Understanding Viral Load Assays for Cytomegalovirus and Epstein-Barr Virus

Variability

March 2010

An assay must first be calibrated with a known amount of virus or nucleic acid before it can be used to determine the level of virus in a patient specimen. The types of calibrators that are commonly used range from live virus to dead virus to viral nucleic acid. The matrix, or solution, in which the calibrator material is suspended can also affect the performance of the assay. After calibration, there are other variables to consider, such as the

• technology used for viral quantification,
• the specimen source being analyzed,
• and the units in which the results are reported.

All of these variables mean that results of viral load assays are usually not comparable between laboratories, and therefore, decision points must be determined locally for each practice.

< Previous Slide

Variability

Next Slide >

 

Jump to section:

• Introduction
• Cytomegalovirus and Epstein-Barr Virus Background
• Patients and Immunosuppression
• CMV in Transplant Patients
• When to Treat CMV?
• CMV Treatment Strategies
• EBV and Posttransplantation Lymphoproliferative Disorder
• When to Treat EBV?
• Treatment for EBV Infection or PTLD
• The Balancing Act of Transplant Immunology
• The Balancing Act of Transplant Immunology: Less immunosuppression
• The Balancing Act of Transplant Immunology: More immunosuppression
• The Balancing Act of Transplant Immunology
• Crucial Questions
• Viral Load Assays
• Viral Load Assays, cont.
• Variability
• Ideal Standards
• Comparing Results
• Logarithmic (log) Processes
• Advantages of Logarithmic (log) Numbers
• Integer, Scientific Notation, Logarithm
• Log vs Fold
• Disadvantages of Log
• Remember These?
• System Precision/Imprecision
• What is Significant Change?
• Reality Check
• Literature is Helpful But...
• Interpreting Viral Loads
• Review
• References
• Questions?