Term
| What is the difference between an infestation and an infection? |
|
Definition
infestation = ectoparasites
infection = endoparasites |
|
|
Term
| List some endoparasitic multicellular organisms. |
|
Definition
-nematodes
-trematodes
-cestodes |
|
|
Term
| List some endoparasitic unicellular organisms. |
|
Definition
-protazoa
-fungi
-bacteria
-mycoplasmas
-rickettsia
-chlamydia |
|
|
Term
| List some endoparasitic acellular organisms. |
|
Definition
|
|
Term
| What is the defining difference between bacteria and mycoplasmas? |
|
Definition
| mycoplasmas lack a cell wall |
|
|
Term
|
Definition
-obligate intracellular parasites that resemble mitos
-retain segregation of genome from that of the host |
|
|
Term
|
Definition
obligate intracellular parasites that resemble mitos except they lack cytochrome and lack the ability to produce ATP
-retain segregation of genome from that of the host |
|
|
Term
| List the stages of the viral life cycle. |
|
Definition
-transmission (extracellular)
-attachment and penetration
-production of viral proteins
-replication of viral genome
-assembly and release of viral progeny |
|
|
Term
| What cell types are prions found in high concentration? |
|
Definition
| neurons and lymphoid cells |
|
|
Term
| What is the nucleocapsid? |
|
Definition
-made of capsomeres
-functionally analogous to chromatin
-functions to protect genome and regulate its expression |
|
|
Term
| What are the two nucleocapsid arrangements? Describe them. |
|
Definition
-Cubical aka isosahedral = repeating subunits forming a container that may look spherical by EM
-Helical aka filamentous = form a helix, ALWAYS contains RNA genome |
|
|
Term
|
Definition
-infectious viral particle
- |
|
|
Term
| What is the most abundantly expression viral protein? |
|
Definition
|
|
Term
| What do you detect the presence of capsomeres? |
|
Definition
|
|
Term
| What is the difference between (+)sense and (-)sense single stranded genomes? |
|
Definition
(+)sense = sequence is identical to that of mRNA
(-)sense = sequence is complementary to mRNA |
|
|
Term
| What are some general characteristics of viral genomes? |
|
Definition
-haploid
-encode few proteins
-much info in small amount of sequence (frameshifts, alt splicing) |
|
|
Term
| What is a defining behavioral difference between DNA and RNA viruses? |
|
Definition
-DNA = latent infections
-RNA = high genetic drift/plasticity |
|
|
Term
| What are some non-structural proteins that would be encoded in viral genomes? What is the clinical relevance of these proteins? |
|
Definition
-RNA-dependent RNA polymerase
-reverse transcriptase
-other regulatory proteins
Clin: can be targets for therapeutic intervention |
|
|
Term
| What are some pros and cons to having proteins directly associated with the nucelocapsid? |
|
Definition
Pro: hardy
Con: hard to change proteins on capsid |
|
|
Term
| What are some pros and cons to having proteins on the viral envelope? |
|
Definition
Pro:easy to change proteins
Con: can dry out |
|
|
Term
| What are some proteins associated with viral envelopes? |
|
Definition
-membrane glycoproteins (attachment, penetration)
-matrix proteins (mediate enveloped virus assembly) |
|
|
Term
| Which types of viruses are more hardy, enveloped or non-enveloped? Why? |
|
Definition
| non-enveloped! don't need to worry about drying out and are not affected by detergents |
|
|
Term
| What is the heirachy of classification of viruses based on struction? |
|
Definition
| viral family; viral genera; viral species; viral type, subtype, strain, and variants |
|
|
Term
| What are some examples of the classification of viruses based on route of transmission? |
|
Definition
| respiratory viruses, arboviruses |
|
|
Term
| What is a representative of Parvoviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-canine parvovirus
-ssDNA
-non-enveloped |
|
|
Term
| What is a representative of Papovaviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-papillomaviruses
-dsDNA
-non-enveloped |
|
|
Term
| What is a representative of Adenoviridae? It this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-infectious canine hepatitis virus
