SPECIMEN COLLECTION AND CULTIVATION OF VIRUSES Flashcards
- Specimen collection depends on the ____, ____
- In the requisition, the ____ and ____ should be included.
- Must be collected as early as possible after the onset of symptomatic disease
____ -interfere with nucleic acid based tests, recovery of some enveloped viruses, and fluorescent-antibody test
SPECIMEN COLLECTION FOR VIROLOGY
- specific disease syndrome, viral agents
suspected
- specimen type
- suspected virus
- Calcium alginate swabs
SUCCESSFUL LABORATORY INVESTIGATIONS
✓Collection of adequate and appropriate specimens
✓Sufficient documentation
✓Biosafety and decontamination
✓Correct packaging
✓Rapid transport
✓Choice of a laboratory that can accurately perform the tests
✓Timely communication of results
Specialized medium used to transport and store viral samples
VIRAL TRANSPORT MEDIUM (VTM)
Buffering Agents
Phosphate-Buffered saline: pH stability
and osmotic balance
▪Hanks’ balanced salt solution (HBSS):
mixture of salts and nutrients
Stabilizers
Glycerol: preservation of viral particles
▪Protein Stabilizers: bovine serum albumin
to stabilize the viral particles
Antimicrobial Agents
Antibiotics: penicillin, streptomycin,
gentamicin
▪Antifungal agents: amphotericin B
Throat swabs
1
2
3
Enteroviruses , Adenoviruses, HSV
Nasopharyngeal swab or aspirate
1
2
3
RSV , Influenza, Parainfluenza
Nasal Specimen
Rhinovirus
-____ are superior to swabs
-Swabs should be made of __,___,___,__
-Often are contaminated with bacteria.
> Contaminants may be removed by concentrating the sample through
___
THROAT, NASOPHARYNGEAL SWAB OR ASPIRATE
- aspirate
-polyester, Dacron, or rayon with plastic oraluminum shafts
- centrifugation
- Hold tongue away with tongue depressor
- Locate areas of inflammation and
exudate in ____, tonsillar region of throat behind uvula - Avoid swabbing ___; do not touch tongue
- Rub area back and forth with cotton or ___ swab
THROAT SWAB : POSTERIOR PHARYNGEAL SWAB
- posterior pharynx
- soft palate
- Dacron
1 Tilt head backwards
2 Insert _____ into nostril and back
to nasopharynx
3 Leave in place a few seconds
4 Withdraw slowly; rotating motion
NASOPHARYNGEAL SWAB
- flexible fine-shafted polyester swab
- Tilt head slightly backward
- Instill ___of VTM /sterile normal
saline into one nostril - Use ____
- Insert ___ in nostril and
aspirate the secretion gently by
suction in each nostril
NASOPHARYNGEAL ASPIRATE
- 1-1.5 ml
-aspiration trap
- silicon catheter
Specimen for detecting viruses that infect the lower respiratory tract( ___ and___)
Should be centrifuged to remove contaminating materials
>Not necessary if sample are for ____ and ____
BRONCHIAL AND BRONCHOALVEOLAR WASHES
- (Influenza and Adenoviruses)
- antigen
- nucleic acid testing
RECTAL SWABS AND STOOL is Used to detect __,__,___
- Rotavirus, enteric adenoviruses (serotypes 40 and 41), and enteroviruses.
preferable for rotavirus and enteric adenovirus testing.
Stool
___ - acceptable for detecting enteroviruses in patients suspected of having an enteroviral disease, such as ___
Rectal swabs
- aseptic meningitis
Due to bacterial contamination in ____, centrifugation, filtration or both are
necessary for cell cultures for the recovery of viral agents
Storage: ____
stool
- 4°C or -15°C (Ag detection and PCR)
Urine is for detection of __,__,__,__,__,__
Improved recovery: at least ___ from clean catch first morning urine
Interference of urine __ and ___ may affect viral replication
>Urine is centrifuged or filtered to remove contaminants and neutralizing pH with____
- CMV, Mumps, Rubella and Measles Virus,
Polyomavirus and Adenovirus - 10mL
- pH and bacteria
- 7.5% solution of sodium bicarbonate
- Detection of HSV or VZV may require a ___ if PCR testing is not available
> are prepared by carefully unroofing the
vesicle.
