Virology

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What is Fuzeon? What does it have to do with HIV?
- Fuzeon is an entry inhibitor.
- Prevents the fusion of HIV--> used for drug resistant HIV infection
Mechanism of Fuzeon
- pg120 binds to CD4-->
- conformational change-->
- hydrophobic region of gp41 exposed-->
- virus membrane fuses host cell membrane
What are the characterics of rash?
- Abundant on face, forearm, lower limbs
- Sparce on torso
Umbilicated: indent on the postule

*postules are caused by immune response*
Why was it possible to eradicate smallpox?
- It's a DNA virus
- (humans host ONLY)
How is Molluscum contagiosum manifestated?
- Umbilicated nodules: waxy, pearly w plug when squeezed
- Aggregated in an area-- cluster of 5-20
- Cytoplasmic inclusion: cytoplasm of infected cell full of inclusions
What is Cytoplasmic inclusions?
- Nucleus is pushed to the side
- Cell becomes LARGER than normal
- Inclusion body: viral accumulation in cellular compartment
- Ex:
- CMV
- Herpes
How is Molluscum contagiosum transmitted?
- Common in the tropics: Can be easily spread from towel to towel
- Sexual contact: nodules in pubic area
List the different kinds of vaccines
- Inactivated: contain inactivated viruses
- Attenuated/live: contain altered viruses so they can't cause disease
- Recombinant protein
- Live vaccine
What is the structure and nature of transmitting HPV?
- Naked, icosahedral DNA virus
- Transmitted from formites, direct contact, and sexual contact
Where does the HPVirus replicate in the skin?
- HPV infects epithelial cells of skin or
- mucous membranes
Which is NOT true regarding adsorption?

a) Requires ATP
b) Virus attaches to host membrane
c) Nonenveloped viruses attach via exposed capsid regions
d) Process is random and reversible
e) All

a) Requires ATP
Viruses are classified according to all of the following EXCEPT:

a) Type of replication
b) Structure of virion
c) Host required for survival
d) Type of nucleic acid
e) Structure of virus

c) Host required for survival
Which of the following is NOT true regarding caspids?

a) Able to self-assemble into virions
b)Helical structure has fixed number of subunits and is spherical in shape
c) composed of repeating subunits
d) Only A and B
e) All

d) Only A and B
A particular virus' genetic material first needs to be copied
into positive sense SS-RNA (Single Strand RNA). What type of virus is this?
- a) SS Positive-Sense RNA
- b) SS Negative-Sense RNA
- c) DS RNA
- d) DS DNA
A particular virus' genetic material first needs to be copied
into positive sense SS-RNA (Single Strand RNA). What type of virus is this?

c) DS RNA
Adenoviidae, Poxviridae, and Herpesviridae are

Double-stranded DNA
What type of immunity is most responsible for fighting viral infections

Cell-Mediated Immunity
TRUE/FALSE:
All viruses have a protein caspid AND an envelope
- FALSE
- some viruses do no possess envelope
TRUE/FALSE:
AIDS is caused by HIV

TRUE
TRUE/FALSE:
Viral attachment protein and protein receptor are the same
- FALSE
- VAP is the viral protein which attaches to the host cell from the virus
- Cellular protein is the receptor on host cell surface to which VAP attaches
TRUE/FALSE:
Rhinovirus is naked DNA virus and has an icosahedral shape
- FALSE
- Rhinovirus is an (+)ssRNA, naked w icosahedral shape
Adenovirus is naked DNA virus w icosahedral shape
Transmission of Adenovirus
- Aerosol,
- close contact,
- fecal-->oral,
- contaminated swimming pool
What does Adenovirus infect?
- Mucoepithelial cells in respiratory tract
- GI tract
- conjuctiva or cornea
*causes cell damage directly since VIRUS PERSIST IN LYMPHOID TISSUE
Common infections caused by Adenovirus
- 1. Upper Respiratory Tract:
- a) Acute febrile pharyngitis- strep throat
- b) Pneumonia-
- Permanent lung damage
- Measles predisposes children to more severe Adenovirus
- 2. Conjuctivitis: pink eye--> HIGHLY infectious
- 3. Tonsillitis: inflammation of the tonsils
- a) unresponsive to antibiotic therapy
- b) blood chemistry is the same fro viral and bacterial tonsillitis
- 4. Hemorrhagic cystitis:
- a) bladder infection
- b) bleeding of the bladder
- 5. Gastroenteritis: GI tract
- a) watery non bloody diarrhea
Adenovirus portal of entry
- Respiratory tract: olfactory route
- Alimentary canal
- Skin
Adenovirus site of shedding
- Respiratory/coughing
- Skin lessions: Herpes, HPV- wart
- Fecal to oral: HepA, Polio
- Secretion: blood/semen
- Nosocomial: spread infection in the hospital
Whats the difference btwn shedding and spreading?

