Molecular epidemiology of JCV genotypes in patients and healthy subjects from Northern Italy.

Very little is known about JCV infection and genotype distribution with respect to the different demographic and clinical characteristics of the Italian population. A cross-sectional study was carried out on the prevalence of JCV genotypes in 323 Caucasian subjects (mean age: 37.5 years, range: 2-70 years). Urine samples from 200 immunocompromised patients, including patients affected by Multiple Sclerosis (MS), Human Immunodeficiency Virus (HIV), colon cancer, inflammatory diseases and Progressive Multifocal Leukoencephalopathy (PML), and 123 immunocompetent individuals were tested by quantitative real time PCR. Sequencing of the JCV viral protein 1 (VP1) and transcriptional control region (TCR) was performed. In this series, the overall prevalence of JCV excretion was 32.8% without significant differences between males and females. JCV was detected in 39.5% of patients and in 22% of healthy individuals (P = 0.004). The most prevalent JCV genotype excreted was genotype 1 (69.8%), followed by genotype 2 (22.6%) and genotype 4 (7.5%). Distribution of genotypes between patients and healthy subjects showed a statistically significant difference for the type 1 compared to the other variants (P < 0.01). Of note, JCV genotype 2 was found to be associated to young patients (P = 0.0001) and to patients treated with immunomodulator drugs (P = 0.0001), but not to PML subjects. The non-pathogenic archetype IIS (singular, insert) form was present in all JCV strains detected. This result allows to hypothesize a possible JCV genotype selection in response to pressure by immunomodulatory drugs.

Secondary lymphoid tissue as an important site for WU polyomavirus infection in immunocompetent children.

The polyomaviruses KI and WU (KIPyV and WUPyV) have been identified in respiratory specimens from children with acute respiratory infections, which suggests the respiratory tract as a possible site of infection. However, the persistence of infection in the lymphoid system is unknown. Fresh samples (n = 211) of tonsils, adenoids, and peripheral blood mononuclear cells (PBMCs) from 83 immunocompetent children (mean age 4.8 years) were tested for amplification of the KIPyV VP1 and WUPyV VP2 genes. The known BK and JC polyomaviruses and the lymphotropic human herpesvirus (HHV)-6 were also investigated by quantitative real-time PCR and direct sequencing. In addition, 98 nasopharyngeal swabs collected from children (mean age 6.2 years) affected by seasonal influenza-like illness were tested. Of the lymphoid tissues, 34.9% were positive for WUPyV, 4.8% for BK virus, and 33.8% for HHV-6. KIPyV and JC virus were not detected in these specimens. None of the polyomaviruses were detected in PBMCs. Among the nasopharyngeal samples, the prevalence of WUPyV was 27.5%, although 70% of the positive samples were co-infected with at least one of the following respiratory viruses: influenza virus, adenovirus, and respiratory syncytial virus. Phylogenetic analysis revealed high sequence homology (99%) between lymphoid- and nasopharynx-derived WUPyV strains. These results suggest that the tonsils and adenoids of immunocompetent children are a reservoir for WUPyV infection; probably due to the respiratory route of transmission. In addition, the prevalence of WUPyV was high among the children, and the virus was identified more frequently in older children than during the first years of life.