Viruses, viroids, and prions

Viruses, Viroids, and Viruses, Viroids, and PrionsPrions

Bits and Pieces that cause Bits and Pieces that cause diseasedisease

Are Viruses Living Are Viruses Living or Non-living?or Non-living?

Viruses are both and neitherViruses are both and neither They have They have some properties of life some properties of life

but not othersbut not others For example, viruses can be killed, For example, viruses can be killed,

even crystallized like table salteven crystallized like table salt However, they However, they can’t maintain a can’t maintain a

constant internal stateconstant internal state (homeostasis).(homeostasis).

What are Viruses?What are Viruses? Viruses are genetic Viruses are genetic

elements that replicate elements that replicate independent of the cell’s independent of the cell’s chromosome(s) but not chromosome(s) but not independently of the independently of the cells themselves.cells themselves.

Have an Have an extra cellularextra cellular form-can exist ouside form-can exist ouside the host(the host(VIRIONVIRION))

To multiply-should enter To multiply-should enter cell-cell-InfectionInfection

VirusesViruses Viruses contain DNA or RNA and a Viruses contain DNA or RNA and a

protein coatprotein coat Some are enclosed by an envelopeSome are enclosed by an envelopeNaked/envelopedNaked/enveloped Some viruses have spikesSome viruses have spikes Most viruses infect only specific Most viruses infect only specific

types of cells in one hosttypes of cells in one host Host range is determined by Host range is determined by

specific host attachment sites and specific host attachment sites and cellular factorscellular factors

CharacteristicsCharacteristics Some viruses are enclosed Some viruses are enclosed

in an protective in an protective envelopeenvelope Some viruses may have Some viruses may have

spikesspikes to help attach to to help attach to the host cellthe host cell

Most viruses infect only Most viruses infect only SPECIFIC host cellsSPECIFIC host cells

CAPSID

ENVELOPE

DNA

SPIKES

CharacteristicsCharacteristics Non living structuresNon living structures NoncellularNoncellular Contain a protein coat called the Contain a protein coat called the capsidcapsid Have a nucleic acid core containing Have a nucleic acid core containing DNA or DNA or

RNARNA Complete complex of NA and Protein Complete complex of NA and Protein

packaged is called NUCLEOCAPSID.packaged is called NUCLEOCAPSID. Capable of reproducingCapable of reproducing only when inside a only when inside a

HOST cellHOST cell

CharacteristicsCharacteristicsViral Viral capsidscapsids (coats) are made of (coats) are made of individual individual protein protein subunitssubunitsIndividual subunits Individual subunits are called are called capsomeres.capsomeres.(20sides)(20sides)Process –Process –self-assembly self-assembly

CAPSOMERES

CharacteristicsCharacteristicsOutside of host cells, Outside of host cells, viruses are viruses are inactiveinactiveLack ribosomes and Lack ribosomes and enzymesenzymes needed for needed for metabolismmetabolismUse the Use the raw materials raw materials and enzymes of the hostand enzymes of the host cell to be able to cell to be able to reproducereproduce

EBOLA VIRUS

HIV VIRUS

CharacteristicsCharacteristicsSome viruses cause Some viruses cause diseasediseaseSmallpox, measles, Smallpox, measles, mononucleosis, influenza, colds, mononucleosis, influenza, colds, warts, AIDS, Ebolawarts, AIDS, EbolaSome viruses may cause Some viruses may cause some some cancers like leukemiacancers like leukemiaVirus-free cells are Virus-free cells are rarerare

MEASLES

Viral HistoryViral History

Tobacco Mosaic VirusTobacco Mosaic VirusWendell StanleyWendell Stanley (1935) crystallized (1935) crystallized sapsap from sick from sick tobacco plantstobacco plantsHe discovered He discovered viruses were made of viruses were made of nucleic acid and nucleic acid and proteinprotein

Discovery of VirusesDiscovery of VirusesBeijerinckBeijerinck (1897) coined (1897) coined the Latin name “virus” the Latin name “virus” meaning meaning poisonpoisonHe studied He studied filtered plant filtered plant juicesjuices & found they & found they caused healthy plants to caused healthy plants to become sickbecome sick

SmallpoxSmallpoxEdward Jenner Edward Jenner (1796)(1796) developed a developed a smallpox vaccine using smallpox vaccine using milder milder cowpox virusescowpox virusesDeadly viruses are Deadly viruses are said to be said to be virulentvirulentSmallpox has been Smallpox has been eradicated in the eradicated in the world todayworld today

