The molecular basis of malignant catarrhal fever

Alcelaphine herpesvirus-1 (A1HV-1) is gammaherpesvirus that can cause the devastating, fatal disease malignant catarrhal fever (MCF) in susceptible ruminant hosts but not in its natural host the blue wildebeest. Despite its scientific and economic importance little is known about the underlying molecular basis of MCF pathogenesis. The purpose of this study is to characterise four unique open reading frames (ORFs) of A1HV-1 and examine their contribution to viral pathogenesis. These ORFs are located at the left hand end of the genome, a region known to contain unique transforming and immunomodulatory genes in other gammaherpesviruses, and are predicted to encode two small gene products with no significant homology to any known proteins (ORF A1 and ORF A4), a transcription factor (ORF A2) and a member of the semaphorin family (ORF A3).A 6.2 Kb fragment from A1F1V-1 containing all four ORFs under their natural promoters was cloned into the left hand end region of murine gammaherpesvirus-76 (MHV-76). This allowed for the study of the in vivo contribution to pathogenesis of the gene products in a well characterised small animal model. The recombinant virus showed no difference in its ability to replicate in vitro. Viral titres and lung pathology in infected mice were also comparable although the A1HV-1 gene transcripts were detectable.The ORF A2 gene product expressed as a recombinant fusion protein in mammalian cells consistently showed nuclear localisation, supporting the prediction that this protein functions as a transcription factor. However, attempts to conclusively demonstrate transcriptional activity of this protein were unsuccessful

Improved synchronous production of Plasmodium falciparum gametocytes in vitro.

The sexual stages of the Plasmodium falciparum life cycle are attractive targets for vaccines and transmission blocking drugs. Difficulties in culturing and obtaining large amounts of sexual stage P. falciparum parasites, particularly early stages, have often limited research progress in this area. We present a new protocol which simplifies the process of stimulating gametocytogenesis leading to improved synchronous gametocyte production. This new method can be adapted to enrich for early stage gametocytes (I and II) with a higher degree of purity than has previously been achieved, using MACS magnetic affinity columns. The protocol described lends itself to large scale culturing and harvesting of synchronous parasites suitable for biochemical assays, northern blots, flow cytometry, microarrays and proteomic analysis

Continuous control of autoimmune disease by antigen-dependent polyclonal CD4+CD25+ regulatory T cells in the regional lymph node

This study investigated the unresolved issue of antigen-dependency and antigen-specificity of autoimmune disease suppression by CD4+CD25+ T cells (T regs). Based on autoimmune ovarian disease (AOD) in day 3 thymectomized (d3tx) mice and polyclonal T regs expressing the Thy1.1 marker, we determined: (a) the location of recipient T cell suppression, (b) the distribution of AOD-suppressing T regs, and (c) the relative efficacy of male versus female T regs. Expansion of recipient CD4+ T cells, activation/memory marker expression, and IFN-γ production were inhibited persistently in the ovary-draining LNs but not elsewhere. The cellular changes were reversed upon Thy1.1+ T reg depletion, with emergence of potent pathogenic T cells and severe AOD. Similar changes were detected in the regional LNs during autoimmune dacryoadenitis and autoimmune prostatitis suppression. Although the infused Thy1.1+ T regs proliferated and were disseminated in peripheral lymphoid organs, only those retrieved from ovary-draining LNs adoptively suppressed AOD at a suboptimal cell dose. By depriving d3tx recipients of ovarian antigens, we unmasked the supremacy of ovarian antigen-exposed female over male T regs in AOD suppression. Thus, disease suppression by polyclonal T regs depends on endogenous antigen stimulation; this occurs in a location where potent antigen-specific T regs accumulate and continuously negate pathogenic T cell response

Evolution of CD8(+) T Cell Responses after Acute PARV4 Infection

PARV4 is a small DNA human virus that is strongly associated with hepatitis C virus (HCV) and HIV infections. The immunologic control of acute PARV4 infection has not been previously described. We define the acute onset of PARV4 infection and the characteristics of the acute-phase and memory immune responses to PARV4 in a group of HCV- and HIV-negative, active intravenous drug users. Ninety-eight individuals at risk of blood-borne infections were tested for PARV4 IgG. Gamma interferon enzyme-linked immunosorbent spot assays, intracellular cytokine staining, and a tetrameric HLA-A2-peptide complex were used to define the T cell populations responding to PARV4 peptides in those individuals who acquired infection during the study. Thirty-five individuals were found to be PARV4 seropositive at the end of the study, eight of whose baseline samples were found to be seronegative. Persistent and functional T cell responses were detected in the acute infection phase. These responses had an active, mature, and cytotoxic phenotype and were maintained several years after infection. Thus, PARV4 infection is common in individuals exposed to blood-borne infections, independent of their HCV or HIV status. Since PARV4 elicits strong, broad, and persistent T cell responses, understanding of the processes responsible may prove useful for future vaccine design

Peripheral primitive neuroectodermal tumour - A rare cause of a popliteal fossa mass: A case report and review of the literature

A literature review of peripheral primitive neuroectodermal tumours, illustrated with an index case report describing an 80-year-old woman who presented with a mass in the left popliteal fossa, is reported. An excision biopsy was performed, revealing a possible peripheral primitive neuroectodermal tumour as the primary pathology. Normally confined to the chest wall and axial soft tissues of children and young adults, reports of this tumour existing in other areas and in the elderly population are scarce

Targeted killing of Pseudomonas aeruginosa by pyocin G occurs via the hemin transporter hur

Pseudomonas aeruginosa is a priority pathogen for the development of new antibiotics, particularly because multi-drug-resistant strains of this bacterium cause serious nosocomial infections and are the leading cause of death in cystic fibrosis patients. Pyocins, bacteriocins of P. aeruginosa, are potent and diverse protein antibiotics that are deployed during bacterial competition. Pyocins are produced by more than 90% of P. aeruginosa strains and may have utility as last resort antibiotics against this bacterium. In this study, we explore the antimicrobial activity of a newly discovered pyocin called pyocin G (PyoG). We demonstrate that PyoG has broad killing activity against a collection of clinical P. aeruginosa isolates and is active in a Galleria mellonella infection model. We go on to identify cell envelope proteins that are necessary for the import of PyoG and its killing activity. PyoG recognizes bacterial cells by binding to Hur, an outer-membrane TonB-dependent transporter. Both pyocin and Hur interact with TonB1, which in complex with ExbB-ExbD links the proton motive force generated across the inner membrane with energy-dependent pyocin translocation across the outer membrane. Inner-membrane translocation of PyoG is dependent on the conserved inner-membrane AAA+ ATPase/protease, FtsH. We also report a functional exploration of the PyoG receptor. We demonstrate that Hur can bind to hemin in vitro and that this interaction is blocked by PyoG, confirming the role of Hur in hemin acquisition