Stealth adaptation is a generic immune evasion mechanism, which can potentially occur with all viruses [1-4]. It involves the deletion or mutation of the genes coding for the relatively few virus components typically targeted by the cellular immune system. A further characteristic of certain stealth adapted viruses is the incorporation of additional genetic sequences of cellular and bacterial origins [5-8]. These “renegade” genetic sequences can be subsequently transmitted between humans as components of infectious stealth adapted viruses. The best characterized stealth adapted virus, referred to in GenBank as stealth virus 1, is a derivative of an African green monkey simian cytomegalovirus (SCMV) [2,4,9]. It was repeatedly cultured from a patient with the chronic fatigue syndrome (CFS) [10]. A similar virus (stealth virus-2) was isolated from the cerebrospinal fluid of a comatose patient with a 4-year history of a bipolar psychosis [11]. Stealth virus-1 was cloned and the complete or partial DNA sequences of 248 clones were submitted to GenBank. Of these clones, 200 of the sequences correspond to regions of the SCMV genome. The sequences are unevenly distributed over the genome of the originating SCMV, with clear evidence of major deletions and genetic instability. Fourteen clones contained genetic sequences that were derived from non-coding regions of the human genome. These incorporated cellular sequences have also undergone genetic changes indicative of the genetically unstable stealth adapted virus genome [12].
Read full abstract