-dsDNA
-non-enveloped |
|
|
Term
| What is a representative of Herpesviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-rhinotracheitis viruses
-dsDNA
-enveloped |
|
|
Term
| What is a representative of Poxviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-contagious pustular dermatitis (ORF)
-dsDNA
-enveloped |
|
|
Term
| What is a representative of Picornaviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-foot in mouth disease
-ssRNA
-non-enveloped |
|
|
Term
| What is a representative of Caliciviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-feline calicivirus
-ssRNA
-non-enveloped |
|
|
Term
| What is a representative of Togaviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-equine encephalitis virus
-ssRNA
-enveloped |
|
|
Term
| What is a representative of Flaviviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-bovine viral diarrhea (BVD)
-ssRNA
-enveloped |
|
|
Term
| What is a representative of Coronaviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-calf corona virus (neonatal diarrhea)
-ssRNA
-enveloped |
|
|
Term
| What is a representative of Paramyxoviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-canine distemper virus
-ssRNA
-enveloped |
|
|
Term
| What is a representative of Rhabdoviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-rabies virus
-ssRNA
-enveloped |
|
|
Term
| What is a representative of Orthomyxoviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-influenza A
-ssRNA, seg
-enveloped |
|
|
Term
| What is a representative of Reoviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-rotavirus
-dsRNA, seg
-non-enveloped |
|
|
Term
| What is a representative of Retoviridae? Is this DNA or RNA, and is it enveloped or non-enveloped? |
|
Definition
-FeLV
-ssRNA, diploid
-enveloped |
|
|
Term
| What is attachment of the virus? |
|
Definition
| -viral ligand-host cell receptor interaction |
|
|
Term
| What is penetration of the virus? What are the two modes of penetration? |
|
Definition
-viral genome entering the cell
-can be via endocytosis or via fusion to the cell surface |
|
|
Term
| Describe endocytosis of a virus. |
|
Definition
-receptor-mediated
-membrane at receptor-ligand invaginates
-vesicle containing virion fuses with acidic endosome, which triggers release of viral genome into cyto |
|
|
Term
| Describe fusion of a virus with the cell. |
|
Definition
-viral envelope fuses to plasma membrane, mediated by a viral fusion glycoprotein
-viral fusion protein activated by host proteases |
|
|
Term
| During replication, what are the early viral proteins of DNA viruses? |
|
Definition
-proteins that redirect cellular protein/nucleic acid production (DNA-dependent RNA pol II)
-proteins that regulate transcription of viral genome
-enzymes required for replication of viral genome |
|
|
Term
| During replication, what are the late viral proteins of DNA viruses? |
|
Definition
| -structural proteins required for assembly of progeny (capsid, envelope, attachment proteins, etc) |
|
|
Term
| What is the main difference in replication of ssDNA and dsDNA viruses? |
|
Definition
| to initiate transcription, ssDNA viruses must first produce dsDNA (using cellular DNA pol), which then serves as a template for DNA-dep RNA pol II) |
|
|
Term
| Why are members of Poxviridae special compared to other dsDNA viruses? |
|
Definition
-they replicate in cyto, therefore they need to bring their own machinery!
-viral DNA-dep RNA pol produces transcripts and viral DNA-dep DNA pol is produced for genomic replication |
|
|
Term
| During replication, what happens to (+) ssRNA viruses? |
|
Definition
| (+)ssRNA is directly translated to viral proteins (including RNA-dep RNA pol which is needed to genome replication) |
|
|
Term
| During replication, what happens to (-) ssRNA viruses and dsRNA viruses? |
|
Definition
| virion carries RNA-dep RNA pol since it can't be directly translated |
|
|
Term
| During replication, what happens to (+) ssRNA diploid retroviruses? |
|
Definition
-the (+)sense genome is NOT directly translated!
