Neutralizing Monoclonal Antibodies Block Human Immunodeficiency Virus Type 1 Infection of Dendritic Cells and Transmission to T Cells

Prevention of the initial infection of mucosal dendritic cells (DC) and interruption of the subsequent transmission of HIV-1 from DC to T cells are likely to be important attributes of an effective human immunodeficiency virus type 1 (HIV-1) vaccine. While anti-HIV-1 neutralizing antibodies have been difficult to elicit by immunization, there are several human monoclonal antibodies (MAbs) that effectively neutralize virus infection of activated T cells. We investigated the ability of three well-characterized neutralizing MAbs (IgG1b12, 2F5, and 2G12) to block HIV-1 infection of human DC. DC were generated from CD14⁺ blood cells or obtained from cadaveric human skin. The MAbs prevented viral entry into purified DC and the ensuing productive infection in DC/T-cell cultures. When DC were first pulsed with HIV-1, MAbs blocked the subsequent transmission to unstimulated CD3⁺ T cells. Thus, neutralizing antibodies can block HIV-1 infection of DC and the cell-to-cell transmission of virus from infected DC to T cells. These data suggest that neutralizing antibodies could interrupt the initial events associated with mucosal transmission and regional spread of HIV-1.     

Structural assembly of two-domain proteins by rigid-body docking

Background  

Modelling proteins with multiple domains is one of the central challenges in Structural Biology. Although homology modelling has successfully been applied for prediction of protein structures, very often domain-domain interactions cannot be inferred from the structures of homologues and their prediction requiresab initiomethods. Here we present a new structural prediction approach for modelling two-domain proteins based on rigid-body domain-domain docking.     

Human immunodeficiency virus type 1 neutralization measured by flow cytometric quantitation of single-round infection of primary human T cells

There is currently intensive research on the design of novel human immunodeficiency virus type 1 (HIV-1) vaccine immunogens that can elicit potent neutralizing antibodies. A prerequisite for comparing and optimizing these strategies is the ability to precisely measure neutralizing antibody responses. To this end, we sought to develop an assay that directly quantifies single-round HIV-1 infection of peripheral blood mononuclear cells (PBMC). Initial experiments demonstrated that essentially all productively infected PBMC could be identified by flow cytometric detection of intracellular p24 antigen (p24-Ag). After infection of PBMC with HIV-1, p24(+) lymphocytes could be distinguished beginning 1 day postinfection, and the majority of CD8(-) T cells were p24-Ag positive by 3 to 4 days postinfection. To directly quantify first-round infection, we included a protease inhibitor in PBMC cultures. The resulting 2-day assay was highly sensitive and specific for the detection of HIV-1-infected PBMC. Serial dilutions of virus stocks demonstrated that the number of target cells infected was directly related to the amount of infectious virus input into the assay. In neutralization assays, the flow cytometric enumeration of first-round infection of PBMC provided quantitative data on the number of target cells infected and on the inactivation of infectious virus due to reaction with antibody. We also used this single-round assay to compare the percentage of cells expressing p24-Ag to the number of copies of HIV-1 gag per 100 PBMC. The precision and reproducibility of this assay will facilitate the measurement of HIV-1 neutralization, particularly incrementally improved neutralizing antibody responses generated by new candidate vaccines.     

Primary ciliary dyskinesia (Siewert's / Kartagener's Syndrome): Respiratory symptoms and psycho-social impact

Background

Although the pathophysiological defect in primary ciliary dyskinesia (PCD; Siewert's / Kartagener's syndrome) is now well characterised, there are few studies of the impact of the condition upon health function, particularly in later life. This study assesses the health impact of the condition in a large group of patients. In addition, it assesses the similarity in age of diagnosis, symptoms and problems of those with situs inversus (PCD-SI) and those with situs solitus (PCD-SS).

Methods

Postal questionnaire sent to members of the UK Primary Ciliary Dyskinesia Family Support Group. The questionnaire contained the St. George's Respiratory Questionnaire (SGRQ) and the SF-36 questionnaire for assessing health status.

Results

93 questionnaires were returned, representing a 66% response rate. Replies were received from similar numbers of PCD-SI and PCD-SS. Individuals with PCD-SI did not show a significant tendency to be diagnosed earlier, and neither did they show any difference in their symptoms, or the relationship of symptoms to age. Respiratory symptoms were fairly constant up until the age of about 25, after which there was a slow increase in symptoms, and a decline in health status, patients over the age of 40 being about one and a half standard deviations below the mean on the physical component score of the PCS. Patients diagnosed earlier in life, and hence who had received more treatment for their condition, had better scores on the SGRQ Impact and Activity scores.

