mediated endocytosis or by direct penetration (viropexis)

Front 30

Replication of viral genome of DNA viruses

Back 30

Occurs in host cell nucleus (except pox) - ssDNA must synthesize a 2nd DNA strand and then replicate like dsDNA
-Pox: replicate in host cytoplasm & require several encapsidated viral enzymes

Front 31

What is different about Hepadnavirus genome replication?

Back 31

It is a dsDNA circular genome.
-synthesizes an RNA genomic intermediate that is transcribed into mRNA and full length RNA that serves as template for synthesis of the genome by RT

Front 32

Replication of genome of RNA viruses.

Back 32

Most RNA viruses replicate in the cytoplasm - requiring virally encoded enzymes.

Front 33

+ssRNA retrovirus replication

Back 33

+ssRNA is converted into cDNA that integrates into host chromosome.
Host makes mRNA, proteins, and full length RNA genome copies

Front 34

-ssRNA virus replication.

Back 34

Must first synthesize a +ssRNA for mRNA and as a template for genomic RNA
**must bring its own transcriptase

Front 35

dsRNA virus replication

Back 35

dsRNA is separated - +ssRNA acts as mRNAs while -ssRNA can be transcribed into mRNAs by viral RNA pol.

Front 36

Assembly of virion and cell exit.

Back 36

Mature virions are packaged and encapsulated.
Exit from the cell via cell lysis or budding from cell membranes

Front 37

Why do mutations readily occur in viruses?

Back 37

1. Poor fidelity of viral pol
2. Lack of proof-reading enzymes
3. Rapid rate of replication

Front 38

Mutations in non-essential genes can be beneficial to the virus because?

Back 38

May allow it to aquire resistance to antiviral therapy or altered antigenicity/pathogenicity

Front 39

What is the benefit of recombination in viruses?

Back 39

New viral strains can be produced by intramolecular genetic exchange between viruses or between virus and host cell.

Front 40

What is the benefit of re-assortment?

Back 40

Viruses with segmented genome can form hybrid strains upon co-infection of a host cell with different viral strains.
ex. influenza virus

Front 41

what is the benefit of complementation?

Back 41

A defective virus can be rescued by the replication of another virus producing the missing gene product.