Post-transcriptional splicing can occur in a slow-moving zone around the gene

Splicing is the stepwise molecular process by which introns are removed from pre-mRNA and exons are joined together to form mature mRNA sequences. The ordering and spatial distribution of these steps remain controversial, with opposing models suggesting splicing occurs either during or after transcription. We used single-molecule RNA FISH, expansion microscopy, and live-cell imaging to reveal the spatiotemporal distribution of nascent transcripts in mammalian cells. At super-resolution levels, we found that pre-mRNA formed clouds around the transcription site. These clouds indicate the existence of a transcription-site-proximal zone through which RNA move more slowly than in the nucleoplasm. Full-length pre-mRNA undergo continuous splicing as they move through this zone following transcription, suggesting a model in which splicing can occur post-transcriptionally but still within the proximity of the transcription site, thus seeming co-transcriptional by most assays. These results may unify conflicting reports of co-transcriptional versus post-transcriptional splicing.

CTCF/cohesin organize the ground state of chromatin-nuclear speckle association

The interchromatin space in the cell nucleus contains various membrane-less nuclear bodies. Recent findings indicate that nuclear speckles, comprising a distinct nuclear body, exhibit interactions with certain chromatin regions in a ground state. Key questions are how this ground state of chromatin-nuclear speckle association is established and what are the gene regulatory roles of this layer of nuclear organization. We report here that chromatin structural factors CTCF and cohesin are required for full ground state association between DNA and nuclear speckles. Disruption of ground state DNA-speckle contacts via either CTCF depletion or cohesin depletion had minor effects on basal level expression of speckle-associated genes, however we show strong negative effects on stimulus-dependent induction of speckle-associated genes. We identified a putative speckle targeting motif (STM) within cohesin subunit RAD21 and demonstrated that the STM is required for chromatin-nuclear speckle association. In contrast to reduction of CTCF or RAD21, depletion of the cohesin releasing factor WAPL stabilized cohesin on chromatin and DNA-speckle contacts, resulting in enhanced inducibility of speckle-associated genes. In addition, we observed disruption of chromatin-nuclear speckle association in patient derived cells with Cornelia de Lange syndrome (CdLS), a congenital neurodevelopmental diagnosis involving defective cohesin pathways, thus revealing nuclear speckles as an avenue for therapeutic inquiry. In summary, our findings reveal a mechanism to establish the ground organizational state of chromatin-speckle association, to promote gene inducibility, and with relevance to human disease.

Nuclear speckles regulate HIF-2α programs and correlate with patient survival in kidney cancer

Nuclear speckles are membrane-less bodies within the cell nucleus enriched in RNA biogenesis, processing, and export factors. In this study we investigated speckle phenotype variation in human cancer, finding a reproducible speckle signature, based on RNA expression of speckle-resident proteins, across >20 cancer types. Of these, clear cell renal cell carcinoma (ccRCC) exhibited a clear correlation between the presence of this speckle expression signature, imaging-based speckle phenotype, and clinical outcomes. ccRCC is typified by hyperactivation of the HIF-2α transcription factor, and we demonstrate here that HIF-2α drives physical association of a select subset of its target genes with nuclear speckles. Disruption of HIF-2α-driven speckle association via deletion of its speckle targeting motifs (STMs)-defined in this study-led to defective induction of speckle-associating HIF-2α target genes without impacting non-speckle-associating HIF-2α target genes. We further identify the RNA export complex, TREX, as being specifically altered in speckle signature, and knockdown of key TREX component, ALYREF, also compromises speckle-associated gene expression. By integrating tissue culture functional studies with tumor genomic and imaging analysis, we show that HIF-2α gene regulatory programs are impacted by specific manipulation of speckle phenotype and by abrogation of speckle targeting abilities of HIF-2α. These findings suggest that, in ccRCC, a key biological function of nuclear speckles is to modulate expression of a specific subset of HIF-2α-regulated target genes that, in turn, influence patient outcomes. We also identify STMs in other transcription factors, suggesting that DNA-speckle targeting may be a general mechanism of gene regulation.

TOX2 coordinates with TET2 to positively regulate central memory differentiation in human CAR T cells

Chimeric antigen receptor (CAR) T cell therapy is used in treating human hematological malignancies, but its efficacy is limited by T cell exhaustion (TEX). TEX arises at the expense of central memory T cells (TCM), which exhibit robust antitumor efficacy. Reduction of the TET2 gene led to increased TCM differentiation in a patient with leukemia who experienced a complete remission. We show that loss of TET2 led to increased chromatin accessibility at exhaustion regulators TOX and TOX2, plus increased expression of TOX2. Knockdown of TOX increased the percentage of TCM. However, unexpectedly, knockdown of TOX2 decreased TCM percentage and reduced proliferation. Consistently, a TCM gene signature was reduced in the TOX2 knockdown, and TOX2 bound to promoters of numerous TCM genes. Our results thus suggest a role for human TOX2, in contrast to exhaustion regulator TOX, as a potentiator of central memory differentiation of CAR T cells, with plausible utility in CAR T cell cancer therapy via modulated TOX2 expression.

Abstract 3602: Mechanisms of CAR T cell dysfunction and identification of transcription factors that drive the exhaustion phenotype

Chimeric antigen receptor (CAR) T cell immunotherapy is FDA approved for the treatment of a subset of B cell malignancies but has shown limited clinical success in solid tumor therapy. T cell exhaustion is an important factor involved in treatment failure, and can, in part, result from continuous stimulation of the CAR by tumor cells expressing the cognate antigen. To gain deeper understanding of CAR T cell exhaustion induced by chronic antigen exposure (CAE), we developed and validated a robust in vitro model, in which mesothelin-redirected CAR T cells (M5CAR) were continuously stimulated with mesothelin-expressing AsPC-1 pancreatic tumor cells such that tumor cells were never cleared, and we characterized these CAE CAR T cells by gene expression at population and single-cell levels, and by epigenetic analyses.

CAE M5CAR T cells recapitulate the hallmarks of T cell exhaustion, including reduced proliferation, down-modulation of surface CAR, decreased cytokine production, and reduced cytotoxicity. In addition, CAR T cells undergoing CAE have a transcriptional signature and an epigenetic landscape consistent with exhaustion. Further, transcriptomic analysis revealed that CAE M5CAR T cells undergo a transition from T cells to a post-thymic NK-like T cell phenotype. This plasticity was confirmed by TCR lineage tracing and was also detected in CD19 CAR T cells analyzed from post-infusion blood from DLBCL patients and in M5CAR T cells infiltrating relapsed tumors derived from a xenograft NSG/AsPC-1 mouse model. The dysfunctional signature and the NK phenotype were further detected in vivo by transcriptomic analysis in Ly95 TCR-specific TILs infiltrating NY-ESO-1 tumors. Among the genes included in the dysfunctional signature, the transcription factors SOX4 and ID3 were identified as potential regulators of dysfunction by differential gene expression and pathway analyses. To determine their role in the establishment of a dysfunctional phenotype, we generated ID3KO.M5 and SOX4KO.M5 CAR T cells using CRISPR technology in primary human lymphocytes. The cytotoxic potential of the M5 CAR T cell product generated was not modified by the genetic disruption of the transcription factors. However, when CAR T cells were challenged with chronic antigen stimulation, KO CAR T cells showed a significant reduction of the dysfunctional signature and the NK-like T cell gene expression. Importantly, CAE KO CAR T cells exhibit improved cytotoxicity as compared to Mock.M5CAR T cells.

