Di-, tri- and tetra-5'-O-phosphorothioadenosyl substituted polyols as inhibitors of Fhit: Importance of the α-β bridging oxygen and β phosphorus replacement

BACKGROUND: The human FHIT gene is inactivated early in the development of many human cancers and loss of Fhit in mouse predisposes to cancer while reintroduction of FHIT suppresses tumor formation via induction of apoptosis. Fhit protein, a diadenosine polyphosphate hydrolase, does not require hydrolase activity to function in tumor suppression and may signal for apoptosis as an enzyme-substrate complex. Thus, high affinity nonhydrolyzable substrate analogs may either promote or antagonize Fhit function, depending on their features, in Fhit + cells. Previously synthesized analogs with phosphorothioadenosyl substitutions and "supercharged" branches do not bind better than natural substrates and thus have limited potential as cellular probes. RESULTS: Here we link adenosine 5'-O-phosphates and phosphorothioates to short-chain polyols to generate a series of substrate analogs. We obtain structure-activity data in the form of in vitro Fhit inhibition for four types of analog substitutions and describe two compounds, inhibitory constants for which are 65 and 75-fold lower than natural substrates. CONCLUSIONS: The best Fhit inhibitors obtained to date separate two or more 5'-O-phosphoromonothioadenosyl moieties with as many bond lengths as in AppppA, maintain oxygen at the location of the α-β bridging oxygen, and replace carbon for the β phosphorus

Criteria to define interruption of transmission of human cytomegalovirus from organ donor to recipient

In this review article, we consider results suggesting that transmission of human cytomegalovirus (HCMV) from a donor of a solid organ to an immunologically naive individual can be reduced. Two randomized controlled trials have been conducted recently, one of active immunization of recipients pretransplant and another of passive immunization with monoclonal antibodies specific for HCMV given at the time of transplant. Although the available data are encouraging—providing evidence of a reduction in the incidence of HCMV viraemia—they fall short of what would be required to prove definitively that transmission has been completely prevented. Here, we reflect on these studies and propose a set of 5 criteria, which, if satisfied in the future, could be taken as proof that active and/or passive immunization against HCMV effectively interrupts transmission of virus from the donor. We suggest that these criteria are considered when designing future randomized controlled trials

Epitope-specific humoral responses to human cytomegalovirus glycoprotein-B vaccine with MF59 adjuvant in seropositive solid organ transplant recipients: anti-AD2 levels correlate with protection from viraemia

The human cytomegalovirus (HCMV) virion envelope protein glycoprotein B (gB) is essential for viral entry and represents a major target for humoral responses following infection. Previously, a phase-2 placebo-controlled clinical trial conducted in solid organ transplant candidates demonstrated that vaccination with gB plus MF59 adjuvant significantly increased gB ELISA antibody levels whose titer correlated directly with protection against post-transplant viremia. The aim of the current study was to investigate in more detail this protective humoral response in vaccinated seropositive transplant recipients. We focussed on four key antigenic domains (AD) of gB; AD1, AD2, AD4 and AD5 measuring antibody levels in patient sera and correlating these with post-transplant HCMV viremia. Vaccination of seropositive patients significantly boosted pre-existing antibody levels against the immunodominant region AD1 as well as against AD2, AD4 and AD5. A decreased incidence of viremia correlated with higher antibody titers against AD2 but not with antibody titers against the other three ADs. Overall, these data support the hypothesis that antibodies against AD2 are a major component of the immune protection of seropositives seen following vaccination with gB/MF59 vaccine and identify a correlate of protective immunity in allograft patients

A temperature dependent virus binding assay reveals the presence of neutralising antibodies in human cytomegalovirus gB vaccine recipients’ sera

Human cytomegalovirus (HCMV) remains an important cause of mortality in immune-compromised transplant patients and following congenital infection. Such is the burden, an effective vaccine strategy is considered to be of the highest priority. The most successful vaccines to date have focused on generating immune responses against glycoprotein B (gB) – a protein essential for HCMV fusion and entry. We have previously reported that an important component of the humoral immune response elicited by gB/MF59 vaccination of patients awaiting transplant is the induction of non-neutralizing antibodies that target cell-associated virus with little evidence of concomitant classical neutralizing antibodies. Here we report that a modified neutralization assay that promotes prolonged binding of HCMV to the cell surface reveals the presence of neutralizing antibodies in sera taken from gB-vaccinated patients that cannot be detected using standard assays. We go on to show that this is not a general feature of gB-neutralizing antibodies, suggesting that specific antibody responses induced by vaccination could be important. Although we can find no evidence that these neutralizing antibody responses are a correlate of protection in vivo in transplant recipients their identification demonstrates the utility of the approach in identifying these responses. We hypothesize that further characterization has the potential to aid the identification of functions within gB that are important during the entry process and could potentially improve future vaccine strategies directed against gB if they prove to be effective against HCMV at higher concentrations

