Diagnostic Assays. The difficulty in diagnosing chronic HHV-6 infections in the brain is that his virus is tends to retreat to the tissues and is very difficult to detect in the spinal fluid and plasma except during the primary infection or an acute reactivation.

In other words, there may be no viral DNA in the serum and spinal fluid in spite of active infection in the brain tissue.

Since it is difficult to find direct evidence of the virus

in the periphery, researchers are now looking for indirect evidence: antibodies or proteins in the serum that might be able to pinpoint which patients might have active disease.

There are currently no assays available that can reliably detect HHV-6 infection in MTLE. Elevated antibodies may be a sign of chronic reactivation, but there are no guidelines established to be able to compare the antibody levels to epilepsy patients to those of healthy individuals. Also, there is no antibody assay to differentiate HHV-6A from

HHV-6B. This can only be done by an analysis of the cells with special staining (immunohistochemistry) or by PCR DNA testing of the tissues affected.

Research is urgently needed to determine if elevated antibodies against HHV-6 might be a useful clue to identify epilepsy patients with chronic HHV-6B reactivation.