Final Exam - Virology

Translated second in HIV

Gag-pol polyprotein

Hepadnaviridae Family

Hepatitis B virus

Cancer

Hepatitis C

ss DNA genome

Human B19 virus

A nucleic acid-protein assembly packaged within the virus particle

Nucleocapsid

True or False: One of the common features of oncogenic viruses is that they are also able to cause latent infection

True

True or False: Retroviruses are able to carry mutated genes from one cell to another and cause cellular transformation.

True

True or False: Some Influenza mRNAs encode for multiple proteins

True

True or False: The Fc receptor is involved in antibody dependent enhancement of Dengue infection.

True

True or False: The host response to viral infection can be responsible for some of the disease symptoms.

True

True or False: The metastability of viral capsids refers to the ability of the maintain structural integrity outside the host, yet dissemble quickly once inside the host cell.

True

True or False: The replication complexes used by Dengue viruses form on the cytoplasmic side of the endoplasmic reticulum.

True

True or False: Unlike ss(-) RNA viruses, the mRNA of Reoviruses are full length copies of the viral genome

True

True or False: Viral capsids and glycoproteins often undergo a conformational change when they interact with their host cell receptor.

True

True or False: Viral capsids are generally made from a small number of structural subunits that are repeated to form a regular, symmetrical structure.

True

True or False: Viral infection can result in no apparent change in an infected cell.

True

True or False: ssDNA viruses are unique in that the whole viral particle can enter the nucleus

True

true or false: Antiviral drugs that target the M2 ion channel of Influenza function by inhibiting RNA release from the endosome into the cytoplasm.

True

Flaviviridae Family

Zika Virus

Mosquito Transmitted

Zika Virus

ss(+) RNA genome

Zika Virus

Which of the following symptoms are characteristic of peak infection with Ebola virus? Check all that apply. a. hemorrhaging b. coma c. convulsions d. arthritis

a & b & c

Which of the following are complications that can result from measles infection? Check all that apply. a. pneumonia b. immune amnesia c. liver failure d. diarrhea

a & b & d

Which of the following is a difference between VSV and Influenza virus? Check all that apply. a. the VSV genome is unimolecular while the Influenza genome is segmented. b. VSV replicates in the cytoplasm, while Influenza replicates in the nucleus c. only VSV mRNAs are capped and polyadenylated d. only VSV uses an N protein to aid in production of a full length (+) RNA e. VSV makes one long mRNA while Influenza virus makes individual mRNAs

a & b & d & e

Which of the following are unique characteristics of Reoviruses compared to other RNA viruses discussed in this course? Choose all that apply. a. They have two concentric shells b. they have a segmented genome c. all of their RNA production occurs with in the viral core structure d. they package their RdRp

a & c

Which of the following virus families are being developed as an oncolytic virus to treat cancer? Check all that apply. a. herpes virus b. calicivirus c. flavivirus d. parvovirus

a & c

Which of the following statements are true regarding the genome influenza virus? check all that apply. a. the genome segments are each coiled. b. there are 6 segments of the influenza genome c. each genome segments is transcribed into an mRNA. d. the genome segments are bound by an RdRp

a & c & d

During a latent infection which phase of infection is associated with overt symptoms? Check all that apply. a. the acute phase b. latent viruses dont cause symptomatic infection. c. the reactivation phase d. the latent phase

a and c

Which of the following viruses has a subunit vaccine? Check all that apply. a. Human Papilloma Virus b. Rotavirus c. HIV d. Hepatitis B

a and d

For which of the following viruses are their vaccines available? Check all that apply. a. influenza virus b. varicella zoster virus c. hepatitis c d. hepatitis b virus e. ebola virus

a, b, and d

Which of the following viruses are able to infect dendritic cells? Check all that apply. a. poliovirus b. ebola virus c. HIV d. Zika virus e. rotavirus

a, b, d

Which of the following viruses have an antiviral available for treatment of infection? Check all that apply. a. Influenza virus b. Ebola virus c. herpes virus d. hepatitis c virus e. polio virus

a, c, & d

The T4, T7 and lambda phages share which structural characteristics in common? These characteristics are common to most phage. Check all that apply. a. tail fiber b. tail spikes c. tail d. head

a, c, d

How long do influenza symptoms last? a. about one week b. 18-24 hrs c. several weeks