Viewing VirusesViewing VirusesViruses are Viruses are smaller smaller than the smallest cellthan the smallest cellMeasured in nmMeasured in nm(20-300nm)(20-300nm)

Viruses couldn’t be Viruses couldn’t be seen until the seen until the electron electron microscopemicroscope was was invented in the invented in the 2020thth centurycentury

Size of VirusesSize of Viruses

Viral StructureViral Structure

Viral ShapesViral ShapesViruses come in a Viruses come in a variety of shapesvariety of shapesSome may be Some may be helicalhelical shape like the shape like the Ebola Ebola virusvirusSome may be Some may be polyhedral polyhedral (ICOSAHEDRAL)(ICOSAHEDRAL) shapes like the shapes like the influenzainfluenza virus virusOthers have more Others have more complex shapescomplex shapes like like bacteriophagesbacteriophages

Helical VirusesHelical Viruses

Polyhedral (icosahedral) Polyhedral (icosahedral) VirusesViruses

Complex VirusesComplex Viruses

Taxonomy of VirusesTaxonomy of Viruses

Viral TaxonomyViral Taxonomy FamilyFamily names end in names end in -viridae-viridae GenusGenus names end in names end in -virus-virus Viral speciesViral species: A group of viruses sharing : A group of viruses sharing

the same genetic information and the same genetic information and ecological niche (host).ecological niche (host).

Common namesCommon names are used for are used for speciesspecies SubspeciesSubspecies are designated by a are designated by a numbernumber

Viral Taxonomy ExamplesViral Taxonomy Examples HerpesviridaeHerpesviridae HerpesvirusHerpesvirus Human herpes virus 1, HHV 2, HHV 3Human herpes virus 1, HHV 2, HHV 3

RetroviridaeRetroviridae LentivirusLentivirus Human Immunodeficiency Virus 1, HIV 2Human Immunodeficiency Virus 1, HIV 2

Herpes VirusHerpes Virus

SIMPLEX I and II

AdenovirusAdenovirus

COMMON COLD

Influenza VirusInfluenza Virus

Chickenpox VirusChickenpox Virus

Papillomavirus – Papillomavirus – Warts!Warts!

HOST they infect;HOST they infect;bacteriophages,animal,plantbacteriophages,animal,plant RNA or DNA Virus: ss or dsRNA or DNA Virus: ss or ds

RNA DNA virusesRNA DNA virusesSs RNA = Retroviruses; ds DNA= HepadnavirusSs RNA = Retroviruses; ds DNA= Hepadnavirus

Do or do NOT have an envelopeDo or do NOT have an envelope Capsid shape:Capsid shape:helical ;icosahedral; complexhelical ;icosahedral; complex

Used for Virus Used for Virus IdentificationIdentification

BacteriophagesBacteriophages

PhagesPhagesViruses that attack Viruses that attack bacteria are called bacteria are called bacteriophagebacteriophage or just or just phagephageT-phagesT-phages are a specific are a specific class of bacteriophages class of bacteriophages with with icosahedral headsicosahedral heads, , double-stranded double-stranded DNADNA, , and and tailstails

T-phagesT-phagesThe most commonly studied The most commonly studied T-phages are T-phages are T4 and T 7T4 and T 7They infect They infect E. coliE. coli , an , an intestinal bacteriaintestinal bacteriaSix small Six small spikesspikes at the base at the base of a contractile tail are used of a contractile tail are used to to attach to the host cell attach to the host cell Inject viral DNAInject viral DNA into cell into cell

Escherichia ColiEscherichia Coli Bacterium Bacterium

T - EVEN PHAGES ATTACK THIS BACTERIUM

T-Even T-Even BacteriophagesBacteriophages

Diagram of T-4 Diagram of T-4 BacteriophageBacteriophage

Head with Head with 20 20 triangulartriangular surfacessurfacesCapsid contains Capsid contains DNADNAHead & tailHead & tail fibers made of fibers made of proteinprotein

