Infectious, Rhesus Monkey-Derived Cellular DNA Sequences in Certain Stealth Adapted Viruses

The risks of using monkey kidney cells to produce poliovirus vaccines have included the transmission of monkey viruses to humans. This occurred with SV‐40 virus from rhesus monkeys and with simian cytomegalovirus (SCMV) from African green monkeys. Vaccine contaminating viruses can undergo an immune evasion process referred to as stealth adaptation. This results from the deletion or mutation of the genes coding for the relatively few virus components normally targeted by the cellular immune system. Stealth adapted viruses can further incorporate cellular and bacterial genetic sequences, which become components of the replicating viruses. Cytopathic stealth adapted viruses have been cultured from many patients with the chronic fatigue syndrome (CFS). Some of the cultures were further tested using a low stringency polymerase chain reaction (PCR). When performed on stealth adapted virus cultures from three CFS patients, the PCR assay amplified various genetically unstable, rhesus monkey genome‐derived genetic sequences. Although slightly different due to genetic instability, the three cultures have some common rhesus monkey‐derived genetic sequences. This finding confirms the inclusion of these sequences in human to human transmission. In one of the patients, additional cellular‐derived sequences were of human origin, probably arising from homologous recombination. If this were to occur in germ cells, the substitution of a monkey for a human sequence in the human genome would have long‐lasting multi‐generational consequences. The cellular sequences so far identified in stealth adapted viruses are from non‐coding regions with no apparent ascribed cellular functions. Still, these viruses can potentially acquire oncogenic cellular sequences, which would then be transmitted between humans. In conclusion, stealth adapted viruses can act as interspecies carriers of genetically unstable cellular sequences. The available sequence data on the monkey and cellular DNA incorporated into stealth adapted viruses cultured from different CFS patients will be presented.