mcb4503 exam 2

Rotavirus: symptoms, transmission, affected age groups

-symptoms: vomiting and (non-bloody) diarrhea "two bucket disease" -transmission: oral-fecal route -age groups affected: children; leading cause of diarrhea in infants and small children

Explain how rolling circle replication produces concatemers of genomic DNA that must be cleaved or separated for packaging

-the enzyme moves around in a circle and doesn't stop -this results in a long repeated sequence of genomic material (concatemer) -viral enzymes can cut and liagate the concatemer inbetween the full intact genomes

Influenza symptoms and transmission

- 1-4 days after infection; headache, fever, cough, runny nose, bronchitis, pneumonia, croup, and sinusitis -transmitted via airborne droplets containing the virus -influenza A and B infect humans

Explain how HSV LATs affect chromatin structure and which type of chromatin is associated with active or inactive gene expression.

-LATs condense chromatin which encourages DNA to wind around histones and forms heterochromatin, which inactivates gene expression

What disease could cause "Immune Amnesia"? A) Rabies B) Chickenpox C) HIV D) Measles

D

Strand exchange

RNAse H does not degrade all of the RNA template strand

Concatemer

a DNA molecule comprising of multiple copies of a viral genome joined end to end

Hairpin

a U-shaped structure found at either end of the ssDNA genome of AAV

Latent

when a virus is dormant but present within a host, few viral genes are expressed but no virions are produced

List the stages and properties of rabies infection (transmission, incubation period, symptoms, initial replication, movement, vaccination, mortality rate)

-transmission: animal vectors -incubation period: 1-3 months -symptoms: fever, malaise, itching, headaches, hydrophobia, foaming at the mouth, sweating, dilated pupils, and even coma -initial replication: virus enters muscle cells via nicotinic receptors and replicates in neurons -vaccines usually given to at risk populations -usually fatal by respiratory failure

List the stages of measles (transmission, incubation, symptoms, location of replication, and complications)

-transmission: saliva or respiratory droplets -incubation: 10-14 days -symptoms: (prodromal stage- 3 days) high fever, cough, conjunctivitis, and kolpik spots (exanthem stage- 4 days) red spots on head that travel down -complications: inflammation of the brain 7-10 years later, occurs during persistent infection mood changes seizures, and death are common

List the stages of ebola (transmission, symptoms, initial replication, subsequent dissemination, immune system dysregulation, effects on the circulatory system)

-transmission: single zoonotic event followed by multiple horizontal transmission events -symptoms: fever, fatigue, muscle pain, headache, sore throat, rash, vomiting, diarrhea, internal/external bleeding, coma -incuabtion, early, peak, and recovery stages -immune system dysregulation: viral infection of dendritic cells that cannot activate T cells -effects on circulatory: complications of immune dysregulation leads to capillary leakage and blood leaking from the body

Hep B: transmission, prevention, detection, treatment, and at risk population

-transmission: through blood, sex, needles, and /or mother to child -prevention: proper use and disposal of needles, immunization, condoms -detection: serum antibody and antigen test (look for HBsAG, HBsAb, and HBcAb) -treatment: symptom management (acute) or antivirals and liver transplant (chronic) - at risk population: high IV drug users, infants with mother that have Hep B, healthcare professionals, men who have sex with other men

Which of the following proteins does Influenza directly use to read through termination and polyA signals to create full-length ss(-)RNA from mRNA? A) NP protein B) Hemoglobin C) Glycoprotein D) Matrix protein

A

Which of the following viruses is used as a safer model to study rabies in the laboratory? A) Vesiculovirus B) Dichoravirus C) Drulisvirus D) Nucleorhabdovirus

A

Select the viruses that are both persistent and pathogenic: A) Human immunodeficiency virus type 1 B) Herpes simplex virus 1 C) Human T-cell lymphotropic virus Rotavirus

A & C

Which of the following is a double-stranded DNA virus that uses reverse transcription to go through an RNA intermediate to replicate its genome? (Choose all that apply) A. Hepatitis B virus B. Rotavirus C. Herpes simplex virus D. Cauliflower mosaic virus

A & D

Which viral genomes utilize rolling circle replication? Select all that apply. A) dsDNA B) dsRNA C) ssRNA D) ssDNA

A & D

Why can mRNAs not be used as a template to make new negative sense viral genome for Influenza? Select all that apply. A) The 5' end of the mRNA has a 5' cap derived from its host B) The mRNA has a truncated poly-A-tail C) The 3' end of the mRNA is 20 nucleotides longer than the negative sense template strand D) The 5' end of the mRNA is 20 nucleotides shorter than the negative sense template strand

