scholarly journals Towards a New Reference Test for Surra in Camels

2009 ◽  
Vol 16 (7) ◽  
pp. 999-1002 ◽  
Author(s):  
Thao Tran ◽  
Filip Claes ◽  
Didier Verloo ◽  
Henri De Greve ◽  
Philippe Büscher
Keyword(s):  
Antigenic Variation ◽  
Trypanosoma Evansi ◽  
Surface Glycoprotein ◽  
Antibody Detection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Reference Test ◽  
Perfect Agreement ◽  
Cutoff Value ◽  
Variable Surface ◽  
Variable Antigen

ABSTRACT Current serological diagnosis of Trypanosoma evansi infection in camels is based on the native variable antigen type RoTat 1.2. The goal of this study was to develop a novel serological diagnostic test based on a nonvariable protein and freed from the use of rats or mice for its production. An enzyme-linked immunosorbent assay using a recombinant extracellular domain of invariant surface glycoprotein 75 (ELISA/rISG75) was developed and tested on a collection of 184 camel sera. The results were compared to those obtained from three established antibody detection tests based on variable surface glycoprotein RoTat 1.2: an ELISA for T. evansi (ELISA/T. evansi), a card agglutination test for trypanosomiasis (CATT/T. evansi), and an immune trypanolysis (TL) assay. The ELISA/rISG75 and the ELISA/T. evansi showed a sensitivity of 94.6% (95% confidence interval [CI], 87.8 to 98.2%, at 19% positivity cutoff value) and 98.9% (95% CI, 94.1 to 99.8, at 12% positivity cutoff value), respectively. The ELISA/rISG75 had 100% specificity (CI, 95.9 to 100%), while the ELISA/T. evansi showed 98.9% specificity (CI, 95.9 to 100%). The ELISA/rISG75 demonstrated an almost perfect agreement with the TL assay, the CATT/T. evansi, and the ELISA/T. evansi, with kappa scores of at least 0.94. The ELISA/rISG75, having a performance comparable to that of the gold standard (the TL assay) and being independent of antigenic variation, may become a new reference test for surra in camels. It opens avenues for the diagnosis of T. evansi infections in other hosts as well as for the development of a pan-Trypanozoon test for detection of Trypanosoma brucei brucei, T. b. gambiense, T. b. rhodesiense, T. evansi, and T. equiperdum.

scholarly journals Targeting the Variable Surface of African Trypanosomes with Variant Surface Glycoprotein-Specific, Serum-Stable RNA Aptamers

2003 ◽  
Vol 2 (1) ◽  
pp. 84-94 ◽  
Author(s):  
Mihaela Lorger ◽  
Markus Engstler ◽  
Matthias Homann ◽  
H. Ulrich Göringer
Keyword(s):  
Antigenic Variation ◽  
Sleeping Sickness ◽  
Rna Aptamers ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Parasite Protein ◽  
African Trypanosomes ◽  
Variable Surface ◽  
New Strategy

ABSTRACT African trypanosomes cause sleeping sickness in humans and Nagana in cattle. The parasites multiply in the blood and escape the immune response of the infected host by antigenic variation. Antigenic variation is characterized by a periodic change of the parasite protein surface, which consists of a variant glycoprotein known as variant surface glycoprotein (VSG). Using a SELEX (systematic evolution of ligands by exponential enrichment) approach, we report the selection of small, serum-stable RNAs, so-called aptamers, that bind to VSGs with subnanomolar affinity. The RNAs are able to recognize different VSG variants and bind to the surface of live trypanosomes. Aptamers tethered to an antigenic side group are capable of directing antibodies to the surface of the parasite in vitro. In this manner, the RNAs might provide a new strategy for a therapeutic intervention to fight sleeping sickness.

Serological and molecular survey of Trypanosoma evansi in Camels (Camelus dromedarius) in Maiduguri, North-east, Nigeria

2021 ◽  
Vol 42 (1) ◽  
pp. 56-62
Author(s):  
S.A. Mamman ◽  
G. Abongaby ◽  
O. Salami ◽  
J.P. Yidawi ◽  
D.A. Dakul
Keyword(s):  
Diagnostic Techniques ◽  
Trypanosoma Evansi ◽  
Surface Glycoprotein ◽  
Dromedary Camel ◽  
Serological Method ◽  
Cross Sectional ◽  
North East ◽  
Variable Surface ◽  
Pcr Targeting ◽  
Pcr Techniques

