Abed Nasereddin

Bio: Abed Nasereddin is an academic researcher from Hebrew University of Jerusalem. The author has contributed to research in topics: Leishmania tropica & Plasmodium falciparum. The author has an hindex of 10, co-authored 17 publications receiving 459 citations. Previous affiliations of Abed Nasereddin include Al-Quds University & Hadassah Medical Center.

Identification and Differentiation of Leishmania Species in Clinical Samples by PCR Amplification of the Miniexon Sequence and Subsequent Restriction Fragment Length Polymorphism Analysis

Abstract: We recently developed a new PCR-restriction fragment length polymorphism (RFLP)-based assay using the miniexon sequence from the genus Leishmania. Here we report the application of this new genotyping method to naturally infected clinical samples for the differentiation of New and Old World Leishmania species. Of the newly developed assay and four currently applied diagnostic tests (i.e., in vitro cultivation, serology, and two other molecular assays using either the small subunit-internal transcribed spacer sequence or a repetitive genomic sequence), the miniexon assay showed the highest sensitivity, 89.7%, compared to 70.6, 57.1, 51.7, and 79.3%, respectively. Species differentiation was robust and reliable compared with that by two other Leishmania genotyping techniques. The assay provides a valuable tool for the identification of Leishmania directly from clinical samples and enables determination of the infecting species by a facile technique with high discrimination power. Since Leishmania causes a broad spectrum of diseases distinguished by different parasite and host factors, detection and characterization of the infecting species is crucial for the confirmation of a diagnosis as well as the establishment of the clinical prognosis and the initiation of an adequate therapeutic approach. The miniexon PCR-RFLP assay will facilitate such determination and might improve diagnosis and treatment of leishmaniasis.

PfSec13 is an unusual chromatin-associated nucleoporin of Plasmodium falciparum that is essential for parasite proliferation in human erythrocytes.

Abstract: Summary In Plasmodium falciparum , the deadliest form of human malaria, the nuclear periphery has drawn much attention due to its role as a sub-nuclear compartment involved in virulence gene expression. Recent data have implicated components of the nuclear envelope in regulating gene expression in several eukaryotes. Special attention has been given to nucleoporins that compose the nuclear pore complex (NPC). However, very little is known about components of the nuclear envelope in Plasmodium parasites. Here we characterize PfSec13, an unusual nucleoporin of P. falciparum , which shows unique structural similarities suggesting that it is a fusion between Sec13 and Nup145C of yeast. Using super resolution fluorescence microscopy (3D-SIM) and in vivo imaging, we show that the dynamic localization of PfSec13 during parasites9 intra-erythrocytic development corresponds with that of the NPCs and that these dynamics are associated with microtubules rather than with F-actin. In addition, PfSec13 does not co-localize with the heterochormatin markers HP1 and H3K9me3, suggesting euchromatic location of the NPCs. The proteins associated with PfSec13 indicate that this unusual Nup is involved in several cellular processes. Indeed, ultrastructural and chromatin immunoprecipitation analyses revealed that, in addition to the NPCs, PfSec13 is found in the nucleoplasm where it is associated with chromatin. Finally, we used peptide nucleic acids (PNA) to downregulate PfSec13 and show that it is essential for parasite proliferation in human erythrocytes.

Molecular Detection of Rickettsia africae, Rickettsia aeschlimannii, and Rickettsia sibirica mongolitimonae in Camels and Hyalomma spp. Ticks from Israel

