JC polyoma virus and kidney disease

To the Editor: In a recent article, Divers et al.1 describe the interaction between apolipoprotein L1 (APOL1) genotypes and JC viruria, and their relationship with nondiabetic nephropathy in African Americans. The authors found that in African Americans with two APOL1 risk alleles, the prevalence of kidney disease was lower for those with JC viruria compared with those without JC viruria. In a cohort of 282 renal transplant recipients (80% white, 239 JC negative and 43 JC positive), we found that isolated JC viruria, without JC or BK viremia, was associated with protection from acute renal allograft rejection (13.8% for JC− vs. 2.3% for JC+, P=0.04). Kaplan–Meier analysis for acute rejection–free survival was also favorable for JC+ compared with that for JC− (log-rank P=0.05) recipients. There was no difference for death-censored graft survival (P=0.6) or patient survival (P=0.1). JC+ recipients tended to be less likely to be coinfected with BK virus (7% for JC+ vs. 14.2% for JC−, P=0.2). Divers et al.,1 and an accompanying editorial by Kopp2 speculate that JC virus may protect against other polyomaviruses that are associated with kidney disease or it may alter cellular function rendering the kidney less susceptible to damage. Our findings support their speculations for the protective role of isolated JC viruria and expand the implications to the kidney transplant population in addition to the African-American population.