Tzanck smear
___, ___,____ , and in rare cases ___ or ___ can be detected in vesicular lesions of the skin and mucous membranes.
>Once the vesicle has ____ , detection of the virus is difficult
- Enteroviruses, HSV, VZV
- CMV or pox viruses
- ulcerated or crusted
STERILE BODY FLUIDS OTHER THAN BLOOD
-may contain ___, __,___,___,____
- Collected aseptically by the physician and sent to the laboratory forprocessing
-Must not be diluted with VTM-causes___
- Specimens contaminated with blood may inhibit viral cultivation due to presence of ___
- CSF and pericardial and pleural fluids, Amniotic Fluid
- enteroviruses, HSV, VZV, influenza viruses, or CMV
- false negative results
- antibodies
Amniotic Fluid
1
2
3
.Delay in processing: Storage at refrigerated temp for ___ or ___ if longer
congenital CMV, VZV and parvovirus B19
- 48hrs or -70°C
Viral culture of blood is used primarily to detect __; however, __,__,__,__ occasionally may be encountered
CMV
- HSV, VZV, enteroviruses and adenovirus
___ of anticoagulated blood collected in a whole blood tube is needed
- __,__,___ anticoagulated blood is acceptable for CMV detection
5-10 mL
- Heparinized, citrated, or ethylene diaminetetraacetic acid (EDTA)
__ and __ should be used for samples collected for nucleic acid testing, because other anticoagulants may interfere with the enzyme functions required for PCR amplification.
Serum may be used for ___ and ____
EDTA and Citrated blood
- serologic tests and nucleic acid assays
For BONE MARROW
__ or __ anticoagulants are acceptable for culture
__ and ___ for nucleic acid testing
Heparin or EDTA
EDTA and ACD
Useful for detecting viruses that commonly infect the lungs (___,___,__,__), brain (___), and gastrointestinal tract (__).
Collected during surgical procedures.
- ___ is preferred for nucleic acid assays, but __ and ___ may be used after removal of the paraffin (deparaffinization) and extraction
Tissue
- CMV, influenza virus, adenovirus, sin nombre virus
- HSV
- CMV
- Fresh TISSUE
- formalin-fixed and paraffin-embedded tissues
GENITAL SPECIMENS
Detection of __ and __
Must be place in appropriate VTM
HSV and HPV
should be used for ulcerations and placed in
appropriate viral transport media.
Genital swabs
may be collected using a swab or brush and
placed in viral transport media.
Some manufactured __ or ___ are appropriate for nucleic acid testing
Cervical specimens
- endocervical or liquid-based cytology devices
__ and ___ specimens may be needed to detect
antibody to specific viruses
- Acute specimens should be collected as soon as possible after the
appearance of symptoms
Acute and convalescent serum
is collected a minimum of 2 to 3 weeks after the acute specimen
Convalescent specimen
Appropriate specimen is ___ of serum collected by venipuncture.
3 to 5 mL
Throat and Nasopharynx
Respiratory:
1 Adenoviruses Y
2 Parainfluenza virus Y
3 Influenza virus W
4 Respiratory syncytial virus W
5 Metapneumovirus W
6 SARS coronavirus W
nasal:+++ in respiratory
Rhinoviruses y
(other:serum) in respiratory
Sin nombre virus sp, s
Dermatologic and mucous membrane vesicular
Throat and Nasopharynx
Stool
Vesicle fluid or scrapping
Entero virus S F
Dermatologic and mucous membrane vesicular
Vesicle fluid or scrapping
Herpes simplex virus Y
Moknkeypox Y
Dermatologic and mucous membrane vesicular
Throat and Nasopharynx
Vesicle fluid or scrapping
Varicella zoster virus Y
Dermatologic and mucous membrane Exanthematous
Throat and Nasopharynx
Stool
Enterovirus S
Dermatologic and mucous membrane Exanthematous
Throat and Nasopharynx
Urine
Serum
Measles Y
Dermatologic and mucous membrane Exanthematous
Urine
Serum
Rubella Y
Dermatologic and mucous membrane Exanthematous
Serum
Amniotic fluid
Parvoviirus Y
Dermatologic and mucous membrane Pustular/Nodular
Tissue
Molluscum contagiosum, orf Y
Dermatologic and mucous membrane Pustular/Nodular
Tissue/ cells, thin prep
Warts Y