a. about one week

Which of the following viruses has antiviral drugs that are only capable of targeting mRNA synthesis? In other words, the drugs against this virus do not target any other viral functions or steps in infection. a. cytomegalovirus b. hepatitis A virus c. papillomavirus d. HIV

a. cytomegalovirus

Out of the DNA viral genomes, which is the only one that can be converted directly to mRNA? a. dsDNA b. ssDNA c. gapped DNA d. all of them can be directly converted to mRNA

a. dsDNA

What is the phase of a virus growth cycle where no infectious virus particles can be detected? a. eclipse period b. burst phase c. exponential phase d. asynchronous phase

a. eclipse period

Which of the following techniques can overestimate the number of infectious viral particles present? Check all that apply. a. genetic assays b. plaque assays c. antibody-based assays

a. genetic assays c. antibody-based assays

A bacteriophage consist of a. head, tail, and sheath b. head and legs c. head and tail d. head, neck, and legs

a. head, tail, and sheath

"A filamentous or rod shared structure" describes which type of capsid shape? a. helical b. enveloped c. icosahedral d. none of the answers are correct

a. helical

Allantoic inoculation of embryonate chicken eggs with ____ is still a commonly used method of generating the virus today. a. influenza virus b. rubella virus c. polio virus d. smallpox virus

a. influenza virus

Which characteristic of gene therapy viruses is primarily responsible for long term gene expression? a. integration into the chromosome b. residing in an episomal state c. high infection efficiency d. a large genome capacity

a. integration into the chromosome

Which of the following mechanisms of cellular uptake is NOT used by viruses to enter cells? a. phagocytosis b. macropinocytosis c. endocytosis

a. phagocytosis

Which of the following vaccine types is made by isolating a specific component of a pathogen that can be given as a vaccine? a. subunit vaccine b. killed vaccine c. attenuated vaccine

a. subunit vaccine

What is the first step in formulating the influenza vaccine each year? a. surveillance of influenza infections at various locations around the world. b. creating the viral strains to be included in the vaccine c. testing the vaccine against new strains of influenza d. selecting the strains that are hypothesized to be present in the upcoming flu season

a. surveillance of influenza infections at various locations around the world

What key concept about viruses was demonstrated by the Hershey-Chase experiments? a. that nucleic acids were the genetic material of viruses b. that proteins were the genetic material of viruses c. that viruses were obligate intracellular parasites d. that viruses were small, filterable agents

a. that nucleic acids were the genetic material of viruses

The best way to prevent infection with Zika virus is... a. to not get pregnant b. to get the Zika virus vaccine c. nothing. there is no way to avoid Zika virus infection. d. to take steps to avoid being bitten by mosquitos.

d. to take steps to avoid being bitten by mosquitos

Translated third in HIV

envelope proteins

Translated first in HIV

gag polyprotein

nuclear shrinking

pyknosis

all viruses encode these proteins

regulating timing of replication

cell fusion

syncytium formation

Outer protein shell that surrounds the viral genome

Capsid

Occurred First

Discovery of Microscope

Occurred Second

Discovery of TMV

Occurred third

Discovery of first human virus

True or False: There is no correlation between viral genome size and the number of proteins that can be encoded in a viral genome, therefore a virus with a very small genome is capable of encoding for more proteins than a virus with a very large genome.

False

True or False: Transformation of a cell always leads to oncogenesis

False

True or False: Viral RNA-dependent RNA polymerases can only convert (-) RNA into (+) RNA

False

True or False: Viral polymerases are responsible for generating new ssDNA genomes.

False

True or False: Virally transformed cells are characterized by increased production of viral particles.

False

True or False: Viruses used in gene therapy or oncolytic therapy do not have to undergo modification prior to being use as a treatment in patients

False

True or False: ss(-) RNA viruses make new viral genomes from their mRNA.

False

True or False: the mRNA made generated from the influenza virus genome segements are full length copies of the genomic RNA

False

True or false: VSV replicates in the nucleus of the cell

False

Animal Bite Transmission

Rabies virus

Incovenient Illness

Rhinovirus

True or False: Children are more likely than adults to develop chronic hepatitis after infection with hepatitis B virus

True

True or False: Coxsackie and Adenoviruses share the same receptor.

True

True or False: New influenza virus particles are formed in the cytoplasm.

True

Parvoviridae Family

AAV (Human Adeno-Associated Virus)

ss (-) RNA genome

Ebola Virus

Contact with bodily fluids containing virus (Tranmission)

Ebola virus

Life Threatening

Ebolavirus

The host cell-derived lipid bilayer carrying viral glycoproteins that forms the outer layer for some viruses

Envelope

True or False: A positive Anti-EBNA antibody test indicates the patient has an active EBV infection.

