Diagnostic Testing for CMV and BK Virus in Transplant Recipients
CMV Testing
- The Infectious Diseases Society of America recommends quantitative CMV DNA testing by NAT (viral load) in plasma or whole blood for CMV detection and monitoring in transplant recipients, as it is the most sensitive and specific method 1, 2
- CMV serology (IgG and IgM antibodies) is not recommended for transplant recipients, but may be used as first-line testing in immunocompetent individuals suspected of having acute CMV infection 1
- The American Society of Transplantation prefers CMV viral load by NAT over antigenemia testing as it is more sensitive and has become the standard of care 1
BK Virus Testing
- The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend quantitative BK virus DNA testing by NAT (viral load) in plasma for BK virus detection and monitoring in transplant recipients 3, 5
- Urine testing for BK virus may be used as a screening test, but is less specific than plasma testing due to common viral shedding in urine 5
- BK virus DNA quantification in plasma provides an early indication of BK virus-associated nephropathy 5
Monitoring Schedule
- The American Society of Transplantation recommends weekly monitoring of CMV by NAT or pp65 antigenemia in patients with CMV disease 3, 4
- The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend monthly screening for BK virus for the first 3-6 months after transplantation, and every 3 months until the end of the first post-transplant year 3, 4
Clinical Interpretation
- A plasma viral load persistently greater than 10,000 copies/ml (10^7 copies/L) indicates a need for reduction in immunosuppressive medications for BK virus 3, 4
- Viral load testing is used as a marker for preemptive therapy, to diagnose CMV-associated signs and symptoms, and to monitor response to antiviral therapy for CMV 1