Diagnostics Virology

• What is the primary purpose of diagnostic virology?

  Diagnosis confirmation informed by primary clinical diagnosis
• What are the four main purposes of diagnostic virology?

  Diagnosis confirmation, surveillance, identification of chronic infection, confirmation of notifiable disease
• What are the diagnostic methods for virus isolation and identification?

  • Standard and enhanced cell culture
  • Direct detection methods
  • Serological diagnosis
  • Molecular diagnosis
  • Anti-viral susceptibility testing
• What is the definition of cell culture?

  Cells growing in vitro under conditions in which the cells are no longer organized into tissues
• What types of cell lines are used in cell culture?

  Primary, diploid, and heteroploid lines
• What is required for the detection of viral presence in cell culture?

  Cytopathic Effect (CPE) to occur
• What are some morphological changes due to viral replication?

  Cell rounding, formation of foci, refractile cells, cell clumping, vacuolation, giant cells, syncytium formation, cell destruction, lysis
• Why is it necessary to compare infected cells with uninfected control cells?

  To indicate active viral replication and infection
• What are the key factors that viral diagnostic methods depend on?

  They depend on virus type, specificity, sensitivity, quality, reproducibility, and speed.
• Why is optimization important in viral diagnostics?

  Optimization is important to ensure accurate and reliable results.
• What are the cell lines sensitive to common viruses and their CPE percentages?

  • HSV: Primary Rabbit Kidney >90% on Day 3
  • VZV: Human Fibroblast <2% on Day 3
  • CMV: Human Fibroblast 10% on Day 3
  • Enterovirus: Primary Monkey Kidney 60% on Day 3
  • Rhinovirus: Human Fibroblast 40% on Day 3
  • RSV: HEp-2 <2% on Day 3
  • Adenovirus: HEp-2 30% on Day 3
  • Influenza: Primary Monkey Kidney 65% on Day 3
• How does automation impact viral diagnostics?

  Automation increases speed and throughput in diagnostic processes.
• What is the purpose of fixing and staining cells in cell culture?

  To visualize changes in the cells
• What does NGS stand for in the context of viral diagnostics?

  NGS stands for Next-Generation Sequencing.
• What does POCT stand for?

  POCT stands for Point of Care Testing.
• What stains are used for visualizing changes in cell culture?

  Haemotoxylin and Eosin (H&E), Giemsa stain
• What is the purpose of Crystal Digital PCR?

  Crystal Digital PCR is used for precise quantification of nucleic acids.
• What is hemadsorption in virology?

  It is the binding of viruses that express glycoproteins to red blood cells
• What is an interference assay in virology?

  It assesses the ability to interfere with growth and CPE development of a challenge virus
• What is the significance of "Lab in a Cartridge" technology?

  It allows for simplified and rapid testing in a compact format.
• What are the advantages and disadvantages of cell culture techniques?

  Advantages:

  • Sensitive and specific
  • Identification of productive infection

  
  

  Disadvantages:

  • System may not be available or complicated
  • Time to isolation
  • Cost effectiveness
• What is the name of the system developed by Cepheid for clinical IVD tests?

  The system is called GenXpert.
• What are the direct detection methods for viruses?

  • Electron Microscopy
  • Histopathology and Cytopathology
  • Immunofluorescence and Immunochemistry
  • Solid-phase immunoassay
• What is Extreme PCR used for?

  Extreme PCR is used for enhancing the sensitivity of PCR tests.
• What future prospects are considered for improving laboratory diagnostics?

  • Achieving better diagnostic accuracy
  • Improving testing speed and efficiency
  • Developing new methodologies and technologies
• What is the purpose of Transmission Electron Microscopy (TEM) in virology?

  It is useful for non-cultivable viruses and new and emerging viruses
• What questions should laboratories consider regarding their diagnostics?

  They should consider what they want to achieve, if they can improve diagnostics, and how to approach development.
• What are the advantages and limitations of Transmission Electron Microscopy (TEM)?

  Advantages: fast; Limitations: high cost, skilled operator, high [virus] required
• What is the preparation process for a sample in TEM?

  Serial dilution of specimen, specimen adsorbed onto carbon film, specimen mesh grid placed on carbon, specimen grid lifted off, stain with phosphotungstic acid or uranyl acetate
• What are some examples of DNA viruses?

  • Adenovirus
  • Papillomavirus
  • Herpesvirus
  • Hepatitis B virus
  • Parvovirus
• What are some examples of RNA viruses?

  • Influenza
  • Rotavirus
  • Paramyxovirus
  • Enterovirus
  • Ebola Virus
  • Retrovirus
• What are the advantages and disadvantages of histopathology and cytopathology?

  Advantages:

  • Rapid

  
  

  Disadvantages:

  • Insensitive
  • Limited ability to distinguish certain viruses
• What is the role of immunofluorescence and immunochemistry in virology?

  Direct antibody staining of clinical specimens with antibodies specific to viral antigens
• What are the advantages and disadvantages of Direct Fluorescent Antibody (DFA) testing?

  Advantages: speed and simplicity, sensitive and specific; Disadvantages: microscopy requirements, multiple virus presence
• What is solid-phase immunoassay?

  • Antigen or serum bound to a solid surface
  • Tube and microplate enzyme immunoassays (EIA)
  • Radioimmunoassay (RIA)
  • Rapid and highly specific
  • Less sensitive than virus isolation
• What are examples of solid-phase immunoassays?

  Xpect Flu A&B, BD Directigen EZ Flu A+B
• What factors should be considered when interpreting serology for viral infection?

  • Virus
  • Early infection
  • Reactivation
  • Confirmation by viral isolation
• What are the types of molecular testing in virology?

  • PCR based assays
  • DNA or RT-PCR
  • Qualitative or quantitative
  • NASBA or TMA
  • Nucleic Acid sequencing
• What is the purpose of quantification of viral genomes by real-time PCR?

  For resistance/typing/transmission studies/surveillance/monitoring
• What information is needed to determine which virology test to use?

  • Symptoms, including date of onset and duration
  • Travel history
  • Vaccination history
  • Risk factors (food, animals, insect bites, etc.)
  • Contact with confirmed or suspected cases
  • Age, immune status, co-morbidities