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10 Cards in this Set
- Front
- Back
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What are the major components of a virus?
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Genome:
either DNA or RNA Proteins: capsid or enzymes Envelope: a lipoprotein bilayer associated glycoprotein peplomers and sometimes a matrix protein |
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Is the virus stable at room temperature?
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No.
Stability of Viral Infectivity: 55-60ºC for minutes 4 ºC for a few days -70 ºC for years -196 ºC for long-term storage (liquid nitrogen) |
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Is the virus stable at acid and basic conditions?
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Ionic Environment and pH
-Best preserved in an isotonic environment at physiologic pH -Most envelopes virus are inactivated at pH 5-6 -Rotavirus and picornavirus are acid resistant (naked viruses - no envelope) Lipid Solvents and detergents -Envelope viruses are sensitive to ether, chloroform, and bleach (envelope very susceptible to organics) |
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What is the key to obtaining a viral specimen from patients?
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Specimens must be taken at the right time and right place. Infections from acute viremia are only present in the blood for 2 weeks.
Collect samples ASAP after death -affected organs and gut loops Collect sample ASAP after the animal first develops clinical signs -The site from which the specimen is collected will be influenced by the clinical signs. (Runny nose? Collect the discharge) |
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Depending on the symptoms, where do you take tissue samples from to send in?
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In all of these, get blood.
Syndrome Specimen Respiratory Nasal or throat swab, nasopharyngeal aspirate Enteric Feces Genital Genital swab Eye Conjunctival swab Skin Vesicle swab or scraping; biopsy of solid lesion CNS cerebrospinal fluid, feces, nasal swab Generalized Nasal swab, feces, blood leukocytes Autopsy/biopsy Relevant Organ Any disease Blood for serology |
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What temperature should viral specimens be stored at for virus isolation?
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Specimens intended for virus isolation must always kept cold (4 ºC) and moist
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How should you store a swab for tissue culture? (in what kind of solution)
What about the tissues themselves? |
Swab should be stored in small amount of medium (0.5 -1.0 ml PBS, Tissue Cultural media containing antibiotics)
Place tissues in 10% buffered formalin - < 1 cm thick Place tissues and swabs in plastic, sealed containers labeled with water proof ink. |
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What information do you include with the sample for the diagnostic lab?
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Case history and suspected pathogen(s)
Treatment Vaccinations Number of animals involved List of specimens |
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How much sample is needed for virus diagnosis?
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less than a cm, or 1 to 2 ml, even if you have a bucket of poo.
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What are the principles and objectives of virus diagnosis?
What is the ideal way and then the less ideal way to detect and id viruses? |
-Visual information (clinical signs)
-Detection and identification of viral antigens -Direct detection and identification of viral nuclei acids -Virus Isolation and identification (if the tissue sample is good) - ideal way -Detection and quantitation of antiviral antibodies (from the blood, if the tissue sample wasn't good) - less ideal way |