RetrovirusesRetroviruses

Characteristics of Characteristics of RetrovirusesRetroviruses

Contain Contain RNARNA, not DNA, not DNAFamily Family RetroviridaeRetroviridaeContain enzyme called Contain enzyme called Reverse Reverse TranscriptaseTranscriptaseWhen a retrovirus infects a cell, it When a retrovirus infects a cell, it injects its injects its RNA and reverse RNA and reverse transcriptase enzymetranscriptase enzyme into the into the cytoplasm of that cellcytoplasm of that cell

ENZYME

RetrovirusesRetrovirusesThe enzyme The enzyme reverse reverse transcriptasetranscriptase (or RTase), (or RTase), which causes synthesiswhich causes synthesisof a complementary DNA of a complementary DNA molecule molecule (cDNA)(cDNA) using using virus RNA as a template virus RNA as a template

RTase

RetrovirusesRetrovirusesHIV, the AIDSHIV, the AIDS virus, is a retrovirusvirus, is a retrovirus

Feline Leukemia Feline Leukemia VirusVirus is also a is also a retrovirusretrovirus

Enzymes in virionsEnzymes in virions

LysozymeLysozyme RNA dependant DNA polymerase-RNA dependant DNA polymerase-

Reverse transcriptaseReverse transcriptase NeuraminadasesNeuraminadases

Viroids & PrionsViroids & Prions

ViroidsViroidsSmall, circular ss-Small, circular ss-RNARNA molecules molecules without without a protein coata protein coatInfect Infect plantsplantsDo not infect animalsDo not infect animalsPotato faminePotato famine in in IrelandIrelandResemble intronsResemble introns cut cut out of eukaryoticout of eukaryoticMechanism of Mechanism of infection unclearinfection unclear

ViriodsViriods ssRNAssRNA Size from 246 to 399 nmSize from 246 to 399 nm Show considerable sequence homologyShow considerable sequence homology Cause a no of plant diseases:Cause a no of plant diseases: Coconut cadang cadang viroid-246 nucleotidesCoconut cadang cadang viroid-246 nucleotides Citrus exocortis viroid- 375 nucleotidesCitrus exocortis viroid- 375 nucleotides Potato spindle tuber viroid -359 nucleotidesPotato spindle tuber viroid -359 nucleotides

Extracellular form=naked RNAExtracellular form=naked RNA RNA has no protein encoding geneRNA has no protein encoding gene Viroid totally dep on host for its replication.Viroid totally dep on host for its replication. Tho’ ssRNA circular,secondary structure=resembling Tho’ ssRNA circular,secondary structure=resembling

ds molecule with closed ends.ds molecule with closed ends. Enters plant through wound:by insect or mechanical Enters plant through wound:by insect or mechanical

damage.damage. Replicated by plant RNA polymerasesReplicated by plant RNA polymerases Symptomless or mild to lethal symptomsSymptomless or mild to lethal symptoms Severe symptoms growth related.-are type of Severe symptoms growth related.-are type of

regulatory RNAregulatory RNA

PrionsPrionsPrions are Prions are “infectious proteins”“infectious proteins” They are normal body proteins They are normal body proteins that get that get converted into an alternate converted into an alternate configurationconfiguration by contact with other by contact with other prion proteinsprion proteins They have They have no DNA or RNAno DNA or RNAThe main protein involved in human The main protein involved in human and and mammalian prion diseasesmammalian prion diseases is is called called “PrP”(neurons)“PrP”(neurons)Prions don’t simply subvert host Prions don’t simply subvert host enzymes in the cell but convert a enzymes in the cell but convert a normal protein into a self normal protein into a self propagating conformational state.propagating conformational state.

PrionsPrions

Figure 13.21

PrPcPrPSc

1 2 3 4

5 6 7 8

Endosome

Lysosome

Prion DiseasesPrion DiseasesPrions form Prions form insoluble insoluble deposits in the braindeposits in the brainCauses neurons to Causes neurons to rapidly degeneration.rapidly degeneration.Mad cow diseaseMad cow disease (bovine spongiform (bovine spongiform encephalitis: BSE) is an encephalitis: BSE) is an exampleexamplePeople in New Guinea People in New Guinea used to suffer from used to suffer from kurukuru, which they got , which they got from eating the brains from eating the brains of their enemiesof their enemies

