Nested PCR for detection of BK virus and JC virus DNA

The national incidence of PML in Sweden, 1988-2013

Objective

To investigate the incidence of progressive multifocal leukoencephalopathy (PML) and patient characteristics in Sweden between 1988 and 2013.

Methods

All PML diagnoses in Sweden between 1988 and 2013 were identified in the National Patient Register. Information to validate the diagnosis and patient characteristics was obtained from medical records.

Results

Medical record review classified 108 out of 250 patients (43%) as definite (n = 84), probable (n = 4), or possible (n = 20) PML according to diagnostic criteria. Accurate diagnoses were more common in records obtained from neurology departments (82% of patients seen in neurology departments) compared with other departments (31%) (p < 0.001). The incidence of PML increased from a largely stable level at 0.026 (95% confidence interval [CI] 0.021–0.031) per 100,000 individuals per year during 1988–2010 to 0.11 (95% CI 083–0.137) during 2011–2013, during which time there was a notable increase (p < 0.001). Hematologic malignancies (n = 34), HIV/AIDS (n = 33), and autoimmune disease (n = 23) were the most common underlying diseases. Treatment with a monoclonal antibody prior to PML diagnosis was identified in 26 patients.

Conclusion

An increased incidence of PML in Sweden was observed and coincided with the prior use of monoclonal antibody treatment. The high level of misdiagnosis emphasizes the importance of immediate contact with a neurology center upon suspicion of PML.

Discovery and epidemiology of the human polyomaviruses BK virus (BKV) and JC virus (JCV)

Although discovered over thirty years ago, many aspects of the epidemiology of BKV and JCV in the general population, such as the source of infectious virus and the mode of transmission, are still unknown. Primary infection with both BKV and JCV is usually asymptomatic, and so age seroprevalence studies have been used to indicate infection. BKV commonly infects young children in all parts of the world, with the exception of a few very isolated communities, adult seroprevalence rates of 65-90% being reached by the age of ten years. In contrast, the pattern of JCV infection appears to vary between populations; in some anti-JCV antibody is acquired early as for BKV, but in others anti-JCV antibody prevalence continues to rise throughout life. This indicates that the two viruses are probably transmitted independently and by different routes. Whilst BKV DNA is found infrequently in the urine of healthy adults, JCV viruria occurs universally, increasing with age, with adult prevalence rates often between 20% and 60%. Four antigenic subtypes have been described for BKV and eight genotypes are currently recognized for JCV. The latter have been used to trace population movements and to reconstruct the population history in various communities.

Detection of JC virus DNA in cerebrospinal fluid from multiple sclerosis patients

JC virus (JCV), the causative agent of progressive multifocal leukoencephalopathy (PML), has been proposed as a possible aetiopathogenic factor in multiple sclerosis (MS). We performed a study to search the LT region of JCV genome by nested PCR in cerebrospinal fluid (CSF), peripheral blood mononuclear cell (PBMC) and urine samples collected from 121 MS patients, 24 patients with other neurological disorders (OND), 30 non neurological patients (NND) and in PBMCs and urine of 40 healthy subjects. JCV DNA has been found in the CSF of 11 MS patients (9%) while all the CSFs from the 24 OND and the 30 NND cases were negative. No significant differences have been observed as regard to the frequency of JCV DNA detection in PBMCs and urine between the MS patients and the control groups. Nucleotide sequences analysis of seven JCV CSF isolates showed that five strains were identical the prototypal strain, while the other two had a base mutation (T-->C) in 4286 nucleotide (nt). The finding of JCV DNA in the CSF of MS patients suggest that JCV could play a role in the triggering and/or in the maintenance of MS aetiopathogenic process, and therefore it should be taken in consideration when monitoring this disease.

JCV-DNA and BKV-DNA in the CNS tissue and CSF of AIDS patients and normal subjects. Study of 41 cases and review of the literature

SUMMARY

We studied the distribution and localization of the human papova-viruses JCV and BKV in the central nervous system (CNS) and cerebrospinal fluid (CSF) of HIV-positive patients with and without progressive multifocal leukoencephalopathy (PML) as compared with HIV-seronegative patients. The presence of JCV-DNA and BKV-DNA was evaluated by nested polymerase chain reaction (PCR) and in situ hybridization (ISH) on CNS autopsy tissues of AIDS patients with (group A, n = 13) and without (group B, n = 16) PML and of HIV-negative patients (group C, n = 12). PCR for JCV-DNA and BKV-DNA was also performed on CSF samples collected 7-420 days before death in all the 29 AIDS patients. Tissue PCR for JCV-DNA was positive in all the cases in group A, in 44 percent of the patients in group B, and in 33 percent of the patients in group C. ISH was positive in all the cases with PML and in three AIDS cases without PML (12 percent), but negative in all the HIV-negative cases. BKV-DNA was detected in two cases from group A and in one case from group B. CSF was PCR-positive for JCV-DNA in 8 of 13 (62 percent) AIDS patients with PML, but in none of the HIV patients without PML, irrespective of the presence of JCV-DNA in CNS tissues. No CSF sample was positive for BKV-DNA. Our data demonstrates that JCV-DNA and, rarely, BKV-DNA can be detected in the CNS of immunocompromised patients with and without PML and also in the CNS of HIV-negative subjects. However, only HIV-positive patients with clinically evident PML and JCV-DNA in the brain have PCR-detectable JCV-DNA in their CSF.