To date, camels still remain an important work animal as well as source of protein to humans in the Sudan and Sahel regions of Nigeria. Therefore, a cross-sectional study was conducted on 150 camels slaughtered in Maiduguri central abattoir to determine the prevalence of Trypanosoma evansi using Card Agglutination Test (CATT) and Polymerase Chain Reaction (PCR) techniques. Overall, 30 (20%) of the camels tested were seropositive while PCR targeting the 227 base pair of the Variable Surface Glycoprotein (VSG) gene of T. evansi detected the DNA of the parasite in 9 out of the 30seropositive camels. Higher infection was found among adult compared to the young camels using the two diagnostic techniques; 24.1% vs 19.0% and 10.3% vs 4.6%, for CATT and PCR techniques, respectively. However, the differences being not statistically significant (P > 0.05) for the two methods of diagnosis. Furthermore, significantly (P < 0.05)higher prevalence of infection was recorded among male compared to female camels using the serological method of diagnosis, while (P > 0.05) using the molecular method; 27.5% vs 13.6% for CATT and 10.1% vs 2.5% for PCR. Camels with PCV =24 %( mean: 19.8923 ± 4.0931) recorded significantly (P < 0.05) higher prevalence of 23.1% than those with PCV = 25% (mean 31.7294 ± 5.50584), where the prevalence was 17.6%.The results of this study showed that camel trypanosomosis is endemic in the study area.  Furtherstudiesto elucidate the epidemiology and socioeconomic impact of this disease in the northeast region of Nigeria are desirable. Keywords:Serology, PCR, Dromedary camel, T.evansi, Maiduguri

scholarly journals Trypanosoma brucei Interaction with Host: Mechanism of VSG Release as Target for Drug Discovery for African Trypanosomiasis

2019 ◽  
Vol 20 (6) ◽  
pp. 1484 ◽  
Author(s):  
Cláudia Moreno ◽  
Adriana Temporão ◽  
Taffarel Torres ◽  
Marcelo Sousa Silva
Keyword(s):  
Drug Discovery ◽  
Phospholipase C ◽  
Trypanosoma Brucei ◽  
Antigenic Variation ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
African Trypanosomiasis ◽  
Variable Surface Glycoprotein ◽  
Variable Surface ◽  
Major Surface

The protozoan Trypanosoma brucei, responsible for animal and human trypanosomiasis, has a family of major surface proteases (MSPs) and phospholipase-C (PLC), both involved in some mechanisms of virulence during mammalian infections. During parasitism in the mammalian host, this protozoan is exclusively extracellular and presents a robust mechanism of antigenic variation that allows the persistence of infection. There has been incredible progress in our understanding of how variable surface glycoproteins (VSGs) are organised and expressed, and how expression is switched, particularly through recombination. The objective of this manuscript is to create a reflection about the mechanisms of antigenic variation in T. brucei, more specifically, in the process of variable surface glycoprotein (VSG) release. We firstly explore the mechanism of VSG release as a potential pathway and target for the development of anti-T. brucei drugs.

Expressed truncated N-terminal variable surface glycoprotein (VSG) of Trypanosoma evansi in E. coli exhibits immuno-reactivity

2012 ◽  
Vol 187 (1-2) ◽  
pp. 1-8 ◽  
Author(s):  
P.P. Sengupta ◽  
M. Balumahendiran ◽  
V. Balamurugan ◽  
G.R. Rudramurthy ◽  
K. Prabhudas
Keyword(s):  
Trypanosoma Evansi ◽  
Surface Glycoprotein ◽  
E Coli ◽  
Variable Surface Glycoprotein ◽  
Variable Surface

scholarly journals Predominance of Duplicative VSG Gene Conversion in Antigenic Variation in African Trypanosomes

1999 ◽  
Vol 19 (9) ◽  
pp. 5839-5846 ◽  
Author(s):  
Nicholas P. Robinson ◽  
Nils Burman ◽  
Sara E. Melville ◽  
J. David Barry
Keyword(s):  
Gene Duplication ◽  
Antigenic Variation ◽  
Surface Glycoprotein ◽  
African Trypanosomes ◽  
Highly Active ◽  
Genetic Switches ◽  
Transcriptional Switch ◽  
Switch Mechanism ◽  
First Relapse ◽  
Variable Antigen

ABSTRACT A number of mechanisms have been described by which African trypanosomes undergo the genetic switches that differentially activate their variant surface glycoprotein genes (VSGs) and bring about antigenic variation. These mechanisms have been observed mainly in trypanosome lines adapted, by rapid syringe passaging, to laboratory conditions. Such “monomorphic” lines, which routinely yield only the proliferative bloodstream form and do not develop through their life cycle, have VSG switch rates up to 4 or 5 orders of magnitude lower than those of nonadapted lines. We have proposed that nonadapted, or pleomorphic, trypanosomes normally have an active VSGswitch mechanism, involving gene duplication, that is depressed, or from which a component is absent, in monomorphic lines. We have characterized 88 trypanosome clones from the first two relapse peaks of a single rabbit infection with pleomorphic trypanosomes and shown that they represent 11 different variable antigen types (VATs). The pattern of appearance in the first relapse peak was generally reproducible in three more rabbit infections. Nine of these VATs had activatedVSGs by gene duplication, the tenth possibly also had done so, and only one had activated a VSG by the transcriptional switch mechanism that predominates in monomorphic lines. At least 10 of the donor genes have telomeric silent copies, and many reside on minichromosomes. It appears that trypanosome antigenic variation is dominated by one, relatively highly active, mechanism rather than by the plethora of pathways described before.

