Lab2 Flashcards
Viruses that have surface proteins (haemagglutinins)?
Orthomyxoviridae, Paramyxoviridae, Coronaciridae, Parvoviridae
what makes lattice formation at the bottom of the tube?
The sedimentation of the virus-joined red blood cells
What can be demonstrated with haemagglutination test?
The method is not sensitive, so it is not perfect method to demonstrate the presence of low number of virions, but because of its simplicity it provides a very convenient assay if high concentration of virions are available
The haemagglutination titre is?
The end (highest) dilution of a virus suspension, where the haemagglutination still appears
What is the red blood cell suspension used for haemagglutination titre?
0.5-1% washed erythrocytes
What is haemagglutinins?
Surface proteins able to bind to erythrocytes
What is haemagglutination?
lattice-formation
What is used in haemagglutination inhibition tests?
HA unit of viruses
CPEs are alterations in the morphology of cells due to?
virus infection
CPE is mainly observed in?
cell cultures
CPE is usually a result of?
degenerative processes
ex of: toxic effect of adsorption?
Adenoviruses
ex of: Virus proteins inhibit cellular translation?
Herpes-, pox-, togaviruses
example of: Early proteins inhibit cellular nucleic acid transcription and replication?
herpes-, adenoviruses
ex of: Viral proteins damage the cytoplasmic membrane permability - osmotic change
herpesviruses
ex of: cytoskeleton depolimerization
herpes, paramyxoviruses
ex of: expression of fusion proteins
herpes, paramyxoviruses
Inclusion bodies appear at?
the site of assembly of nucleocapsid
Inclusion bodies are?
virus depositions
How can inclusion bodies be observed?
In stained cells (of cell cultures or organ sections):
- they have homogenous staining, surrounded by a narrow light stripe, the so called “halo” due to shrinkage after fixation
What causes the “halo”?
Shrinking after fixation. of stained inclusion bodies.
Intranuclear inclusion bodies is caused by?
DNA and sometimes RNA
Intranuclear inclusion bodies caused by DNA viruses?
Replicating in the nucleus.
Parvo-, papilloma-, polyoma-, adeno-, herpesviruses
Intranuclear inclusion bodies caused by RNA viruses?
Orthomyxo-, paramyxo-, arteri-, bornaviruses.
Cowdry-A, Cowdry-B types depends on?
the state of the synthesis of macromolecules.
How can Intranuclear inclusion bodies be stained?
Basophil = parvo Amphophil = adeno Eosinophil = herpes
When can caryomegalia and/or perichromasia be observed?
in case of high nuber of inclusion bodies or large inclusion bodies in the nucleus
Intracytoplasmic inclusion bodies caused by?
RNA viruses, sometimes DNA (if the viruses replicate in the cytoplasm )
What can be de DNA viruses replicating in the cytoplasm of Intracytoplasmic inclusion bodies?
Poxviruses, ASFV
How can Intracytoplasmic inclusion bodies be stained?
Eosinophil or rarely basophil (poxviruses) particles.
What are the Negri bodies and the Guarnieri bodies?
Pathognomic inclusion bodies of Intracytoplasmic inclusion bodies.
- Negri bodies: neuron cells, rabies
- Guarnieri bodies: epithelial cells, small pox
What is the reason for Cell rounding?
Cytoskeleton depolymerisation and a loss of electrolytes.
What is observed if the cell rounding is UNstained?
Double refraction, detachment and shrinkage
What is Syncytium-formation caused by?
enveloped viruses.
What are the enveloped viruses causing Syncytium formation?
Alphaherpes-, paramyxo-, pneumo-, coronaviruses
Where are the fusion proteins (of the Syncytium-formation) found?
On the surface of the virus and on the cytoplasmic membrane of the cell
What are the fusion proteins on the surface of the virus used for?
Viral penetration.
What are the fusion proteins on the cytoplasmic membrane used for?
cause fusion of the neighboruing cell´s membranes, infected and non-infected
What happens when membrane tunnels are formed between the cells?
(in consequence of the fusion proteins?
makes the intracellular spread of viruses possible
What are polykaryocytes and/or syncytia?
Giant cells with many nuclei, which is formed because of the fusion of the cells (syncytium formation)
Lumpy cell nucleus is the consequence of?
chromatin conglomeration, rearrangement or changed refraction (caused by parvovirus).
The lumpy disintegration of the nucleus is characteristic for?
EHV-1 (horse herpesvirus type1) in the liver of foals and African Swine Fever Virus (ASFV) in lymphatic system
Where can the vacuoles appear?
Cell vacuolisation
- in the nucleus (i.e by adenovirus infection)
- in the cytoplasm (i.e by flavi-, herpes- and retrovirus infections)
Cytolysis occurs bacause of?
the damage of the cell membrane or caused by lysosomal enzymes.
The cell can also explode when?
cytolysis
when the virions are released, in case of certain enteroviruses.
