The Biogenesis of Dengue Virus Replication Organelles Requires the ATPase Activity of Valosin-Containing Protein

The dengue virus (DENV) causes the most prevalent arthropod-borne viral disease worldwide. While its incidence is increasing in many countries, there is no approved antiviral therapy currently available. In infected cells, the DENV induces extensive morphological alterations of the endoplasmic reticulum (ER) to generate viral replication organelles (vRO), which include convoluted membranes (CM) and vesicle packets (VP) hosting viral RNA replication. The viral non-structural protein NS4B localizes to vROs and is absolutely required for viral replication through poorly defined mechanisms, which might involve cellular protein partners. Previous interactomic studies identified the ATPase valosin-containing protein (VCP) as a DENV NS4B-interacting host factor in infected cells. Using both pharmacological and dominant-negative inhibition approaches, we show, in this study, that VCP ATPase activity is required for efficient DENV replication. VCP associates with NS4B when expressed in the absence of other viral proteins while in infected cells, both proteins colocalize within large DENV-induced cytoplasmic structures previously demonstrated to be CMs. Consistently, VCP inhibition dramatically reduces the abundance of DENV CMs in infected cells. Most importantly, using a recently reported replication-independent plasmid-based vRO induction system, we show that de novo VP biogenesis is dependent on VCP ATPase activity. Overall, our data demonstrate that VCP ATPase activity is required for vRO morphogenesis and/or stability. Considering that VCP was shown to be required for the replication of other flaviviruses, our results argue that VCP is a pan-flaviviral host dependency factor. Given that new generation VCP-targeting drugs are currently evaluated in clinical trials for cancer treatment, VCP may constitute an attractive broad-spectrum antiviral target in drug repurposing approaches.     

A high prevalence of p53 mutations in pre‐malignant oral erythroplakia

Oral squamous‐cell carcinoma is thought to be preceded by a number of precursor stages which induce morphological changes in cells of the oral mucosa resulting in clinically detectable pre‐malignant lesions such as erythroplakia or leukoplakia. To better understand the etiology of oral erythroplakia, we have examined the p53 tumor‐suppressor gene (exons 5–9) for mutations in 24 oral erythroplakia lesions of varying dysplastic phenotypes by PCR/single‐strand conformational polymorphism and direct DNA‐sequencing analyses. A total of 12 p53 mutations were detected in 11 of 24 (46%) erythroplakia specimens (one specimen contained two different p53 mutations); 25% were single‐base‐pair deletions and 33% were either G:C→T:A transversions or G:C→A:T transitions. A high prevalence of p53 mutation was observed in all categories of erythroplakia lesions: 33% for mildly dysplastic lesions, 50% for lesions exhibiting moderate to severe dysplasia and 50% for lesions that were carcinoma in situ. Although the combined prevalence of p53 mutations observed in erythroplakia was significantly higher (p = 0.02) than that observed earlier for leukoplakia, the prevalence of p53 mutations was similar in erythroplakia and leukoplakia specimens from smokers. The prevalence and spectrum of p53 mutations observed in this series of erythroplakia lesions are similar to those observed for oral squamous‐cell carcinoma. These results indicate that mutations of the p53 gene may be linked to the high malignant potential of erythroplakia and provide further evidence that p53 mutation may be an early event in the genesis of oral squamous‐cell carcinoma. Int. J. Cancer 80:345–348, 1999. © 1999 Wiley‐Liss, Inc.     

FcγR interaction is not required for effective anti-PD-L1 immunotherapy but can add additional benefit depending on the tumor model

Immunomodulatory antibodies blocking interactions of coinhibitory receptors to their ligands such as CTLA-4, PD1 and PD-L1 on immune cells have shown impressive therapeutic efficacy in clinical studies. The therapeutic effect of these antibodies is mainly mediated by reactivating antitumor T cell immune responses. Detailed analysis of anti-CTLA4 antibody therapy revealed that an optimal therapeutic efficacy also requires binding to Fc receptors for IgG, FcγR, mediating depletion of intratumoral regulatory T cells. Here, we investigated the role of Fc binding in anti-PD-L1 antibody therapy in the MC38 C57BL/6 and CT26 BALB/c colon adenocarcinoma tumor models. In the MC38 tumor model, all IgG subclasses anti-PD-L1 showed similar therapeutic efficacy when compared to each other in either wild-type mice or in mice deficient for all FcγR. In contrast, in the CT26 tumor model, anti-PD-L1 mIgG2a, the IgG subclass with the highest affinity for activating FcγR, showed stronger therapeutic efficacy than other IgG subclasses. This was associated with a reduction of a myeloid cell subset with high expression of PD-L1 in the tumor microenvironment. This subclass preference for mIgG2a was lost in C57BL/6 × BALB/c F1 mice, indicating that the genetic background of the host may determine the additional clinical benefit of the high affinity antibody subclasses. Based on these data, we conclude that FcγR are not crucial for anti-PD-L1 antibody therapy but might play a role in some tumor models.     

Aspects épidémiologiques et sémiologiques des troubles fonctionnels intestinaux dans les centres de santé de référence de Bamako

The main goal of this study was to evaluate epidemiological and clinical aspects of irritable bowel syndrome (IBS) in health districts of Bamako. It was a cross-sectional study conducted from June 2006 to November 2006. During the period of study, 104 of 487 patients, 21.35% of the examined population, met the inclusion criteria. The average age was of 30.5 ± 11.5 years, the age group of 16–26 years predominated with 45.2%. The sex-ratio was 0.5 in favor of women. The signs most frequently found were abdominal pain (97.1%), abdominal distension (51.9%), and constipation (45.2%). A frequent absenteeism was reported by 65.8% of the patients. The IBS can be regarded as a public health problem. Treatment and exploration costs and frequent absences with work constitute true socioeconomic problems.     