In summary, we have developed a robust in vitro model that recapitulates the hallmarks of T cell exhaustion and that facilitated the identification of a gene signature defining CAR dysregulation, a T-to-NK-like-T cell transition as a novel feature of CAR T cell dysfunction and the transcription factors SOX4 and ID3 as key regulators of CAR T cell exhaustion.

Citation Format: M. Angela Aznar, Charly R. Good, Shunichiro Kuramitsu, Parisa Samareh, Sangya Agarwal, Greg Donahue, Kenichi Ishiyama, Nils Wellhausen, Austin K. Rennels, Yujie Ma, Lifeng Tian, Sonia Guedan, Katherine A. Alexander, Zhen Zhang, Philipp C. Rommel, Nathan Singh, Karl M. Glastad, Max W. Richardson, Keisuke Watanabe, Janos L. Tanyi, Mark H. O’Hara, Marco Ruella, Simon F. Lacey, Edmund K. Moon, Stephen J. Schuster, Steven M. Albelda, Lewis L. Lanier, Regina M. Young, Shelley L. Berger, Carl H. June. Mechanisms of CAR T cell dysfunction and identification of transcription factors that drive the exhaustion phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3602.

Reverse Transcriptase Inhibition Disrupts Repeat Element Life Cycle in Colorectal Cancer

Altered RNA expression of repetitive sequences and retrotransposition are frequently seen in colorectal cancer, implicating a functional importance of repeat activity in cancer progression. We show the nucleoside reverse transcriptase inhibitor 3TC targets activities of these repeat elements in colorectal cancer preclinical models with a preferential effect in p53-mutant cell lines linked with direct binding of p53 to repeat elements. We translate these findings to a human phase II trial of single-agent 3TC treatment in metastatic colorectal cancer with demonstration of clinical benefit in 9 of 32 patients. Analysis of 3TC effects on colorectal cancer tumorspheres demonstrates accumulation of immunogenic RNA:DNA hybrids linked with induction of interferon response genes and DNA damage response. Epigenetic and DNA-damaging agents induce repeat RNAs and have enhanced cytotoxicity with 3TC. These findings identify a vulnerability in colorectal cancer by targeting the viral mimicry of repeat elements.

SIGNIFICANCE

Colorectal cancers express abundant repeat elements that have a viral-like life cycle that can be therapeutically targeted with nucleoside reverse transcriptase inhibitors (NRTI) commonly used for viral diseases. NRTIs induce DNA damage and interferon response that provide a new anticancer therapeutic strategy. This article is highlighted in the In This Issue feature, p. 1397.

An NK-like CAR T cell transition in CAR T cell dysfunction

Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable success in hematological malignancies but remains ineffective in solid tumors, due in part to CAR T cell exhaustion in the solid tumor microenvironment. To study dysfunction of mesothelin-redirected CAR T cells in pancreatic cancer, we establish a robust model of continuous antigen exposure that recapitulates hallmark features of T cell exhaustion and discover, both in vitro and in CAR T cell patients, that CAR dysregulation is associated with a CD8+ T-to-NK-like T cell transition. Furthermore, we identify a gene signature defining CAR and TCR dysregulation and transcription factors, including SOX4 and ID3 as key regulators of CAR T cell exhaustion. Our findings shed light on the plasticity of human CAR T cells and demonstrate that genetic downmodulation of ID3 and SOX4 expression can improve the efficacy of CAR T cell therapy in solid tumors by preventing or delaying CAR T cell dysfunction.

Abstract 60: Induction of T cell dysfunction and NK-like T cell differentiation in vitro and in patients after CAR T cell treatment

Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable success in hematological malignancies but remains largely ineffective in solid tumors. A major factor leading to the reduced efficacy of CAR T cell therapy is T cell dysfunction, and the mechanisms mediating this dysfunction are under investigation. Here we establish a robust model to study dysfunction of mesothelin-redirected CAR T cells in pancreatic cancer. Continuous antigen exposure results in hallmark features of exhaustion including reduced proliferation capacity and cytotoxicity, and severe defects in cytokine production. Here we identified a transcriptional signature at both population and single-cell levels in CAR T cells after continuous antigen exposure. In addition, TCR lineage tracing revealed a CD8+ T-to-NK-like T cell plasticity that results in reduced tumor cell killing. The transcription factors SOX4 and ID3 are specifically expressed in the dysfunctional CAR NK-like T cells and are predicted to be master regulators of the dysfunction gene expression signature and the post-thymic acquisition of an NK-like T cell fate. Finally, we identified the emergence of NK-like CAR T cells in a subset of patients after infusion of CAR T cells. The findings gleaned from this study shed light on the plasticity of human CAR T cells and suggest new approaches to improve the efficacy of CAR T cell therapy in solid tumors by preventing or revitalizing CAR T cell dysfunction.

Citation Format: Charly R. Good, Shunichiro Kuramitsu, Parisa Samareh, Greg Donahue, Kenichi Ishiyama, Yujie Ma, Nils Wellhausen, Lifeng Tian, Sangya Agarwal, Sonia Guedan, M. Angela Aznar, Katherine A. Alexander, Zhen Zhang, Nathan Singh, Max W. Richardson, Keisuke Watanabe, Janos L. Tanyi, Mark H. O'Hara, Marco Ruella, Simon F. Lacey, Edmund K. Moon, Stephen J. Schuster, Steven M. Albelda, Lewis L. Lanier, Regina M. Young, Shelley L. Berger, Carl H. June. Induction of T cell dysfunction and NK-like T cell differentiation in vitro and in patients after CAR T cell treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 60.

Genetically engineered myeloid cells rebalance the core immune suppression program in metastasis

Metastasis is the leading cause of cancer-related deaths, and greater knowledge of the metastatic microenvironment is necessary to effectively target this process. Microenvironmental changes occur at distant sites prior to clinically detectable metastatic disease; however, the key niche regulatory signals during metastatic progression remain poorly characterized. Here, we identify a core immune suppression gene signature in pre-metastatic niche formation that is expressed predominantly by myeloid cells. We target this immune suppression program by utilizing genetically engineered myeloid cells (GEMys) to deliver IL-12 to modulate the metastatic microenvironment. Our data demonstrate that IL12-GEMy treatment reverses immune suppression in the pre-metastatic niche by activating antigen presentation and T cell activation, resulting in reduced metastatic and primary tumor burden and improved survival of tumor-bearing mice. We demonstrate that IL12-GEMys can functionally modulate the core program of immune suppression in the pre-metastatic niche to successfully rebalance the dysregulated metastatic microenvironment in cancer.

Dendritic Cell Paucity Leads to Dysfunctional Immune Surveillance in Pancreatic Cancer

Here, we utilized spontaneous models of pancreatic and lung cancer to examine how neoantigenicity shapes tumor immunity and progression. As expected, neoantigen expression during lung adenocarcinoma development leads to T cell-mediated immunity and disease restraint. By contrast, neoantigen expression in pancreatic ductal adenocarcinoma (PDAC) results in exacerbation of a fibro-inflammatory microenvironment that drives disease progression and metastasis. Pathogenic T_H17 responses are responsible for this neoantigen-induced tumor progression in PDAC. Underlying these divergent T cell responses in pancreas and lung cancer are differences in infiltrating conventional dendritic cells (cDCs). Overcoming cDC deficiency in early-stage PDAC leads to disease restraint, while restoration of cDC function in advanced PDAC restores tumor-restraining immunity and enhances responsiveness to radiation therapy.