Shedding: outside the body

Spreading: spread through local tissue w/i body
Which of the following viruses can cross the placenta?
a) Rubella
b) HIV
c) CMV
d) B and C only
e) All

e) All
What are neurotropic viruses?
- Viruses that move along the neurons
- Ex:
- Polio: damage to motor neuron--> paralysis
- Herpes: to brain via olfactory nerve (nose)
Viral pathways to brain
- 1) Neural: Polio, Yellow fever, Rabbies, Herpes 1&2
- 2) Olfactory: Herpes and Coronavirus
- 3) Hematogenous: Polio, Mumps, CMV, and Herpes
Localized infections. Give examples.

do NOT spread in the body, shed the SAME place they entered

Ex. Rhinovirus, Influenza, Adenovirus
Generalized infections. Give examples.

Spread in other tissues, shed through DIFFERENT entry

Ex: Measles, Rubella, Varicella
TRUE/FALSE
Viremia is an active virus
- FALSE
- it is passive, no nucleus in RBCs
What is Syncytia?
- accumulaiton of viral antigens in host membrane
- causes fusion of cells resulting in LARGE multinucleated cell
- enveloped virus ONLY
Ex: Herpes on cervix and Measles
Viruses and Cancer
- HIV
- Epstein barr
- HepB
- HepC: liver cancer
- HTLV
- HPV
Which of the following uses the Respiratory Tract as a portal of entry but causes generalized infection?
- Mumps
- Measles
- Rubella
Viruses caused by breaks in the skin
- Minor trauma
- Herpes Simplex
- HepB
- insect bites
- Injections
- HepB
- HIV, HTLV
- CMV
- Ebola
- Animal bites
- Rabbies
- HerB
- Genital tract
- Herpes simplex
- HIV, HTLV
- HepB nnd C
- Conjuctiva
- Adenoviruses
- Enterovirus 70
What is the difference between naked and enveloped viruses?

Naked: non-enveloped viruses are more resistant to drugs.

Enveloped viruses are more fragile and easily deactivated. Their envelope is composed of a lipid bilayer from host's membrane.
Give examples of naked viruses
- Retroviruses,
- Rotaviruses,
- rhinoviruses,
- poliovirused,
- Erboviruses,
- Norwalk virus,
- HPV,
- Adenovirus
Give examples of enveloped viruses
- Smallpox- viriolla virus,
- herpes simplex virus,
- varicella- zoster virus,
- Cytomegalovirus
- Epstein- barr virus,
- Measles, mumps, rubella virus,
- Respiratory syncytial virus,
- Influenza virus
- Hepatitis, rabies
RNA viruses...

High rate of mutation, drug resistant.

Heterogeneous: cross btwn human and animals.
RNA viruses- positive vs. negative

Positive: can be translated into a protein.

Negative: template that has to be transcribed into a + RNA b4 translation into protein.
What is an RNA-dependent-DNA-polymerase?

Reverse transcriptase (virus ONLY--> RNA» DNA)
DNA viruses...

Human only, evolve with host
DNA viruses examples
- Adenovirus
- HPV
- Herpes simplex
- Varicella- zoster
- Cytomegalovirus
- Epstein- Barr
- Hepatitis B
- Smallpox, cow, and monkey viruses
- Vaccinia virus
True/false:
Envelope of enveloped viruses ONLY contain proteins of host origin OR viral origin

