Introduction to Virology Flashcards
What are the viruses capable of causing encephalitis? (5)
-JC virus -measles -LCM virus -Arbovirus -Ravies
What are the viruses capable of causing common cold? (3)
-Rhinoviruses -Parainfluenza virus -Respiratory syncytial virus
What are viruses capable of causing pharyngitis? (3)
-Adenovirus -Epstein-Barr virus -Cytomegalovirus
What is the virus capable of causing gingivostomatitis?
herpes simplex type 1
What is the virus capable of causing cardiovascular disease?
Coxsackie B virus
What are the viruses capable of causing Hepatitis? (5)
Hepatitis virus types A, B, C, D, E
What are viruses capable of causing skin infections? (9)
-Varicella zoster virus -Human herpesvirus 6 -smallpox -Molluscum contagiosum -Human papillomavirus -Parvovirus B19 -Rubella -Measles -Coxsackie A virus
What are viruses capable of causing eye infections? (3)
-Herpes simplex virus -Adenovirus -Cytomeglovirus
What is the virus capable of causing parotitis?
-Mumps virus
What are viruses capable of causing pneumonia? (6)
-Influenza virus A and B -Parainfluenza virus -Respiratory syncytial virus -Adenovirus -SARS coronavirus -COVID19
What are viruses capable of causing myelitis? (2)
-Poliovirus -HTLV-1
What are viruses capable of causing gastroenteritis? (5)
-Adenovirus -Rotavirus -Norovirus -Astrovirus -Coronavirus
What are sexually transmitted disease caused by viruses? (3)
-Herpes simplex type 2 -Human papillomavirus -HIV
Wha is the virus that causes pancreatitis?
-Coxsackie B virus
This type of viral RNA genome is able to be directly translated into proteins
sense RNA genome
This type of viral RNA genome must first be reverse-transcribed to produce appropriate mRNA for protein translation.
anti-sense RNA genome
-RNA (template RNA genome)
Nucleic acid inside a protein coat
nucleocapsid
What is the name for viruses whose nucleocapsid is surrounded by a lipid membrane? Wha is the name for viruses whose nucleocapsid is NOT surrounded by a lipid membrane?
Enveloped; Naked
What are the four stages of capsid formation?
Individual proteins –> subunit –> protomers –> capsomeres –> procapsid or capsid
What is the name for an assembled capsid that does not yet include genome?
procapsid
What is an example of a virus that has two lipid bilayer membranes?
Poxvirus
What is the origin of the lipid bilayer envelope surrounding some viruses? When is it acquired?
the host cell membrane, it is acquired as the nucleocapsid buds out
Characteristics of enveloped viruses? (5)
-sensitive to the environment and GI tract -transmission requires close personal or sexual contact -spreads in large droplets, secretions -spread from organ transplant and blood transfusion -critical role of cell-mediated immune response
Characteristics of naked viruses? (5)
-released after lysis of the infected cell -stable (temperature, acid, proteases, detergents, drying) -resistant to poor sewage treatment, GI conditions -Spread easily (fomites, hand to hand, dust, small droplets) -Antibodies may be sufficient for immuno-protection
What are the 4 key steps in viral propagation?
- Recognition fo target cell 2. Attachment, penetration, and uncoating 3. Macromolecular synthesis 4. Assembly and Release
What features are responsible for determining which cell a virus will infect?
Host receptors and Viral Associated protein (VAP)
What is the difference between how naked viruses and enveloped viruses enter a cell?
Naked viruses enter using receptor mediated endocytosis (dumping genome inside) Enveloped viruses fuse with cell membrane to deliver nucleocapsid
What is the name of viral hydrophobic proteins that help the viral genome slip into a host cell?
viropexis
Name the process of nucleocapsid digestion by cellular proteolytic enzymes. What does this accopmlish?
uncoating; this abolishes virus-identifiable structure
What is the time period between uncoating and new virion creation?
Eclipse period
Almost all viruses with DNA genome send their genome to the cell’s nucleus. What is the exception?
poxvirus - they replicate in the cytoplasm
Almost all viruses with RNA genome replicate their genomes in the cytoplasm. What are the exceptions?
retroviruses, othomyxo viridae family members- they replicate in the nucleus
Almost all DNA viruses use the host cell’s RNA polymerase to make RNA. What is the exception to this?
poxvirus encodes all enzymes for replication and transcription
What enzyme must RNA viruses bring with them to replicate their genome?
RNA polymerase, because they replicate in the cytoplasm and the host cell does not have RNA polymerase in the cytoplasm
What genes are transcribed early in the viral replication cycle? Late in the cycle? What triggers the transcription of late genes?
Early genes- DNA-binding proteins and polymerases (nonstructural proteins) Late genes- structural and other viral proteins * triggered by genome replication
What is the difference between viral encoded DNA polymerase and host DNA polymerase? Why is this clinically important?
viral encoded DNA polymerases are faster but more prone to error Nucleotide analogs serve as antiviral drugs
Which types of viruses tend to use host DNA polymerase? Which types of viruses tend to encode their own DNA polymerase? What implications would this have for the types of cells they can infect? Provide examples.
small viruses (parvovirus) use host DNA polymerase– can only infect growing cells w/ active DNA polymerases larger, more complex viruses encode their own (herpes & poxvirus)– can infect grown or non-growing cells
What pathway is depicted in the image? Draw it.

Lysogenic pathway
RNA polymerase will be produced very quickly inside infected cells for RNA viruses. Why is this important?
RNA is very unstable, so it is important to replicate the genome before it degrades
Many +RNA viruses produce a __________, which is then processed by proteases to produce active proteins.
polyprotein
What does reverse transcriptase (RT) produce? What is the course of this product after it is made?
circular cDNA
cDNA travels to the nucleus, and integrated into host chromatin
as a result, viral genome become integral to host genome
All viruses depend on these 3 host cell contributions for propagation.