TOX transcriptionally and epigenetically programs CD8+ T cell exhaustion

Exhausted CD8+ T (Tex) cells in chronic infections and cancer have limited effector function, high co-expression of inhibitory receptors and extensive transcriptional changes compared with effector (Teff) or memory (Tmem) CD8+ T cells. Tex cells are important clinical targets of checkpoint blockade and other immunotherapies. Epigenetically, Tex cells are a distinct immune subset, with a unique chromatin landscape compared with Teff and Tmem cells. However, the mechanisms that govern the transcriptional and epigenetic development of Tex cells remain unknown. Here we identify the HMG-box transcription factor TOX as a central regulator of Tex cells in mice. TOX is largely dispensable for the formation of Teff and Tmem cells, but it is critical for exhaustion: in the absence of TOX, Tex cells do not form. TOX is induced by calcineurin and NFAT2, and operates in a feed-forward loop in which it becomes calcineurin-independent and sustained in Tex cells. Robust expression of TOX therefore results in commitment to Tex cells by translating persistent stimulation into a distinct Tex cell transcriptional and epigenetic developmental program.

p63 establishes epithelial enhancers at critical craniofacial development genes

The transcription factor p63 is a key mediator of epidermal development. Point mutations in p63 in patients lead to developmental defects, including orofacial clefting. To date, knowledge on how pivotal the role of p63 is in human craniofacial development is limited. Using an inducible transdifferentiation model, combined with epigenomic sequencing and multicohort meta-analysis of genome-wide association studies data, we show that p63 establishes enhancers at craniofacial development genes to modulate their transcription. Disease-specific substitution mutation in the DNA binding domain or sterile alpha motif protein interaction domain of p63, respectively, eliminates or reduces establishment of these enhancers. We show that enhancers established by p63 are highly enriched for single-nucleotide polymorphisms associated with nonsyndromic cleft lip ± cleft palate (CL/P). These orthogonal approaches indicate a strong molecular link between p63 enhancer function and CL/P, illuminating molecular mechanisms underlying this developmental defect and revealing vital regulatory elements and new candidate causative genes.

Comparison of genotoxic versus nongenotoxic stabilization of p53 provides insight into parallel stress-responsive transcriptional networks

The tumor suppressor protein p53 is activated in response to diverse intrinsic and extrinsic cellular stresses and controls a broad cell-protective gene network. Whether p53:DNA binding and subsequent transcriptional activation differs downstream of these diverse intrinsic and extrinsic activators is controversial. Using primary human fibroblasts, we assessed the genome-wide profile of p53 binding, chromatin structure, and transcriptional dynamics after either genotoxic or nongenotoxic activation of p53. Activation of p53 by treatment with either etoposide or the small-molecule MDM2 inhibitor nutlin 3A yields strikingly similar genome-wide binding of p53 and concomitant changes to local chromatin modifications and structure. DNA damage, but not p53 activation per se, leads to increased expression of genes in an inflammatory cytokine pathway. The NF-κB pathway inhibitor Bay 11-7082 abrogates etoposide-mediated activation of the inflammation gene signature but does not affect expression of canonical p53 target genes. Our data demonstrate that differential activation of p53 within the same cell type leads to highly similar genome-wide binding, chromatin dynamics, and gene expression dynamics and that DNA damage-mediated signaling through NF-κB likely controls the observed pro-inflammatory cytokine gene expression pattern.

Urban blue: A global analysis of the factors shaping people's perceptions of the marine environment and ecological engineering in harbours

Marine harbours are the focus of a diverse range of activities and subject to multiple anthropogenically induced pressures. Support for environmental management options aimed at improving degraded harbours depends on understanding the factors which influence people's perceptions of harbour environments. We used an online survey, across 12 harbours, to assess sources of variation people's perceptions of harbour health and ecological engineering. We tested the hypotheses: 1) people living near impacted harbours would consider their environment to be more unhealthy and degraded, be more concerned about the environment and supportive of and willing to pay for ecological engineering relative to those living by less impacted harbours, and 2) people with greater connectedness to the harbour would be more concerned about and have greater perceived knowledge of the environment, and be more supportive of, knowledgeable about and willing to pay for ecological engineering, than those with less connectedness. Across twelve locations, the levels of degradation and modification by artificial structures were lower and the concern and knowledge about the environment and ecological engineering were greater in the six Australasian and American than the six European and Asian harbours surveyed. We found that people's perception of harbours as healthy or degraded, but not their concern for the environment, reflected the degree to which harbours were impacted. There was a positive relationship between the percentage of shoreline modified and the extent of support for and people's willingness to pay indirect costs for ecological engineering. At the individual level, measures of connectedness to the harbour environment were good predictors of concern for and perceived knowledge about the environment but not support for and perceived knowledge about ecological engineering. To make informed decisions, it is important that people are empowered with sufficient knowledge of the environmental issues facing their harbour and ecological engineering options.

Building blue infrastructure: Assessing the key environmental issues and priority areas for ecological engineering initiatives in Australia's metropolitan embayments

Ecological engineering principles are increasingly being applied to develop multifunctional artificial structures or rehabilitated habitats in coastal areas. Ecological engineering initiatives are primarily driven by marine scientists and coastal managers, but often the views of key user groups, which can strongly influence the success of projects, are not considered. We used an online survey and participatory mapping exercise to investigate differences in priority goals, sites and attitudes towards ecological engineering between marine scientists and coastal managers as compared to other stakeholders. The surveys were conducted across three Australian cities that varied in their level of urbanisation and environmental pressures. We tested the hypotheses that, relative to other stakeholders, marine scientists and coastal managers will: 1) be more supportive of ecological engineering; 2) be more likely to agree that enhancement of biodiversity and remediation of pollution are key priorities for ecological engineering; and 3) identify different priority areas and infrastructure or degraded habitats for ecological engineering. We also tested the hypothesis that 4) perceptions of ecological engineering would vary among locations, due to environmental and socio-economic differences. In all three harbours, marine scientists and coastal managers were more supportive of ecological engineering than other users. There was also greater support for ecological engineering in Sydney and Melbourne than Hobart. Most people identified transport infrastructure, in busy transport hubs (i.e. Circular Quay in Sydney, the Port in Melbourne and the Waterfront in Hobart) as priorities for ecological engineering, irrespective of their stakeholder group or location. There were, however, significant differences among locations in what people perceive as the key priorities for ecological engineering (i.e. biodiversity in Sydney and Melbourne vs. pollution in Hobart). Greater consideration of these location-specific differences is essential for effective management of artificial structures and rehabilitated habitats in urban embayments.

Disruption of TET2 promotes the therapeutic efficacy of CD19-targeted T cells

Cancer immunotherapy based on genetically redirecting T cells has been used successfully to treat B cell malignancies^1-3. In this strategy, the T cell genome is modified by integration of viral vectors or transposons encoding chimaeric antigen receptors (CARs) that direct tumour cell killing. However, this approach is often limited by the extent of expansion and persistence of CAR T cells^4,5. Here we report mechanistic insights from studies of a patient with chronic lymphocytic leukaemia treated with CAR T cells targeting the CD19 protein. Following infusion of CAR T cells, anti-tumour activity was evident in the peripheral blood, lymph nodes and bone marrow; this activity was accompanied by complete remission. Unexpectedly, at the peak of the response, 94% of CAR T cells originated from a single clone in which lentiviral vector-mediated insertion of the CAR transgene disrupted the methylcytosine dioxygenase TET2 gene. Further analysis revealed a hypomorphic mutation in this patient's second TET2 allele. TET2-disrupted CAR T cells exhibited an epigenetic profile consistent with altered T cell differentiation and, at the peak of expansion, displayed a central memory phenotype. Experimental knockdown of TET2 recapitulated the potency-enhancing effect of TET2 dysfunction in this patient's CAR T cells. These findings suggest that the progeny of a single CAR T cell induced leukaemia remission and that TET2 modification may be useful for improving immunotherapies.

