Papilloma viruses can evolve into carcinomas 

the most common association with papilloma viruses is being a major cause of human cervical cancer.

What are Papilloma- Polyoma- and Adenomaviruses have in common in regards to replication?

These can infect and replicate in "resting" cells.

They are able to do this because they can "turn on" resting cells, and can be transcribed immediately because they are already double stranded 

Which virus can not be grown in cell culture, and instead is classified using Nucleic acid sequencing:

Papillomaviruses 

or 

Polyomaviruses ??

Papillomaviruses!

Polyomaviruses on the other hand grow readily in cell culture. 

Papillomaviruses:

Only one strand is of ds DNA is transcribed.

Early proteins = E5, 6, 7

Polyomaviruses:

Both strands of ds DNA are transcribed.

Early proteins = T antigens

Both can "turn on" resting cells because they are double stranded and ready to be transcribed.

"French Molt" - feather defect (mild form of disease)

generalized disease: 

weakness, pallor, crop stasis, dehydration

HIGH MORTALITY - up to 80% 

Survivors shed virus in feces for 6 months.

Progressive multifocal leukoencephalopathy (CNS disease) - immunosuppressed rhesus macaques.

Solid tumors of newborn rodents 

What are some lesions that are caused by JC virus

(a polyomavirus)?

it causes progressive multifocal leukoencephalopathy in humans 

(this is similar to the disease produced in macaques by SV40) 

These are early proteins that initiate the replication process, prepares the cell for mitosis. 

They interact with cell tumor supressor proteins (p53/Rb) that regulate cell growth, that would normally keep the cell at rest. Binds to promoter region and turns off production of itself, when critical level reached.

Produces: DNA binding proteins, cell DNA dep DNA polymerase, ribonucleotide reductase. 

ALSO has Helicase-like activity, opening of ds DNA (lets DNA binding proteins in).  Allows for expression of late genes (structural proteins).  Initiates DNA replication!

What are some examples of tumor supressor proteins?

What is their function in the cell? 

Examples: p53, Rb (Retinoblastoma gene product)

Function: regulate cell growth by keeping the cell at rest

These are early proteins that initiate the cell for replication and prepare for mitosis.  They bind to tumor supressor proteins that regulate cell growth that maintain the cell at rest. Binds to promoter region and turns off production of itself, when critical level reached.

ALSO has Helicase-like activity, opening of ds DNA (lets DNA binding proteins in).  Allows for expression of late genes (structural proteins).  Initiates DNA replication!

Attachment 

Penetration 

Movement along microtubules - Nucleocapsid disintegrates

DS DNA goes through nuclear pore 

Transcription - transcription of early mRNA

Movement to cytoplasm (where ribosomes are)

Translation - generates T antigens - binds to p53/Rb

Cell turned on - producing DNA binding proteins, cDNAdepDNA polymerase

DNA replication

Late structural proteins produced - then moved to nucleus 

Nucleocapsids packaged 

Egression by lysis 

DNA binding proteins

Cell DNA dependent DNA polymerase 

Ribonucleotide reductase 

The PR region - this codes for viral protease, which is unique to the virus. 

Protease inhibitors are good anti-viral therapies for retroviruses. 

IT IS RANDOM

If I see it once more in my notes, ill cry 

Insertional mutagenesis

Cis-activation

Transduction

Transactivation

-The sight of the provirus insertion (6 total known) 

-Mutations in surface receptors or envelop (utilizing different receptors) 

-LTR efficacy variability

FeSV is an imcompetant ENDOgenous virus - doesnt have all the necessary elements to replicate.  The FeLV (Exogenous type) will "rescue" this when there is a co-infection and provide the required genes for replication.  Once transcribed, the FeSV will be packaged with an FeLV envelope!

-Papillomaviridae - human genital warts, cerival cancer, bovine and rabbit lesions

-Polyomaviridae (SV40) 

-Adenoviridae (some)

-Hepadnaviridae - liver cancer 

-Herpesviridae (epstein-barr, berkits lymphoma, mareks disease virius) 

Small 

naked - Non enveloped

icosahedral symmetry 

DS Circular DNA 

What are the physical characteristics of Polyomaviruses?

Small

Non enveloped (naked) 

Icosahedral symmetry 

DS Circular DNA 

Which type of proteins are associated with Oncogenesis:

Early or Late?

Early proteins 

These proteins are non structural and are responsible for regulating the virus and prepare it for replication.