- ribosome
- tRNA
- post translationsal machinery
Where do DNA viruses assemble? Where do RNA viruses assemble?
DNA viruses assemble in the nucleus (except poxvirus). RNA + poxviruses assemble in the cytoplasm.
Where are viral glycoproteins sent after being produced?
ribosomes–> golgi, sent to specific region of membrane virus will take as envelope
Release of what type of virus is slow and continuous?
enveloped virus
What are the 7 DNA virus families?
- Parvoviridae
- Polyoma
- papilloma-viridae
- Adenoviridae
- Herpesviridae
- Poxviridae
- Hepadnaviridae
Describe the characteristics of the Parvoviridae family.
genome type, enveloped/naked, shape, members
genome type: DNA
enveloped/naked: naked
shape: icosahedral
members: parvovirus B19
Describe the characteristics of the Polyoma family.
genome type, enveloped/naked, shape, members
genome type: DNA
enveloped/naked: naked
shape: icosadeltahedral
members: JC virus, BK virus
Describe the characteristics of the Papillmaviridae family
genome type, enveloped/naked, shape, members
genome type: DNA
enveloped/naked: Naked
shape: icosadeltahedral
members: papilomavirus
Describe the characteristics of theAdenoviridae family
genome type, enveloped/naked, shape, members
genome type: DNA
enveloped/naked: Naked
shape: icosadeltahedral wiht fibers
members: adenovirus
Describe the characteristics of the Herpesviridae family.
genome type, enveloped/naked, shape, members (8)
genome type: DNA
enveloped/naked: Enveloped
shape: icosadeltahedral
members: HSV-1&2, varicella-zoster virus, EBV, CMV, HHV - 6, -7, and -8
Describe the characteristics of the Poxviridae family
genome type, enveloped/naked, shape, members
genome type: DNA
enveloped/naked: Enveloped
shape: brick-shaped
members: smallpox virus, molluscum contagiosum
Describe the characteristics of the Hepadnaviridae family
genome type, enveloped/naked, shape, members
genome type: DNA
enveloped/naked: Enveloped
shape: spheircal
members: Hepatitis B virus
Describe the characteristics of the Reoviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: naked
segmented: segmented
shape: icosahedral
members: rotavirus, colorado tick fever virus
Describe the charachteristics of the Picornaviridae family.
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: naked
segmented (yes/no): no
shape: icosahedral
members: rhinoviruses, polioviruses, echoviruses, coxsackievirus, hepatitis A virus
Describe the charachteristics of the Calciviridae family.
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: naked
segmented (yes/no): no
shape: icosahedral
members: Norwalk virus, calcivirus
Describe the charachteristics of the Paramyxoviridae family.
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): no
shape: shperical
members: measels virus, parainfluenza virus, mumps, RSV, Nipah and Hendra virus
Describe the charachteristics of the Orthomyxoviridae family.
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): segmented
shape: spherical
members: Influenza A, B, C
Describe the charachteristics of the Coronavirus family.
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): no
shape: spherical
members: coronaviruses, SARS-CoV, MERS-CoV, COVID-19
Describe the characteristics of the Arenaviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): segmented
shape: spherical
members: lymphocytic choriomeningitis virus, lassa fever virus
Describe the characteristics of the Rhabdoviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): no
shape: bullet-shaped
members: rabies virus
Describe the characteristics of the Filoviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveoped
segmented (yes/no): no
shape: filamentous
members: ebloa virus, marbug virus
Describe the characteristics of the Bunyaviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): segmented
shape: spherical
members: california encephalitis virus, hemorrhagic fever virus, Hanta virus
Describe the characteristics of the Retroviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): no
shape: spherical
members: Human T-cell leukemia virus type I and II, human immunodeficienty virus
Describe the characteristics of the Togaviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): no
shape: icosahedral
members: rubella, WEEV, EEEV, VEEV, chikungunya
Describe the characteristics of the Flaviviridae family
genome type, enveloped/naked, segmented (yes/no), shape, members
genome type: RNA
enveloped/naked: enveloped
segmented (yes/no): no
shape: spherical
members: Yellow fever virus, dengue virus, St. Louis encephalitis, West Nile virus, HCV
Name the three naked RNA virus families
- Reoviridae
- Picornaviridae
- Caliciviridae
Name the 4 segmented RNA viruses
- Reoviridae
- Orthomyxoviridae
- Arenaviridae
- Bunyaviridae
Name the 4 naked DNA viruses
- Parvoviridae
- Polyomaviridae
- Papillomaviridae
- Adenoviridae
What are the three signs that a cell has been infected by a virus?
- presence of ds RNA
- viral proteins on cell surface
- Presence of inclusions in cytoplasm or nucleus
What does the outcome and severity of a viral infection depend on?
- tissue tropism
- virulence of the virus
- inoculum
- health of host
What are the four outcomes of a viral infection?
- Failed infection (abortive infection)
- Cell death (lytic infection)
- Replication without vell death (persistent infection)
- Latency with potential for reactivation
Antibodies are important for __________ viruses; whereas cell mediated immunity is critical for ___________ viruses.
naked; enveloped
Titer of virus causing CPE in 50% of cells
Tissue culture dose (TCD50)
Viral titer equired to kill 50% of the test population
Lethal dose (LD50)
Viral titer that causes 50% exposed to become ill
Infectious dose (ID50)
A viral “colony” or CPE units
Plaque-forming units (PFU)
4-fold titer increase between acute adn convalescent phases (~3 weeks)
seroconversion