ABSTRACT
The human polyomavirus BK virus (BKV) is a common virus for which 80 to 90% of the adult population is seropositive. BKV reactivation in immunosuppressed patients or renal transplant patients is the primary cause of polyomavirus-associated nephropathy (PVN). Using the Dunlop strain of BKV, we found that nuclear factor of activated T cells (NFAT) plays an important regulatory role in BKV infection. Luciferase reporter assays and chromatin immunoprecipitation assays demonstrated that NFAT4 bound to the viral promoter and regulated viral transcription and infection. The mutational analysis of the NFAT binding sites demonstrated complex functional interactions between NFAT, c-fos, c-jun, and the p65 subunit of NF-kappaB that together influence promoter activity and viral growth. These data indicate that NFAT is required for BKV infection and is involved in a complex regulatory network that both positively and negatively influences promoter activity and viral infection.
Subject(s)
BK Virus/genetics , BK Virus/immunology , NFATC Transcription Factors/metabolism , Animals , BK Virus/pathogenicity , Base Sequence , Binding Sites/genetics , Chlorocebus aethiops , DNA Primers/genetics , Genes, Viral , Humans , Mutation , Polyomavirus Infections/etiology , Promoter Regions, Genetic , Transcription, Genetic , Tumor Virus Infections/etiology , Vero CellsABSTRACT
BK virus (BKV) is a polyomavirus that establishes a lifelong persistence in most humans and is a major impediment to success of kidney grafts. The function of the innate immune system in BKV infection and pathology has not been investigated. Here we examine the role of antimicrobial defensins in BKV infection of Vero cells. Our data show that alpha-defensin human neutrophil protein 1 (HNP1) and human alpha-defensin 5 (HD5) inhibit BKV infection by targeting an early event in the viral lifecycle. HD5 treatment of BKV reduced viral attachment to cells, whereas cellular treatment with HD5 did not. Colocalization studies indicated that HD5 interacts directly with BKV. Ultrastructural analysis revealed HD5-induced aggregation of virions. HD5 also inhibited infection of cells by other related polyomaviruses. This is the first study to demonstrate polyomavirus sensitivity to defensins. We also show a novel mechanism whereby HD5 binds to BKV leading to aggregation of virion particles preventing normal virus binding to the cell surface and uptake into cells.
Subject(s)
Anti-Infective Agents/pharmacology , BK Virus/metabolism , Polyomavirus Infections/metabolism , Virus Internalization/drug effects , alpha-Defensins/pharmacology , Animals , Anti-Infective Agents/metabolism , BK Virus/ultrastructure , Chlorocebus aethiops , Humans , Polyomavirus Infections/pathology , Vero Cells , Virion/metabolism , Virion/ultrastructure , alpha-Defensins/metabolismABSTRACT
The human polyomavirus, JCV, causes the fatal demyelinating disease progressive multifocal leukoencephalopathy in immunocompromised patients. We found that the serotonergic receptor 5HT2AR could act as the cellular receptor for JCV on human glial cells. The 5HT2A receptor antagonists inhibited JCV infection, and monoclonal antibodies directed at 5HT2A receptors blocked infection of glial cells by JCV, but not by SV40. Transfection of 5HT2A receptor-negative HeLa cells with a 5HT2A receptor rescued virus infection, and this infection was blocked by antibody to the 5HT2A receptor. A tagged 5HT2A receptor colocalized with labeled JCV in an endosomal compartment following internalization. Serotonin receptor antagonists may thus be useful in the treatment of progressive multifocal leukoencephalopathy.