False

True or False: All +RNA is mRNA

False

True or False: Attachment of viruses to cellular receptors occurs through a covalent interaction.

False

True or False: Direct viral vector delivery is useful for targeting hard-to-reach cell types

False

True or False: During chicken pox, skin lesions results from the primary viremia.

False

True or False: During the lytic cycle, bacteriophage incorporate their DNA into the bacterial host chromosome.

False

True or False: For most viruses, fusion proteins bind specific cellular receptors

False

True or False: HCV can undergo lytic and lysogenic replication.

False

True or False: Herpes simplex virus can only be spread by symptomatic patients

False

True or False: In hepatitis B replication, viral enzymes are responsible for generating the pre-genomic RNA.

False

True or False: Like HIV, Hepatitis B DNA is integrated into the host genome as a provirus.

False

True or False: Like many dsDNA viruses, Pox viruses replicate in the nucleus.

False

True or False: Plaque assays are useful for identifying the specific virus(es) present in a sample.

False

True or False: Replication of the genome of ss(+) RNA viruses is not associated with vesicles. (DO NOT INCLUDE RETROVIRUSES)

False

True or False: Retroviruses only package one copy each of the Reverse Transcriptase, Integrase, and Protease enzymes.

False

True or False: The cellular origin hypothesis of the evolution of viruses states that viruses evolved from escaped nucleic acids.

False

True or False: An advantage of using primary cells to grow and study viruses is they have a high degree of biological relevance.

True

True or False: Anal and genital infections with HPV can result in wart formation

True

True or False: Antiviral drugs against Influenza that target neuraminidase inhibit infection by preventing the ability of newly formed viruses to spread to other cells.

True

True or False: Bacteriophage can switch between the lytic and lysogenic cycles of replication.

True

What feature of Norovirus replication contributes to its rapid nature of replication? a. the norovirus RNA-dependent RNA polymerase can recognize both the poly-A tail and the 5' cap b. it has a low infectious dose c. it evolves quickly allowing new viruses to better overcome immune responses d. it is a non-enveloped virus which allows it to uncoat more quickly.

a. the norovirus RNA-dependent RNA polymerase can recognize both the poly-A tail and the 5' cap.

Which of the following characterisitics is shared among all ss(+) RNA viruses? (DOES NOT INCLUDE RETROVIRUSES) a. they all have a (-) strand replication intermediate. b. they all perfectly replicate in immune cells c.they are all non-enveloped viruses d. they all have relatively large genomes

a. they all have a (-) strand replication intermediate

Which of the following are not characteristic of viral nucleic acids? a. they are always linear b. they can be double stranded or single stranded c. they are used to classify viruses d. they are stored in the capsid or nucleocapsid

a. they are always linear

Which of the following proteins are only encoded by some viruses? a. those involved in packaging of the genome. b. those involve in genome replication c. those that modulate the host immune response d. proteins involved in energy production

a. those involved in packaging of the genome

Which of the following viruses have a segmented genome? Check all that apply? a. vesicular stomatitis virus b. rotavirus c. influenza virus d. norovirus

b & c

Which of the following is a disadvantage of using AAV as a gene therapy vector? Check all that apply. a. long term gene expression b. difficult to produce in culture c. small genome capacity d. many available serotypes

b and c

During the virus replication cycle, ALL viruses must.... (Check all that apply). a. incorporate the viral DNA into the host genome b. translate mRNA into viral proteins before new viral genomes can be made c. lyse the host cell to escape d. bind to a cellular receptor for either attachment or entry

b and d

Which of the following is the proper sequence of events in HIV replication? a. the viral RNA is released into the cytoplasm, the RdRp copies the viral RNA into mRNA, integrase takes the mRNA to the nucleus for translation alongside host proteins. b. Reverse transcriptase converts HIV RNA into DNA. Integrase transports the new DNA to the nucleus and integrates it into the host chromosome and the viral genome gets translated to mRNA when the host transcribes its own RNA. c. HIV binds to CD4 molecules and a co-receptor on the cell surface, the viral and host cell membrane fuse which release the capsid into the nucleus, the capsid travels to the nuclear membrane where the RNA is released directly into the nucleus and immediately translated into protein

b. Reverse Transcriptase converts HIV RNA into DNA. Integrase transports the new DNA to the nucleus and integrates it into the host chromosome and the viral genome gets translated to mRNA when the host transcribes its own RNA.