-viral RNA-dep DNA pol converts the genome into a circular dsDNA copy
-circular dsDNA copy is inserted into the host DNA as a provirus |
|
|
Term
| What is permissiveness and tropism? |
|
Definition
-Cell that supports viral replication is permissive to viral infection
-Virus that can replicate in a cell has a tropism for that cell type |
|
|
Term
| Cellular permissiveness depends on what? |
|
Definition
-regulatory proteins (promoter, enhancer)
-chaperones (HSPs) which can enhance viral gene expression
-cellular kinases
-cellular proteases |
|
|
Term
| What are the two methods of assembly and release of enveloped viruses? |
|
Definition
|
|
Term
| Describe budding of enveloped viruses. |
|
Definition
-nucleocapsid associates with plasma membrane in areas that contain viral glycoproteins
-matrix proteins induce budding |
|
|
Term
| Describe exocytosis of enveloped viruses. |
|
Definition
-virus buds through golgi, RER, or nuclear membrane
PRO: viral proteins never shown on surface |
|
|
Term
| Describe how non-enveloped viruses release viral progeny. |
|
Definition
|
|
Term
| What are the three basic strategies to prevent the spread of viruses? |
|
Definition
-immunization
-direct inhibition of replication
-supportive care |
|
|
Term
| What are some ways to directly inhibit replication of a virus? |
|
Definition
-prevent viral attachment and penetration
-stop virus-encoded enzymes
-hit multiple steps in the replication cycle
-specificity |
|
|
Term
| What are some ways to prevent viral attachment and penetration? |
|
Definition
-receptor analogues to prevent the virus from interacting with target cells
-protease inhibitors to block processing of polyproteins
-ion channel blockers to stop the acidification of the virion |
|
|
Term
| How do we prevent virus-encoded enzyme activities? |
|
Definition
-neuraminidase releases viral attachment carbohydrates from the virus so it can't attach
-reverse transcriptase inhibitors
-inhibiting the activity of viral DNA polymerase (herpesvirus) |
|
|
Term
| What is the best way to prevent the spread of viruses? |
|
Definition
|
|
Term
| What are viral inclusion bodies? |
|
Definition
| a type of cytopathic effect with/without functional consequences to the cell |
|
|
Term
| What are 2 types of intranuclear inclusion bodies? |
|
Definition
-viral replication factories that aggregate and may displace hos cell DNA from the matrix
-nuclear bodies that look eosinophilic and may enhance RNA processing within the cell |
|
|
Term
| What are cytoplasmic inclusion bodies? |
|
Definition
| agregates of viral nucleocapsid or formed viral particles |
|
|
Term
| What are some cytopathic effects causing loss of cell luxury function or even cell death? |
|
Definition
-viral alteration of hos cell DNA replication/transcription
-viral interference with host cell transcript processing/translation
-adverse effects of viral envelope glycoproteins on host cell membrane function
-depletion of cellular ATP |
|
|
Term
| How does the virus alter host cell DNA replication and transcription? |
|
Definition
-DNA and RNA pol may be re-directed towards viral templates
-early viral proteins may inhibit hos transcription/replication
CLIN: cells live, however lose specialized function |
|
|
Term
| How does the virus interfere with hos transcript processing and translation? |
|
Definition
-selective interference with host cell transcript metabolism (cap snatching)
-high level of viral transcript production
CLIN: Loss of specialized function |
|
|
Term
| What are some adverse effects of viral envelope glycoproteins present on the host cell membrane? |
|
Definition
-syncytia formation
-target for antibody-dep cellular cytotoxic responses (innate immunity)
-altered ion permeability (electrical impulses gone, may lead to cell swelling) |
|
|
Term
| How do viruses hide the expression of viral glycoproteins on the surface of infected cells? |
|
Definition
-use diff promoters
-attenuate transcription along the length of the genome
-have the glycoproteins only insert onto internal membranes |
|
|
Term
| What happens when viruses deplete cellular ATP? |
|
Definition
-swelling, death
-ion pumps responsible for osmoregulation shut down, resulting in swelling
-lysosome spill contents, pH drops, cellular proteins denature
CLIN: this is good for non-enveloped viruses which need lysis to happen |
|
|
Term
| What are three cellular defense mechanisms associated with viral infection? |
|
Definition
-interferons
-ubiquitins
-fever |
|
|
Term
| How do interferons impose anti-viral activities? |
|
Definition
-create a hostile environment
-IFN-a and IFN-b induce anti-viral proteins |
|
|
Term
| What induces the expression of IFNs? |
|
Definition
|
|
Term
| What proteins do IFNs induce, and what is the function? |
|
Definition
-PKR: supresses all protein expression
-2-5A synth: nuclease
-Mx protein: inhibits viral transcription |
|
|
Term
