Ruimei Li

Simian virus 40 (SV40), a monkey polyomavirus that is believed to have entered the human population through contaminated vaccines, is known to be renotropic in simians. If indeed SV40 is endemic within the human population, the route of transmission is unknown. It was therefore hypothesized that SV40 might be renotropic in humans and be detected more frequently in samples obtained from patients with kidney diseases. This study found that typical polyomavirus cytopathic effects (CPE) were present and SV40 T antigen was detected in CV-1 cells cultured with peripheral blood mononuclear cells (PBMC) or urinary cells obtained from patients with kidney disease and healthy volunteers. DNA sequences homologous to the SV40 viral regulatory genome were detected by PCR in urinary cells from 15 (41%) of 36 patients with focal segmental glomerulosclerosis (FSGS), 2 (10%) of 20 patients with other kidney diseases, and 1 (4%) of 22 healthy volunteers (FSGS compared with other glomerular disease, P < 0.02; FSGS compared with healthy volunteers, P = 0.003). SV40 viral regulatory region genome was detected from PBMC at similar frequencies in patients with FSGS (35%), other glomerular diseases (20%), and healthy volunteers (22%). SV40 genome was detected by PCR in kidney tissues from 17 (56%) of 30 of patients with FSGS and 4 (20%) of 20 patients with minimal change disease and membranous nephropathy (P < 0.01). Considerable genetic heterogeneity of the viral regulatory region was detected, which argues against laboratory contamination. SV40 genome was localized to renal tubular epithelial cell nuclei in renal biopsies of patients with FSGS by in situ hybridization. This study demonstrates for the first time that human kidney can serve as a reservoir for SV40 replication and that SV40 may contribute to the pathogenesis of kidney disease, particularly FSGS.

BACKGROUND: Polyomavirus (PV) nephropathy has been attributed to reactivation of BK virus (BKV) or more rarely JC virus (JCV). The simian virus (SV) 40 is PV that was likely introduced into the human population through contaminated vaccines. The purpose of this study was to identify and characterize the PV that is associated with PV nephropathy. METHODS: The clinical diagnosis of PV nephropathy (PVN) was made in patients with acute deterioration in renal function whose renal biopsies showed typical viral cytopathic changes in tubular epithelial cells and staining for PV T antigen. Polymerase chain reaction (PCR) amplification of DNA from peripheral blood mononuclear cells (PBMC), urinary cells, and renal biopsy tissue was performed using specific primers for the transcription control regions of BKV, JCV, and SV40, respectively. RESULTS: Six cases of PV nephropathy were identified in 91 renal transplant recipients (7%). Immunosuppressive therapy was modified in all patients. Renal function stabilized or improved in four patients and deteriorated in two patients, and one patient has lost his allograft, after follow-up from 2 to 25 months. PCR detection demonstrated BKV genome in three of five PBMC samples, six of six urinary cell samples, and two of four renal biopsies. SV40 genome was detected in two of five PBMC samples, one of six urinary cell samples, and two of four renal biopsies. Infectious SV40 and BKV was demonstrated in CV-1 co-cultures using urine from one patient. JCV was not detected in any PVN sample. Co-infection with BKV and SV40 was found in two PVN patients. Urine samples obtained 12 months after transplant from 26 transplant recipients without PVN on simultaneous protocol renal biopsy were analyzed by PCR; BKV genome was demonstrated in 5 of 25 samples, JCV genome was demonstrated in 3 of 25 samples, and SV40 genome was demonstrated in 0 of 25 samples. CONCLUSION: The authors report molecular evidence that co-infection with BKV and SV40 occurs in renal transplant patients with PVN, suggesting that SV40 may contribute to PVN after renal transplant.

Extracellular nucleotides that constitute a "danger signal" play an important role in the regulation of immune responses. However, the function and mechanism of extracellular UDP and P2Y6 in antiviral immunity remain unknown. In this study, we demonstrated the in vitro and in vivo protection of UDP/P2Y6 signaling in vesicular stomatitis virus (VSV) infection. First, we demonstrated that VSV-infected cells secrete UDP from the cytoplasm as a danger signal to arouse surrounding cells. Meanwhile, expression of the UDP-specific receptor P2Y6 also was enhanced by VSV. Consequently, UDP protects RAW 264.7 cells, murine embryonic fibroblasts, bone marrow-derived macrophages, and L929 cells from VSV and GFP lentivirus infection. This protection can be blocked by the P2Y6 selective antagonist MRS2578 or IFN-α/β receptor-blocking Ab. VSV-induced cell death and virus replication were both enhanced significantly by knocking down and knocking out P2Y6 in different cells. Mechanistically, UDP facilitates IFN-β secretion through the p38/JNK- and ATF-2/c-Jun-signaling pathways, which are crucial in promoting antiviral immunity. Interestingly, UDP was released through a caspase-cleaved pannexin-1 channel in VSV-induced apoptotic cells and protected cells from infection through P2Y6 receptor in an autocrine or paracrine manner. Furthermore, UDP also protected mice from VSV infection through P2Y6 receptors in an acute neurotropic infection mouse model. Taken together, these results demonstrate the important role of extracellular UDP and P2Y6 as a danger signal in antiviral immune responses and suggest a potential therapeutic role for UDP/P2Y6 in preventing and controlling viral diseases.