A & D

Place the steps of Hepatitis B replication cycle in order. A) the genome is packaged and fully synthesized B) the multivesicular body forms C) new virion is released D) the nucleocapsid buds into the endoplasmic reticulum

ADBC

During virus infection, synthesis of the large quantities of structural proteins needed for assembly of progeny virus particles is restricted to... A) the late phase of infection B) the early phase of infection C) the replication phase D) endosomes in the cytoplasm

A

What does influenza take or "steal" from the host for translation of viral mRNA? What is this known as? A) The 5' cap, known as "cap snatching" B) The 3' poly-A tail, known as "stability sneaking" C) The 5' cap, known as an internal ribosome entry site or IRES D) The 3' poly-A tail, known as "tail snatching"

A

Which (-)ssRNA virus has a 100% mortality rate? A) Rabies virus B) Mumps virus C) Measles virus D) Ebola virus

A

Which is an example of Cystoviridae and how many segments does it contain? A) Infectious Pancreatic Necrosis Virus; 2 segments B) Pseudomonas phi6; 3 segments C) Rotavirus; 11 segments D) Infectious Bursal Disease Virus; 3 segments

B

Which of the following is FALSE? A. Rolling circle replication is used by nanoviridae B. Rolling circle replication is also known as "strand displacement" C. Rolling circle replication involves a nick created by a viral rep protein D. Rolling circle replication is used by geminiviridae

B

Which of the following is not among the three functional activities of the hepatitis viral polymerase? A) DNA synthesis B) convert pre-genomic viral DNA into viral RNA C) convert pre-genomic viral RNA into viral DNA D) Priming

B

Which of the following is not an Orthomyxoviridae virus? A) Influenzavirus B) Lyssavirus C) Thogotovirus D) Quaranjavirus

B

Which receptor does Ebolavirus bind to in order to initiate fusion with the endosome? A) CD4 B) NPC1 C) CCR5 D) Sialic acid

B

Which symptom listed is not the correct symptom of rotavirus? A) non-bloody diarrhea B) bloody diarrhea C) vomiting D) fever

B

Which type of virus does NOT use rolling circle replication? A) Nanoviridae B) Parvoviridae C) Microviridae D) CRESS-DNA Viruses

B

While budding out of the cell, sialic acid residues stick to influenza particles and prevent them from being released. Which viral protein cleaves sialic acid residues that stick to budding particles to facilitate their release? A) hemagglutinin B) neuraminidase C) nucleocapsid protein D) matrix protein 2

B

In Bacteriophages, gene expression is separated into various classes. Genes associated with structural proteins and lysis proteins are classified as? A) Class I "Early" genes B) Class II "Middle" genes C) Class III "Late" genes D) None of the above

C

Which of the following is responsible for controlling the switch between making mRNAs and making a genome copy for influenza? A) N protein B) P protein C) NP protein D) None of the above

C

Which ss (-) RNA virus causes its host cell to develop inclusion bodies (specifically negri bodies)? A) Influenza B) Measles C) Rabies D) Ebola

C

Which statement is FALSE about Hepatis B Virus replication? A) Hepatitis B virus has pre-packaged rdrp B) Heparan sulfate is the binding receptor C) Non-Covalently closed circular DNA is formed D) DNA copying occurs in the cytoplasm

C

Why does rotavirus cause severe diarrhea in children? A) The virus got dehydrated B) The viral capsid binds to the GI tract C) Due to the enterotoxin encoded in the viral genome D) All of the above

C

Why is the human papillomavirus (HPV) vaccine only effective prior to infection? A) HPV can cause cancer B) HPV mutates too quickly, so the immune system needs to be primed and ready C) Immune cells cannot detect HPV before particle release D) It is still just as effective after infection

C

An infection is defined as Persistent Pathogenic when: A) There is a constant production of virions without outward signs of infection. B) Virions are produced periodically, with quiescent periods between. C) There is production of virions with outward signs of infection, but both are cleared after a short period of time. D) The virus is produced at low levels for a long time, then later at high levels when symptoms may reappear.