The Transcriptional Repressive Activity of KRAB Zinc Finger Proteins Does Not Correlate with Their Ability to Recruit TRIM28

KRAB domain Zinc finger proteins are one of the most abundant families of transcriptional regulators in higher vertebrates. The prevailing view is that KRAB domain proteins function as potent transcriptional repressors by recruiting TRIM28 and promoting heterochromatin spreading. However, the extent to which all KRAB domain proteins are TRIM28-dependent transcriptional repressors is currently unclear. Our studies on mouse ZFP568 revealed that TRIM28 recruitment by KRAB domain proteins is not sufficient to warrant transcriptional repressive activity. By using luciferase reporter assays and yeast two-hybrid experiments, we tested the ability of ZFP568 and other mouse KRAB domain proteins to repress transcription and bind TRIM28. We found that some mouse KRAB domain proteins are poor transcriptional repressors despite their ability to recruit TRIM28, while others showed strong KRAB-dependent transcriptional repression, but no TRIM28 binding. Together, our results show that the transcriptional repressive activity of KRAB-ZNF proteins does not correlate with their ability to recruit TRIM28, and provide evidence that KRAB domains can regulate transcription in a TRIM28-independent fashion. Our findings challenge the current understanding of the molecular mechanisms used by KRAB domain proteins to control gene expression and highlight that a high percentage of KRAB domain proteins in the mouse genome differ from the consensus KRAB sequence at amino acid residues that are critical for TRIM28 binding and/or repressive activity.

TRIM28 Controls Genomic Imprinting through Distinct Mechanisms during and after Early Genome-wide Reprogramming

Genomic imprinting depends on the establishment and maintenance of DNA methylation at imprinting control regions. However, the mechanisms by which these heritable marks influence allele-specific expression are not fully understood. By analyzing maternal, zygotic, maternal-zygotic, and conditional Trim28 mutants, we found that the transcription factor TRIM28 controls genomic imprinting through distinct mechanisms at different developmental stages. During early genome-wide reprogramming, both maternal and zygotic TRIM28 are required for the maintenance of methylation at germline imprints. However, in conditional Trim28 mutants, Gtl2-imprinted gene expression was lost despite normal methylation levels at the germline IG-DMR. These results provide evidence that TRIM28 controls imprinting after early embryonic reprogramming through a mechanism other than the maintenance of germline imprints. Additionally, our finding that secondary imprints were hypomethylated in TRIM28 mutants uncovers a requirement of TRIM28 after genome-wide reprogramming for interpreting germline imprints and regulating DNA methylation at imprinted gene promoters.

Overcoming barriers in evaluating outbreaks of diarrheal disease in resource poor settings: assessment of recurrent outbreaks in Chobe District, Botswana

BACKGROUND

Diarrheal illness remains a leading cause of global morbidity and mortality, with the majority of deaths occurring in children <5 years of age. Lack of resources often prohibits the evaluation of outbreak characteristics and limits progress in managing this important disease syndrome, particularly in Africa. Relying only on existing medical staff and hospital resources, we assess the use of a questionnaire survey tool to identify baseline outbreak characteristics during recurrent diarrheal outbreaks in Chobe, Botswana.

METHODS

Using historical surveillance data (2006-2009), the temporal pattern of recurrent diarrheal outbreaks was evaluated among patients <5 years of age presenting to health facilities in Chobe District. Using a questionnaire survey tool, medical staff from selected health facilities assessed patients (all ages) presenting with diarrheal disease during two diarrheal outbreaks (2011-2012). Cluster analysis and classification and regression trees (CART) were used to evaluate patient attributes by outbreak.

RESULTS

We identified a bimodal, annual pattern of acute diarrhea in children <5 years of age across years (Wilcox test, W = 456.5, p = 0.052). Historical outbreak periods appeared to coincide with major hydrological phenomena (rainfall/flood recession). Across health facilities, a significant percent of patients in the prospective study were in the ≥5 age class (44%, n = 515 and 35%, n = 333 in the dry and wet season outbreaks, respectively). Cluster analysis of questionnaire data identified two main branches associated with patient age (<5 and ≥5 years of age). Patients did not cluster by outbreak or village. CART examination identified sex and hospitalization as being most predictive of patients <5 years and household diarrhea in patients ≥5 years. Water shortages and water quality deficiencies were identified in both outbreaks.

CONCLUSIONS

Diarrhea is a persistent, seasonally occurring disease in Chobe District, Botswana. Lack of variation in outbreak variables suggests the possibility of environmental drivers influencing outbreak dynamics and the potential importance of human-environmental linkages in this region. Public health strategy should be directed at securing improved water service and correcting water quality deficiencies. Public health education should include increased emphasis on sanitation practices when providing care to household members with diarrhea. While global diarrheal disease surveillance is directed at the under-5 age group, this may not be appropriate in areas of high HIV prevalence such as that found in our study area where a large immune-compromised population may warrant increased surveillance across age groups. The approach used in this study provided the first detailed characterization of diarrheal disease outbreaks in the area, an important starting point for immediate intervention and development of working hypotheses for future disease investigations. While data derived from this approach are necessarily limited, they identify critical information on outbreak characteristics in resource poor settings where data gaps continue and disease incidence is high.

Tracking pathogen transmission at the human-wildlife interface: banded mongoose and Escherichia coli

A primary challenge to managing emerging infectious disease is identifying pathways that allow pathogen transmission at the human-wildlife interface. Using Escherichia coli as a model organism, we evaluated fecal bacterial transmission between banded mongoose (Mungos mungo) and humans in northern Botswana. Fecal samples were collected from banded mongoose living in protected areas (n = 87, 3 troops) and surrounding villages (n = 92, 3 troops). Human fecal waste was collected from the same environment (n = 46). Isolates were evaluated for susceptibility to 10 antibiotics. Resistant E. coli isolates from mongoose were compared to human isolates using rep-PCR fingerprinting and MLST-PCR. Antimicrobial resistant isolates were identified in 57 % of the mongoose fecal samples tested (range 31-78% among troops). At least one individual mongoose fecal sample demonstrated resistance to each tested antibiotic, and multidrug resistance was highest in the protected areas (40.9%). E. coli isolated from mongoose and human sources in this study demonstrated an extremely high degree of genetic similarity on rep-PCR (AMOVA, F ST = 0.0027, p = 0.18) with a similar pattern identified on MLST-PCR. Human waste may be an important source of microbial exposure to wildlife. Evidence of high levels of antimicrobial resistance even within protected areas identifies an emerging health threat and highlights the need for improved waste management in these systems.

