African green monkey origin of the atypical cytopathic ‘stealth virus’ isolated from a patient with chronic fatigue syndrome

Background: A cytomegalovirus-like ‘stealth virus’ had previously been isolated from a patient with the chronic fatigue syndrome (CFS). Objective: To determine the original derivation of this virus. Study design: DNA sequencing of cloned regions of the virus was performed and the sequences were compared using BLASTN and FASTA analyses against the entire GenBank database. Viral sequences were also used to design primers for the polymerase chain reaction (PCR). Results: DNA and amino acid sequence comparisons showed that the stealth virus was more closely related to the Colburn strain of simian cytomegalovirus (SCMV) than to CMV of either human or rhesus monkey origin or to any other sequenced herpesvirus. Similarity, but non-identity, between the stealth virus and SCMV, was confirmed using PCR. Conclusion: The findings implicate the African green monkey as the probable source of the virus isolated from this CFS patient.