Dermatologic and mucous membrane Pustular/Nodular
cervical
Papillomavirus
Meningoencephalitis/encephalitis
CSF and Serum
Arboviruses S, F
Meningoencephalitis/encephalitis
Throat and Nasopharynx
CSF
Urine
Enteroviruses S, F
Meningoencephalitis/encephalitis
CSF
Brain biopsy
Herpes simplex virus Y
Meningoencephalitis/encephalitis
Serum
Lymphocytic choriomeningitis Y
Mumps virus Y
Meningoencephalitis/encephalitis
Brain biopsy
HIV Y
Polyomavirus (JC virus) Y
Meningoencephalitis/encephalitis
Corneal cels, brain
Rabies virus
Gastrointestinal dse
Stool
Adenoviruses (serotypes 40-41) Y
Noroviruses S
Rotavirus W, SP
Myocarditis, Pericarditis, and Pleurodynia
Throat and nasopharynx
csf
pericardial fluid
CoxsackieB S, F
Hemorrhagic fevers
Tissue, respiratory secretions and serum
Ebola/Malburg viruses Y
Hemorrhagic fevers
Throat and nasopharynx
URINE
Throat washes, serum
Lassa fever virus
Hepatitis
blood
Hepatitis Y
Dermatologic and Mucous membrane
Congenital and Perinatal
Throat/Nasopharynx
CSF
Urine
Enterovirus S
Dermatologic and Mucous membrane
Congenital and Perinatal
Vesicle fluid
Herpes simplex virus Y
Dermatologic and Mucous membrane
Congenital and Perinatal
Amniotic fluid, liver tissue
Parvovirus Y
Dermatologic and Mucous membrane
Congenital and Perinatal
Urine
serum
CMV Y
Rubella Y
Zika Y
Dermatologic and Mucous membrane
Eye (Ocular dse)
Throat and nasopharynx
conjunctival swab or scraping
Adenoviruses Y
Dermatologic and Mucous membrane
Eye (Ocular dse)
conjunctival swab or scraping
Herpes simplex virus Y
Varicella- zoster virus Y
Dermatologic and Mucous membrane
Post transplantation syndrome
urine
blood
tissue
Cytomegalovirus Y
Dermatologic and Mucous membrane
Post transplantation syndrome
Blood tissue
Epstein barr virus Y
Dermatologic and Mucous membrane
Post transplantation syndrome
BLOOD
Human herpesvirus-6 Y
Dermatologic and Mucous membrane
Post transplantation syndrome
Tissue
herpes simplex Y
Since the viruses are obligate intracellular parasites, they cannot be grown on any inanimate culture medium
Viruses can be cultivated within suitable hosts, such as a___
living celL
The primary purposes of viral cultivation are:
1
2
3
- To isolate and identify viruses in clinical specimens
- To prepare viruses for vaccines
- And to do detailed research on viral structure, multiplication
cycles, genetics, and effects on host cells
The earliest method for the cultivation of viruses causing human diseases was inoculation into human volunteers.
>___ and ___ used human volunteers for
their pioneering work on yellow fever.
- Due to serious risk involved, human volunteers are used only when no other method is available and when the virus
is relatively harmless
Reed and colleagues (1900)
LABORATORY DIAGNOSIS OF VIRAL INFECTION
I. Identification of the virus in cell culture
II. Microscopic identification in the specimen
III. Serological procedures to detect a rise in antibody titer
IV. Detection of viral antigen in blood or body fluids
V. Detection of viral nucleic acids
METHODS OF VIRAL ISOLATION
- Animal Inoculation
- Embryonated Egg Inoculation
- Tissue Culture
Primary isolation of certain viruses
* For the study of pathogenesis, immune
response and epidemiology of viral
diseases
* For the study oF ___
Animal Inoculation
- oncogenesis
Laboratory animals play an essential role in studies of viral pathogenesis
* __ AND ___ -Monkeys for the isolation of poliovirus
* ____ -white mice
* monkeys, mice, rabbits,
guinea pigs, ferrets
Animal Inoculation
- Landsteiner and Popper (1909)
- Theiler (1903)
limited application in virology
Monkey
Infant:
Routes of inoculation of Animal inoculation: ____,___,___,___
Death, disease or visible lesions
Suckling mice
Coxsackie and arbovirus
Intracerebral, subcutaneous,
intraperitoneal, intranasal
Animal Inoculation Disadvantages
1
2
3
4
5
- Costly
- Maintenance
- Interference of immune
system - Individual variations