D

Which influenza virus protein is translated in the ER? A) HA B) NA C) M2 D) All the Above

D

Which of the following steps specifically applies to only the lysogenic infection cycle? A) genome translocation via tube into the cytoplasm B) early gene expression C) initial attachment to primary receptor D) integration of viral genome into the host genome

D

Chromatin, heterochromatin, and euchromatin:

are various structures of DNA within a nucleus with chromatin being the generic term for structured DNA; euchromatin is the "loose" version which can be accessed for transcription while heterochromatin is tightly wound to prevent transcription

cccDNA

covalently closed circular DNA ; the repaired product of host DNA repair mechanisms once the gapped genome has entered the host nucleus

Sialic acid

entry factor for influenza virus; recognized by hemagglutinin and cleaved by nureminidase

Inverted terminal repeat

gene sequences on either side of the AAV genome that induce the formation of the hairpin

Persistent

an infection which is productive and ongoing for a long duration

Cap snatching

the process by which influenza genomes steal a 5' cap from host cell RNA for their own genomes

Reactivation

the process in which host or environmental facotrs lead to antoher period of acute replication and possible pathology in a latent virus

Concentric shells

the structure of reoviruses, contains three capsid layers

Infectious subviral particle

the structure produced when the outer capsid protein of reovirus is removed

Reassortment

the way in which segemented virsues (ie influenza or rotavirus) can experience an antigenic shift when two strains infect the same cell and pieces of their genomes mix and match to produce new strains

Strand displacement

the way in which ssDNA genomes replicate; as a newly formed strand is produced it displaces one of the original DNA strands

Hemagglutinin

viral protein of influenza which recognizes sialic acid on target cells

Neuraminidase

viral protein of influenzae which cleaves sialic acid to allow for proper exit of virions from infected cells

Lytic-lysogeny switch

-determined by early genes, if no swtich, middle and late genes repressed -depends on factors like: host cell physiolofy, host cell density, number of viruses present, environmental stress, UV damage to DNA

Steps of poxvirus infection

-entry via RME -uncoated in the cytoplasm -early genes transcribed (anti-host defense, uncoating, replication proteins) -intermediate genes are transcribed (proteins for late genes) -late genes are transcribed (structural and packaged proteins) -ER wraps around immature capsid (1st membrane) then golgi wraps around when mature (2nd membrane) -exocytosis by budding or propelling with actin

Infection cycle of Hepatitis B

-entry via endocytosis -uncoats into nucleus -genome is repaired to form cccDNA -RNA is made from ccDNA including pregenomic DNA -mRNA exit nucleus into cytoplasm to make structural and capsid proteins -pregenomic RNA is enclosed in capsid -RNA undergoes RT to create (-) DNA - (+)DNA made from (-) strand -nucleocapsid enters ER where it is enveloped, structural, recognition proteins -mature virus exits the cell

Unique properties of RT DNA virus genomes

-gaps: genomes have 1 to 3 gaps on the strands of the dsDNA -pregenomic RNA: mRNA that is a little longer than the genome and can be reverse transcribed to produce the gapped dsDNA genome in Hepadnaviruses -location of replication: pregenomic RNA is reversed transcribed into genomic DNA in the cytoplasm -replication of intermediates: pregenomic RNA is synthesized by host RNA polymerases in the nucleus -associated proteins: P protein, DNA repair mechanisms, reverse transcriptase, RNAse H, terminal protein

Rhabdoviridae gene expression and genome replication (VSV and rabies) [ss (-) RNA]

-genome is coated in N protein and associated with L/P protein (RdRp) -RdRp synthesizes multiple mRNAs that are translated in the cytoplasm and ER -newly made N protein binds intergenic regions of ss(+) RNA -RdRp is now able to read through the termination signals and replicate the genome

Stages of strand displacement replication (aka rolling hairpin replication).

-hairpin structure at 3' is self-primer for new DNA; begins with host DNA polymerase binds to ORI and moves along ssDNA (makes complementary strand & hairpin is flat) -first mRNA produced encodes for rep protein; this mRNA leaves nucleus to produce rep protein -rep protein copies genome and activates transcription of other AAV genes in the nucleus -rep protein nicks the viral genome at terminal receptor and the hairpin flattens out -host DNA polymerase copies hairpin sequence that forms 2 hybrid strands of DNA (old and new pieces of DNA) -host DNA polymerase makes new genome and displaces one of the original strands -at the end there are two products that are both made up of the template and newly synthesized DNA

Enzymes involved in Hep B infection cycle

-host enzyme: DNA repair mechanisms, RNA pol II -viral enzyme: reverse transcriptase, P protein

Describe persistent asymptomatic, and persistent pathogenic infections (kinetics, symptoms, example)