Mycobacterium tuberculosis components stimulate production of the antimicrobial peptide hepcidin

We investigated the in vitro production of the antimicrobial peptide hepcidin by cells of the innate immune system that harbor Mycobacterium tuberculosis. Stimulation of mouse lung macrophages with M.?tuberculosis or IFN-γ?+?M.?tuberculosis induced hepcidin mRNA. In human alveolar A549 epithelial cells, lipoglycans of M.?tuberculosis, in particular mannose-capped lipoarabinomannan and phosphatidyl-myo-inositol mannosides, were strong inducers of hepcidin mRNA. In mouse dendritic cells, hepcidin mRNA was increased by subcellular fractions and culture filtrate proteins of M.?tuberculosis and by TLR2 and TLR4 agonists, but not by TLR9 agonists, IL-1α, IL-6 or TNF-α. Flow cytometry evaluation of human peripheral blood mononuclear cells demonstrated that CD11c(+) myeloid dendritic cells stimulated with killed M.?tuberculosis or live M.?bovis BCG produced hepcidin. The production of the antimicrobial peptide hepcidin by cells that interact with M.?tuberculosis suggests a host defense mechanism against mycobacteria.     

Enhanced Diagnosis of Pneumococcal Bacteremia Using Antigen- and Molecular-Based Tools on Blood Specimens in Mali and Thailand: A Prospective Surveillance Study

Prior antibiotic use, contamination, limited blood volume, and processing delays reduce yield of blood cultures for detection of Streptococcus pneumoniae. We performed immunochromatographic testing (ICT) on broth from incubated blood culture bottles and real-time lytA polymerase chain reaction (PCR) on broth and whole blood and compared findings to blood culture in patients with suspected bacteremia. We selected 383 patients in Mali and 586 patients in Thailand based on their blood culture results: 75 and 31 were positive for pneumococcus, 100 and 162 were positive for other pathogens, and 208 and 403 were blood culture negative, respectively. ICT and PCR of blood culture broth were at least 87% sensitive and 97% specific compared with blood culture; whole blood PCR was 75–88% sensitive and 96–100% specific. Pneumococcal yields in children < 5 years of age increased from 2.9% to 10.7% in Mali with > 99% of additional cases detected by whole blood PCR, and from 0.07% to 5.1% in Thailand with two-thirds of additional cases identified by ICT. Compared with blood culture, ICT and lytA PCR on cultured broth were highly sensitive and specific but their ability to improve pneumococcal identification varied by site. Further studies of these tools are needed before widespread implementation.     

Global epidemiology of invasive meningococcal disease

Neisseria meningitidis is one of the leading causes of bacterial meningitis globally and can also cause sepsis, pneumonia, and other manifestations. In countries with high endemic rates, the disease burden places an immense strain on the public health system. The worldwide epidemiology of invasive meningococcal disease (IMD) varies markedly by region and over time. This review summarizes the burden of IMD in different countries and identifies the highest-incidence countries where routine preventive programs against Neisseria meningitidis would be most beneficial in providing protection. Available epidemiological data from the past 20 years in World Health Organization and European Centre for Disease Prevention and Control collections and published articles are included in this review, as well as direct communications with leading experts in the field. Countries were grouped into high-, moderate-, and low-incidence countries. The majority of countries in the high-incidence group are found in the African meningitis belt; many moderate-incidence countries are found in the European and African regions, and Australia, while low-incidence countries include many from Europe and the Americas. Priority countries for vaccine intervention are high- and moderate-incidence countries where vaccine-preventable serogroups predominate. Epidemiological data on burden of IMD are needed in countries where this is not known, particularly in South- East Asia and Eastern Mediterranean regions, so evidence-based decisions about the use of meningococcal vaccines can be made.     

Measurement of tetanus antitoxin in oral fluid: a tool to conduct serosurveys

BACKGROUND: Serosurveys that measure tetanus antitoxin can complement immunization coverage surveys to allow evaluation of immunization services in developing countries. Measurement of IgG tetanus antitoxin in oral fluid was investigated as a practical and noninvasive alternative to and correlate of serum antibodies. METHODS: Serum and oral fluid were collected from Malian infants, toddlers and adults (males without a history of tetanus vaccination). Specific IgG tetanus antitoxin was measured by enzyme-linked immunosorbent assay in serum (S-ELISA) and oral fluid (OF-ELISA). RESULTS: One hundred forty-two pairs of serum and oral fluid samples were collected from infants, 35 pairs from toddlers and 35 pairs from adults. IgG tetanus antitoxin titers measured by OF-ELISA were 100-fold lower than those measured by S-ELISA but they correlated strongly (r = 0.90, P < 0.001). All 35 toddlers who had received 2 or 3 doses of diphtheria-tetanus-pertussis (DTP) vaccine (100%) had serum tetanus antitoxin levels >or=0.15 IU/mL and 28 of 35 (80%) had oral fluid values >or=0.0015 IU/mL. Among adults lacking a history of tetanus immunization, only 6 of 35 (17.1%) had serum titers >or=0.15 IU/mL and 4 of 35 (11%) had oral fluid titers >or=0.0015 IU/mL in oral fluid. CONCLUSIONS: IgG tetanus antitoxin in oral fluid correlates well with levels in serum. OF-ELISA values >or=0.0015 IU/mL constitute protection against tetanus and in subjects >12 months of age imply multiple prior contacts with immunization services. IgG tetanus antitoxin measured by OF-ELISA provides a logistically practical alternative for performing seroprevalence surveys.