- Difficulty in choosing of
animals for particular
virus
____, further developed by Burnet
* 8-11 days old
* Incubated for 2-9 days
Embryonated Egg Inoculation
Goodpasture (1931)
Eggs provide a suitable means for:
1
2
3
- the primary isolation and identification of
viruses - the maintenance of stock cultures
- and the production of vaccines
Embryonated Egg Inoculation
Routes of Inoculation
1
2
3
4
- Chorioallantoic membrane(CAM)
- Amniotic Cavity
- Allantoic Cavity
- Yolk sac
Has been widely used in veterinary virology
* Viruses grow readily or can be adapted to grow on it
* Produces visible lesions ____
* ____, can be used for the assay of pock- forming viruses
* Different viruses have different pock morphology
Chorioallantoic Membrane
(CAM)
- (pocks)
- Pock counting
Most popular
* Provides a rich yield of influenza
and some paramyxoviruses for
vaccine production
* ___,__, __,___
* Fluid is examined for ___ or
____
Allantoic Cavity
- Influenza Virus, Mumps Virus,
Newcastle disease virus, Avian
Adenovirus
- turbidity or hemagglutination
Virus is introduced directly into it, that bathes the developing embryo
* Volume of fluid in the infected____
* Recommended for the primary isolation of human viruses:
1
2
* Has little application in veterinary virology
* Newly isolated influenza viruses may require several passages before they adapt to growth by other routes, such as ___
Amniotic Cavity
- amniotic sac is small (1-2 ml)
-Mumps virus
*Influenza A, B and C viruses
- allantoic
Simplest method for growth
and multiplication of virus
- __,__,__,__
* Immune interference mechanism can be detected in most __ viruses
* Can also be used for the
cultivation of __, and __
Yolk Sac
- * Influenza, HSV, Vaccinia
and some Arboviruses
- avian
-Chlamydia and Rickettsia
Process of holding a strong light above or below the egg to observe the embryo
A candling lamp consists of a strong
electric bulb covered by a plastic or
aluminum container that has a handle
and an aperture
Egg Candling
Detection of Viral Growth
1
2
3
- Death of the embryo
- Defects in embryonic development
- Localized areas of damage in the membranes
(pocks)
A crucial technique in viral isolation that involved cultivating viruses in living
cells or tissues.
- Provides a controlled environment for studying replication, pathogenesis
and development of antiviral drugs and vaccines
Tissue Culture
TYPES OF TISSUE CULTURES
1
2
3
- Organ Culture
- Explant Culture
- Cell Culture
Small bits of organs can be maintained in ___
* Useful for the isolation of some viruses which appear to be highly specialized parasites of certain organs
Organ Culture
- vitro
Fragments of minced tissue can be grown as
‘explant’ embedded in ___
* _____ were used for the isolation of adenoviruses
Explant Culture
- plasma clots
- Adenoid tissue explant
culture
Routinely used
* Dissociated using __ and ____
* Growth medium contains
__,__,__,___ and a buffering system of
____ in equilibrium with atmosphere
containing____
Cell Culture
- proteolytic enzymes (trypsin) and
mechanical shaking
-essential amino acids, vitamins, salts, glucose
-bicarbonate
- 5% carbon dioxide
Supplemented with up to 5% calf or fetal calf serum
* ___ to prevent bacterial contamination
* ___ as indicator
Cell Culture
-Antibiotics
- Phenol red
CLASSIFICATION OF CELL CULTURES
3 Types based on:
Origin
▪ Chromosomal characteristics
▪ Number of generations through which they can be maintained
CLASSIFICATION OF CELL CULTURES
1
2
3
- Primary Cell Cultures
- Diploid Cell Lines
- Continuous Cell Lines
Normal cells obtained from fresh organs of animals or human being and cultured.
* Capable of only limited growth in culture and cannot be maintained in serial culture (1-2
passages)
1
2
3
* Commonly employed for primary isolation of viruses and in preparation of vaccine
Primary Cell Cultures
- Monkey kidney cell culture.
- Human embryonic kidney.