-persistent asymptomatic: after acute stage the immune system bring viral titer down very low, but virus continues to produce progeny at low levels; mild to no symptoms during acute followed by lifetime infection w/ no symptoms; BK virus -persistent pathogenic: after acute stage immune system brings viral titer down but virus may overwhelm after a certain point; mild symptoms can occur in acute (can last decades) later stages include severe symptoms that can lead to death; ex. HIV

Functions of Hep B polymerase

-polymerase binds to the promoter and produces the promoter -polymerase produces the (-) DNA strand of the new genome -RNAse degrades the RNA template -then after a second template exchange the polymerase

Symptoms and transmission of HSV infection

-primary infection is usually asymptomatic but hosts are still contagious - oral: skin lesions, fever lymphadenopathy (children), and pharyngitis (older children and adults) -genital: Ulcers and pustules on labia majora, labia minora, mons pubis, vaginal mucosa, cervix, and shaft -serious infection: keratoconjunctivitis, meningitis, and encephalitis during reactivation and viremia -can be transferred by saliva or genital secretions and from mother to child

Unique properties of rotavirus, norovirus, and poliovirus

-rotavirus: infants and children are mostly affected, severe dehydration, lasts 3-8 days, lifelong immunity, contagious before symptoms (sometimes afterwards) -norovirus: more common in adults, no vaccine, last 2.5 days, can get infected repeatedly, contagious before symptoms (sometimes afterwards) -poliovirus: mostly infants, small children, and unvaccinated, (flu-like) symptoms last 1-2 weeks if present, some develop paralysis, contagious before and after symptoms

ss(-) RNA vs dsRNA: location/mechanism of genomic dsRNA synthesis

-ss (-) RNA: (cytoplasm; except influenza-> nucleus) N protein is anti-terminator stoping RdRp from terminating the production of RNA ; the positive sense copies made can be used as templates that can be packaged -dsRNA: (cytoplasm) new inner capsid molecules are assembled and given positive sense mRNA strands and RdRps; negative sense complements are made for positive sense strands in the inner capsid

ss(-) RNA vs dsRNA: capsid structure

-ss (-) RNA: genome coated with a nucleocapsid protein inside capsid -dsRNA: capsid w/ 3 concentric layers

ss(-) RNA vs dsRNA: location/mechanism of mRNA synthesis

-ss (-) RNA: mRNA produced in cytoplasm shorter than the genome (except influenza) -dsRNA: mRNA synthesis occurs within the core of the viral particle in the cytoplasm of the host cell , mRNA enters the cytoplasm and use host ribosomes for proteins

ss(-) RNA vs dsRNA: uncoating

-ss (-) RNA: uncoated -dsRNA: RME w/ low pH that induces a conformational chagne in the virion, never fully uncoats

List the symptoms of HPV disease, diagnosis, treatment, and methods of prevention.

-symptoms: non-genital cutaneous infections (benign warts), mucous membranes (respiratory), papillomatosis, voice changes, high pitched breathing, anal & genital infections -diagnosis: warts, endoscope (for checking upper respiratory tract), pap smear; definitive diagnosis cannot be made without molecular testing of biopsied cells for viral DNA or RNA -treatment: removal of wart and precancerous lesions or immune modifiers -prevention: limiting contact with potentially infected persons, getting the HPV vaccine before 1st exposure to infection source, condoms -vaccines: 3 major HPV vaccines which utilize an "empty" capsid protein shell since the majority of HPV virions are made up of a single type of protein, L1; generates a robust immune response effective before first exposure

Which category of dsRNA virus has the fewest capsid layers and genome segments? A) Reoviridae B) Cystoviridae C) Birnaviridae D) Paramyxoviridae

C

Which of the following harbors the most types of Hemagglutinin and Neuraminidase proteins? A) Humans B) Pigs C) Wild birds D) All of the above harbor the same amount of types

C

Explain how EBV Zta affects gene expression by binding methylated DNA and inducing acetylation.

-EBV Zta is able to bind to methylated (repressed) regions of DNA which induces acetylation, activating those regions for gene expression -no Zta means these regions would be methylated and inactive, not expressing their genes

Describe the EBV latency programs, how they relate to symptoms and transmission, and complications resulting from infection, including the links to cancer.

-EBV infects B cells and expresses genes down regulating apoptosis and uplifting cell division -Epithelial cells: nasopharyngeal carcinoma -B cells: Hodgkin lymphoma and non-Hodgkin lymphoma -T cell: t cell lymphoma -transmission: passing saliva from one person to another.