Foreign-Body Reaction Mimicking Postneurosurgical Infection After Cranioplasty

The case of a 57-year-old woman who suffered a fall is presented. After a polymethyl malacrylate revision cranioplasty, she presented with signs, symptoms, and intraoperative findings consistent with postneurosurgical infection. Dural foreign-body reaction was diagnosed, and parenteral antibiotic therapy was discontinued successfully

Seronegative patients vaccinated with cytomegalovirus gB-MF59 vaccine have evidence of neutralising antibody responses against gB early post-transplantation

Background Human cytomegalovirus (HCMV) causes a ubiquitous infection which can pose a significant threat for immunocompromised individuals, such as those undergoing solid organ transplant (SOT). Arguably, the most successful vaccine studied to date is the recombinant glycoprotein-B (gB) with MF59 adjuvant which, in 3 Phase II trials, demonstrated 43–50% efficacy in preventing HCMV acquisition in seronegative healthy women or adolescents and reduction in virological parameters after SOT. However, the mechanism of vaccine protection in seronegative recipients remains undefined. Methods We evaluated samples from the cohort of seronegative SOT patients enroled in the Phase II glycoprotein-B/MF59 vaccine trial who received organs from seropositive donors. Samples after SOT (0–90 days) were tested by real-time quantitative PCR for HCMV DNA. Anti-gB antibody levels were measured by ELISA. Neutralization was measured as a decrease in infectivity for fibroblast cell cultures revealed by expression of immediate-early antigens. Findings Serological analyses revealed a more rapid increase in the humoral response against gB post transplant in vaccine recipients than in those randomised to receive placebo. Importantly, a number of patient sera displayed HCMV neutralising responses – neutralisation which was abrogated by pre-absorbing the sera with recombinant gB. Interpretation We hypothesise that the vaccine primed the immune system of seronegative recipients which, when further challenged with virus at time of transplant, allowed the host to mount rapid immunological humoral responses even under conditions of T cell immune suppression during transplantation

Distribution of graph-distances in Boltzmann ensembles of RNA secondary structures

Large RNA molecules often carry multiple functional domains whose spatial arrangement is an important determinant of their function. Pre-mRNA splicing, furthermore, relies on the spatial proximity of the splice junctions that can be separated by very long introns. Similar effects appear in the processing of RNA virus genomes. Albeit a crude measure, the distribution of spatial distances in thermodynamic equilibrium therefore provides useful information on the overall shape of the molecule can provide insights into the interplay of its functional domains. Spatial distance can be approximated by the graph-distance in RNA secondary structure. We show here that the equilibrium distribution of graph-distances between arbitrary nucleotides can be computed in polynomial time by means of dynamic programming. A naive implementation would yield recursions with a very high time complexity of O(n^11). Although we were able to reduce this to O(n^6) for many practical applications a further reduction seems difficult. We conclude, therefore, that sampling approaches, which are much easier to implement, are also theoretically favorable for most real-life applications, in particular since these primarily concern long-range interactions in very large RNA molecules.Comment: Peer-reviewed and presented as part of the 13th Workshop on Algorithms in Bioinformatics (WABI2013

Dunning rat prostate adenocarcinomas and alternative splicing reporters: powerful tools to study epithelial plasticity in prostate tumors in vivo

Using alternative splicing reporters we have previously observed mesenchymal epithelial transitions in Dunning AT3 rat prostate tumors. We demonstrate here that the Dunning DT and AT3 cells, which express epithelial and mesenchymal markers, respectively, represent an excellent model to study epithelial transitions since these cells recapitulate gene expression profiles observed during human prostate cancer progression. In this manuscript we also present the development of two new tools to study the epithelial transitions by imaging alternative splicing decisions: a bichromatic fluorescence reporter to evaluate epithelial transitions in culture and in vivo, and a luciferase reporter to visualize the distribution of mesenchymal epithelial transitions in vivo

Fox-1 family of RNA-binding proteins

The Fox-1 family of RNA-binding proteins are evolutionarily conserved regulators of tissue-specific alternative splicing in metazoans. The Fox-1 family specifically recognizes the (U)GCAUG stretch in regulated exons or in flanking introns, and either promotes or represses target exons. Recent unbiased bioinformatics analyses of alternatively spliced exons and comparison of various vertebrate genomes identified the (U)GCAUG stretch as a highly conserved and widely distributed element enriched in intronic regions surrounding exons with altered inclusion in muscle, heart, and brain, consistent with specific expression of Fox-1 and Fox-2 in these tissues. Global identification of Fox-2 target RNAs in living cells revealed that many of the Fox-2 target genes themselves encode splicing regulators. Further systematic elucidation of target genes of the Fox-1 family and other splicing regulators in various tissues will lead to a comprehensive understanding of splicing regulatory networks