Which strain of Ebola virus has the highest mortality rate? a. Sudan b. Zaire c. Bundibugyo

b. Zaire

Of the viruses used in gene therapy discussed in the lecture, which can be easily grown in cell culture? a. retroviruses b. adenoviruses c. AAV

b. adenoviruses

Which of the following statements is false? a. all retroviruses have matrix proteins underneath their envelope. b. all retroviruses have icosahedral shaped nucleocapsids c. all retroviruses package 2 copies of ss(+) RNA d. HIV encodes for more spliced proteins compared to simple retrovirus genomes.

b. all retroviruses have icosahedral shaped nucleocapsids

Which of the following statements about Alphaviruses is FALSE? a. alphavirus subgenomic mRNA is generated from the negative sense copy of the genome. b .alphaviruses produce a subgenomic mRNA to generate their RdRp. c. alphavirus subgenomic mRNA is made by the RdRp. d. alphaviruses produce a subgenomic mRNA to generate their structural proteins

b. alphaviruses produce a subgenomic mRNA to generate their RdRp

What is the first step to all viral infectious cycles? a. replication of viral genome b. attachment of virus to host cell c. assembly of virion d. production of viral proteins

b. attachment of virus to host cell

If a disease can be prevented by vaccination, why do we see increased incidences of those diseases in some populations? a. because the vaccine isn't 100% effective b. because the number of vaccinated people in the population has dropped below the threshold for herd immunity c. because some people will get sick no matter what d. because vaccines don't control disease that well

b. because the number of vaccinated people in the population has dropped below the threshold for herd immunity

What is the classic shape of pox viruses? a. circular b. brick shaped c. filamentous

b. brick shaped

What type of receptor mediated endocytosis results in the formation of a caveosome? a. clathrin dependent endocytosis b. caveolin-dependent endocytosis c. clathrin and cave-in independent endocytosis d. lysosomal endocytosis

b. caveolin-dependent endocytosis

Which of the following is an outcome that can result from chronic hepatitis C infection? a. septicemia b. cirrhosis c. jaundice d. splenomegaly

b. cirrhosis

In which type of virus would you find a nucleocapsid? a. non-enveloped virus b. enveloped virus

b. enveloped virus

After the initial conversion of ssDNA viral genomes into dsDNA, what is the next step in replication? a. strand displacement b. generation of mRNA to produce the Rep 78/68 protein c. nicking of the hairpin at the 3' end d. packaging of the viral DNA

b. generation of mRNA to produce the Rep 78/68 protein

Which structure on the viral surface of Influenza is responsible for binding to the host cell receptor? a. vp40 b. hemagglutinin c. F protein d. neuraminidase

b. hemagglutinin

Which of the following is not a concern when using phage therapy to treat bacterial infections? a. phage-host range limitations b. high toxicity of phages to humans c. phage selection d. unfamiliarity with phages

b. high toxicity of phages to humans

Which of the following is the correct term for viral movement from one individual to another? a. vertical transmission b. horizontal transmission c. zoonotic transmission

b. horizontal transmission

Which of the following is a function of some of the early proteins produced by Pox viruses? a. counteract host immune defense mechanism b. inducing proliferation of neighboring host cells c. stop cellular translation d. induce membrane ruffling

b. inducing proliferation of neighboring host cells

Which of the following are modes of transmission for HIV? Check all that apply. a. respiratory droplets b. intravenous drug abuse c. fecal-oral transmission d. mother-to-child transmission e. sexual contact

b. intravenous drug abuse d. mother-to-child transmission e. sexual contact

Which T cell count is used to mark the formation of Acquired Immune Deficiency Syndrome (AIDS)? a. greater than 500 T cells/mm3 b. less than 200 T cells/mm3 c. T cell counts aren't involved in the determination for AIDS d. 200 - 500 T cells/mm3

b. less than 200 T cells/mm3

By which entry mechanism does HIV enter cells? a. reverse transcriptase b. membrane fusion c. integration of it's genetic material d. receptor mediated endocytosis

b. membrane fusion

Which of the following viruses cause both vomiting and diarrhea upon infection? a. viruses only cause vomiting or diarrhea, not both b. norovirus and rotavirus c. only norovirus d.only poliovirus e. only rotavirus

b. norovirus and rotavirus

The major antiviral drug against HSV is what type of chemical? a. GTPase b. nucleoside analog c. anti-interferon c. protease inhibitor

b. nucleoside analog

At an MOI = 1, which of the following statements is correct? a. there will be no eclipse period in the growth curve b. on average, approximately 1 virus was added per 1 target cell c. only 1% of the cells in the culture will be infected. d. all of the choices are correct.