PrionsPrions Distict extracellular formDistict extracellular form Cause scrapie in sheepCause scrapie in sheep BSE in cattleBSE in cattle Chronic wasting disease in deer and elkChronic wasting disease in deer and elk Kuru and Creutzfeldt-Jacob disease CJD in humansKuru and Creutzfeldt-Jacob disease CJD in humans Prion diseases =transmissible spongiform Prion diseases =transmissible spongiform

encephalopathies –TSEencephalopathies –TSE 1997-Stanley Pruisner –noble prize1997-Stanley Pruisner –noble prize 1996 prion causing BSE can cause a new variant nv-1996 prion causing BSE can cause a new variant nv-

CJD in humans by consuming beef with BSECJD in humans by consuming beef with BSE

Viral ReplicationViral Replication

Viral AttackViral Attack

Viruses are very specific as to which Viruses are very specific as to which species they attackspecies they attack

HOST specificHOST specific Humans rarely share viral diseases with Humans rarely share viral diseases with

other animalsother animals Eukaryotic virusesEukaryotic viruses usually have usually have

protective protective envelopesenvelopes made from the made from the host cell membranehost cell membrane

Lytic vs LysogenicLytic vs Lysogenic

Lytic cycleLytic cycle Phage causes lysis and death of Phage causes lysis and death of

host cellhost cell

Lysogenic cycleLysogenic cycle Prophage DNA incorporated in Prophage DNA incorporated in

host DNAhost DNA

5 Steps of Lytic Cycle5 Steps of Lytic Cycle 1. 1. AttachmentAttachment to the cell to the cell 2. 2. PenetrationPenetration (injection) of viral DNA or (injection) of viral DNA or

RNARNA 3. 3. Replication (Biosynthesis)Replication (Biosynthesis) of new viral of new viral

proteins and nucleic acidsproteins and nucleic acids 4. 4. AssemblyAssembly (Maturation) (Maturation) of the new of the new

virusesviruses 5. 5. ReleaseRelease of the new viruses into the of the new viruses into the

environment (cell lyses)environment (cell lyses)

AttachmentAttachment Phage attaches by tail fibers Phage attaches by tail fibers to host cell1to host cell1

PenetrationPenetration Phage lysozyme opens cell Phage lysozyme opens cell wall, tail sheath contracts to force tail wall, tail sheath contracts to force tail core and DNA into cellcore and DNA into cell

BiosynthesisBiosynthesis Production of phage DNA Production of phage DNA and proteinsand proteins

MaturationMaturation Assembly of phage particlesAssembly of phage particles Release Release Phage lysozyme breaks cell wallPhage lysozyme breaks cell wall

Lytic Cycle ReviewLytic Cycle Review

BacteriophageBacteriophage ReplicationReplicationBacteriophage inject Bacteriophage inject their nucleic acidtheir nucleic acidThey They lyse (break open)lyse (break open) the bacterial cell when the bacterial cell when replication is finishedreplication is finished

Attachment:Phage attaches to host cell.

Penetration:Phage pnetrates host cell and injects its DNA.

Merozoites released into bloodsteam from liver may infect new red blood cells

1

2

3

Bacterial cell wall

Bacterial chromosome

Capsid DNA

Capsid

SheathTail fiberBase platePinCell wall

Tail

Plasma membrane

Sheath contracted

Tail core

4 Maturation:Viral components are assembled into virions.

Tail

5 Release:Host cell lyses and new virions are released.

DNA

Capsid

Tail fibers

One-step Growth One-step Growth CurveCurve

Viral LatencyViral LatencySome viruses have the ability to become Some viruses have the ability to become dormantdormant inside the cell inside the cellCalled Called latent viruseslatent virusesThey may remain They may remain inactiveinactive for long for long periods of time (years)periods of time (years)Later, they Later, they activateactivate to produce new to produce new viruses viruses in response to some external in response to some external signalsignalHIVHIV and and HerpesHerpes viruses are examples viruses are examples

Lysogenic CycleLysogenic CyclePhage DNAPhage DNA injected injected into host cell into host cell Viral DNA joins host Viral DNA joins host DNA forming a DNA forming a prophageprophageWhen an When an activation activation signalsignal occurs, the phage occurs, the phage DNA starts replicatingDNA starts replicating

Lysogenic CycleLysogenic Cycle

Viral DNA (part of Viral DNA (part of prophage) may stay prophage) may stay inactiveinactive in host cell for in host cell for long periods of timelong periods of timeReplicated during each Replicated during each binary fissionbinary fissionOver time, Over time, many cells many cells form containing the form containing the prophagesprophages

