The 19th Internation Herpesvirus Workshop
University of British Columbia
July 30-August 5, 1994
A virus was repeatedly isolated from blood and cerebrospinal fluid (CSF) of a patient with the chronic fatigue syndrome (CFS). Herpesvirus-like particles lining cytoplasmic vacuoles were seen by electron microscopy yet infected cells did not stain with antisera specific for CMV, HSV, or HHV-6. PCR assays for these viruses were also negative. Two distinct PCR products of approximately 1.5 kilobase pairs were amplified from virally infected cells using the HTLV-II tax gene reactive primer, SK44, in low stringency PCR. Sequencing of one of the amplified products showed a 750 base pair region of highly significant homology with the UL34 gene of CMV. The sequence of the other PCR product did not correspond with CMV or with any other virus. DNA extracted from material pelleted by ultracentrifugation of filtered culture supernatants has been cloned and partially sequenced. Again the data indicate regions of significant homology to CMV contiguous with sequences which appear to have diverged widely from CMV. There was no evidence of an inflammatory response in the patient's CSF at the time of viral isolation. It is suggested that this type of virus may have arisen by deletion of genes coding viral antigens normally responsible for evoking anti-viral inflammatory responses. Such viruses have been provisionally termed "stealth viruses". They have a wide host range and have been found in association with a variety of neurological and other illnesses.