Polyomaviruses, Papillomaviruses, and Adenoviruses 

These are DNA viruses that produce early proteins (early mRNA products) that will interact with tumor supression proteins.  They are also double stranded so they are ready to replicate!

It egresses by lysis of the cell. 

this is because it has taken over the resources of the cell so it can no longer maintain its cell membrane integrity, and it becomes fragile and lyses. 

If there is a viral integration in the host cell genome, when the T antigens build up they move back to the nucleus as normal, but ARE NOT ABLE to turn off their own production.  

This is because the integration has altered the genome causes FAILURE of feedback regulation! 

it is a gene that transcribes mRNA that's translated into proteins that regulate cell activity (replication). 

CELL oncogene contain both an "active" component and an "inhibitory" component, that allows for regulation. 

Avian leukosis virus - which causes systemic disease in chickens and other poultry.  This causes a slow onset of Lymphoid leukosis, osteopetrosis, renal tumors.  

Mouse mammary tumor virus- can be transmitted vertically in milk, integrates into the lymphocytes of milk can can cause breast cancer in these mice.

Ovine pulmonary adenomatosis virus- multisystemic disease of sheep causing pulmonary carcinoma, chronic wasting and overproduction of surfactant causing Fluid accumulation. 

Feline leukemia virus- feline lymphosarcoma, fibrosarcoma, myeloproliferative disease. Also anemia, immunosuppression, immune mediated disease.

Feline sarcoma virus

Murine leukemia virus 

Human leukemia virus

Bovine Leukemia virus- 

contains the oncogene coding for tax protein.  Causes a mononucleosis that can progress to a B cell lymphoma. 

HIV- 

FIV- 3 stage immune disease of cats, destroys CD4+ T cells, can incubate for years, infective for life. 

SIV- 

EIA- spread by biting flies (mech vector), acute anemia and fatality, chronic relapsing disease (PI), lifelong silence.

Caprine arthritis encephalitis virus- (sheep and goats) arthritis in older goats (more common), Encephalomyelitis and ascending paralysis in kids

Visna (CNS) virus- (Sheep) Slow virus, progressing "wasting" 

Maedi (Lungs) virus- (Sheep) Ovine progressive pneumonia, slow virus.

Medium sized 

Enveloped 

Icosahedral symmetry nucleocapsid

DS +RNA (covalently linked at one end) 

SU - surface protein (glycoprotein)

TM - transmembrane that attaches SU to envelope

Packaged with RNA dep RNA polymerase (Reverse transcriptase and integrase) 

Reverse transcriptase 

integrase 

(RNA dep RNA polymerase) 

Alpha, beta and Gamma - retroviruses

 Such as: avian leukosis virus, ovine pulmonary adenomatosis virus, FeLV, FeSV, Human leukemia virus 

Delta, Epsilon and Lenti- retroviruses.

Such as: Bovine leukemia virus, HIV, FIV, SIV, Equine Infectious Anemia, Caprine arthritis encephalitis virus, VIsna/Maedi virus, dermal sarcomas and hyperplasia of Walleyes. 

The complex and simple retroviruses are very similar gentically (has LRT, GAG, POL, TM, envelope) 

BUT the complex retroviruses have lots of genes that code for small regulatory proteins.  

These proteins can determine pathogenesis and replication.

LRT - promoter (R-U5----U3-R) both sides

GAG - structural proteins

POL - reverse transcriptase and integrase

ENV - Surface protein (SU) and transmembrane portion (TM)

This is a POWERFUL promoter region that enhances expression of provirus.  Determines that the segement is a provirus, located on both 5' and 3' ends of the provirus. 

R-U5 ------ U3-R

This codes for structural proteins.

It can be read straight through and cleaved into individual proteins, or can be directly made into individual precursors. 

These are surface glycoproteins.

The fuse to a host cell via fusion from without. 

New SU is made - its transcription and translation is associated with the ER. The proteins are generated through the ER and transported in a vesicle.  They are finalized in the golgi and transported in vesicles that fuse with the cell membrane. 

The rest of the virion is packaged and egresses from the host cell.

This is the protease incoding region, which is specific to viruses. So this is a good target for anti-virals.  

