Latent viral infections in young patients with inflammatory diseases treated with biological agents: prevalence of JC virus genotype 2.

Treatment with biological drugs is associated with increased susceptibility to viral infections. Reactivation of JC virus (JCV) and human cytomegalovirus (HCMV) in adults after therapy has been documented. The long-term effects of biological and conventional therapy on human herpesviruses and polyomaviruses infections in young patients were assessed. One hundred eighty-six samples [urine, serum, and blood cells (PBMCs)] from 62 patients (15.8 ± 6.2 years old) with Crohn's disease, ulcerative rectocolitis or juvenile rheumatoid arthritis treated with immunotherapy or conventional therapy for over 12 months were tested by real time PCR. One hundred twenty-four samples (urine and blood) from 62 matched healthy volunteers (13.8 ± 8.6 years old) were included as controls. Sequencing of the JCV viral protein 1 (VP1) and transcriptional control region (TCR) was performed. Herpes simplex virus 1/2 and varicella zoster virus genomes were not detected in any patients, whereas Epstein-Barr virus, HCMV, and human herpesvirus-6 genomes were detected in 4.8%, 3.2%, and 1.6% of the patients, respectively. JCV was detected in 22.6% (14/62) of urine samples from patients and in 8% (5/62) from controls, in 50% (7/14) of sera from patients shedding JCV, and in 71.4% (5/7) of matched PBMCs. There was a significant association between infliximab treatment and excretion of JCV genotype 2. Subclinical infection/reactivation of JCV genotype 2 in young patients during infliximab therapy was demonstrated. Conversely, increased susceptibility to herpesviruses infection was not shown. Future studies are warranted to investigate the effects of JCV reactivation on the health of young patients treated with infliximab.