Abstract: In this study, we aimed to identify and genetically characterize spotted fever group (SFG) rickettsiae in ticks, domestic one-humped camels, and horses from farms and Bedouin communities in southern Israel. A total of 618 ixodid ticks (Hyalomma dromedarii, Hyalomma turanicum, Hyalomma excavatum, and Hyalomma impeltatum) collected from camels and horses, as well as 152 blood samples from 148 camels and four horses were included in the study. Initial screening for rickettsiae was carried out by targeting the gltA gene. Positive samples were further analyzed for rickettsial ompA, 17kDa, ompB, and 16S rRNA genes. Rickettsia aeschlimannii DNA was detected in the blood of three camels and 14 ticks (H. dromedarii, H. turanicum, and H. excavatum). Rickettsia africae was found in six ticks (H. turanicum, H. impeltatum, H. dromedarii, and H. excavatum). In addition, Rickettsia sibirica mongolitimonae was detected in one H. turanicum tick. These findings represent the first autochthonous detection of R. africae in Israel. Previous detections of R. africae in Asia were reported from the Sinai Peninsula (Egypt) and Istanbul, only. Furthermore, we report for the first time the finding of R. aeschlimannii in H. turanicum and H. excavatum ticks, as well as the first identification of R. sibirica mongolitimonae in H. turanicum ticks. The tick species identified to harbor R. africae and other SFG rickettsiae have been reported to occasionally feed on people, and, therefore, physicians should be aware of the possible exposure of local communities and travelers, especially those in contact with camels, to these tick-borne rickettsial pathogens.

Leishmania tropica in northern Israel: A clinical overview of an emerging focus

Abstract: Background In Israel, most cutaneous leishmaniasis (CL) is caused by Leishmania major . Recently a new focus of CL caused by Leishmania tropica has been described in Tiberias and the surrounding area of northern Israel. Objective The aim of this study was to evaluate clinical (size, number, location, and type of lesion) and laboratory (culture and polymerase chain reaction [PCR] analysis) parameters at diagnosis, response to treatment, and outcome of patients with CL due to L tropica . Methods Between September 2002 and March 2004, patients with direct smear-confirmed CL were evaluated; clinical records were reviewed and a telephone survey was performed. Results Forty nine patients, 34 (69%) male and 15 (31%) female, were studied. Mean age was 31.1 years (median 26 years, range 1-70); 76% of patients live in Tiberias and the surrounding area. The mean number of lesions was 2.6 (median 2, range 1-10). Lesions were commonly located on the face (61%) and upper limbs (57%). PCR analysis was performed in 27 patients and was positive for L tropica in 26. Fifty percent of patients studied received multiple therapeutic regimens because of incomplete response or treatment failure. Topical paromomycin was used in 44 patients (90%), with a complete response reported in only 17 (39%); of the 9 patients treated with intralesional sodium stibogluconate, a complete response was reported in 6 (67%); of the 5 patients treated with intravenous sodium stibogluconate, 4 (80%) were cured. Limitations The relatively small number of patients studied combined with the fact that some were assessed retrospectively limit our conclusions. In addition, 50% of the patients studied received multiple therapeutic regimens because of failure of, or incomplete responses to, their initial therapy, thereby making comparisons difficult. Conclusions The cure rate in those completing a course of antimony therapy, either 10 or more days of intravenous therapy or therapy administered intralesionally, was 75% (95% confidence interval [CI], 50.5-99.5%) as compared with 45% (95% CI, 28.9-60.5%) among those completing at least 10 days of topical paromomycin. To date, no standardized, simple, safe, and highly effective regimen for treating L tropica exists. Large, controlled clinical trials to evaluate current treatment regimens as well as new medications for CL, and especially CL attributed to L tropica, are urgently needed.

Amphotericin B-loaded nanoparticles for local treatment of cutaneous leishmaniasis.

Abstract: Cutaneous leishmaniasis (CL) is an infectious, parasitic disease caused by the protozoan Leishmania. Amphotericin B (AMB) is a macrolide polyene antibiotic presenting potent antifungal and antileishmanial activity, but due to poor water solubility at physiological pH, side effects, and toxicity, its therapeutic efficiency is limited. In the present study, poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with AMB were generated to reduce drug toxicity and facilitate localized delivery over a prolonged time. AMB NPs were characterized for particle size, zeta potential, polydispersity index, and degree of aggregation. In vitro assessments demonstrated its sustained activity against Leishmania major promastigotes and parasite-infected macrophages. A single intralesional administration to infected BALB/c mice revealed that AMB NPs were more effective than AMB deoxycholate in terms of reducing lesion area. Taken together, these findings suggest that AMB NPs improve AMB delivery and can be used for local treatment of CL.

Leishmania and the leishmaniases: a parasite genetic update and advances in taxonomy, epidemiology and pathogenicity in humans.

