Methods of Diagnostic Virology Flashcards
What are the different methods of diagnostic virology?
Direct detection
Virus Isolation Culture
Nucleic Acid-based detection
Serologic assays to detect antiviral antibodies
A method of diagnostic virology that is:
- Not as sensitive as culture methods
- Performed in a few minutes
- Allow clinicians to make relevant decisions about therapy and hospitalization
Direct detection
Individual virus particles are too small to be seen by bright-field microscopy except for the _____.
Poxvirus
This type of microscopy can detect noncultivatable viruses
Electron microscopy
These are noncultivatable viruses in stool filtrates that can be seen using electron microscopy.
Norwalk viruses
These are characteristic visual changes in infected cells (lymphocytes) produced by many viruses.
Cytopathic effects (CPE)
What is the specimen used to detect cytopathic effects?
Cell scrapings from infected sites
This type of smear can detect Cowdry type A bodies (“Owl Eyes”) from herpes simplex virus (HSV) and Varicella-Zoster virus (VZV).
Tzanck smear
This type of smear can reveal human papillomavirus (HPV)-associated koilocytosis-squamous cells with an enlarged nucleus surrounded by a non-staining halo.
Papanicolaou (Pap) smear
Rabies is sometimes diagnosed by detecting _____ bodies, which are eosinophilic cytoplasmic inclusions in neurons.
Negri
This is the gold standard against which all other methods of diagnostic virology are compared.
Isolating viruses
What are the three methods used for the isolation of viruses in diagnostic virology?
Cell culture
Animal inoculation
Embryonated eggs
This is the most used method for the isolation of viruses.
Cell culture
This method of isolating viruses is extremely costly and is used only as a special resource and in reference laboratories
Animal inoculation
This is a term used to indicate culture of cells in vitro; the cells are not organized into a tissue.
Cell culture
This term is used to denote growth of tissues or an organ in any way that preserves the architecture or function of the tissue or organ.
Tissue culture or Organ culture
What are the three categories of cell cultures?
Primary
Low passage (or finite)
Continuous
This type of cell culture is obtained from tissue removed from an animal.
Primary cell culture
What are the steps in preparing a primary cell culture?
The tissue is finely minced
It is treated with an enzyme such as Trypsin to disperse individual cells further
Cells are seeded onto a surface to form a monolayer, such as in a flask or tube
Give an example of a commonly used primary cell culture.
Primary monkey kidney (PMK) cells
To maintain cell viability, they must periodically be removed from the surface, diluted, and placed into a new container. This process is referred to as _____.
Splitting or Passaging
Enumerate some primary cell cultures that have the same karyotype and chromosome number as the original tissue.
Human embryonic kidney HEK
Rabbit embryonic kidney REK
Primary monkey kidney PMK
Rhesus monkey kidney RMK
Cynomolgus monkey kidney CMK
African green monkey kidney AGMK
It is a type of cell culture also known as the diploid cell line.
Low Passage (Finite) Cell culture
Low Passage (Finite) Cell cultures can divide, but passage is limited to ___ generations.
50
Finite cell lines and primary cell lines are (diploid/haploid), meaning they contain two copies of each chromosome.
Diploid
Give an example of a standard finite cell culture used in diagnostic virology.
Human neonatal lung (HNL)
This is a subcultivated primary cell culture wherein >/= 75% of cells have the same karyotype as the normal cells
Cell line
These are cell cultures that are capable of infinite passage.
Continuous Cell line/culture
This is the cell culture also known as the Heteroploid cell line.
Continuous Cell line/culture
Continuous Cell line/culture are _____, meaning they have an abnormal and variable number of chromosomes that is not a multiple of the normal haploid cell.
Heteroploid
These are cell lines wherein <75% of cells have the same karyotype as the normal cells
Heteroploid or immortal cell lines
Enumerate some examples of continuous cell cultures.
Human cervical carcinoma HeLa Human laryngeal carcinoma Hep-2 Nasopharyngeal carcinoma KB Human lung carcinoma A-549 African green monkey kidney Vero
What are the different cytopathic effects on cell culture?
- Rounding
- Clumping
- Vacuolation
- Granulation
- Giant multinucleated cell
- Syncytial formation
- Cell destruction
- Cell lysis
This is a virus that grows rapidly on many different cell lines and frequently produces CPE within 24 hours. Produces a focal CPE and plaques, or clusters of infected cells.
Human simplex virus (HSV)
The combination of rapid growth , plaque formation, and growth on many different cell types such as MRC-5, human frobroblasts, Vero, HEp-2, mink lung, rabbit kidney cells, and PMK, is presumptive evidence for the identification of what virus?