List the viral proteins involved in HSV and EBV latency

-HSV latency proteins: LAT (affects chromatin structure), miRNA -EBV latency proteins: LMP (latent membrane proteins), EBNAs (Epstein-Barr Nuclear Antigen), and Zta (immediate-early gene involved in reactivation).

State where HSV, EBV, and VZV reside during persistent infection

-HSV: infects neurons -EBV: infects B cells -VZV: infects sensory neurons

Compare latent mammalian dsDNA viruses to lysogenic dsDNA bacteriophages

-Lysogenic dsDNA bacteriophages infect their host cells and can integrate themselves into host DNA as a prophage similar to latent mammalian dsDNA viruses -Lysogenic bacteriophages can exist as an extrachromosomal episome, (can happen in dsDNA mammalian viruses as well) -Ultimately, bacteriophages will kill their host; the mammalian latent viruses rarely kill their hosts.

Describe acute and latent infections (kinetics, symptoms, example)

-acute: infection starts at lower viral titer then rapidly increase as the virus replicates before the immune system kicks in; prodromal symptoms prior to peak of viral titer & new/worsening symptoms in later stages of infection; ex. rhinovirus infection -latent: follows acute, immune system controls titer, viral DNA may not be detected and no virions produced until reactivation; mild, moderate, or no symptoms during acute stage leads to asymptomatic during latency with symptoms possible after reactivation; ex. Herpes simplex virus

how CRESS-DNA viruses were first identified; how are they distinguished from other ssDNA viruses

-Much of what we have discovered has come from studying genetic material directly from environmental samples -all have the same replication associated protein (rep protein)

Orthomyxoviridae gene expression and genome replication (influenza) [ss (-) RNA]

-N and P coated genome enters the nucleus -they are transcribed by the viral RdRp into 1-3 mRNAs -mRNAs exit the nucleus and are translated in the cytoplasm of ER -newly made NP protein binds to polyA/termination signals on ss(+) RNA -RdRP can read through and synthesize the full length genome

Replication cycle of rabies

-RME and uncoats unimoleular genome in cytoplasm -5 mRNAs are synthesized from the ss(-) RNA genome & one glycoprotein (G) is translated in the ER -genome is replicated when N protein binds to ss(+) RNA in cytoplasm - new genome coated in N protein are bound by L/P proteins and packaged/released

Replication cycle of ebola

-RME and uses TIM as a receptor -binds to co-receptor NPC1 inside of endosome -multiple mRNA are synthesized in the cytoplasm from a unimolecular genome -proteins are translated from mRNA in the cytoplasm -viral genomes are replicated in inclusion bodies that are formed by VP35 and NP proteins -GP and matrix proteins gather at membrane where genome is packaged

Replication cycle of influenza

-RME using sialic acid that is bound by viral hemagglutinin -the virus uncoated in the cytoplasm and enters the nucleus where RdRp synthesizes mRNAs from segmented genome -viral mRNA is translated into protein -M1 proteins bind to ss(+) RNA to stop genome replication and genome packaging -new genomes are packaged into capsids at the membrane -nuraminidase cleaves sialic acid to allow exiting and to prevent rebinding of the virus cells

List characteristics of VZV transmission, disease, reactivation, and complications.

-VZV is shed from lesions in the skin then remain latent in sensory neurons -complication: pneumonia, meningitis, encephalitis, stroke, death, miscarriage, birth deformities, secondary bacterial infection, keratitis/retinitis, and Ramsay Hunt Syn. -reactivation: VZV may travel back and forth to the skin from sensory neurons via anterograde transport

Which species of ebola can infect humans; which strains have the highest case fatality rates

-Zaire, Sudan, Tai Forest, and Bundibugyo species can infect humans -Zaire kills 60-90% -Sudan kills 40-60% -Bundibugyo kills 25%

Stages of Hep B infection (characteristics, signs/markers, symptoms)

-acute: fever joint pain, rash, cough, dark urine, light stool color, jaundice, encephalitis, splenomegaly, hepatomegaly -chronic: infection lasting longer than 6 months, inflammation of portal tract, risk for cirrhosis and liver cancer, similar symptoms as acute just worse -liver damaged is caused by inflammation of the liver cells

Explain how the stages of papillomavirus infection are related to the stages of cell differentiation.