Abstract: Leishmaniases remain a major public health problem today despite the vast amount of research conducted on Leishmania pathogens. The biological model is genetically and ecologically complex. This paper explores the advances in Leishmania genetics and reviews population structure, taxonomy, epidemiology and pathogenicity. Current knowledge of Leishmania genetics is placed in the context of natural populations. Various studies have described a clonal structure for Leishmania but recombination, pseudo-recombination and other genetic processes have also been reported. The impact of these different models on epidemiology and the medical aspects of leishmaniases is considered from an evolutionary point of view. The role of these parasites in the expression of pathogenicity in humans is also explored. It is important to ascertain whether genetic variability of the parasites is related to the different clinical expressions of leishmaniasis. The review aims to put current knowledge of Leishmania and the leishmaniases in perspective and to underline priority questions which 'leishmaniacs' must answer in various domains: epidemiology, population genetics, taxonomy and pathogenicity. It concludes by presenting a number of feasible ways of responding to these questions.

Comparison of PCR Assays for Diagnosis of Cutaneous Leishmaniasis

Abstract: Three PCR assays for diagnosing leishmaniasis were compared and validated against parasite cultures and microscopic evaluation of stained tissue smears using 92 specimens from suspected cases of cutaneous leishmaniasis (CL) in Israel and the West Bank. Samples from imported and locally acquired disease were examined. The kinetoplast DNA (kDNA) PCR showed the highest sensitivity (98.7%) of any assay, correctly diagnosing 77/78 of the confirmed positive samples, followed by the rRNA gene internal transcribed spacer 1 (ITS1) PCR (71/78 positive, 91.0% sensitivity) and then the spliced leader mini-exon PCR (42/78 positive, 53.8% sensitivity). Either parasite culture or microscopy alone detected 62.8% (49/78) or 74.4% (58/78) of the positive specimens, respectively, while culture and microscopy together improved overall sensitivity to 83.3% (65/78). Except for the kDNA PCR that had six false positives, all other assays were 100% specific. Further, restriction enzyme analysis of the ITS1 PCR product enabled identification of 74.6% of the positive samples, which included strains of Leishmania major (50.9%), Leishmania tropica (47.2%), and the Leishmania braziliensis complex (1.9%). This suggests that a PCR using kDNA should be used for the diagnosis of CL and that an ITS1 PCR can be reliably used for the diagnosis of CL when rapid species identification is needed.

Cutaneous leishmaniasis: recent developments in diagnosis and management.

Abstract: This review focuses on recent developments in the diagnosis, treatment, management, and strategies for the prevention and control of cutaneous leishmaniasis (CL) caused by both Old and New World Leishmania species CL is caused by the vector-borne protozoan parasite Leishmania and is transmitted via infected female sandflies The disease is endemic in more than 98 countries and an estimated 350 million people are at risk The overall prevalence is 12 million cases and the annual incidence is 2–25 million The World Health Organization considers CL a severely neglected disease and a category 1 emerging and uncontrolled disease The management of CL differs from region to region and is primarily based on local experience-based evidence Most CL patients can be treated with topical treatments, but some Leishmania species can cause mucocutaneous involvement requiring a systemic therapeutic approach Moreover, Leishmania species can vary in their sensitivity to available therapeutic options This makes species determination critical for the choice of treatment and the clinical outcome of CL Identification of the infecting parasite used to be laborious, but now the Leishmania species can be identified relatively easy with new DNA techniques that enable a more rational therapy choice Current treatment guidelines for CL are based on poorly designed and reported trials There is a lack of evidence for potentially beneficial treatments, a desperate need for large well-conducted studies, and standardization of future trials Moreover, intensified research programs to improve vector control, diagnostics, and the therapeutic arsenal to contain further incidence and morbidity are needed

Diagnosis and Treatment of Leishmaniasis: Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH)

Abstract: It is important to realize that leishmaniasis guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. The IDSA and ASTMH consider adherence to these guidelines to be voluntary, with the ultimate determinations regarding their application to be made by the physician in the light of each patient's individual circumstances.