b. on average, approximately 1 virus was added per 1 target cell

Which of the following are NOT a virus family that is being developed as an oncolytic virus to treat cancer? a. poxvirus b. parvovirus c. calcivirus d. reovirus

b. parvovirus

The titer or concentration of a virus stock can be measured using a plaque assay and is calculate in... a. virions per centimes squared b. plaque forming units (PFU) per milliliter c. colony forming units d. you don't use plaque forming assays to quantify viruses

b. plaque forming units (PFU) per milliliter

Which of the following viruses has a 100% mortality rate? a. Zika virus b. rabies virus c. measles virus d. ebola virus

b. rabies virus

Which virus is the leading cause of diarrheal disease in children? a. norovirus b. rotavirus c. influenza virus d. parvovirus

b. rotavirus

Which of the following characteristics must describe a cell in order for it to take up and replicate virus? a. alive and kicking b. susceptible and permissive c. competent and infectable d. resistant and permissive

b. susceptible and permissive

Which of the following statements about viral infection is false? a. microtubules are commonly used to transport viruses within the cell. b. the cell cytoplasm is largely empty which allows viruses to move freely c. viruses use established cellular pathways to enter cells d. viruses have evolved to exploit cellular protein receptors that normally serve other functions

b. the cell cytoplasm is largely empty which allows viruses to move freely

Which of the following highlights a primary difference between the replication of dsDNA genomes and gapped dsDNA genomes? a. only the gapped genomes uses viral enzymes in copying of the genome. b. the gapped genomes use mRNA as the template for generating new copies of the viral genome c. both genomes contain dsDNA and so there are no differences in their replication d. the gapped genomes can be directly converted into mRNA.

b. the gapped genomes use mRNA as the template for generating new copies of the viral genome

What is the term for the community of viruses that colonizes the human intestinal tract? a. microbiome b. virome c. Trick question! Humans are not colonized by viruses. d. Biofilm

b. virome

When should treatment with antiviral drugs against influenza be started? a. within 10 days of symptom onset b. within 2 days of symptom onset c. within 8 days of symptom onset d. there is no ideal treatment window for influenza antiviral drugs

b. within 2 days of symptom onset

Which of the following cells do HSV1 and HSV2 target? Check all that apply. a. endothelial cells b. lymphocytes c. epithelial cells d. sensory neurons

c and d

Which type of Influenza is most likely to mutate upon infection? a. C b. B c. A

c. A

Of the viruses used in gene therapy that were discussed in the lecture, which has a low capsid stability? a. HIV b. Adenoviruses c. AAV

c. AAV

Which herpesvirus tegument protein stimulates transcription of immediate early genes? a. VP24 b. VHS c. VP 16 d. VP 31

c. VP16

Why are parvovirus infections in animals commonly lethal? a. because the viruses infect vital organs b. because animals have weak immune responses. c. because infections result in dehydration which can lead to death. d. none of the answer choices are correct

c. because infections result in dehydration which can lead to death

In VSV replication, why is mRNA produced before the viral genome is copied for packaging and making new viruses? a. the mRNA isn't made before the genome is copied. Viral genomes are always made first. b. because the segmented genome of VSV must be fused before it can be copied. c. because the viral N protein must be made before the full length (+) strand RNA can be made. d. because the mRNA is made in the cytoplasm and the genome has to be copied in the nucleus

c. because the viral N protein must be made before a full length (+) strand RNA can be made