-infects basal layer of epithelial cells (immature and undifferentiated) -as the basal cells mature they move closer to the out layer of the skin -early genes are expressed in the basal layer to drive infection and latency -in the mid layers the virus begins late gene expression and viral genome amplification -E5/E6/E7 act to prevent apoptosis and drive cell proliferation, to amplify the virus -there is a deletion in the E2 gene of the virus genome, which regulates the production of E6/E7 leading to over-expression and uncontrolled cell growth/division

How are influenza genomes replicated and why mRNA cannot be used as a templare for ss(-) RNA genome replication

-influenza genomes are synthesized when viral NP proteins binds to 3- polyA/termination signals and allows for read through to ensure sequence is present -genomes are not replicated from mRNA because the mRNA has a 5' cap that is "snatched" from host cells

How are poxviruses unique?

-large genome (180 kbp) -encodes many of its own proteins for replication -2 double membrane (hour glass shape) -replicates in the cytoplasm -produces viral factories where viral proteins and genomes come together

Molecular mechanisms determining EBV latency vs. reactivation

-latency: LMPs (latent membrane proteins) are involved in cell signaling; embedded in the host membrane EBNAs (Epstein Barr nuclear antigen) are transcriptional activators; found in the nucleus and modify the expression of viral and cellular genes -Zta and lytic cell: -the switch to lytic infection is marked by the expression of Zta (IE gene) that activates other lytic genes -Zta binds to methylated (repressed) DNA and induces acetylation (activation)

Lytic, lysogenic, and latent infections

-lytic: viral genome is actively replicated in host cell, packaged, released (early, middle, and late genes transcribed) -lysogenic: viral genome is integrated into genome or remaining as a plasmid (early genes are expressed) -latent: viral genome is maintained in host cells but is not actively assembling particles can use lytic infection after time

Replication cycle of measles

-measles binds to sialic acid using hemagglutinin protein and enter fusion (CD150 receptor) -unimolecular genome synthesizes multiple mRNAS -N protein binds to ss(+) RNA and is responsible for the genome replication switch -N and P proteins bind new genome and matrix proteins coast virions after packaging -neuramidinase cleaves sialic acid to prevent rebinding of the virus cells

Stages of rolling circle replication

-nick is introduced in one strand of the replicative form; caused by rep protein -host DNA polymerase comes and engages in DNA replication using inner strand as a template - multiple rounds of DNA synthesis forms a concatemer

Match the ss (-) RNA virus to its receptor: 1. CD150/SLAM 2. Nicotinic Acetylcholine Receptor 3. Sialic Acid 4. TIM and NPC1 a. Influenza b. Ebola c. Rabies d. Measles

1d 2c 3a 4b

Regarding the Parvovirus B19 (Human erythroparvovirus 1), which type of antigen does it contain as an attachment receptor? A) P antigen B) A antigen C) B antigen D) A and B antigens

A

How do dsRNA viruses synthesize host-translatable mRNA from their genome? A) Their genomic dsRNA is directly translatable, there is no need for another intermediate step B) Virus-packaged RdRp is used to synthesize mRNA C) Virus-packaged reverse transcriptase is used to synthesize DNA from the viral genome, which is then transcribed D) Host RNA polymerase directly transcribes viral dsRNA to mRNA

B

Rabies glycoproteins bind to ______________ receptors on the plasma membrane of muscle cells and allows virus to enter. A) neuraminidase B) nicotinic acetylcholine C) hemagglutinin D) matrix protein

B

What makes CRESS-DNA viruses difficult to study? A) They are only found in prokaryotes. B) They are mostly detected in metagenomic studies. C) They are very rare. D) They all have different replication proteins.

B

Select all of the single-stranded-DNA viruses known for infecting prokaryotic organisms. A) Parvoviridae B) Microviridae C) Inoviridae D) Rotavirus

B & C

What are characteristics of adeno-associated viruses? A) They are a dsDNA virus B) They partakes in rolling circle mechanism for replication C) They are a ssDNA virus D) They rely on dependoviruses for replication cycle completion

B & C

The steps of rolling circle replication have been scrambled below. Place the steps in order of occurrence. A) The ends of the genome are ligated together. B) The viral replication protein nicks one of the strands at 3' OH. C) The original genomic strand is displaced. D) The viral replication protein nicks the genome to free it from the rolling circle. E) The host DNA polymerase binds to the origin of replication

BECDA

Explain early, middle, and late gene expression (gene expression cascade)

