Supportive Data

Analytical Sensitivity/Limit of Detection:

Spiked specimens in cerebrospinal fluid (CSF) with human herpesvirus-6 (HHV-6) DNA subtypes A/B (40 for each subtype) for a total of 80 positive specimens were used for establishment of the limit of detection (LOD). The lower LOD of this assay was determined to be 500 copies/mL for HHV-6A and 250 copies/mL for HHV-6B.

Analytical Specificity:

DNA from a panel of 10 organisms from culture collections along with well characterized laboratory strains that cause similar disease or organisms commonly found in CSF were tested to determine if there is any cross-reactivity against the Altona RealStar HHV-6 PCR (polymerase chain reaction) Kit 1.0. No cross-reactivity was observed with the specificity panel.

Analytical specificity was determined by the kit manufacturer (Altona Diagnostics) and did not exhibit cross-reactivity with any of the following targets: BK virus, cytomegalovirus, Epstein-Barr virus, hepatitis A virus, hepatitis B virus, hepatitis C virus, herpes simplex virus 1, herpes simplex virus 2, human herpesvirus 7, human herpesvirus 8, human parvovirus B19, JC virus, varicella-zoster virus.

Due to new sequence data, cross reactivity of the HHV6-B detection systems (Cy5/Cy5.5) with some strains of HHV-6A cannot be ruled out. A signal in the HHV-6A detection channel (FAM) and HHV-6B (Cy5/Cy5.5) can be observed. This is a known limitation of the assay and will be incorporated in analysis and reporting processes.

Reference Range:

A total of 20 CSF samples collected for noninfectious disease testing (eg, CSF chemistry) were analyzed by the Altona RealStar HHV-6 PCR assay. Of these, 19 were negative. One sample did have a low level of HHV-6 DNA. Given that HHV-6 undergoes latency following primary infection, it is possible to detect viral DNA that may not be associated with active infection or disease. Also, in approximately 1% of patients, HHV-6 may become chromosomally integrated, yielding a positive result by molecular tests.

Although the reference range is typically "negative" for this assay, this assay may detect viral DNA in asymptomatic individuals. However, this assay is only to be used for patients with a clinical history and symptoms consistent with HHV-6 infection and must be interpreted in the context of the clinical picture. This test should not be used to screen asymptomatic patients.

Reportable Range:

The reportable range for this assay is 500 copies/mL to 5,000,000 copies/mL.