| How do donkeys and horses differ in their expression of Mx protein? What is the clinical significance? |
|
Definition
donkeys: express Mx
horses: no Mx
Therefore, horses are susceptible to equine influenze and donkeys are not |
|
|
Term
| How can a virus circumvent IFN induction? |
|
Definition
-keep ssRNA genomes encapsulated
-express viral proteins that inhibit IFNs |
|
|
Term
| What is a latent infection? |
|
Definition
| -viral genome is present but is transcriptionally silent |
|
|
Term
| What is a persistent infection? |
|
Definition
| -vital genome is present and transcriptionally active at very low levels |
|
|
Term
| What is a persistent non-cytopathic viral infection? |
|
Definition
| no damage is done to the cell |
|
|
Term
| What is a persistent cytopathic viral infection? |
|
Definition
|
|
Term
| What is a persistent productive viral infection? |
|
Definition
| viral particles are being released |
|
|
Term
| What is persistent non-productive viral infection? |
|
Definition
| viral particles are being made, but not to the degree where they are released from the cell |
|
|
Term
| What is a lytic infection? |
|
Definition
| cytopathic effect where the cell dies from lysis with a huge release of viral progeny |
|
|
Term
| What are the selectional pressures for viral evolution? |
|
Definition
-immunologic (need to escape the immune system)
-preservation of the host (need the factory!) |
|
|
Term
| How do we get viral variation? |
|
Definition
-point mutations (can be good or bad, can lead to genetic drift)
-genetic recombination between viruses within the same cell (genetic shift)
-genetic recombination between viruses and the host cell genome (provirus) |
|
|
Term
| How do we get live attenuated viruses for immunizations? |
|
Definition
-get virus, grow it up on a tissue culture or other tissue that is very different
-this virus learns to grow best on this artificial medium
-when introduced to its natural host, it will be inadequate
-host can mount an immune response without getting sick because the virus is not able to induce disease |
|
|
Term
|
Definition
| gradual changes due to point mutations |
|
|
Term
|
Definition
| sudden changes due to reassortment of viral genomes |
|
|
Term
| What are the three ways we get viral variation? |
|
Definition
-point mutations
-genetic recombination between viruses
-genetic recombination between viruses and the host cell genome |
|
|
Term
|
Definition
| measure of the pathogenicity of a virus |
|
|
Term
|
Definition
| the ability of the host to control or eliminate viral infection or viral-induced disease |
|
|
Term
|
Definition
| The affinity of a virus for a particular cell type (can be specific or systemic) |
|
|
Term
| What is intramolecular recombination? |
|
Definition
| strand-switching between homologous regions of nucleic acids |
|
|
Term
| What determines the virus' entry into the target cell? |
|
Definition
| expression of the correct receptors |
|
|
Term
|
Definition
|
|
Term
| What physiologic factors affect host resistance? |
|
Definition
-age
-state of nutrition
-stage of cell differentiation
-hormones, pregnancy, stress |
|
|
Term
| What is the route of transmission in arboviruses? |
|
Definition
| arthropod vector, entry through skin |
|
|
Term
| Describe virus entry via respiratory tract. |
|
Definition
-common
-particle size determines position
-localized or systemic infection
examples: canine influenze, feline calicivirus |
|
|
Term
| Describe virus entry via oropharynx/intestinal tract. |
|
Definition
-virus ingested
-non-enveloped |
|
|
Term
|
Definition
-virus in the blood
-secondary viremia can then be established in organs |
|
|
Term
|
Definition
-skin via contact
-nasal/oral secretions
-fomites
-feces/urine
-milk/colostrum
-blood/organs |
|
|
Term
| When can you get systemic disease with a virus with a tropism for a single cell type? |
|
Definition
| when that cell type is found throughout the body (vessels, nerves, etc) |
|
|
Term
|
Definition
viruses can infect multiple cell types, leads to generalized disease
example: canine distemper can affect canids, mustelids, big cats, etc |
|
|
Term
| What are radiomimetic viruses? |
|
Definition
| can replicate only in dividing cells |
|
|
Term
| Describe the pathogenesis of CDV. |
|
Definition
-ssRNA, enveloped
-aerosol transmission
-affects young, immunocompromised
-forms syncytia
-primary viral pneumonia, viral gastroenteritis
-viral shedding in feces, respiratory secretions, milk, skin (hardpad) |
|
|
Term
| What happens in FIP? Should we vaccinate? |
|
Definition
-antibodies bind coronavirus but doesn't neutralize
-immune complexes deposit on walls of small vessels causing vasculitis
-vaccination could prime animal for this disease, so DON'T VACCINATE! |
|
|
Term
| Describe lytic respiratory infections. |
|
Definition
-enveloped viruses (mainly)
-stimulates cough, sneeze
-host has mucin, IFN, neutrophils, alveolar macrophages and IgA to protect it from infection |
|
|
Term
