No abstract

FOXP3-expressing naturally occurring CD4+CD25high T regulatory cells (Treg) are relevant in the control of autoimmunity, and a defect in this cell population has been observed in several human autoimmune diseases. We hypothesized that altered functions of peripheral Treg cells might play a role in the immunopathogenesis of myasthenia gravis, a T cell-dependent autoimmune disease characterized by the presence of pathogenic autoantibodies specific for the nicotinic acetylcholine receptor. We report in this study a significant decrease in the in vitro suppressive function of peripheral Treg cells isolated from myasthenia patients in comparison to those from healthy donors. Interestingly, Treg cells from prednisolone-treated myasthenia gravis patients showed an improved suppressive function compared with untreated patients, suggesting that prednisolone may play a role in the control of the peripheral regulatory network. Indeed, prednisolone treatment prevents LPS-induced maturation of monocyte-derived dendritic cells by hampering the up-regulation of costimulatory molecules and by limiting secretion of IL-12 and IL-23, and enhancing IL-10. In addition, CD4+ T cells cultured in the presence of such tolerogenic dendritic cells are hyporesponsive and can suppress autologous CD4+ T cell proliferation. The results shown in this study indicate that prednisolone treatment promotes an environment that favors immune regulation rather than inflammation.

Koi herpesvirus (KHV), an emerging pathogen causing mass mortality in koi and common carp, possesses the largest known herpesvirus genome of 295 kbp predicted to encode 156 different proteins. However, none of them has been identified or functionally characterized up to now. In this study, a rabbit antiserum was prepared against a bacterial fusion protein that permitted detection of the predicted type III membrane protein encoded by ORF81 of KHV. In Western blot analyses, the abundant ORF81 gene product of KHV exhibited an apparent mass of 26 kDa and appeared to be non-glycosylated. It could be localized in the cytoplasm of infected cells and in virion envelopes by indirect immunofluorescence and immunoelectron microscopy, respectively. The antiserum was also suitable for the detection of pORF81 in sections of gills, kidneys, hepatopancreas and skin of KHV-infected carp by immunohistochemistry.

Homologues of the UL7 gene of herpes simplex virus type 1 are conserved in alpha-, beta-, and gammaherpesviruses. However, little is known about their functions. Using a monospecific rabbit antiserum raised against a bacterial fusion protein, we identified the UL7 gene product of the neurotropic alphaherpesvirus pseudorabies virus (PrV). In Western blot analyses of infected cells and purified PrV particles the serum specifically detected a 29-kDa protein, which matches the calculated mass of the 266-amino-acid translation product of PrV UL7. For functional analysis, UL7 was deleted by mutagenesis of an infectious full-length clone of the PrV genome in Escherichia coli. The obtained recombinant PrV-⌬UL7F was replication competent in rabbit kidney cells, but maximum virus titers were decreased nearly 10-fold and plaque diameters were reduced by ca. 60% compared to wild-type PrV. Electron microscopy of infected cells revealed that in the absence of UL7, formation and nuclear egress of nucleocapsids were not affected, whereas secondary envelopment of cytoplasmic nucleocapsids appeared to be delayed and release of mature virions was less efficient. The observed replication defects were corrected by repair of the viral UL7 gene or by propagation of PrV-⌬UL7F in UL7-expressing cells. PrV-⌬UL7F was moderately attenuated in mice. Compared to wild-type virus, mean survival times were prolonged from 2 to 3 days after intranasal infection. However, neuroinvasion and transneuronal spread of PrV were not abolished in the absence of UL7. Thus, UL7 encodes a virion protein of PrV, which plays a role during virion maturation and egress both in vitro and in vivo.