Parvovirus B19, HHV-6 and HHV-7 Infection Markers in Synovial Fluid and Synovial Tissues of Patients with Rheumatoid Arthritis and Osteoarthritis

Objectives. Rheumatoid arthritis (RA) and osteoarthritis (OA) are the most common chronic connective tissue diseases. Despite many long-term studies, the precise triggering agent of RA is unknown. Persistent viral infections can contribute to the development of RA as well as to OA inflammation. The goal of this study was to examine the presence of HHV-6, HHV-7 and parvovirus B19 (B19V) infection markers in synovial fluid and synovial tissue of RA and (OA) patients.
Methods. 6 synovial fluid and 7 synovial tissue samples from RA patients, as well as 32 synovial fluid and 54 synovial tissue samples from OA patients, were analyzed for the presence of viral genomic sequences using nPCR and for the presence of viral antigens using immunohistochemistry. For immunohistochemical reactions, anti-HHV-6 monoclonal antibody raised against viral lysate, anti-HHV-7 raised against the tegument protein pp85 of HHV-7, and anti-parvovirus B19 NCL-PARVO monoclonal antibody raised against VP1/VP2 viral antigens were used.
Results. HHV-6 and/or HHV-7 genomic sequences were found in 5/6 RA patients and in 13/34 OA patients synovial fluid as well as in 4/7 RA and in 20/54 OA patients synovial tissues DNA samples. B19V sequence was detected in one RA and in 6 OA patients’ synovial fluid, and in 3 RA and in 3 OA synovial tissue DNA samples. The more frequent concurrent HHV-6 and -7 genomic sequences were detected in synovial tissue DNA samples of RA patients compared with OA patients (p = 0.0166). In B19V PCR-positive RA and OA synovial tissue samples, expression of B19V VP1/VP2 antigen, but in HHV-6 PCR-positive RA and OA synovial tissue samples expression of HHV-6 antigens was demonstrated.
Conclusions. The presence of HHV-6, HHV-7, and B19V infection markers in local inflammation site allows suggest these viruses as one of the etiopathogenic factors in RA and OA development.