6320 research outputs found
Sort by
Measurement of recent exposure to Phlebotomus argentipes, the vector of Indian visceral Leishmaniasis, by using human antibody responses to sand fly saliva
No full textAntibody (IgG) responses to the saliva of Phlebotomus argentipes were investigated using serum samples from regions of India endemic and non-endemic for visceral leishmaniasis (VL). By pre-adsorbing the sera against the saliva of the competing human-biting but non-VL vector P. papatasi, we significantly improved the specificity of a P. argentipes saliva enzyme-linked immunosorbent assay. Using this method, we observed a statistically significant correlation between antibodies to P. argenitpes saliva and the average indoor density of female sand flies. Additionally, the method was able to detect recent changes in vector exposure when sera from VL patients were assayed before, during, and after hospitalization and protected from sand fly bites under untreated bed nets. Collectively, these results highlight the utility of antibodies to P. argentipes saliva as an important tool to evaluate VL vector control program
HIV-1 V3 envelope deep sequencing for clinical plasma specimens failing in phenotypic tropism assays
No full textBACKGROUND:HIV-1 infected patients for whom standard gp160 phenotypic tropism testing failed are currently excluded from co-receptor antagonist treatment. To provide patients with maximal treatment options, massively parallel sequencing of the envelope V3 domain, in combination with tropism prediction tools, was evaluated as an alternative tropism determination strategy. Plasma samples from twelve HIV-1 infected individuals with failing phenotyping results were available. The samples were submitted to massive parallel sequencing and to confirmatory recombinant phenotyping using a fraction of the gp120 domain.RESULTS:A cut-off for sequence reads interpretation of 5 to10 times the sequencing error rate (0.2%) was implemented. On average, each sample contained 7 different V3 haplotypes. V3 haplotypes were submitted to tropism prediction algorithms, and 4/14 samples returned with presence of a dual/mixed (D/M) tropic virus, respectively at 3%, 10%, 11%, and 95% of the viral quasispecies. V3 tropism prediction was confirmed by gp120 phenotyping, except for two out of 4 D/M predicted viruses (with 3 and 95%) which were phenotypically R5-tropic. In the first case, the result was discordant due to the limit of detection for the phenotyping technology, while in the latter case the prediction algorithms were not computing the viral tropism correctly.CONCLUSIONS:Although only demonstrated on a limited set of samples, the potential of the combined use of "deep sequencing + prediction algorithms" in cases where routine gp160 phenotype testing cannot be employed was illustrated. While good concordance was observed between gp120 phenotyping and prediction of R5-tropic virus, the results suggest that accurate prediction of X4-tropic virus would require further algorithm developmen
Barriers to VCT despite 13 years of community-based awareness campaigns in a peri-urban township in northern Limpopo
No full textAn estimated 5.7 million people in South Africa live with HIV/AIDS. In 2008, it was estimated that 12.5% of the Limpopo population aged 15 - 49 was HIV-positive, while the national HIV prevalence estimate was 18.8%. Over the past 8 years, the South African government has supported prevention campaigns, expanded voluntary counselling and testing (VCT) sites, and increased the access to antiretroviral therapy (ART) to decrease the burden of the epidemic. VCT was offered at 87% of primary health care facilities in Limpopo Province in 2003. By 2007, 42% of the people in need of ART in South Africa had commenced it. Despite VCT's benefits and the increased number of testing sites, many South Africans remain untested for HIV for various reasons. In Bela-Bela, the HIV/AIDS Prevention Group (HAPG) has been active since 1996, providing VCT and care and support to people with HIV/AIDS. Its activities include prevention campaigns, free VCT and ART, home-based care and orphan care. Each year, 39.4 - 42.2% of the HAPG VCT attendees test HIV-positive. In 2005, 254 HIV/AIDS prevention activities were organised, reaching 15 570 participants (73% women). We studied motivations for, and barriers to, VCT uptake among black South Africans living in Bela-Bela, a peri-urban town with a population of 55 844 and an unemployment rate of 21
Sensitivity and specificity of the Leishmania OligoC-TesT and NASBA-oligochromatography for diagnosis of visceral leishmaniasis in Kenya
