Infrequency of detection of particle-associated MSRV/HERV-W RNA in the synovial fluid of patients with rheumatoid arthritis

Objectives. To determine whether the recently identified multiple sclerosis -associated retrovirus, MSRV, is detectable in the serum and synovial fluid of patients with rheumatoid arthritis (RA). Methods. A reverse transcription-polymerase chain reaction (RT-PCR) assay w as used to seek evidence of particle-associated MSRV/HERV-W RNA in the plas ma and synovial fluid of patients with RA and controls. Stringent precautio ns were taken to avoid detection of contaminating human genomic DNA and cel lular RNA sequences. Results. Thirty-seven plasma samples were tested (20 from RA patients and 1 7 from controls) but none had detectable MSRV/HERV-W RNA. Synovial fluid sa mples were available from nine patients with RA and 10 controls. Particle-a ssociated MSRV/HERV-W RNA was reproducibly detected in two of nine synovial fluid samples from RA patients and in one control sample. The identity of RT-PCR products was confirmed by sequencing. Conclusion. MSRV/HERV-W RNA sequences are detectable in the synovial fluid of a small proportion of RA patients, but this phenomenon may not be specif ic to RA.