Protease inhibitors are often used against immunodeficiency viruses. 

vif - degrades the protein APOBEC 3G- which is part of the hosts intrinsic defense (gets incorporated into progeny virions and prevents replication) 

tat - facilitates transactivation of viral genes 

tax - facilitates transactivation of viral genes (of Bovine leukemia virus only) 

rev - export of viral RNA (less important) 

nef - down regulates CD4 receptors 

What is the function of the protein vif?

Which viruses can it been found in? 

The vif protein can be found in

LENTIVIRUSES (complex retroviruses).

Its function is to bind and degrade the protein APOBEC 3G, which is a part of intrinsic defense that interferes with virion replication. 

What is the function of the protein APOBEC 3G?

Which type of viruses can it be found in?

It is found in LENTIVIRUSES.

The function of APOBEC 3G is part of the intrinsic defense. It gets incorporated into progeny virions and interferes with subsequent replication. 

Competent retroviruses are exogenous, can be transmitted horizontally, contains a complete set of genes required for replication. 

Incompetent retroviruses are endogenous, can be transmitted genetically, missing genes needed to replicate so will remain in the host cell as a provirus.  Can be assisted by a "rescue" virus that IS Competent and will provide the necessary proteins and envelop for replication.

Insertional mutagenesis

Cis-activation 

Transduction 

Transactivation 

This is where a provirus is inserted directly into a cellular oncogene.  

THIS IS A RANDOM OCCURRANCE

Retroviruses are not able to transfer genetic material within and between species.

True or False?

FALSE 

These are referred to as XENOTROPIC retroviruses and have the potential to transfer genetic elements within and between species. 

Rous Sarcoma Virus

This is where a viral DNA provirus viral oncogene is inserted into the cell DNA. 

the feedback inhibition mechanism region is blocked on cell oncoprotein.

This is when the retrovirus codes for regulatory proteins that affects cell growth activity. 

Ie. tax (of Bovine leukemia virus) and tat (of HIV)

This is when the Cellular DNA dependent RNA polymerase (transcriptase) transcribes the RNA of the provirus and continues past, thus also transcribing cell oncogene. 

This will then be packaged into a new virion and will have the provirus and a portion of the cell oncogene. 

Attachment - fusion from without (loses envelope) 

moves along microtubules while nucleocapsid is degraded

reverse transcriptase uses both +ss RNA 

creates negative sense DNA

Positive sense DNA is then used to make double stranded DNA - which is circular 

Integrase passes Circular ds DNA into nucleus

transcription of mRNA occurs

leaves the nucleus to the cytoplasm where translation occurs. 

Transduction involves intramolecular recombination of viral and cellular DNA that is then incorporated into a progeny virion.

True or False?

True

recombination occurs during the reverse transcription and gets incorporated into the circular DNA that composes progeny virions. 

Which subtypes of FeLV can replicate in human cells?

Is there evidence of human infection?

Which FeLV subtype is always present? 

Why is this so?

Subtype A 

because subtypes B and C arise de novo from intramolecular recombinations of env gene and endogenous subtype A. 

the ENV gene and receptor specificity - - 

this detemines how they use receptors.

Day 0 - FeLV infection (through bite or contact) 

0-3 days - primary viremia

7- 14 days - secondary viremia (once reached target organs)

after 14 days - first is shed 

Immune response may terminate the virus after 16 weeks 

If longer than 16 weeks - persistantly infected

Lymphosarcomas:

Mutlicentric, thymic, alimentary, non lymphoid T cell invasions

Myeloproliferative disease and anemia

IMMUNE SUPRESSION - decrease T cells 

Fibrosarcoma 

kittens with concurrent FeSV infections

Because there are 6 loci associated with oncogenesis (cell transformation)

Mutations can occur at antireceptor location

Efficiency of LTR

Generation of subtypes from intramolecular recombinations of FeLV A

ELISA - The FeLV p27 antigen capture ELISA is used

positive testing does NOT mean persistant infection unless 16+ weeks of viremia occur.

TEST needs to be RECHECKED in a few weeks.

Direct FA - look for p27 antigen in neutrophils and platelets, positive test indicates PI (most likely) 

RT-PCR - detect viral nucleic acids

+ IFA - detects p27 antigen in neutrophils and platelets. Since neutrophils are not dividing, the neutrophil progenitors in the bone marrow is where the virus would get in. Since it is in neutrophils, there has been enough time for them to do this and mature. (+ after 3wks of infection) 

Also MULTIPLE ELISA assays can be run, and if the viremia persists for more than 16 weeks, it can be considered Persistantly Infected.