Viral LatencyViral LatencyOnce a Once a prophage cell is activatedprophage cell is activated, host , host cell enters the lytic cellcell enters the lytic cellNew viruses form a & the New viruses form a & the cell lyses cell lyses (bursts)(bursts)Virus said to be Virus said to be virulent (deadly)virulent (deadly)

INACTIVE STAGEACTIVESTAGE

Virulent VirusesVirulent Viruses

HOST CELL

LYSES & DIES

The Lysogenic CycleThe Lysogenic Cycle

Latency in EukaryotesLatency in EukaryotesSome Some eukaryotic eukaryotic virusesviruses remain dormant remain dormant for many years in the for many years in the nervous system tissuesnervous system tissues ChickenpoxChickenpox (caused by (caused by the virus the virus Varicella Varicella zosterzoster) is a childhood ) is a childhood infectioninfectionIt can It can reappear later in reappear later in life as life as shinglesshingles, a painful , a painful itching rash limited to itching rash limited to small areas of the bodysmall areas of the body

SHINGLES

Latency in EukaryotesLatency in EukaryotesHerpesHerpes viruses also viruses also become become latent in the latent in the nervous systemnervous systemA herpes infection A herpes infection lasts lasts for a person’s lifetimefor a person’s lifetimeGenital herpesGenital herpes (Herpes (Herpes Simplex 2)Simplex 2)Cold sores or fever Cold sores or fever blistersblisters (Herpes (Herpes Simplex1)Simplex1)

SKIN TO SKIN CONTACT

PASSED AT BIRTH TO BABY

Treatment for Treatment for Viral DiseaseViral Disease

VaccinesVaccines An An attenuated virusattenuated virus is a weakened, less is a weakened, less

vigorous virusvigorous virus ““Attenuate"Attenuate" refers to procedures that refers to procedures that

weaken an agent of disease weaken an agent of disease (heating)(heating) A A vaccinevaccine against a viral disease can be against a viral disease can be

made from an attenuated, less virulent made from an attenuated, less virulent strain of the virusstrain of the virus

Attenuated virus is capable of Attenuated virus is capable of stimulating stimulating an immune responsean immune response and creating and creating immunity, immunity, but not causing illnessbut not causing illness

Other Viral TreatmentsOther Viral Treatments

InterferonInterferon are naturally are naturally occurring proteins occurring proteins made made by cellsby cells to fight viruses to fight virusesGenetic alteringGenetic altering of of viruses (attenuated viruses (attenuated viruses)viruses)Antiviral drugsAntiviral drugs (AZT) (AZT)Protease inhibitorsProtease inhibitors – – prevent capsid formationprevent capsid formation

Growing VirusesGrowing Viruses

Viruses must be Viruses must be grown in living grown in living cells.cells.

Bacteriophages Bacteriophages form plaques on form plaques on a lawn of a lawn of bacteria. bacteria.

Figure 13.6

Growing VirusesGrowing Viruses

Animal Animal viruses may viruses may be grown in be grown in living animals living animals or in or in embryonated embryonated eggs.eggs.

Figure 13.7

Growing VirusesGrowing Viruses Animal and plants viruses may be grown Animal and plants viruses may be grown

in cell culture.in cell culture. Continuous cell lines may be maintained Continuous cell lines may be maintained

indefinitely.indefinitely.

Figure 13.8

Cytopathic effectsCytopathic effects Serological testsSerological tests

Detect antibodies against viruses in a patientDetect antibodies against viruses in a patient Use antibodies to identify viruses in neutralization Use antibodies to identify viruses in neutralization

tests, viral hemagglutination, and Western blottests, viral hemagglutination, and Western blot Nucleic acidsNucleic acids

RFLPsRFLPs PCRPCR

Virus IdentificationVirus Identification

Virus IdentificationVirus Identification

Figure 13.9

Multiplication of Animal Multiplication of Animal virusesviruses

AttachmentAttachment Viruses attaches to cell Viruses attaches to cell membranemembrane