| What is the pathogenesis of equine influenza? |
|
Definition
-initial URI
-antigenic shift = evasion
-clearance by IFN |
|
|
Term
| What is enzootic calf pneumonia (shipping fever)? |
|
Definition
| need at least one viral and one bacterial pathogen |
|
|
Term
| Describe acute lytic intestinal diseases. |
|
Definition
-infection early, via oral route
-young animals
-short incubation period |
|
|
Term
| Describe rotavirus infection. |
|
Definition
-non-enveloped, segmented genome
-replicate in cyto, undergo reassortment
-diarrhea due to destruction of intestinal villi and due to effect on enteric nervous system (spasms)
-excreted in feces |
|
|
Term
| Describe coronavirus infection (TGE in swine. |
|
Definition
-(+)ssRNA, proteins highly immunogenic
-high frequency of mutation
-pathogenesis similar to rotavirus |
|
|
Term
| Describe acute lytic intestinal disease by parvovirus (panleuk, parvo). |
|
Definition
-small, non-enveloped, DNA genome
-replicate in dividing cells
-infects crypt epithelium
-replicates in the nucleus
-need direct dog-dog contact or fomite |
|
|
Term
| Describe herpesvirus (BHV-1) infection. |
|
Definition
-enveloped, dsDNA
-latency after recovery
-nasal discharge (bed nose)
-virions move into cranial and spinal ganglia via axons of sensory nerves
-latently live in episome (extrachromasomal) |
|
|
Term
| Describe foot-in-mouth disease. |
|
Definition
-picornavirus
-non-enveloped, ssRNA, cyto replication
-infection of oropharynx
-fever, anorexia, lip smacking, drooling, lameness
-direct/indirect contact, vectors, airborne |
|
|
Term
| Describe vesicular stomatitis virus signs. |
|
Definition
| Looks like foot in mouth, but from a rhabdovirus |
|
|
Term
| Give examples of retroviral infections. |
|
Definition
-Enveloped, RNA
-includes FeLV, FIV (a lenti virus), ALV, MuLV |
|
|
Term
| Describe lentivirus infection in sheep and goats. |
|
Definition
-CAEV -arthritis and encephalomyelitis
-OvLV aka Maedi-Visna -lymphoid interstitial pneumonia, air hunger and wasting
-transmitted by body fluids
-is a persistent infection of monocytes or tissue macrophages
- |
|
|
Term
| Describe primate lentivirus infection. |
|
Definition
| -CD4+ T helper cell depletion |
|
|
Term
| Describe feline lentivirus infection. |
|
Definition
-common in catteries
-spread primarily by biting
-CD4+ cells depleted, get opportunistic infections |
|
|
Term
| Describe Equine Infections Anemia. |
|
Definition
-lentivirus infection
-increased clearance of RBCs or bone marrow suppression
-see petechial hemorrhages (punctate hemm. on mucous membranes) |
|
|
Term
| What is the difference between cis- and trans- tumor induction by retroviruses? |
|
Definition
-cis = retroviral promotor inserted upstream of protooncogene (ex. FeLV)
-trans = retroviral genome inserted distant from site of gene expression
(ex. BLV) |
|
|
Term
| Describe the mechanism of DNA viral oncogenesis. |
|
Definition
-don't rely on homologs in cellular genes
-directly encode oncogenic proteins (early viral proteins) that alter the cell cycle |
|
|
Term
|
Definition
| -disrupt apoptosis and innate immune responses |
|
|
Term
| How do papilloma viruses work? |
|
Definition
-virions found in terminally differentiated epithelial cells
-non-enveloped, dsDNA, replicate in nucleus |
|
|
Term
| How does BPV-1 (bovine papilloma virus) work? |
|
Definition
| inactivates Rb, cells continually proliferate |
|
|
Term
| What is a test sensitivity? |
|
Definition
| measure of the proportion of positive test results that are true positive |
|
|
Term
| What is a test of specificity? |
|
Definition
| measure of the proportion of negative test results that are true negatives |
|
|
Term
| What factors prevent erdication of zoonotic viral infections? |
|
Definition
-wildlife reservoir host
-carrier animals with persistent viral infections
-recurrent disease and viral shedding
-unstable viral genome (strain variation)
-lack of effective vaccine and control program |
|
|
Term
| What are some requirements for a good vaccine? |
|
Definition
-stimulation of APCs
-activation of B and T cells
-response to multiple epitopes
-antigen persistence
-safety, efficacy, and cost
-ability to diagnostically differentiate vaccinated from infected animals |
|
|
Term
| Describe cytotoxic T cells. |
|
Definition
-major class of effectors cells in viral immunity
-recognize short peptides of viral proteins in MHC I |
|
|
Term
| What types of vaccines are available? |
|
Definition
-live
-modified live
-inactivated/killed
-recombinant subunit |
|
|
Term
| What are the pros and cons to killed vaccines? |
|
Definition
-safe, provide protection during pregnancy
-shorter-lived immunity |
|
|
Term
| What are the pros and cons to attenuated vaccines? |
|
Definition
-need single dose, need a little amount
-heat labile, can't use during pregnancy |
|
|
Term
|
Definition
-prolong release or retention of antigen
-activates macrophages
-promotes lymphocyte proliferation |
|
|