Replacement cats - clean/disinfect/wait 10 days

with colonies - test and remove infected cats 

Colonies clean if 2 neg at 12 weeks apart

Vaccines (killed or recombinant) 

Killed vaccine - subunit or whole

Canarypox recombinant - pox virus backbone with SU (foreign gene of FeLV). 

They PREVENT virus from GETTING INTO the cell.

The canarypox recombinant vaccine uses the pox virus as a backbone and has the SU as a foreign antigen. The SU of FeLV contains the antireceptor. But allowing the immune system to build antibodies to the SU, there will be no attachment of the virus to cells. 

Clinical presentations of viral infections occur rapidly, so you can readily prevent systemic infections.

True or False?

FALSE

Although there are some diseases that can present quite rapidly, if there are clinical presentations of a virus, then it chas already spread throughout the body. 

This is why RAPID DIAGNOSTICS are essential

(like snap tests) 

TIMING: Clinical presentation = virus spread throughout body. need rapid diagnostics and prophylatic antiviral use.

Mutants: drug resistant mutants can rapidly arise (like HIV does) 

SAFETY: when developing antivirals, virally unique targets should be selected, because they share many of the same pathways as cells and can cause toxicity. 

Cap-snatching mechanism

Viral RNA dependent RNA polymerase

Viral thymidine kinase 

Viral Protease inhibitor

...and many more

Which type of herpesviruses are faster at replicating:

Alpha or Beta?

ALPHAs 

they are fast replicating viruses (such has IBR, Feline Herpes 1, Canine herpes 1, Equine 1 and 4) 

will replicate as soon as they get into a cell.

Betas are much slower.

Receptor analogs, WINS

(Vaccines can be used to build immunity to surface proteins - this will also inhibit virion-cell binding)

What anti-viral can be used against virus uncoating?

How does it work ?

Amantadine

It places the M2 ion channel that would normally allow for an influx of H ions that decrease pH, which is necessary for the reconfiguration needed for uncoating.

AZT 

(zidovudine) 

HIV tat inhibitors

This is a HERPES VIRUS 

A - Glycoprotein (surface molecules) 

B - Triangular facets of nucleocapsid

C - Nucleocapsid with icosahedral symmetry 

Nucleosides lack phosphate, unlike nucleotides, so if they are incorporated into a growing nucleotide chain, there will be a distortion and the chain will be no longer to extend.

In order to be incorporated into the cell it would need to be in triphosphate form, and will only be done in the presence of viral kinases.

What is IDU?

How does it work?

What is Ara-a?

How does it work?

(adenine arabinoside) 

this was the first effective drug against herpes, and vesicular stomatitis virus.  

It is a nucleoside analog, but it can cause systemic toxicities, so it is only just in heoric situations.

Nucleoside analogs get incorporated into growing nucleotide chains, distorts it, thus preventing transcription.

What is Acyclovir?

How does it work?

Acyclovir is a nucleoside analog, that doesnt have pentose but instead has only 1 hydroxyl group. It will TERMINATE CHAIN formation.  

it also inhibits viral DNA dependent DNA polymerase (more than cellular).  

it is used to treat human herpes.

It is a prodrug that is activated by VIRAL thymidine kinase of herpesviruses.  This is ONLY produced by virally infected cells, so will not effect other cells. 

Thymidine kinase will phosphorylate Acyclovir, cellular kinase enzymes continue to phosphorylate, and then the acyclovir TRIphosphate is incorporated into replicating DNA. This will then terminate chain formation, ceasing replication. 

Valtrex is an acyclovir derivative, that is used systemically because it has better bioavailability than acyclovir.  

The valine additive increases uptake in the gut.  Acyclovir is a nucleoside analong that causes chain termination. 

NA Neuraminidase- regulates progeny release by cleaving HA-salic acid residues (allow progeny egression)

HA hemagglutinin- regulates attachment and fusion of virus

M2 ion channel- regulates uncoating by allowing influx of H+ ions

What is amantidine?

How does it work?

effects uncoating of INFLUENZA virus.

it does so by targeting M2 ion channels that control H+ influx needed to decrease pH- ONLY effective in type A influenza 

effective against type B and C, increases pH by actingas a high base within endosome.

What are some potential side effects of amantadine?

How can this be corrected?

Amantadine can readily cross the blood-brain barrier, so it has CNS side effects. By adding a methyl group (the methylated derivative rimantadine) it is no longer able to cross.  