Conclusions

PCD is a chronic condition which has a progressively greater impact on health in the second half of life, producing significant morbidity and restriction of life style. Early diagnosis, and hence earlier treatment, may improve symptoms and the impact of the condition.     

Human skin Langerhans cells are targets of dengue virus infection

Dengue virus (DV), an arthropod-borne flavivirus, causes a febrile illness for which there is no antiviral treatment and no vaccine. Macrophages are important in dengue pathogenesis; however, the initial target cell for DV infection remains unknown. As DV is introduced into human skin by mosquitoes of the genus Aedes, we undertook experiments to determine whether human dendritic cells (DCs) were permissive for the growth of DV. Initial experiments demonstrated that blood-derived DCs were 10-fold more permissive for DV infection than were monocytes or macrophages. We confirmed this with human skin DCs (Langerhans cells and dermal/interstitial DCs). Using cadaveric human skin explants, we exposed skin DCs to DV ex vivo. Of the human leukocyte antigen DR-positive DCs that migrated from the skin, emigrants from both dermis and epidermis, 60-80% expressed DV antigens. These observations were supported by histologic findings from the skin rash of a human subject who received an attenuated tetravalent dengue vaccine. Immunohistochemistry of the skin showed CD1a-positive DCs double-labeled with an antibody against DV envelope glycoprotein. These data demonstrate that human skin DCs are permissive for DV infection, and provide a potential mechanism for the transmission of DV into human skin.     

Prolactinomas, Cushing's disease and acromegaly: debating the role of medical therapy for secretory pituitary adenomas

Pituitary adenomas are associated with a variety of clinical manifestations resulting from excessive hormone secretion and tumor mass effects, and require a multidisciplinary management approach. This article discusses the treatment modalities for the management of patients with a prolactinoma, Cushing's disease and acromegaly, and summarizes the options for medical therapy in these patients. First-line treatment of prolactinomas is pharmacotherapy with dopamine agonists; recent reports of cardiac valve abnormalities associated with this class of medication in Parkinson's disease has prompted study in hyperprolactinemic populations. Patients with resistance to dopamine agonists may require other treatment. First-line treatment of Cushing's disease is pituitary surgery by a surgeon with experience in this condition. Current medical options for Cushing's disease block adrenal cortisol production, but do not treat the underlying disease. Pituitary-directed medical therapies are now being explored. In several small studies, the dopamine agonist cabergoline normalized urinary free cortisol in some patients. The multi-receptor targeted somatostatin analogue pasireotide (SOM230) shows promise as a pituitary-directed medical therapy in Cushing's disease; further studies will determine its efficacy and safety. Radiation therapy, with medical adrenal blockade while awaiting the effects of radiation, and bilateral adrenalectomy remain standard treatment options for patients not cured with pituitary surgery. In patients with acromegaly, surgery remains the first-line treatment option when the tumor is likely to be completely resected, or for debulking, especially when the tumor is compressing neurovisual structures. Primary therapy with somatostatin analogues has been used in some patients with large extrasellar tumors not amenable to surgical cure, patients at high surgical risk and patients who decline surgery. Pegvisomant is indicated in patients who have not responded to surgery and other medical therapy, although there are regional differences in when it is prescribed. In conclusion, the treatment of patients with pituitary adenomas requires a multidisciplinary approach. Dopamine agonists are an effective first-line medical therapy in most patients with a prolactinoma, and somatostatin analogues can be used as first-line therapy in selected patients with acromegaly. Current medical therapies for Cushing's disease primarily focus on adrenal blockade of cortisol production, although pasireotide and cabergoline show promise as pituitary-directed medical therapy for Cushing's disease; further long-term evaluation of efficacy and safety is important.     

Bluejay 1.0: genome browsing and comparison with rich customization provision and dynamic resource linking

Background  

The Bluejay genome browser has been developed over several years to address the challenges posed by the ever increasing number of data types as well as the increasing volume of data in genome research. Beginning with a browser capable of rendering views of XML-based genomic information and providing scalable vector graphics output, we have now completed version 1.0 of the system with many additional features. Our development efforts were guided by our observation that biologists who use both gene expression profiling and comparative genomics gain functional insights above and beyond those provided by traditional per-gene analyses.