Activated human T cells express alternative mRNA transcripts encoding a secreted form of RANKL

Receptor activator of nuclear factor-kappaB -ligand (RANKL), encoded by the gene TNFSF11, is required for osteoclastogenesis, and its expression is upregulated in pathologic bone loss. Transcript variants of TNFSF11 mRNA have been described that encode a membrane-bound and a putative secreted form of RANKL. We identify a TNFSF11 transcript variant that extends the originally identified transcript encoding secreted RANKL. We demonstrate that this TNFSF11 transcript variant is expressed by the human osteosarcoma cell line, Saos-2, and by both primary human T cells and Jurkat T cells. Of relevance to the production of RANKL in pathologic bone loss, expression of this secreted TNFSF11 transcript is upregulated in Jurkat T cells and primary human T cells upon activation. Furthermore, this transcript can be translated and secreted in Jurkat T cells in vitro and is able to support osteoclast differentiation. Our data highlight the complexity of the TNFSF11 genomic locus and demonstrate the potential for the expression of alternate mRNA transcripts encoding membrane-bound and secreted forms of RANKL. Implications of alternate mRNA transcripts encoding different RANKL protein isoforms should be carefully considered and specifically examined in future studies, particularly those implicating RANKL in pathologic bone loss.

Leptospira interrogans at the human-wildlife interface in northern Botswana: a newly identified public health threat

Leptospirosis is the most widespread zoonosis in the world. In northern Botswana, humans live in close proximity to a diversity of wildlife and peridomestic rodents and may be exposed to a variety of zoonotic pathogens. Little is known regarding the occurrence and epidemiology of L. interrogans in Africa despite the recognized global importance of this zoonotic disease and the threat it poses to public health. In Botswana, banded mongooses (Mungos mungo) live in close proximity to humans across protected and unprotected landscapes and may be a useful sentinel species for assessing the occurrence of zoonotic organisms, such as L. interrogans. We utilized PCR to screen banded mongoose kidneys for leptospiral DNA and identified 41.5% prevalence of renal carriage of L. interrogans (exact binomial 95% CI 27.7-56.7%, n = 41). Renal carriage was also detected in one Selous' mongoose (Paracynictis selousi). This is the first published confirmation of carriage of L. interrogans in either species. This is also the first report of L. interrogans occurrence in northern Botswana and the only report of this organism in a wildlife host in the country. Pathogenic Leptospira are usually transmitted indirectly to humans through soil or water contaminated with infected urine. Other avenues, such as direct contact between humans and wildlife, as well as consumption of mongooses and other wildlife as bushmeat, may pose additional exposure risk and must be considered in public health management of this newly identified zoonotic disease threat. There is a critical need to characterize host species involvement and pathogen transmission dynamics, including human-wildlife interactions that may increase human exposure potential and infection risk. We recommend that public health strategy be modified to include sensitization of medical practitioners to the presence of L. interrogans in the region, the potential for human infection, and implementation of clinical screening. This study illustrates the need for increased focus on neglected zoonotic diseases as they present an important threat to public health.

The incidence of salmonellosis among dairy herds in the northeastern United States

The objectives of this study were to estimate the incidence of salmonellosis among a large sample of dairy herds in the northeastern United States (both at the animal level and the herd level), to describe the serotypes and antimicrobial resistance profiles of the positive samples, and to determine whether various herd-level factors were important predictors of incidence. Participating veterinarians enrolled 831 dairy herds and submitted fecal samples from 2,565 female dairy cattle for Salmonella culture because of suspicion of clinical disease. Estimates of animal-level incidence rates were calculated for each age group as the number of cases per animal time at risk, and an estimate of herd-level incidence rate was calculated as the number of positive herds per herd time at risk. Descriptive analysis of serotype data and level of antimicrobial resistance was performed, and Poisson regression analysis was used to study associations between the within-herd incidence of salmonellosis and certain predictor variables (herd size, housing type, vaccination status, and prior history of Salmonella infection). Salmonella was isolated from 576 (22.5%) samples representing 93 herds. The animal-level incidence rates for preweaned female calves, heifers, and adult cows were 8.1, 0.04, and 1.8 cases per 1,000 animal-years, respectively. The herd-level incidence rate was 8.6 positive herds per 100 herd-years. Salmonella Newport was the predominant serotype, accounting for 41% of the cases, followed by Salmonella Typhimurium. Over 68% of all isolates were resistant to 5 or more antimicrobial agents. Herd size was the only significant predictor of the incidence of salmonellosis in a multivariable model; herds with at least 400 female dairy cattle had a higher incidence rate than smaller herds. Our results shed light on the impact of salmonellosis on the dairy industry in the northeastern United States, and they help clarify the role of dairy cattle as a source of Salmonella serotypes that are also important human pathogens.

The duration of fecal Salmonella shedding following clinical disease among dairy cattle in the northeastern USA

The objectives of this study were to determine the duration of fecal Salmonella shedding among dairy cattle in the northeastern United States following laboratory-confirmed clinical disease and to evaluate whether age group or serotype was associated with either shedding period or mortality. Study farms included 22 dairy herds that had at least two previous salmonellosis cases confirmed by fecal culture. Veterinarians continued to submit culture samples from clinical suspects following herd enrollment, and fecal samples from positive cattle were collected monthly until three sequential negative results were obtained or until loss to follow-up. There were 357 culture-positive clinical cases that each involved a single serotype during the shedding period. The Kaplan-Meier median duration of fecal Salmonella shedding was 50 days, and the maximum was 391 days. S. Newport was the predominant serotype, accounting for 51% of the cases. Age group and serotype were not significant predictors of Salmonella shedding duration in a Cox proportional hazards model, when stratifying by herd. However, the proportion of adult cows shedding for at least two consecutive monthly samples was significantly greater than the proportion of female calves shedding for this duration (Fisher's exact test p-value<0.01). Age group was also associated with mortality in this study; calves with salmonellosis were more likely to die than cows as estimated by a logistic regression model which controlled for herd as a random effect (p-value=0.04).

Multi-host pathogens and carnivore management in southern Africa

A retrospective serosurvey of multi-host feline and canine viruses among carnivore species in southern Africa (n = 1018) identified widespread pathogen exposure even in remote protected areas. In contrast to mortality experienced in East African predators, canine distemper virus (CDV) infection among African wild dogs (Lycaon pictus) in Botswana was not associated with identifiable change in pup survivorship or disease related mortality of adults. A disease outbreak of unknown aetiology occurred in the same population over 4 weeks in 1996. Outbreak boundaries coincided with ecotones, not the spatial distribution of contiguous packs, highlighting the potential importance of landscape heterogeneities in these processes. Direct management of pathogens in domestic animal reservoirs is complicated by the apparent complexity of pathogen maintenance and transmission in these large systems. Conservation effort should be focused at securing large metapopulations able to compensate for expected episodic generalist pathogen invasion and attention directed to addressing underlying causes of population depression such as habitat loss and wildlife conflict.

Bacteremia, central catheters, and neonates: when to pull the line

OBJECTIVES

Physicians who treat neonates who become bacteremic while dependent on central venous catheters face a serious and common dilemma. We sought 1) to evaluate the relationship between central venous catheter removal and outcome in bacteremic neonates, 2) to determine species of bacteria that are associated with an increased risk of infectious complications if the central catheter is not removed promptly, and 3) to provide evidence-based recommendations for central catheter management.

METHOD

A retrospective cohort study of all neonates who had central venous access and developed bacteremia between July 1, 1995, and July 31, 1999, was conducted in the Duke University neonatal intensive care unit.