Resistant mutants can also arise quickly 

 NA interacts with Sialic acid residues on the cell surface and this prevents released progeny virions from accumulating on the cell membrane

NA inhibitors are derivatives of sialic acid and have a greater binding affinity to NA enzyme site. This causes ACCUMULATION of progency virion on surface of cell, making it a perfect target for immune system (macrophage)

Zanamivir (inhaled)

Oseltamivir (orally) 

Pleconaril is a receptor binding site inhibitor - that blocks access to the receptor binding site on the floor of the canyon that is creating on the icosahedral picornaviruses. 

Used for enterovirus encephalitis - heoric effort only.

other picornaviruses include: FMVD, Polioviruses, and Hepatitis A 

The virus specific proteases that are made. 

Reverse transcriptase inhibition 

chain termination 

What is AZT?

How does it work?

chain termination: encorporated into DNA during transcription and missing hydroxyl group so chain cannot elongate

Direct inhibition of reverse transcriptase: higher affinity for AZT than RT 

MUTATIONS are common

inhibit virus specific protease.

often used against HIV, but mutations arise quickly

Side effects are common

it is a phosphorylated acyclic nucleoside analog - 

different from acyclovir because it doesnt need to be phosphorylated by VIRAL kinases, instead triphosphate is completely formed by cell kinases. 

This means it can enter bistander cells and cause neg effects. This is BROAD SPECTRUM for DNA viruses and retroviruses (which are RNA). 

Nucleoside analog 

interferes with capping of mRNA 

effective against many RNA viruses 

works against RNA dep RNA polymerase

can be used against lantavirus, hantaviruses (like 4 corners virus), and human RSV

Used against Hepatitis C - effective. FIP, FIV, FeLV (not proved effective).

Conveys "anti-viral" state to cells. 

Small interfering RNAs - which are generated from a virus.

this is complementary to mRNA that produce a necessary protein for viral survival.  

linked to an endonuclease (RISC) - bind and degrade target mRNA 

Using a "cocktail" of antiviral agents 

that attack more than one target. 

MicroRNA

short nucleotide generated from mammalian RNA of nuclear genes (used in post transcriptional regulation) 

linked with an endonuclease (RISC) that binds to and degrade target mRNA.

By inserting genes for:

IL2 

NS1 - non structural protein that determines efficiency of virus replication. 

"highly fusogenic" F protein - fusion between virus envelope and cytoplasmic membrane (fusion from without) 

Newcastle disease virus 

Adenoviruses 

Vescicular stomatitis virus 

The early proteins code for non structural proteins that prepare the cell for replication and provide the cell with necessary proteins to start replicating.  By removing these early gene products the virus is not conditionally replicative, and will only replicate in actively dividing cells that can provide the necessary elements. 

This allows it to relicate in rapidly dividing tumor cells and avoid most normal cells.

When are adenoviruses used for oncolytic purposes? 

Why?

Needs Plasmid - with Gene of interest 

retrovirus 

packaging cell - needs to package gene because retrovirus is replication incompetent

retroviruses 

adenoviruses 

adeno-associated viruses 

herpesviruses 

How big the GOI is - compared to how big the vector genome is.

target cells - if they are susceptible to infection, if actively dividing 

Injury to host - vector virus carries out function without initiating extra immune response or injurying host

Mutagenesis - how likely is the vector virus to mutate

It is made into a replication incompetant virus vector that contains the GOI CFTR.  

This targets the mucus secreting cells of the respitratory tract, that cause the clinical manifestation of disease. 

these treatments are short lasting.

They are longer lasting because the GOI may integrate into the cell genome. 

Although both viruses' GOI will exist episomally, which means that it doesnt need the host cells to replicate, the AAV can integrate into host cell genomes.

AAV can also be used to both CORRECT genes and add genes to a genome. 

This is the holy grail of gene therapy

Injection (can be IM, SQ, ID)

Eye drop (NDV) 

Aerosol (IBV) 

Water additive (IBR, NDV) 

Feed additive (NDV) 

In ova (mareks disease) 

Scarification (Orf, fowl pox) 

Intranasal (Equine influenza, BHV1, FIP) 

Foramlin, gluteraldehyde, 

with rabies: beta proprilactone

With FMVD: ethylenemine

A wild type can eb given by an unnatural route 

ie. variolation of small pox

Wild type virus in a heterologous host 

attenuated wild type vaccines