During mRNA synthesis ,specific regions of the VSV genome cause the RdRp to stop making mRNA. What is the name of that region? a. stop codon region (sc) b. polymerase inhibition region (pi) c. intergenic region (ig) d. there is no specific name for that region

c. intergenic region

Which of the following is one of the functions of the Hepatitis B polymerase? a. RNA synthesis b. Translation c. Priming d. cleaving of the polyprotein

c. priming

For which type of RNA containing virus do all viruses within the group replicate in the nucleus? a. ss (+) RNA viruses b. dsRNA viruses c. retroviruses d. ss (-) RNA viruses

c. retroviruses

Which bodily fluid is associated with transmission of EBV? a. genital secretions. b. blood c. saliva d. urine

c. saliva

From which cellular structure does Hepatitis B virus bud to gain its envelope? a. the nucleus b. the golgi apparatus c. the endoplasmic reticulum d. the external cellular membrane

c. the endoplasmic reticulum

What is meant by "continuous DNA synthesis" during rolling circle replication? a. replication of herpes genomes is always occuring b. cellular enzymes will repeatedly sit down on the newly synthesized strand of DNA to make the second strand of the dsDNA genome. c. The polymerase repeatedly moves around the circular viral DNA to generate numerous copies of the genome d. none of the answer choices are correct

c. the polymerase repeatedly moves around the circular viral DNA to generate numerous copies of the genome

Which hepatitis B nucleic acid serves as the template for making new Hepatitis B DNA genomes? a. the viral mRNA b. the gapped, ds DNA genome c. the pre-genomic RNA

c. the pregenomic RNA

What is the name of the HIV phase of infection when the virus is integrated into the host genome? a. the intermediate phase b. the incorporated phase c. the proviral phase d. the silent phase

c. the proviral phase

Which of the following are a reason that ssDNA viruses rely heavily on the use of host cellular enzymes? a. they migrate to the nucleus and so can't use cytoplasmic proteins b. some of the enzymes they encode are not functional c. their viral genomes are so small they don't encode many replication proteins d. all of the above

c. their viral genomes are so small they don't encode many replication proteins

What is the purpose of vaccination? a. to make infections less contagious. b. to make money for big drug companies c. to generate a protective immune response against a pathogen by administering a sage vaccine d. there is no purpose to vaccination

c. to generate a protective immune response against a pathogen by administering a safe vaccine

some viruses encode these proteins

capsid proteins

no viruses encode these proteins

complete protein synthesis

The binding of which host receptor induces the conformational change of the HIV fusion protein? a. heparin sulfate b. sialic acid. c. CD4 d. CCR5

d. CCR5

Which of the following are encoded in the genomes of all of the ss(+) RNA viruses? (DO NOT INCLUDE RETROVIRUSES) a. an RNA-dependent RNA polymerase b. viral enzymes (proteases) or non-structural proteins (NS) c. viral structural proteins (VP) d. all the choices are correct

d. all the choices are correct

Which types of viruses package a cellular replication enzyme like Reverse Transcriptase or RNA-dependent RNA polymerase (RdRp) within the viral capsid? a. viruses don't package enzymes b. only dsRNA, retroviruses, and ss(-) RNA viruses c. only dsDNA and gapped DNA viruses d. all types of RNA viruses

d. all types of RNA viruses

What type of antigenic change is responsible for widespread flu pandemics? a. mutations in chickens b. genome conversion c. antigenic drift d. antigenic shift

d. antigenic shift

Which type of infection is characterized by rapid increase in virus concentration that is maintained at a high level for the life of the host? a. slow infection b. acute infection c. latent infection d. chronic infection

d. chronic infection

For most viruses, uncoating occurs in the a. outside the cell b. periplasm c. nucleus d. cytoplasm

d. cytoplasm

Which type of virus must integrate into the host chromosome before it can replicate? a. retroviruses b. ssDNA viruses c. dsRNA viruses d. dsDNA viruses

d. dsDNA viruses

Which of the following is a receptor for Herpes viruses? a. caveolin b. LDL c. Fc receptor d. heparin sulfate

d. heparin sulfate

The term "virus" is derived from the latin term for _____. a. small infectious agent. b. cow c. parasite d. poison.

d. poison

Which type of viral genome can be used directly as mRNA? a. dsDNA b. ss(-) RNA c. dsRNA d. ss(+) RNA

d. ss(+) RNA

The observation that Tobacco Mosaic Virus (TMV) would not replicate in nutrient broth but only when inoculated onto leaves of a plant revealed what characteristic of viruses? a. they are picky b. they are host specific c. they are extremely small d. they are obligate parasites

d. they are obligate parasites

virions in the cytoplasm

negri bodies

Which of the following are characteristic of retroviral integration into the host chromosome? Check all that apply. a. Pieces of host DNA are removed and replaced with viral DNA b. Viral insertion is silent and leaves no distinguishing marks c. Bases are lost from the ends of the LTR regions of the viral genome. d. Host DNA sequences are duplicated at the insertion site

not a&c