RESULTS

The outcome for patients in whom the central catheter was not removed within 24 hours of organism identification was significantly worse (odds ratio = 9.8) than it was for those whose catheters were removed promptly. For patients who were infected with Staphylococcus aureus or with nonenteric Gram-negative rods, delayed removal of the central catheter was associated with complicated bacteremia. Catheter sterilization was attempted in 27 neonates who were infected with enteric Gram-negative rods; only 10 of these infants retained their catheters without infection-related complications. Infants who had 4 consecutive blood cultures that were positive for coagulase-negative staphylococcus (CoNS) were at significantly increased risk for end-organ damage and death, compared with infants who had 3 or fewer positive blood culture for CoNS (odds ratio = 29.58).

CONCLUSIONS

Bacteremic infants experienced fewer infection-related complications when the central catheter was removed promptly. One positive blood culture for S aureus or a Gram-negative rod warrants central line removal in a neonate. Clinicians who are faced with a neonate who has 1 positive culture for CoNS may attempt medical management without central catheter removal, but documentation of subsequent negative blood cultures is crucial. Once a neonate has 3 positive blood cultures for CoNS, the central catheter should be removed.central line, neonate, bacteremia, bacteria, umbilical catheter, Broviac, percutaneous.

Recent advances in diagnosis and therapy of human papillomaviruses

Infection with human papillomavirus is extremely common throughout the world. Almost 50% of sexually active young women are infected with human papillomavirus and although most infections are transient, a subset has the potential to progress to invasive cancer. During the last 20 years, our understanding of the human papillomavirus life cycle and the role of human papillomavirus in human cancer has dramatically increased. Recent technological advances in human papillomavirus detection have provided the means to detect the presence of human papillomavirus with great sensitivity. In the context of patient care, there is still substantial debate regarding the optimal diagnostic and prognostic use of information derived from hybrid capture or polymerase chain reaction-based detection. The inventory of available treatment options is growing somewhat slowly. The most promising advances are being made in the clinical evaluation of candidates for prophylactic vaccination. This review is focused on the current status and future directions of prevention, diagnosis and therapy.

The E1 helicase of human papillomavirus type 11 binds to the origin of replication with low sequence specificity

Expression of the human papillomavirus type 11 E1 and E2 genes is necessary and sufficient to support viral DNA replication. The full-length E2 protein is a transcriptional modulator that also interacts with the E1 helicase to form an E1/E2 complex at the viral origin of replication. Previous studies indicated that efficient binding of this complex to the replication origin is site-specific and that the E2 homodimer was required for efficient E1 binding. Human papillomavirus type 11 E2 and E1 proteins have been purified and their cooperative binding to the HPV type 11 viral replication origin has been characterized. Low-affinity E1 binding to the HPV type 11 replication origin was demonstrated and found to be largely nonspecific. DNA binding by E1 does not require complex formation with E2 and appears to be independent of ATP binding or hydrolysis. E1 binding quantitatively increased with the addition of increasing amounts of E2 and mutations in the E2 binding site demonstrated that the E2BS site is required for E1 and E2 to specifically bind as a high-affinity complex at the replication origin. Analysis of the A/T-rich E1 binding site via mutation showed that it was nonessential for high-affinity E1/E2 complex formation. Thus, although the replication functions between the animal and the human papillomaviruses are well conserved, there are subtle differences in the DNA binding requirements for E1, which may portend mechanistic differences among the DNA replication systems of various papillomavirus types.

Subunit affinities and stoichiometries of the human papillomavirus type 11 E1:E2:DNA complex

The association between the papillomavirus E1 and E2 proteins is an important regulatory interaction, imparting coordinated control of viral transcription and replication. Using fluorescence polarization, we have characterized the interactions between HPV-11 E1, HPV-11 E2, and DNA in solution at equilibrium. For these studies, two double-stranded fluorescein-labeled oligonucleotides were prepared. The first fluorescent oligonucleotide, designated Fl-E2BS and containing a single E2 binding-site palindrome (ACCGN6CGGT), was used to determine the affinity of E2 for its DNA binding site. HPV-11 E2 bound Fl-E2BS with an apparent Kd of 0.84 nM. Binding was saturable and consistent with a single class of noninteracting sites. The second oligonucleotide, designated Fl-E1E2BS, contained both E1 and E2 sites in sequence derived directly from the HPV-11 origin of replication. Under titration conditions identical to those used for Fl-E2BS, the E2 protein exhibited reduced affinity for Fl-E1E2BS (Kd > 100 nM). E1 binding to Fl-E1E2BS was of very low affinity. Addition of excess HPV-11 E1 to Fl-E1E2BS lowered the dissociation constant for the E2:Fl-E1E2BS interaction to 2 nM. This effect was not dependent upon ATP or magnesium ion. Fluorescence polarization and other data suggest formation of a complex containing six E1 molecules and a single dimer of E2 bound to a single Fl-E1E2BS oligonucleotide; E2 dissociation from the final complex did not occur. In summary, physical interaction between E1 and E2 increases the DNA binding affinity of each. The role of this energy coupling may be to promote origin-specific binding of both E1 and E2 to DNA.

The MotA transcriptional activator of bacteriophage T4 binds to its specific DNA site as a monomer

During bacteriophage T4 middle mode gene expression, the MotA transcription factor binds to T4 middle promoters at a -30 mot box consensus sequence to allow activation. Previous binding studies showed that MotA forms multiple gel-shifted complexes with DNA, and structural evidence suggested that MotA dimerizes upon DNA binding. We have shown that a short (13 bp) mot box DNA substrate binds MotA protein but fails to form slower migrating complexes. Therefore, the slower migrating complexes in gel shift assays are caused by DNA-mediated binding events. Competition experiments indicate that the slower migrating complexes are formed by nonspecific binding events, while the first-shifted complex is caused by specific binding to the mot box. Saturation binding experiments revealed that the stoichiometry of MotA binding to DNA is 1:1 in the first-shifted complex, while the slower complexes apparently contain MotA multimers. Gel shift assays using mixtures of MotA and a GST-MotA fusion protein supported the conclusion that the first-shifted complex contains one protein molecule bound to DNA. Furthermore, MotA monomers were cross-linked by glutaraldehyde under conditions where slower complexes exist, but not under conditions that lead to only the first-shifted complex. We conclude that MotA binds specifically to the mot box as a monomer and that additional nonspecific binding events require flanking DNA.

Spontaneous rupture of a primigravid uterus secondary to placenta percreta. A case report

BACKGROUND

Uterine rupture secondary to placenta percreta has been observed in multiparous patients. These cases are typically associated with a prior history of uterine trauma or infection: hysterotomy, myomectomy, cornual resection, dilatation and curettage, manual removal of the placenta or endometritis. Spontaneous rupture of the primigravid uterus without a history of trauma or infection is an exceedingly rare occurrence. This case represents the second reported in the medical literature and the first to result in a live-born infant.

CASE

A 23-year-old, African American primigravida at 26 weeks' gestation presented with acute-onset abdominal pain, severe hypotension, tachycardia and fetal heart rate decelerations. Blood product replacement was initiated, and an emergency laparotomy was performed for a presumptive diagnosis of intraabdominal hemorrhage. A significant hemoperitoneum was encountered, with the fetus floating freely in the peritoneal cavity. The uterus had a fundal rupture with a clinically apparent placenta percreta that necessitated performing a total abdominal hysterectomy. The patient recovered uneventfully, and the infant survived without significant morbidity.

