TOPIC 9 - VIROLOGY PART 2 Flashcards
A fully assembled infective virus
Virion
What is the fundamental component of virion that has the ability to infect host cells and replicate in them; thus ensuring continued survival ?
Nucleoprotein core
Shell of proteins that encloses the genome of vertebrate viruses
Capsid
Used to describe the packaged form
of the genome in the capsid
Nucleocapsid
What are the 2 types of capsid symmetry?
- Icosahedral
- Helical
In many types of viruses the nucleocapsid is covered by an envelope composed of a lipid bilayer and
associated glycoproteins. True or False?
True
The _____ are associated with binding to receptors on host cells, membrane fusion, uncoating of the virion and destruction of receptors on host cells.
Glycoproteins
______ on envelope glycoproteins are often important for inducing protective immune responses
in infected animals.
Epitopes
Used to describe features such as protrusions seen on the surface of
virus particles in electron micrographs
Capsomere
Give the viral families of the following classification:
Double-stranded DNA and enveloped
- Herpesviridae
- Asfarviridae
- Hepadnaviridae
- Poxviridae
Give the viral families of the following classification:
Double-stranded DNA and non-enveloped
- Iridoviridae
- Papillomaviridae
- Adenoviridae
Give the viral families of the following classification:
Single strand DNA and non-enveloped
- Parvoviridae
- Circoviridae
Give the viral families of the following classification:
Single strand RNA and enveloped
- Coronaviridae
- Orthomyxoviridae
- Paramyxoviridae
- Bunyaviridae
- Retroviridae
- Rhabdoviridae
- Togaviridae
- Flaviviridae
- Arteriviridae
- Arenaviridae
- Filoviriae
Give the viral families of the following classification:
Single strand RNA and non-enveloped
- Picornaviridae
- Caliciviridae
Give the viral families of the following classification:
Double-stranded RNA and non-enveloped
- Reoviridae
- Birnaviridae
This viral classification is based on the nature of the genome and pathways of mRNA synthesis.
Baltimore classifications
Give the 5 virus replication stages.
- Attachment to a surface receptor on a susceptible
host cell - Entry into the cell
- Uncoating of viral nucleic acid
- Replication of viral nucleic acid and synthesis of virus-encoded proteins
- Assembly of newly-formed virus particles and
release from host cell
Initial virus-cell interaction is a random event which
related to the number of _____ ____ present and the availability of appropriate _____ ____.
virus particles; receptor molecules
Virus-cell interaction determines both ___ ___ and ____ ____ of viral species.
host range; tissue tropism
In orthomyxoviruses and paramyxoviruses, the
detachment is mediated by _____ _____, a receptor-destroying enzyme.
viral neuraminidase
Entry into the cell of virus is processed in 3 aspects. What are these?
(1) Receptor-mediated endocytosis
(2) Clathrin
(3) Fusion of viral envelope with the plasma membrane
The process whereby the viral genome is released in a form suitable for transcription.
Uncoating
Synthesis of viral proteins requires the production of ?
viral mRNA
For DNA viruses, which replicate in the nucleus, it can avail of host cell _____ to synthesize viral mRNA.
transcriptases
Most viral proteins undergo post-translational modification including ?
- Proteolytic cleavage
- Phosphorylation
- Glycosylation
In _____, sugar side-chains are added to viral proteins in a programmed manner as the proteins are being transferred from the RER to Golgi apparatus in
preparation to final assembly and release from the cell.
glycolysation
Non-enveloped viruses of animals have _____
structure.
icosahedral
Give some examples of viruses that assembles in cytoplasm of the cell.
- Picornaviruses
- Reoviruses
Give some examples of viruses that assembles in the nucleus.
- Parvoviruses
- Adenoviruses
- Papovaviruses
What is the final step in the process of virion assembly?
Involves acquisition of an envelope by budding from cell membranes
These enveloped viruses are cytolytic.
- Togaviruses
- Paramyxoviruses
- Rhabdoviruses
These viruses acquire their envelopes inside cells by budding through the membranes of the RER or the Golgi apparatus and then transported in vesicles to the cell surface where the vesicle fuses with the plasma membrane releasing the virion by exocytosis.
- Flaviviruses
- Coronaviruses
- Arteriviruses
- Bunyaviruses
This virus is unique as it replicates in the nucleus and bud through the inner lamella of the nuclear membrane and accumulate in the space between inner and outer lamellae, in the cisternae of the ER and in cytoplasmic vesicles.
Herpesvirus
This virus assembly and release are a complex process taking several hours.
Poxviruses
Give this method of detection of virus, viral antigens or nucleic acid:
- This method can be used to recognize mixed viral infections and detect viruses which cannot be grown in vitro
- Has limitations (e.g. large numbers of
viral particles must be present in clinical samples)
Electron microscopy
Give this method of detection of virus, viral antigens or nucleic acid:
- Antiviral antibodies labelled with fluorochromes can be used to detect viral antigens in clinical
specimens - Can be used to demonstrate virus or viral antigen in specimens
Immunofluorescence and
Immunohistochemistry
Give this method of detection of virus, viral antigens or nucleic acid:
- Carried out in agar
- Placing a fluid sample
containing the virus
under test in a well in
the agar opposite a well
containing antiserum - Fluids diffuse out of the
wells, a line of precipitate forms if the sample under test contains viral antigen
Immunodiffusion
Give this method of detection of virus, viral antigens or nucleic acid:
- Viruses such as Orthomyxoviridae, paramyxoviridae,
adenoviridae and parvoviridae and togaviridae can interact
with erythrocytes of many animal species causing hemagglutination - Hemadsorption is used to describe binding of erythrocytes to cells infected with hemagglutinating viruses
Hemagglutination and hemadsorption
Give this method of detection of virus, viral antigens or nucleic acid:
- In vitro method is based on the amplification of a particular nucleic acid sequence using a
thermostable DNA polymerase and primers
Polymerase chain reaction (PCR)
Give this method of detection of virus, viral antigens or nucleic acid:
*Enzyme-linked immunosorbent assay
*Serum neutralization test
* Hemagglutination inhibition test
* Complement fixation tests
*Western Blotting
Diagnostic serology