Bacteriophages: -early: modify host physiology, encodes proteins for the expression of middle and late genes, determines if infection continues on the lytic or lysogenic pathway -middle: transcription of late genes and genome replication -late: encode structural proteins and those needed for early processes in next infection Herpesviruses: -immediate early: modify host cell physiology, encodes proteins for expression of delayed early and late genes -delayed early: proteins translated and genome replicated -late: encodes structural, glycoproteins, and teguments needs for assembly

What protein regulates whether Vesicular Stomatitis Virus (VSV) makes mRNA or full-length positive RNA? A) RNA - Dependent RNA Polymerase (RdRp) B) Glycoprotein (G mRNA) C) Nucleoprotein (N mRNA) D) Phosphoprotein (P mRNA) E) Large polymerase protein (L mRNA)

C

What type of cells does parvovirus infect? A) Epithelial cells B) Eosinophil C) Lymphocytes D) Monocyte

C

What type of entry receptor does Measles leverage? A) CD4 B) CD8 C) CD150 (aka SLAM) D) CCR5

C

What occurs in the Reovirus sub-viral particles? A) Translation of the positive strand B) Reassortment of genome segments C) mRNA synthesis D) Addition of polyA tails to the mRNA

C

Which of the following statements most accurately describes why a neuraminidase inhibitor is a useful therapeutic for influenza infection? A) Neuraminidase is required for influenza 5' capping, therefore its inhibition induces degradation. B) Without neuraminidase, the influenza envelope would be unable to self-assemble. C) Inhibiting neuraminidase prevents it from cleaving the sialic acid molecules which tether budding virions to the host cell. D) Neuraminidase forms a pore in the host cell membrane allowing release of the newly formed virion; inhibiting this protein keeps the virus contained.

C Neuraminidase serves to cleave sialic acid which will otherwise bind to hemagglutinin proteins on the virion surface.

Match the following to its corresponding definition: Chronic Latent Acute Persistent Options: -Virus remains in the primary host until the opportunity to infect another organism arises -The continued presence of infectious viruses following the primary infection -Rapid onset of disease, a relatively brief period of symptoms, and resolution within days -When a virus is present in the body but exists in a resting state without producing more virus.

Chronic: the continued presence of infectious viruses following the primary infection Latent: when a virus is present in the body but exists in a resting state without producing more virus. Acute: rapid onset of disease, a relatively brief period of symptoms, and resolution within days Persistent: virus remains in the primary host until the opportunity to infect another organism arises

All of the following are involved in AAV replication EXCEPT: A) The hairpin at the 3' end of the ssDNA acts as a self-primer for new DNA synthesis B) Host DNA polymerase binds to origin of replication and moves along the ssDNA C) The first mRNA that is produced encodes for the rep 78/68 protein D) The hairpin at the 5' end of the ssDNA acts as a self-primer for new DNA synthesis

D

How do Hepadnaviruses replicate their genomes? A) Cellular enzymes synthesize DNA from pre-genomic viral RNA in the nucleus B) The viral Reverse Transcriptase synthesizes DNA from viral RNA in the nucleus after entry C) The DNA genome undergoes rolling circle replication to produce a new genome which can be further amplified or encapsidated D) The viral Reverse Transcriptase synthesizes a gapped dsDNA genome from viral RNA inside of a newly formed capsid

D

Which of the following is a function of the early genes in poxviruses? A) Impair the host's immune defense mechanisms B) Cause uncoating of the viral capsid C) Assist in the replication of the genome within the cytoplasm D) Induce proliferation of neighboring host cells E) All of the above

E

Molecular mechanisms determining HSV latency vs. reactivation

Epithelial cells: lytic infection -VP16 and HCF localize to the nucleus where IE genes are expressed -VP16 and ICP0 reduce heterochromatin formation -Genome associates with euchromatin (loose) -Summary: if VP16 and HCF bind to OCT1, lytic genes are expressed and the infection is lytic Neuronal cells: latent infection -VP16 and HCF are in the cytoplasm; no IE genes are expressed, only LAT -LAT promotes heterochromatin formation and encodes miRNA -Genome associated with heterochromatin (tightly wound) -Summary: if no OCT1 binding, LATs repress IE genes, and the infection is latent

Parvoviruses: hosts, symptoms of disease, and cell types infected

Feline parvovirus (carnivore protoparvovirus 1): - 3-5 day incubation -infects lymphocytes -vaccine-preventable -symptoms: vomiting, diarrhea (can be bloody), weight loss, high fever, anemia, rough hair coat Canine parvovirus (carnivore protoparvovirus 2): -2-3 mutations; jumped from cats to dogs -3-7 incubation -infects lymphocytes -symptoms: abdominal pain, loss of appetite, fever, diarrheas (can be bloody), lethargy, vomiting -vaccine-preventable Parvovirus B19: -infects humans, cells that give rise to red blood cells -symptoms occur in 3 stages: (stage 1) 7-14 days; fever, headache, fatigue, and cold-like symptoms (stage 2) 2-3 weeks; characteristic face rash develops (stage 3): 1-3 weeks; rash spreads to the rest of the body, including the chest, arms, and legs

List immune-privileged sites in the human body and explain why they are immune-privileged.

