Interferon- alpha and - beta restrict polyomavirus JC replication in primary human fetal glial cells: implications for progressive multifocal leukoencephalopathy therapy

One of the major limitations of highly active antiretroviral therapy is its inability to inhibit the replication of polyomavirus JC (JCV), the etiologic agent of progressive multifocal leukoencephalopathy (PML), an acquired immunodeficiency syndrome-defining illness. We previously demonstrated the induction of interferon (IFN)-stimulated genes (ISGs) by JCV. In the present study, we characterize the specific viral events required to induce ISGs and the potential antiviral effects of type I IFN on JCV replication in human fetal glial cells in the presence and absence of type I IFNs. Productive JCV replication was essential for the induction of the antiviral host response. JCV replication at all steps was significantly inhibited in the presence of IFN, and neutralizing anti-IFN antibody rescued the inhibitory effect of IFN. These results support the use of IFN as an adjunct therapy for patients with PML. Because IFN cannot cross the blood-brain barrier to achieve its direct antiviral effect, intrathecal administration of IFN is warranted.

JC virus induces altered patterns of cellular gene expression: interferon-inducible genes as major transcriptional targets

Human polyomavirus JC (JCV) infects 80% of the population worldwide. Primary infection, typically occurring during childhood, is asymptomatic in immunocompetent individuals and results in lifelong latency and persistent infection. However, among the severely immunocompromised, JCV may cause a fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). Virus-host interactions influencing persistence and pathogenicity are not well understood, although significant regulation of JCV activity is thought to occur at the level of transcription. Regulation of the JCV early and late promoters during the lytic cycle is a complex event that requires participation of both viral and cellular factors. We have used cDNA microarray technology to analyze global alterations in gene expression in JCV-permissive primary human fetal glial cells (PHFG). Expression of more than 400 cellular genes was altered, including many that influence cell proliferation, cell communication and interferon (IFN)-mediated host defense responses. Genes in the latter category included signal transducer and activator of transcription 1 (STAT1), interferon stimulating gene 56 (ISG56), myxovirus resistance 1 (MxA), 2'5'-oligoadenylate synthetase (OAS), and cig5. The expression of these genes was further confirmed in JCV-infected PHFG cells and the human glioblastoma cell line U87MG to ensure the specificity of JCV in inducing this strong antiviral response. Results obtained by real-time RT-PCR and Western blot analyses supported the microarray data and provide temporal information related to virus-induced changes in the IFN response pathway. Our data indicate that the induction of an antiviral response may be one of the cellular factors regulating/controlling JCV replication in immunocompetent hosts and therefore constraining the development of PML.

West Nile virus detection in urine

We report West Nile virus (WNV) RNA in urine collected from a patient with encephalitis 8 days after symptom onset. Viral RNA was detected by reverse transcriptase–polymerase chain reaction (RT-PCR). Sequence and phylogenetic analysis confirmed the PCR product to have ≥99% similarity to the WNV strain NY 2000-crow3356.