- Chick embryo cell culture.
have complete set of chromosomes
* Limited lifespan (___ serial passages)
* Useful for isolation of some ___ and for the production of viral vaccines
Diploid Cell Lines
20-50
fastidious pathogens
Cells of a single type, usually derived from ____, that are capable of continuous serial cultivation indefinitely
*__,__ and ___have been used in lab
throughout the world for many years
* Maintained by serial subcultivation
or stored in ____
* Now permitted to be used for vaccine manufacture, for example, ____ for rabies vaccine
Continuous Cell Lines
- cancer cells
- Hela, hep-2 and KB cell lines
- cold (–70°C)
- vero cell
Primary cell cultures
Rhesus monkey kidney cell structure
Human amnion cell culture
Chick embryo fibroblast cell culture
Diploid cell strains
WI-38 (Human Embryonic lung cell strain)
HL-8 (Rhesus embryo cell strain)
Continuous cell line
HeLA (Human carcinoma of cervix cell line)
HEP-2 (Human epithelioma of larynx cell line)
KB ( Human carcinoma nasopharynx cell line)
McCoy (Human synovial carcinoma cell line)
Detroit-6 (Sternal marrow cell line)
Chang C/I/L/K (Human conjunctiva (c), Intestine (I) lIVER (L) Kidney (K) cell lines)
Vero (Vervet monkey kidney cell line)
BHL 21 (Baby Hamster kidney cell line)
- Derived from freshly isolated tissues or organs
- Normal, diploid (46chromosomes)
- limited (1-5 passages)
-Slow growth, contact inhibition - Undergo senescence quickly
Primary Cell Cultures
Derived from normal, diploid cells
Normal, diploid (46 chromosomes in humans)
Finite (typically 20-50 population doublings)
Slow growth, contact inhibition
Undergo senescence after finite number of
passages
Diploid Cell Lines
Derived from cancer cells or transformed
cells
Abnormal, aneuploid (variable number of
chromosomes)
Unlimited (can be maintained indefinitely)
Rapid growth, loss of contact inhibition
Continuous Cell Lines
- Rapid modification of conventional
cell culture - Involved culturing cells in a small,
round-bottomed vial
Inoculated with the clinical sample
and then centrifuged to promote
viral absorption.
Incubated for ___
SHELL VIAL CELL CULTURE
- 24 to 48 hours
DETECTION OF VIRUS GROWTH IN CELL CULTURE
- Cytopathic effect
- Metabolic inhibition
- Hemadsorption
- Interference
- Transformation
- Immunofluorescence
- Detection of virus-specific nucleic acid
- Detection of enzymes
components in an infected cell or abnormal
accumulations of cellular materials resulting from virus-induced metabolic disruption.
Viral inclusions
-aggregates of cells fused to form one large cell
with multiple nuclei
Syncytial cells
Presumptive identification of a virus isolated from a clinical specimen.
Morphological changes in cultured cells
CYTOPATHIC EFFECT
Main Types of CPE
1
2
3
4
5
- Rounding of cells - picornaviruses
- Cell necrosis and lysis – Enteroviruses
- Syncytium formation - measles, respiratory syncytial virus, human
immunodeficiency virus (HIV) - Discrete focal degeneration - Herpes virus
- Rounding and aggregation - Adenovirus
Quantification of cell cytopathic effects
Negative uninfected monolayer
Equivocal +/- Atypical alteration of monolayer invoviving few cells
1+ 1-25% of monolayer exhibits cpe
2+ 25-50% of monolayer exhibits cpe
3+ 50-75% of monolayer exhibits cpe
4+ 76-100% of monolayer exhibits cpe
Viruses interfere with the metabolic activities of infected cells leading to reduction in cellular metabolic processes
Changes in ___ in the culture medium.
Normal cell cultures-medium turns __
Virus in cell culture-__
METABOLIC INHIBITION
- pH
- acidic
- no acid production
Viral envelope proteins may bind glycoproteins expressed on the surface of erythrocytes
Addition of guinea pig erythrocytes to the cultures - __ and ____
HEMADSORPTION
- Influenza and parainfluenza viruses
Non-cytopathogenic virus tested with known cytopathogenic virus
Growth of the first will inhibit the infection of the second virus by this
Phenomenon for which a cell infected by a virus becomes resistant toward a second outcoming infection by a superinfectant virus
INTERFERENCE
Tumor forming (oncogenic) viruses
Growth appears in a piled-up fashion
producing microtumors
1
2
3
4
5
TRANSFORMATION
Herpes viruses
Adenoviruses
Hepadnavirus
Papovaviruses
Retroviruses
Technique used to visualize and localize specific antigens (viral proteins) within cells.
