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).
A reverse transcription-polymerase chain reaction (RT-PCR) assay was used to seek evidence of particle-associated MSRV/HERV-W RNA in the plasma and synovial fluid of patients with RA and controls. Stringent precautions were taken to avoid detection of contaminating human genomic DNA and cellular RNA sequences.
Thirty-seven plasma samples were tested (20 from RA patients and 17 from controls) but none had detectable MSRV/HERV-W RNA. Synovial fluid samples were available from nine patients with RA and 10 controls. Particle-associated 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.
MSRV/HERV-W RNA sequences are detectable in the synovial fluid of a small proportion of RA patients, but this phenomenon may not be specific to RA.