TABLE 1

Overview of diagnostic procedures for HHV-6 infection

Diagnostic approachMethodAdvantages and usefulnessDisadvantages and limitationsb
Indirect (serology)Assays for IgG and IgM detection (IFA, ELISA)a and avidity assaysEasy collection and storage of serum samples, readily accessible techniques, diagnosis of primary infection, seroprevalence studiesLack of interpretation for diagnosis of reactivations, no discrimination between HHV-6A and HHV-B, delayed/altered response if immune deficiency is present, cross-reactivity with other betaherpesviruses
DirectVirus isolation in cell cultureReference method in virology, evidence of infectious virus, precise investigations of virus strainsLabor-intensive method, high cost, limited sensitivity
Antigen detectionUses conventional equipment, gives evidence of virus gene expression, discrimination between HHV-6A and HHV-6BNeed for standardization, limited sensitivity with current reagents, difficulties of readout in some cases
Qualitative viral DNA PCRHigh sensitivity and specificity, discrimination between HHV-6A and HHV-6BNo distinction between active infection, latency, and ciHHV-6
Quantitative viral DNA real-time PCRHigh sensitivity and specificity, discrimination between HHV-6A and HHV-6B, longitudinal follow-up studies, comparison of viral loads in blood versus organsNeed for international standardization, need for specific thresholds for active infections and ciHHV-6
Detection of viral transcripts by RT-PCRDistinction between active and latent infections, recognition of active infection in ciHHV-6 subjectsLimited sensitivity (to be evaluated), need for standardization
Droplet digital PCRPrecise method for measuring nucleic acid amounts, identification of ciHHV-6Limited sensitivity (to be evaluated), adaptation to clinical specimen diversity
  • a IFA, immunofluorescence assay; ELISA, enzyme-linked immunosorbent assay; RT-PCR, reverse transcriptase PCR; ciHHV-6, chromosomally integrated human herpesvirus 6.

  • b The availability of the mentioned tests may be restricted in some medical centers.