Fragile sites that can be easily damaged by inflammation and easier to escape immune surveillance -brain -eyes -testes -uterus -spinal cord

Explain the significance of these antigen and antibodies: (HBsAg, HBcAg, E antigen, IgG, IgM)

HBsAg: surface antigen HBcAg: core antigen E protein: small polypeptide found in the blood of those who have Hep B in active infection and replication IgG: antibody that fights against surface antigens IgM: antibody that fight against core antigens

For unimolecular ss (-) RNA genomes, individual mRNA synthesis is promoted when N protein levels are ______ while full-length genome synthesis is promoted when nucleocapsid N levels are ______.

Low, High

P protein

Phosphoprotein found in the viruses of rhabdoviridae familiy; found in mature virions and helps RdRp function

The ss(-) RNA virus [Blank 1] has a 100% mortality rate because [Blank 2]? Options for Blank 1: - Ebola Virus - Dengue virus - Mumps virus - Rabies virus Options for Blank 2: - It affects the central nervous system and the brain - It is vaccine-preventable - It is non-enveloped - It has CD5 receptors

Rabies, It affects the CNS and the brain

Compare rolling circle and rolling hairpin replication of dsDNA viruses to ssDNA viruses

Rolling circle: -nick created in circular genome -continuous DNA synthesis 5' to 3' -'discontinuous' DNA synthesis 3' to 5' that creates concatemers where genome is repeated -resolvase cleaves into individual genomes Rolling Hairpin: -hairpin on one end melts away so synthesis of new strand can begin (self primer) -as strand synthesis continues, they are covalently linked at the opposite end hairpin region -resolvase separates the two strands by excision and recombination

True or False: The ss(-)RNA Rhabdovirus must package RNA dependent RNA polymerase into the virion for genome replication.

T

CRESS-DNA viruses (Circular Rep-Encoding Single-Stranded DNA)

a group of ssDNA viruses encoding the same rep protein

Antigenic shift

a large change in a virus which allows it to infect new host

Immune amnesia

a phenomenon seen in measles virus pateinst in which their immune systems no longer respond to previously "remembered' pathogens; measles target memeory immune cells via CD150

NP protein

a protein of influenza that functions similarly to N proteins; coats newly made ss(+) RNA and allows viral RdRp to read through polyA/termination signals

Rep protein

a protein that initiates it's own replication at origin of replication; the first protein produced in AAV genome

Antigenic drift

a small change in a virus which is cause by an individual viral mutation inside of a single host cell

Enterotoxin

a toxin produced in or affecting the intestines

Segemented genome

a type of ss(-) RNA genome which is multiple strands of RNA

Unimolecular genome

a type of ss(-) genome that is one signle RNA strand; encodes multiple mRNA segements but packed as a single ss(-) RNA strand in new virions

Satellite virus

a virus that requires the presence of another virus to complete its replication cycle within a host

Nucleosome

is a structural subunit of DNA with DNA wrapped around proteins called a histone

N protien

nucleoprotein found in viruses of the rhabdoviridae family; binds intergenic sequences to be an anti-terminator of transcription of RdRp

Chronic

refers to a condition lasting for many years and/or rest of host's life

Acute

refers to a temporary period of infection and is typically when viruses are most productive and reach their highest titers

immunoprivileged

refers to specific areas of the body such as the brain, spinal cord, testes, eyes, and uterus where immune cells have limited access due to the relative fragility of these organs

intergenic sequence

regions of ss(-) RNA genomes which allows the viral RdRp to "fall off" of the transcript and terminate RNA synthesis

Unique properties of adeno-associated viruses

require adenovirus as a helper virus in order to complete its replication cycle; they are essentially parasites (love that movie!)

Metagenomic analysis

sequencing of samples recovered directly from the environment

Inclusion body

sites of high concentration of viral protein inside infected cells