CONCLUSION

Spontaneous rupture of the primigravid uterus can occur in the absence of a history of uterine trauma or infection. If a gravid woman presents with hypotension, abdominal pain and fetal distress, the differential diagnosis should include rupture of the uterus, regardless of parity or gynecologic history. Rapid diagnosis, blood product replacement and emergency laparotomy are the key steps in successful management.

Rabies among African wild dogs (Lycaon pictus) in the Masai Mara, Kenya

A pack of African wild dogs (Lycaon pictus) ranging to the north of the Masai Mara National Reserve in southwestern Kenya was monitored from 1988 to 1989. During a 6-week period (August 1-September 13, 1989), 21 of 23 members of this pack died. Seven carcasses were retrieved, of which 4 were suitable for necropsy and histopathologic examination. Gross findings varied among individuals and included multiple bite wounds, synovitis, lymphadenopathy, submandibular, cervical, and vocal cord edema, blood in bronchi, bronchioles, stomach, and intestine, and interioventral lung lobe consolidation. Histologic examination of 2 available brain samples revealed nonsuppurative encephalitis with eosinophilic intracytoplasmic inclusions (Negri bodies). An additional brain sample tested positive for rabies via a fluorescent antibody test. Other histologic features included severe suppurative bronchopneumonia, myocarditis, and lymphoid depletion of the lymph nodes, tonsils, and spleen. A 304-base pair (bp) nucleotide sequence from the N gene and a 310-bp sequence from the G gene from rabies isolates of 4 wild dogs indicated that infection was with a rabies variant common among domestic dogs in Kenya and Tanzania.

A fluorescence anisotropy study of DNA binding by HPV-11 E2C protein: a hierarchy of E2-binding sites

Association of the human papillomavirus (HPV) E2 protein with its palindromic DNA-binding site is a necessary step for transcriptional trans-activation. To study the interaction between DNA and E2, the carboxyl-terminal domain of HPV-11 E2 protein (E2C) was expressed in Escherichia coli and purified to homogeneity. The binding affinity of the recombinant E2C protein for a single palindromic DNA recognition site was determined using a 5'-fluorescein-labeled 24 base pair oligonucleotide. Competitive titrations between the fluorescein-labeled oligonucleotide and an unlabeled oligonucleotide of identical sequence yielded a native affinity of 4.5 x 10(-9)M. Sequences from the seven E2-binding sites within the HPV-11 genome were titrated to establish a hierarchy of binding site affinities. All high-affinity E2-binding sites are located within or near the HPV-11 LCR. E2-binding sites distant from the LCR appear to have low affinity for E2. When the location and affinity of each E2-binding site are plotted in relation to a transcription map of HPV-11, it is apparent that the major RNA transcripts produced reflect the high-affinity E2-binding sites within the HPV LCR. To assess the E2C-binding contribution of specific base pairs within the oligonucleotide palindrome, additional double-stranded oligonucleotides were prepared in which the central nonpalindromic sequences were varied. While simple strand transposition of the A4.T4 center had a minimal effect upon the E2C-oligonucleotide binding affinity, replacement with TATA.ATAT or CGCG.GCGC centers substantially decreased the affinity of E2C for its binding site. Alteration of the canonical portions of the E2-binding palindrome reduced the DNA-protein binding affinity dramatically.

Rabies and African wild dogs in Kenya

Three packs of African wild dogs (Lycaon pictus) ranging to the north of the Masai Mara National Reserve in southwestern Kenya were monitored from 1988 to 1990. During a six week period (August 2-September 14, 1989), 21 of 23 members of one of these packs died. Histological examination of two brain samples revealed eosinophilic intracytoplasmic inclusions (Negri bodies), supporting a diagnosis of rabies viral encephalitis. An additional brain sample tested positive for rabies with a fluorescent antibody test. Nucleotide sequence of the rabies viral N and G genes from isolates of four African wild dogs (including an individual from Tanzania) indicated that infection was with a viral variant common among domestic dogs in Kenya and Tanzania. A hypothesis linking African wild dog rabies deaths to researcher handling is evaluated and considered implausible.

African horse sickness and African carnivores

African horse sickness (AHS) is a disease that affects equids, and is principally transmitted by Culicoides spp. that are biological vectors of AHS viruses (AHSV). The repeated spread of AHSV from sub-Saharan Africa to the Middle East, northern Africa and the Iberian peninsula indicate that a better understanding of AHS epizootiology is needed. African horse sickness has long been known to infect and cause mortality among domestic dogs that ingest virus contaminated meat, but it is uncertain what role carnivores play in transmission of the virus. We present evidence of widespread natural AHS infection among a diversity of African carnivore species. We hypothesize that such infection resulted from ingestion of meat and organs from AHS-infected prey species. The effect of AHS on the carnivores is unknown, as is their role in the maintenance cycle of the disease.

Antiviral therapy for human papillomaviruses: rational and prospects

OBJECTIVE

To review the basic virology of human papillomavirus (HPV) and the natural history of HPV infection and to discuss current and potential therapies.

DATA SOURCES

The MEDLINE database (1966 to 1994) was searched to identify English-language articles and abstracts on HPV biology and antiviral chemotherapy.

STUDY SELECTION

Peer-reviewed basic science and clinical research studies on the molecular, cellular, and human biology of HPV infection.

DATA EXTRACTION

Summaries of data from research studies on the biology of papillomavirus infection and information from review articles on the basic and applied pharmacology of antiviral agents.

DATA SYNTHESIS

Papillomavirus infections are very common. Human papillomavirus infections may be asymptomatic or may be manifested in various benign or malignant lesions, most notably anogenital condyloma and anogenital carcinoma. Currently, therapeutic options for HPV infection are limited, expensive, and often ineffective. By understanding the basic virology and natural history of HPV infection, potential sites for pharmacologic intervention can be identified. Although currently available antiviral compounds are inactive against HPV, they serve as models for the rational design of HPV antiviral drugs.

CONCLUSIONS

Although HPV infection causes substantial morbidity and expense, uniformly effective therapy for HPV infection is not currently available. Several processes in the HPV infection cycle are appropriate targets for the development of antiviral agents. The development of compounds active against HPV could prevent the benign and malignant diseases associated with HPV infection.

Evidence of natural bluetongue virus infection among African carnivores

Bluetongue is an International Office of Epizootics List A disease described as the century's most economically devastating affliction of sheep. Bluetongue (BLU) viruses were thought to infect only ruminants, shrews, and some rodents, but recently, inadvertent administration of BLU virus-contaminated vaccine resulted in mortality and abortion among domestic dogs. We present evidence of natural BLU virus infection among African carnivores that dramatically widens the spectrum of susceptible hosts. We hypothesize that such infection occurred after ingestion of meat and organs from BLU virus-infected prey species. The effect of BLU virus on endangered carnivores such as the cheetah and African wild dog requires urgent investigation. Also, the role of carnivores in the epizootiology of this disease needs elucidation.