PenetrationPenetration By endocytosis or fusionBy endocytosis or fusion UncoatingUncoating By viral or host enzymesBy viral or host enzymes BiosynthesisBiosynthesis Production of nucleic acid and Production of nucleic acid and

proteinsproteins MaturationMaturation Nucleic acid and capsid proteins Nucleic acid and capsid proteins

assembleassemble ReleaseRelease By budding (enveloped viruses) or By budding (enveloped viruses) or

rupturerupture

Attachment, Penetration, Attachment, Penetration, and Uncoatingand Uncoating

Figure 13.14

Release of an enveloped virus by Release of an enveloped virus by buddingbudding

Figure 13.20

Multiplication of DNA VirusMultiplication of DNA Virus

Figure 13.15

Virion attaches to host cell

Virion penetrates cell and its DNA is uncoated

Early transcription and translation; enzymes are synthesized

1

2

3

DNA

Late transcription; DNA is replicated

4

Late translation; capsid proteins are synthesized

5

Virions mature6

Capsid

Papovavirus

Host cell

DNA

Cytoplasm

Virions are released7

Capsid proteins

mRNA

Pathways of Multiplication for Pathways of Multiplication for RNA-Containing VirusesRNA-Containing Viruses

Figure 13.17

Multiplication of a RetrovirusMultiplication of a Retrovirus

Figure 13.19

Retrovirus penetrates host cell.

Virion penetrates cell and its DNA is uncoated

The new viral DNA is tranported into the host cell’s nucleus and integrated as a provirus. The provirus may divide indefinitely with the host cell DNA.

1

2

3

DNA

Transcription of the provirus may also occur, producing RNA for new retrovirus genomes and RNA that codes for the retrovirus capsid and envelope proteins.

4

Mature retrovirus leaves host cell, acquiring an envelope as it buds out.

5

CapsidReverse transcriptase

Virus Two identical + stands of RNA

DNA of one of the host cell’s chromosomes

Provirus

Host cell

Reverse transcriptase

Viral RNA

RNA

Viral proteins

Identical strands of RNA

Activated oncogenes transform normal Activated oncogenes transform normal cells into cancerous cells.cells into cancerous cells.

Transformed cells have increased growth, Transformed cells have increased growth, loss of contact inhibition, tumor specific loss of contact inhibition, tumor specific transplant and T antigens.transplant and T antigens.

The genetic material of oncogenic viruses The genetic material of oncogenic viruses becomes integrated into the host cell's becomes integrated into the host cell's DNA.DNA.

CancerCancer

Oncogenic DNA Oncogenic DNA VirusesViruses AdenoviridaeAdenoviridae HeresviridaeHeresviridae PoxviridaePoxviridae PapovaviridaePapovaviridae HepadnaviridaeHepadnaviridae

Oncogenic VirusesOncogenic Viruses

Oncogenic RNA Oncogenic RNA virusesviruses RetroviridaeRetroviridae

Viral RNA is Viral RNA is transcribed to DNA transcribed to DNA which can integrate which can integrate into host DNAinto host DNA

HTLV 1HTLV 1 HTLV 2HTLV 2

Latent vs PersistentLatent vs Persistent Latent Viral InfectionsLatent Viral Infections

Virus remains in asymptomatic host cell for Virus remains in asymptomatic host cell for long periodslong periods Cold sores, shinglesCold sores, shingles

Persistent Viral InfectionsPersistent Viral Infections Disease processes occurs over a long period, Disease processes occurs over a long period,

generally fatalgenerally fatal Subacute sclerosing panencephalitis (measles Subacute sclerosing panencephalitis (measles

virus)virus)

Figure 13.22

Plant VirusesPlant Viruses Plant viruses Plant viruses

enter through enter through wounds or via wounds or via insectsinsects

ViroidsViroids Viroids are Viroids are

infectious infectious RNA; potato RNA; potato spindle tuber spindle tuber diseasedisease

Some Plant VirusesSome Plant Viruses

Table 13.6

Virus FamiliesVirus Families Single-stranded DNA, Single-stranded DNA,

nonenveloped virusesnonenveloped viruses ParvoviridaeParvoviridae

Human parvovirusHuman parvovirus Fifth diseaseFifth disease

Anemia in Anemia in immunocompromised immunocompromised patientspatients

Double-stranded DNA, Double-stranded DNA, nonenveloped virusesnonenveloped viruses

MastadenovirusMastadenovirus Respiratory Respiratory

infections in infections in humanshumans

Tumors in Tumors in animalsanimals


PapillomavirusPapillomavirus (human wart (human wart virus)virus)

PolyomavirusPolyomavirus Cause tumors, Cause tumors,

some cause some cause cancercancer


OrthopoxvirusOrthopoxvirus (vaccinia and (vaccinia and smallpox smallpox viruses)viruses)