Human simplex virus (HSV)
What virus would have these characteristics:
(- growth) (PMK) Primary monkey kidney
(+++) (HDF) Human diploid fibroblasts
(+++) (HEp2) Human laryngeal carcinoma cell line
(+++) (RK) Rabbit kidney
(+++) (A549) Human lung carcinoma cell line
CPE: large rounded cells
Human simplex virus (HSV)
What virus would have these characteristics:
(- growth) (PMK) Primary monkey kidney
(+++) (HDF) Human diploid fibroblasts
(- growth) (HEp2) Human laryngeal carcinoma cell line
(- growth) (RK) Rabbit kidney
(- growth) (A549) Human lung carcinoma cell line
CPE: large rounded cells
Cytomegalovirus (CMV)
What virus would have these characteristics:
(- growth) (PMK) Primary monkey kidney
(+++) (HDF) Human diploid fibroblasts
(- growth) (HEp2) Human laryngeal carcinoma cell line
(- growth) (RK) Rabbit kidney
(-/+) (A549) Human lung carcinoma cell line
CPE: foci or rounded cells; possible syncytia
Varicella-Zoster virus (VZV)
What virus would have these characteristics:
(+) (PMK) Primary monkey kidney
(+) (HDF) Human diploid fibroblasts
(++) (HEp2) Human laryngeal carcinoma cell line
(- growth) (RK) Rabbit kidney
(+) (A549) Human lung carcinoma cell line
CPE: Refractile, round cells in clusters
Enterovirus
What virus would have these characteristics:
(+) (PMK) Primary monkey kidney
(++) (HDF) Human diploid fibroblasts
(+++) (HEp2) Human laryngeal carcinoma cell line
(- growth) (RK) Rabbit kidney
(++) (A549) Human lung carcinoma cell line
CPE: Large, round cells in clusters
Adenovirus
What virus would have these characteristics:
(-/+) (PMK) Primary monkey kidney
(+) (HDF) Human diploid fibroblasts
(+++) (HEp2) Human laryngeal carcinoma cell line
(- growth) (RK) Rabbit kidney
(++) (A549) Human lung carcinoma cell line
CPE: Syncytia
Respiratory syncytial virus
What virus would have these characteristics:
(+++) (PMK) Primary monkey kidney
(-/+) (HDF) Human diploid fibroblasts
(- growth) (HEp2) Human laryngeal carcinoma cell line
(- growth) (RK) Rabbit kidney
(- growth) (A549) Human lung carcinoma cell line
CPE: Variable (none to granular appearance)
Influenza/parainfluenza
This virus shows rapid growth in HDF, but no growth in OMK, HEp2, RK and A549. Its CPE is the appearance of large, rounded cells
Cytomegalovirus (CMV)
These are giant multinucleated cells formed from cell fusion as a result of virus infection
Syncytia
This is a simple method that more rapidly identifies viruses than does the traditional cell culture cell method.
Shell vial culture technique
This is a small, round, flat-bottom tube, generally with a screw cap.
Shell vial
In this type of cell culture, cells are grown on a round cover slip in a shell vial.
Centrifugation-Enhanced Shell vial culture
The shell vial is inoculated with the clinical sample and then centrifuged to promote _____.
Viral absorption
(T/F) Serologic assays are retrospective studies
T
What are the disadvantages of serologic assays?
- Measures host response rather than detection of virus
- Antibody producing capabilities of human hosts vary widely
- Antibody level doses are not necessarily correlated with the acuteness or activity level of the infection
The presence of what immunoglobulin indicates an acute infection?
IgM
What are the indications of serologic testing?
- Diagnosis of infections with non-culturable agents
- Determination of immune status (rubella, measles, VZV, HAV, HBV)
- Monitoring of patients who have immunosuppresion
- Epidemiologic or prevalance status
What are the types of viruses based on nucleic acid?
Double-stranded DNA viruses (dsDNA)
Single-stranded DNA viruses (ssDNA)
Single-stranded RNA viruses (ssRNA)
Double-stranded RNA viruses (dsDNA)
What are the general types of the clinically significant viruses?
Double-stranded DNA viruses (dsDNA) Single-stranded DNA viruses (ssDNA) Single-stranded RNA viruses (ssRNA) Double-stranded RNA viruses (dsDNA) Hepatitis virus
What are the two types of dsDNA?
Enveloped
Naked
What are the two types of enveloped dsDNA?
Icosahedral
Complex
Give a specific type of an icosahedral, enveloped dsDNA?
Herpesviridae (Simplex virus, varicella virus)
Give a specific type of a complex, enveloped dsDNA?
Poxviridae (Orthopoxvirus [Variola, Vaccinia])
Give specific types of icosahedral, naked dsDNA
Papillomaviridae (Papillomavirus)
Adenoviridae (Mastadenovirus)