The viral protein called haemagglutinin incorporates into the?
(haemadsorption)
Cytoplasmic membrane of the infected cell
What happens when the viral protein (haemagglutinin) incorporates into the cytoplasmic membrane of the infected cell?
It is able to adsorb erythrocytes on the surface of the monolayer
Where does the haemagglutinin adsorb the erythrocytes?
on the surface of the monolayer
Haemadsorption has diagnostic value in case of?
- Paramyxoviruses (haemadsorption +, haemagglutniation -)
- ASFV (haemadsorption +, haemagglutination -)
The occurance of the CPEs in a cell culture can be?
diffuse, all around the cell culture or in some cases local/focal?
What is the CPE called when its Local/focal?
Plaque
More plaques are generally formed in?
lower virus concentrations (multiplicity of infection, MOI)
Medium used to supplement the plaque formation?
Agar, carboxymethyl cellulose or metrizamide
What is the result of using medium with agar, carboxymethyl cellulse or metrizamide?
It results in semisolid maintance fluid that retart the free movement of the virus in the cell culturing dish, therefore the viruses are forced to spread from cells to neighboruing cells.
Plaque formation is usefull in case of?
virus purification, when subsequent passages of viruses taken from singular plaques are propagated.
When is establishment of virus strains possible?
virus purification, when subsequent passages of viruses taken from singular plaques are propagated.
When is plaque counting used to determine the quantity of virus particles or antibody content of the sample?
In virus quantification and plaque reduction neutralisation tests (serological investigation)
Does all virus infections result in CPE?
No, and it is not always connected to the pathogenicity.
Ex of what can cause CPE?
Spumaviruses, but they are orphan
The cytophatic character of a virus strain man change due to?
mutations (i.e Bovine viral diarrhea virus- BVDV)
How can you investigte non-cytopathogenic viruses in cell culture?
the propagation of the virus in cell culture should be supplemented by IPA or IF.
the viral antigens are expressed on?
the surface of the cell
using IF test, the infected cells appear?
with yellowish-green spots indicating the prescence of ciral genes
Ex of investigation of non-cytopathic viruses with Electronmicroscopic-investigation?
Rabbit haemorrhagic disease (RHD)
Ex of investigation of non-cytopathic viruses with Immuno-electronmicroscopic (IEM) investigation?
rotaviruses, parvoviruses in faeces sample
Ex of investigation of non-cytopathic viruses with Complement-fixation test?
Foot and mouth disease
Ex of investigation of non-cytopathic viruses with Agar gel-precipitation (AGP) and Agar Gel Immune diffusion (AGID)?
equine infectious anaemia
Ex of investigation of non-cytopathic viruses with Counter current immunoelectrophoresis (ccIEF)?
parvo-, rota-, coronaviruses
Name the test that can be used for investigation of non-cytopathic viruses:
- artificial infection
- electronmicroscopic investigation (EM)
- immuno-electroscopic investigation (IEM)
- complement-fixation test
- Agar-gel-precipitation (AGP)
- Agar gel immune diffusion (AGID)
- Counter current immunoelectrophoresis (ccIEF)
- ELISA (enzyme linked immunosorbent assay)
- RIA (radio-immuno assay)
- Haemagglutination (HA)
- detection of viral nucleic acid by polymerase chain reaction
what can be seen by identification of viruses with microscopic investigation:
CPE, tissue specificity, type of pocks, haemadsorption
what can be seen by identification of viruses with electronmicroscope EM?
the dimension, size, shape of the virion, its symmetry, surface etc.
Identification of viruses by Physico-chemical investigation of vegative viruses:
- enveloped/non-enveloped virus
- DNA/RNA virus
- Single/double stranded nucleic acids
If the virus loses its infectivity after chloroform treatment?
then it is an enveloped virus
What is added to the growth media in DNA/RNA viruses?
Physico-chemical investigation of vegative viruses:
halogenated deoxy-uridine
What does the halogenated deoxy-uridine do in the DNA?
it incorporated into the DNA in place of deoxy-thymidine and this way inhibits the DNA replication, but does not influence RNA replication
How does the halogenated deoxy-uridine inhibit the DNA replication?
it incorporates into the DNA in place of deoxy-thymidine
What happens after acridin-orange staining?
the single strand shows reddish-orange flourescense, and the double strand shows greenish-yellow.
Hos is the nucleus in the dsNA with acridin-orange stained?
green
Hos is the cytoplasm in the ssNA with acridin-orange stained?
orange
What can you use to investigate group-specific antigens?
AGP, IPA, IF, IEM, ccIEF, ELISA, RIA, HA
How can you determine the serotype?
Virus neutralisation test and/or haemagglutination-inhibition test
How can you determine subtype, variant?
- clinical signs
- investigation of nucleic acid (heteroduplex techniwues, hybridization, sequencing)
- investigation with monoclonal antibodies
How can you investigate nucleid acids?
heteroduplex techniques, hybridization, sequencing.