African wild dogs (Lycaon pictus) endangered by a canine distemper epizootic among domestic dogs near the Masai Mara National Reserve, Kenya

A longitudinal study of canine distemper (CD) among domestic dogs on Malsai communal land to the north of the Masai Mara National Reserve in Kenya was conducted from 1989 to 1991. Prevalence of antibodies to CD was very low among domestic dogs in 1989 and 1990 (4%, n = 49; and 1%, n = 119, respectively) and no African wild dogs (Lycaon pictus; n = 16) collected simultaneously from the same area had detectable antibodies. Among 51 domestic dogs sampled in 1991, however, prevalence of CD antibodies rose significantly (P < 0.01) to 76%. Disease-related mortality rates among domestic dogs were estimated from 1990 to 1992; they rose significantly (P < 0.01) from 21% in 1990 to 50% in 1991 and then decreased significantly (P < 0.01) to 38% in 1992. The 1992 mortality rate remained significantly (P < 0.01) higher than that of 1990. Signs observed in clinically ill domestic dogs were consistent with CD and included listlessness, decreased appetite, bilateral serous to mucopurulent oculonasal discharge, and diarrhea. No carcasses could be retrieved for virus isolation and postmortem examination. Concurrent with this CD epizootic in domestic dogs, the known African wild dog packs in this region disappeared.

Serologic survey of selected canine pathogens among free-ranging jackals in Kenya

Serum samples from 76 free-ranging adult jackals of three species from four localities in Kenya were examined for circulating antibodies against four canine pathogens: rabies virus, canine parvovirus (CPV-2), canine distemper virus (CDV), and Ehrlichia canis. Samples were collected between April 1987 and January 1988. Among black-backed jackals (Canis mesomelas), the most sampled species, the mean prevalence of antibodies to CPV-2, CDV, rabies virus, and E. canis was 34% (14 positive/55 sampled), 9% (4/55), 3% (1/28), and 2% (1/36), respectively. There were no significantly differences among sampling locations. In one area, antibody prevalence of CPV-2 was significantly higher for golden jackals (C. aureus; 9/16) than for C. mesomelas (5/26). Only three side-striped jackals (C. adustus) were sampled, but antibodies to CPV-2 and CDV were present. As jackals often are the most abundant wild carnivore in African ecosystems, they could serve as an important indicator species to monitor the potential of exposure of rare and endangered canids to specific canine diseases.

Rabies in the Masai Mara, Kenya: preliminary report

A serosurvey of rabies antibodies among domestic dogs (Canis familiaris, n = 178), spotted hyaenas (Crocuta crocuta, n = 72) and African wild dogs (Lycaon pictus, n = 18) of the Masai Mara, Kenya, was carried out. Rabies antibodies were found in 9.6% of the domestic dog sera, but all wild dog and hyaena sera were negative. Rabies has been confirmed in this region among the above species as well as in a domestic cat (Felis catus) and a cow (Bos indicus) by fluorescent antibody tests (FAT) and/or histopathology. The disease was confirmed in three wild dogs in 1989 and in a fourth dog in early 1991. In 1992, a spotted hyaena attacked six people, one of whom died; the hyaena brain was positive for rabies. To date, rabies has been confirmed in one domestic cow (n = 22; 4.5%), one domestic cat (n = 9; 11.1%) and five domestic dogs (n = 32; 15.6%). The wild dog cases exhibited paralytic rabies whereas in the hyaena, domestic cat and domestic dogs furious rabies was observed. The dynamics of rabies in this ecosystem is not yet fully understood, but based on these preliminary data it is suspected that domestic dogs play a primary role in its maintenance.

Characterization of the calmodulin binding domain of neuromodulin. Functional significance of serine 41 and phenylalanine 42

Neuromodulin (also designated P-57, GAP-43, B-50) is a major presynaptic substrate for protein kinase C. Phosphorylation of neuromodulin decreases its affinity for calmodulin, suggesting that neuromodulin may function to bind and concentrate calmodulin at specific sites within neurons, releasing calmodulin locally in response to phosphorylation by protein kinase C (Alexander, K. A., Cimler, B. M., Meier, K. E., and Storm, D. R. (1987) J. Biol. Chem. 262, 6108-6113). In the present study, we have constructed and characterized several mutant neuromodulins to demonstrate that the amino acid sequence 39-56 is required for calmodulin binding, and that this domain contains the sole in vitro protein kinase C phosphorylation site at serine 41. We also demonstrate that the adjacent phenylalanine 42, interacts hydrophobically with calmodulin. These hydrophobic interactions may be disrupted by the introduction of negative charge at serine 41, and thereby regulate the neuromodulin/calmodulin binding interactions. The sensitivity of the neuromodulin/calmodulin binding interaction to negative charge at serine 41 was determined by substitution of serine 41 with an aspartate or an asparagine residue. The asparagine mutant retained its affinity for calmodulin-Sepharose while the aspartate mutant did not adsorb to calmodulin-Sepharose. We conclude that protein kinase C phosphorylation of neuromodulin abolishes calmodulin binding by introducing negative charges within the calmodulin binding domain at a position adjacent to the phenylalanine.

A program evaluation of a sick child day-care facility

This survey examined the characteristics of families who used a sick child day-care center and the variables that determined their use in comparison with families who did not use such a facility. Families who used sick child day-care had more favorable attitudes toward the facility and a greater need for these services.

Identification and characterization of the calmodulin-binding domain of neuromodulin, a neurospecific calmodulin-binding protein

Neuromodulin (formerly designated P-57) is an abundant, neural specific, calmodulin-binding protein which exhibits higher affinity for calmodulin in the absence of free Ca2+ than in the presence of free Ca2+. In this study a series of proteolytic fragments of neuromodulin were systematically screened for calmodulin-Sepharose binding activity. A 9-amino acid fragment, designated M1-C1 and having the sequence RGHITRKKL, was identified as the putative CaM-binding domain of neuromodulin. Two heptadecapeptides, designated FP57-Phe and FP57-Trp, were synthesized, each containing the M1-C1 sequence and the four flanking amino acids from each site. The FP57-Trp peptide contained a tryptophan residue in place of the native phenylalanine. Anti-FP57-Phe antibody binding to neuromodulin was inhibited by preincubation of antibodies with excess FP57-Phe. 125I-CaM gel overlay of neuromodulin was inhibited by anti-FP57-Phe antibodies. Addition of CaM to FP57-Trp increased peptide tryptophanyl fluorescence. In the presence of Ca2+, the stoichiometry of the FP57-Trp.CaM complex was 1:1, FP57-Trp binding to CaM was competitive with neuromodulin. The Ca2+-independent dissociation constant of the FP57-Phe.CaM complex was 0.41 microM. The Ca2+-dependent affinity of the complex could not be measured directly but appeared to be significantly greater than the Ca2+-independent affinity.

Amino acid sequence of P-57, a neurospecific calmodulin-binding protein

The amino acid sequence was determined for bovine brain P-57, a neurospecific, membrane-associated, calmodulin-binding protein. It consists of a single 239-residue polypeptide chain blocked at its amino terminus and containing an unusually hydrophilic amino acid composition. Seventy percent of the molecule is composed of Glu/Gln, Ala, Lys, Asp/Asn, and Pro; there is only one aromatic residue. A lack of favorable cleavage sites required that a particularly wide variety of digests and subdigests be performed to obtain appropriate sets of overlapping peptides. This protein is clearly homologous with the cDNA-derived sequence of mouse brain P-57, although the bovine protein is 12 amino acid residues longer; the homology is less obvious in the middle sections of the two sequences. Bovine brain P-57 lacks homology with any other protein in an updated sequence database. A segment reported to interact with calmodulin (Arg-Gly-His-Ile-Thr-Arg-Lys-Lys-Leu) is placed at residues 43-51 within the only extended segment of P-57 that carries the net positive charge that would favor that interaction. There is no hydrophobic segment characteristic of many proteins that interact with membranes.