FALSE-- proteins of both the host AND virus
What structure is important in recognition? Example?
Cell-cell interactions and host-cell recognition when glycoproteins are present
- Influenza:
- Neuraminidase- found on surface of Inf. Cleaves residue from Sialic acid. Allows detachment and spread.
- Hemagglutinin- viral attachment protein. Binds to Sialic acid.
- Sialic acid: receptor found in mucoepithelial cells
- HIV:
- gp120- recognizes CD4
- Ngp41- functions in additio
Which of the following is a complex virus. What is a complex virus?
Complex virus: caspid composed of protein bilayer
- Examples:
- Reovirus.
- Viruses belonging to the baculovirus family.
- Herpes, pox viruses
Reassortment
- Segmented genomes, which can be "shuffled" during superinfection.
- Ex:
- influenza virus: 8 different RNA molecules, only infect w 2--» new strains
Define caspid
- Protein coat that packages and stores nucleic acid
- Protection of viral genome from environment
- Maybe involved in host-cell recognition and dumping mechanism
Helical nucleocaspid
Caspid where proteins interact w nucleic acid
- Ex:
- Rabies
- Tobacco mosaic
- Mumps
- Measles
- Influenza
Octahedral caspid
- Icosohedral geometry: from protective shell around caspid
- Common among viruses that infects humans- DNA virus- minimal free energy structure
- Ex:
- Adenovirus
- Rhinovirus
What's the importance of glycoproteins on surface of virus?
- Enveloped- viral attachment
- Naked- surface peptide
Establish tropism
Tropism

Virus specific for its host/cell type
What is and in which virus is Hemagglutinin?
- It's a glycoprotein- viral attachment protein.
- Binds to Sialic acid.
- Receptor found in mucoepithelial cells.
What is, where is it found, what does Neuronaminidase do?
- It is a glycoprotein.
- Found on surface of influenza virus.
- Cleaves galactose residue from Sialic acid.
- Allows for detachment and spread
What's the role of H1N1 glycoproteins?

Neutralize antibodies
Intramuscular vs. oral polio vaccine
- IM is better b/c there's no risk of vaccination turning virulent.
- IM inactivated vaccine no reversion
Antigenic drift

Changes due to NUCLEOTIDE SUBSTITUTION

"subtle" changes over time
Antigenic shift

SUDDEN changes in genetic composition

Ex: reassortment of influenza
Pandemic

Under antigenic shift--» Mutational adaptation and reassortment

50% of genome can mutate w/o affecting its replication
What are the 3 types of penetration?
- 1. Fusion: virus fused with host cell membrane
- Ex: enveloped viruses only
- 2. Endocytosis: internalization of coated pits at cell membrane
- Uptake of virus inside the cell
3. Translocation: receptors carries virus across the membrane
Which of the 3 types of penetration is the most common?

Endocytosis
Which of the 3 types of penetration is rare?

Translocation
What are the stages in replication?
- 1. Attachment
- 2. Penetration
- 3. Uncoating
- 4. Genomic replication
- 5. Gene expression
- 6. Assembly
- 7. Release
What are the molecules in charge of preventing attachment?

Neutralizing bodies
VAP
- virus attachment protein- binds to receptor on cell
- Determines tropism
Interferon

1st line of defense- infected cell-> signal to other cells-> interferon release->attach to receptors of "healthy" cells
What does interferon do when activated? Give example
- Induction of transcription of interferon gene--» induction of immune system response (ache & pain)
- Shut down protein synthesis in cell
Ex: used in treatment of Hepatitis C
What is Crixivan and what does it do?

It is a protease inhibitor that prevents maturation

Its protease activity cleave protein substrate (viral or cellular)
What is AZT (NRTI) and what does it do?

NRTI- nucleoside reverse transcriptase inhibitor: RT inhibitor found on HIV and HepB
What does AZT do?
- It targets replication of genomic material
- leads to premature termination
what is Ribavirin used for?

To prevent replication of viruses by introducing mutations

It is a polymerase inhibitor-- RNA virus
What's the role of vaccines?

To stimulate the development of circulating antibody against the caspid/envelope proteins of virus
Variola

Major and minor causes of chicken pox
Vaccinia
- Comes from cowpox
- Propagated in the lab
Incubation periods
- rhinovirus: 1-3 days
- Chickenpox: 13-17 days
- HepA: 15-40 days
- HepB: 40-150 days
- herpes simplex: 5-8 days
- HIV (AIDS): 1-10 years

Author

laupis8a

37659

Card Set

Virology

Description

Exam 1

Updated

2010-09-28T02:44:55Z

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