No full textSummary Objective To estimate the sensitivity and specificity of the OligoC-TesT and nucleic acid sequence-based amplification coupled to oligochromatography (NASBA-OC) for molecular detection of Leishmania in blood from patients with confirmed visceral leishmaniasis (VL) and healthy endemic controls from Kenya. Methods Blood specimens of 84 patients with confirmed VL and 98 endemic healthy controls from Baringo district in Kenya were submitted to both assays. Results The Leishmania OligoC-TesT showed a sensitivity of 96.4% (95% confidence interval [CI]: 90-98.8%) and a specificity of 88.8% (95% CI: 81-93.6%), while the sensitivity and specificity of the NASBA-OC were 79.8% (95% CI: 67-87%) and 100% (95% CI: 96.3-100%), respectively. Conclusion Our findings indicate high sensitivity of the Leishmania OligoC-TesT on blood while the NASBA-OC is a better marker for active diseas
Profiling of lipids in Leishmania donovani using hydrophilic interaction chromatography in combination with Fourier transform mass spectrometry
No full textThere is evidence from our current research on resistance to stibigluconate and from some previous observations that lipid composition may be altered in resistant Leishmania donovani and in order to explore this we required a comprehensive lipidomics method. Phospholipids can be analysed by direct infusion into a mass spectrometer and such methods can work very well. However, chromatographic methods can also be very effective and are extensively used. They potentially avoid ion suppression effects, associate lipid classes with a retention time range and deliver good quantitative accuracy. In the current study three chromatography columns were compared for their ability to separate different classes of lipid. Butylsilane (C-4), Zic-HILIC and a silica gel column were compared. The best results were obtained with a silica gel column used in hydrophilic interaction chromatography (HILIC) mode with a mobile phase gradient consisting of (A) 20% isopropyl alcohol (IPA) in acetonitrile (v/v) and (B) 20% IPA in 0.02 M ammonium formate. Using these conditions separate peaks were obtained for triglycerides (TG), phosphoinositols (PI), inositol phosphoceramides (IPC), phosphatidylethanolamines (PE), phosphatidylserines (PS), phosphatidylcholines (PC), sphingosines (SG), lysophosphatidyethanolamines (LPE) and lysophosphatidylcholines (LPC). The methodology was applied to the analysis of lipid extracts from Leishmania donovani and by coupling the chromatography with an LTQ Orbitrap mass spectrometer. It was possible to detect 188 lipid species in the extracts with the following breakdown: PC 59, PE 38, TG 35, PI 20, CPI 13, LPC 11, LPE 2 and SG 10. The fatty acid composition of the more abundant lipids was characterised by MS(2) and MS(3) experiments carried out by using an LCQ Deca low-resolution ion trap instrument coupled with the silica gel column. The separation of lipids into well-defined groups gives extra confidence in their identification and minimises the risk of ion suppression effects. High-resolution mass spectrometry was necessary in order to be able to differentiate between acyl- and acyl-alkyl-lipids. Copyright (c) 2010 John Wiley & Sons, Lt
Analysis of infectious virus clones from two HIV-1 superinfection cases suggests that the primary strains have lower fitness
No full textBACKGROUND: Two HIV-1 positive patients, L and P, participating in the Amsterdam Cohort studies acquired an HIV-1 superinfection within half a year from their primary HIV-1 infection (Jurriaans et al., JAIDS 2008, 47:69-73). The aim of this study was to compare the replicative fitness of the primary and superinfecting HIV-1 strains of both patients. The use of isolate-specific primer sets indicated that the primary and secondary strains co-exist in plasma at all time points after the moment of superinfection. RESULTS: Biological HIV-1 clones were derived from peripheral blood CD4+ T cells at different time point, and identified as the primary or secondary virus through sequence analysis. Replication competition assays were performed with selected virus pairs in PHA/IL-2 activated peripheral blood mononuclear cells (PBMC's) and analyzed with the Heteroduplex Tracking Assay (HTA) and isolate-specific PCR amplification. In both cases, we found a replicative advantage of the secondary HIV-1 strain over the primary virus. Full-length HIV-1 genomes were sequenced to find possible explanations for the difference in replication capacity. Mutations that could negatively affect viral replication were identified in the primary infecting strains. In patient L, the primary strain has two insertions in the LTR promoter, combined with a mutation in the tat gene that has been associated with decreased replication capacity. The primary HIV-1 strain isolated from patient P has two mutations in the LTR that have been associated with a reduced replication rate. In a luciferase assay, only the LTR from the primary virus of patient P had lower transcriptional activity compared with the superinfecting virus. CONCLUSIONS: These preliminary findings suggest the interesting scenario that superinfection occurs preferentially in patients infected with a relatively attenuated HIV-1 isolat
Mobile learning for HIV/AIDS healthcare worker training in resource-limited settings