MolluscipoxvirusMolluscipoxvirus Smallpox, Smallpox,

molluscum molluscum contagiosum, contagiosum, cowpoxcowpox

SimplexvirusSimplexvirus (HHV1 and HHV 2) (HHV1 and HHV 2) VaricellavirusVaricellavirus (HHV 3) (HHV 3) LymphocryptovirusLymphocryptovirus (HHV 4) (HHV 4) CytomegalovirusCytomegalovirus (HHV 5) (HHV 5) RoseolovirusRoseolovirus (HHV 6) (HHV 6) HHV 7HHV 7 Kaposi's sarcoma (HHV 8)Kaposi's sarcoma (HHV 8)

Some herpesviruses can remain Some herpesviruses can remain latent in host cellslatent in host cells



HepadnavirusHepadnavirus (Hepatitis B (Hepatitis B virus)virus) Use reverse Use reverse

transcriptase to transcriptase to produce DNA produce DNA from mRNAfrom mRNA

Single-stranded RNA, + Single-stranded RNA, + strand, nonenvelopedstrand, nonenveloped

EnterovirusEnterovirus Enteroviruses Enteroviruses

include include poliovirus and poliovirus and coxsackieviruscoxsackievirus

RhinovirusRhinovirus Hepatitis A Hepatitis A

virusvirus


Hepatitis E virusHepatitis E virus NorovirusNorovirus

(Norwalk agent) (Norwalk agent) causes causes gastroenteritisgastroenteritis


AlphavirusAlphavirus Alphaviruses are Alphaviruses are

transmitted by transmitted by arthropods; arthropods; include EEE, include EEE, WEEWEE

RubivirusRubivirus (rubella virus)(rubella virus)


ArbovirusesArboviruses can can replicate in replicate in arthropods; include arthropods; include yellow fever, dengue, yellow fever, dengue, SLE, and West Nile SLE, and West Nile virusesviruses

Hepatitis C virusHepatitis C virus


CoronavirusCoronavirus Upper Upper

respiratory respiratory infectionsinfections

Single-stranded RNA, – Single-stranded RNA, – strand, one RNA strandstrand, one RNA strand

Vesiculovirus Vesiculovirus LyssavirusLyssavirus

(rabies virus)(rabies virus) Cause numerous Cause numerous

animal diseasesanimal diseases


FilovirusFilovirus Enveloped, Enveloped,

helical viruseshelical viruses Ebola and Ebola and

Marburg Marburg virusesviruses


ParamyxovirusParamyxovirus MorbillivirusMorbillivirus

ParamyxovirusParamyxovirus causes causes parainfluenza, parainfluenza, mumps and mumps and Newcastle Newcastle diseasedisease


Hepatitis D Hepatitis D virusvirus Depends on Depends on

coinfection with coinfection with HepadnavirusHepadnavirus

InfluenzavirusInfluenzavirus (Influenza (Influenza viruses A and B)viruses A and B)

Influenza C Influenza C virusvirus Envelope spikes Envelope spikes

can agglutinate can agglutinate RBCsRBCs

Single-stranded RNA, – Single-stranded RNA, – strand, multiple RNA strandsstrand, multiple RNA strands

BunyavirusBunyavirus (CE virus) (CE virus) HantavirusHantavirus


ArenavirusArenavirus Helical capsids Helical capsids

contain RNA-contain RNA-containing containing granulesgranules

Lymphocytic Lymphocytic choriomeningitischoriomeningitis

VEE and Lassa VEE and Lassa FeverFever


LentivirusLentivirus (HIV) (HIV) Oncogenic virusesOncogenic viruses

Use reverse Use reverse transcriptase transcriptase to produce to produce DNA from viral DNA from viral genomegenome

Includes all Includes all RNA tumor RNA tumor virusesviruses

Single-stranded RNA, two RNA strands, Single-stranded RNA, two RNA strands, produce DNAproduce DNA

Double-stranded RNA, Double-stranded RNA, nonenvelopednonenveloped

ReovirusReovirus (Respiratory (Respiratory Enteric Orphan)Enteric Orphan)

RotavirusRotavirus Mild respiratory Mild respiratory

infections and infections and gastroenteritisgastroenteritis

Colorado tick Colorado tick feverfever

Education

Viruses, viroids, and prions