Gives positive results earlier than other methods
___
IMMUNOFLUORESCENCE
- Fluorescein Isothiocyanate (FITC)
A single labeled antibody is used to directly detect the target viral antigen
- More rapid but less sensitive
- best suited to large quantities of virus
are suspected or when high-quality,
concentrated monoclonal antibodies are
used
Direct Immunofluorescence
A primary antibody is followed by a
labeled secondary antibody, amplifying
the signal and increasing sensitivity
used when lower quantities of virus are
suspected, such as detection of
respiratory viruses in specimens from
adult patients
Indirect Immunofluorescence
Interpretation of Fluorescence intensity using fitc
Negative No apple green fluorescence
1+ Faint yet unequivocal apple green fluorescence
2+ Apple green fluorescence
3+ Bright apple green fluorescence
4+ Brilliant apple green fluorescence
Molecular-based assays, such as polymerase chain reaction
Provide rapid, sensitive, and specific methods of detection
DETECTION OF VIRUS-SPECIFIC NUCLEIC ACID
Identified as reverse transcriptase in ___ , in the culture fluid.
Using antibodies to detect viral antigens or antibodies in the culture medium
DETECTION OF ENZYMES
- retroviruses
Powerful technique used to visualize at a very high resolution
Study the structure, morphology and size of viral particles in detail
ELECTRON MICROSCOPY
- passes a beam of electrons through a thin specimen. The electron that pass
through interact with the specimen, creating an image - Useful in studying the internal structure of viruses. It can reveal presence of ____,___ and ____
Transmission Electron Microscopy (TEM)
- viral capsids, nucleic acid and other internal components
VIRAL ASSAY
- Total virus particles
- Infectious virion assay
Total virus particles
Electron microscopy
Hemagglutination
Infectious virion assay
Quantal assays
Quantitative infectivity assay
Direct virus counting with electron microscopy and latex particles
Electron Microscopy
Step 1: ____ -virus suspension is mixed with a negative stain
Step 2:____-a known concentration of latex particles of a specific size is
added to the virus suspension. The latex particles serve as a ___
Step 3:___ -The sample is examined under an electron microscope. The virus
particles and latex particles can be distinguished based on their ___ and___
Step 4: ____ -virus particles and latex particles are counted in a specific area of the electron micrograph. The ratio between the two can be used to estimate the concentration of the virus particles in the original suspension
Electron Microscopy
- Negative Staining
- Latex Particle Addition
- visual reference
- Electron Microscopy
- size and appearance
- Counting
Used to measure the “all-or-none” response of a population of virus.
Only indicates presence or absence of infectious viruses
can be carried out in animals, eggs or tissue culture for those viruses
Quantal Assays
The virus sample is serially diluted to determine the lowest concentration that can still produce infection
Destruction of the host cell, embryo or animal or the appearance of CPE in cell cultures
Quantal Assays
__ or __: The titer of the original virus suspension is expressed as the 50% infectious
dose or the 50% lethal dose per milliliter
ID50 or LD50
A convenient method of quantitation for certain viruses particularly that possess
hemagglutinin proteins
- is not a very sensitive indicator of the presence of small amount of virus particles.
- approximately ____ are required to produce macroscopic agglutination.
Hemagglutination
- 107 influenza virions
Step 1: ____-Virus suspension is serially diluted
Step 2: ____-fixed volume of red blood cell is added to each dilution
incubate at ___
Step 3:___ -if virus concentration is high enough, red blood
cells will clump together
Step 4: ___-Highest dilution that still produces hemagglutination is determined
Hemagglutination
- Virus Dilution
- Red blood cell addition
- 37°C
- Observation of hemagglutination
- Endpoint Determination
measure the actual number of infectious
particles in the inoculum.
Two methods are available
1
2
Quantitative Infectivity Assay
- plaque assay in monolayer cell culture
and pock assay on chick embryo CAM
Viral suspension is added to a monolayer of cultured cells in a bottle or petri dish allowing time for absorption,
- Removed and replaced with a ___ to prevent virus spreading throughout the culture
- Each infectious viral particle gives rise to a localized focus of infected cells that can be seen with the naked eye. -
PLAQUE ASSAY
- solid agar gel
__ and ___, form pocks when inoculated onto the chorioallantoic membrane of an embryonated egg.
- Such viruses can be assayed by counting the number of pocks formed on cam by appropriate inocula of virus
POCK ASSAY
- Herpes and vaccinia
Each plaque represents ____ in the original virus sample.
1 infectious unit (virion or infected cell)
choriallantoic membrane inoculation
hsv
pox virus
rous sarcoma virus
amniotic inoculation
influenza
mumps
yolk sac inoculation
hsv
allantoic inoculation
influenza
mumps
newcastle dse virus
avian adenovirus