No full textBACKGROUND: We present an innovative approach to healthcare worker (HCW) training using mobile phones as a personal learning environment. Twenty physicians used individual Smartphones (Nokia N95 and iPhone), each equipped with a portable solar charger. Doctors worked in urban and peri-urban HIV/AIDS clinics in Peru, where almost 70% of the nation's HIV patients in need are on treatment. A set of 3D learning scenarios simulating interactive clinical cases was developed and adapted to the Smartphones for a continuing medical education program lasting 3 months. A mobile educational platform supporting learning events tracked participant learning progress. A discussion forum accessible via mobile connected participants to a group of HIV specialists available for back-up of the medical information. Learning outcomes were verified through mobile quizzes using multiple choice questions at the end of each module. METHODS: In December 2009, a mid-term evaluation was conducted, targeting both technical feasibility and user satisfaction. It also highlighted user perception of the program and the technical challenges encountered using mobile devices for lifelong learning. RESULTS: With a response rate of 90% (18/20 questionnaires returned), the overall satisfaction of using mobile tools was generally greater for the iPhone. Access to Skype and Facebook, screen/keyboard size, and image quality were cited as more troublesome for the Nokia N95 compared to the iPhone. CONCLUSIONS: Training, supervision and clinical mentoring of health workers are the cornerstone of the scaling up process of HIV/AIDS care in resource-limited settings (RLSs). Educational modules on mobile phones can give flexibility to HCWs for accessing learning content anywhere. However lack of softwares interoperability and the high investment cost for the Smartphones' purchase could represent a limitation to the wide spread use of such kind mLearning programs in RLS
Canine leishmaniasis in Algeria: true prevalence and diagnostic test characteristics in groups of dogs of different functional type
No full textA Bayesian approach was used to assess the prevalence of Canine leishmaniasis and evaluate three serological diagnostic tests: indirect fluorescent antibody test (IFAT), direct agglutination test, and particle gel immuno-assay (PaGIA) for Canine leishmaniasis (CL) in Algiers. Four hundred and sixty-two dogs were involved in this study and divided in four groups according to their functional type: stray dogs, farm dogs, national guard dogs and pet dogs. The stray dog group showed the highest prevalence of leishmaniasis (11.7%), followed by the national guard dogs (9.7%) and the farm dogs (5.9%). IFAT was shown to be the most sensitive test in all groups. However, IFAT specificity was considerably lowered in the farm dog group: 65.2% versus 94.5% for the stray dogs. A considerable drop in PaGIA specificity was noted in the stray dogs group. The results of the current study demonstrate the variability of test characteristics in different situations and underline the danger of using standard values, without verifying their appropriateness for the specific purpose
Comparison of Leishmania OligoC-TesT PCR with conventional and real-time PCR for the detection of canine Leishmania infection
No full textThere is a need for standardization and simplification of the existing methods for molecular detection of Leishmania infantum in the canine reservoir host. The commercially available OligoC-TesT kit incorporates standardized PCR reagents with rapid oligochromatographic dipstick detection of PCR products, and is highly sensitive in humans, but not yet independently validated in dogs. Here we compare the sensitivity of the OligoC-TesT with that of nested kinetoplast DNA (kDNA) PCR, nested internal transcribed spacer-1 (ITS-1) PCR, and a PCR/hybridization protocol, in longitudinal naturally infected canine bone marrow samples for which parasite burdens were measured by real-time quantitative PCR (qPCR). Sensitivity of the OligoC-TesT in infected dogs was 70% (95% C.I. 63-78%), similar to that of kDNA PCR (72%; 95% C.I. 65-80%; P=0.69), but significantly greater than PCR/hybridization (61%; 95% C.I. 53-69%; P=0.007) and ITS-1 nested PCR (54%; 95% C.I. 45-62%; P<0.001); real-time qPCR had the highest sensitivity (91%; 95% C.I. 85-95%; P<0.001). OligoC-TesT sensitivity was greater in polysymptomatic and oligosymptomatic dogs compared to asymptomatic dogs (93%, 74%, and 61%, respectively; P=0.005), a trend also observed in the other qualitative PCR methods tested (P</=0.05). Test positivity increased with increasing parasite burden measured by real-time qPCR: OligoC-TesT and kDNA PCR detected 100% and 99% of positive samples when parasite burden exceeded 74 and 49 parasites/ml, respectively. The OligoC-TesT has high sensitivity for detection of canine Leishmania infections; ease of operation and interpretation are further advantages for veterinary diagnostic laboratories, and for large-scale survey work in developing countrie