scholarly journals Comparison of Three Immunoassays for Detection of Antibodies to Strongyloides stercoralis

2014 ◽  
Vol 21 (5) ◽  
pp. 732-736 ◽  
Author(s):  
Neil W. Anderson ◽  
Diane M. Klein ◽  
Sarina M. Dornink ◽  
Deborah J. Jespersen ◽  
Joseph Kubofcik ◽  
...  
Keyword(s):  
Strongyloides Stercoralis ◽  
Antibody Detection ◽  
Venn Diagram ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Perfect Agreement ◽  
Content Type ◽  
Culture Techniques ◽  
Intestinal Nematode ◽  
Diagram Analysis

ABSTRACTDue to the limited sensitivities of stool-based microscopy and/or culture techniques forStrongyloides stercoralis, the detection of antibodies to this intestinal nematode is relied upon as a surrogate for determining exposure status or making a diagnosis ofS. stercoralisinfection. Here, we evaluated three immunoassays, including the recently released InBios Strongy Detect IgG enzyme-linked immunosorbent assay (ELISA) (InBios International, Inc., Seattle, WA), the SciMedxStrongyloidesserology microwell ELISA (SciMedx Corporation, Denville, NJ), and the luciferase immunoprecipitation system (LIPS) assay performed at the National Institutes of Health (NIH), for their detection of IgG antibodies toS. stercoralis. A total of 101 retrospective serum samples, previously submitted for routineS. stercoralisantibody detection using the SciMedx assay, were also evaluated by the InBios and LIPS assays. The qualitative results from each assay were compared using a Venn diagram analysis, to the consensus result among the three assays, and each ELISA was also evaluated using the LIPS assay as the reference standard. By Venn diagram analysis, 65% (66/101) of the samples demonstrated perfect agreement by all three assays. Also, the numbers of samples considered positive or negative by a single method were similar. Compared to the consensus result, the overall percent agreement of the InBios, SciMedx, and LIPS assays were comparable at 87.1%, 84.2%, and 89.1%, respectively. Finally, the two ELISAs performed analogously but demonstrated only moderate agreement (kappa coefficient for the two assays, 0.53) with the LIPS assay. Collectively, while the two commercially available ELISAs perform equivalently, neither should be used independently of clinical evaluation to diagnose strongyloidiasis.

scholarly journals Diagnostic Performance of Three Serological Assays for Anti-SARS-CoV-2 Antibody Detection

2021 ◽  
Vol 5 (4) ◽  
pp. 162-165
Author(s):  
Shabnam Dildar ◽  
◽  
Asma Danish ◽  
Mehjabeen Imam ◽  
Arshi Naz ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Diagnostic Performance ◽  
Immunofluorescence Assay ◽  
Lateral Flow ◽  
Antibody Detection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Perfect Agreement ◽  
N Protein ◽  
Assay Performance ◽  
Antibody Elisa

Abstract: Objective: To evaluate the diagnostic performance of Electrochemiluminescence (ECLIA) enzyme linked immunosorbent (ELISA) and lateral flow Immunofluorescence (LFIA) for anti-SARS-COV-2 antibody detection. Materials and Methods: Sensitivity was calculated with convalescent plasma (CP) donor’s samples. Specificity was checked by using pre-pandemic October 2019 samples. All samples were tested for anti-SARS-COV-2 antibody by using Electrochemiluminescence (ECLIA), Enzyme Linked Immunosorbent Assay (ELISA) and Lateral flow Immunofluorescence (LFIA) assay. Results: Total 55 patients were included, 45 patients were CP donors and 10 were Pre-Pandemic October 2019 samples archived from our blood bank. The ECLIA-total antibody, ELISA-IgG and LLFIA-IgG were positive in 41 (91.1%), 34 (75.5%) and 44 (97.75%) respectively. The highest sensitivity was observed for LFIA with highest specificity among all three assays. There was almost perfect agreement between LFIA and ECLIA (k=0.936, p<0.001) but there was fair agreement between LFIA and ELISA (k=0.412, p=0.001) and ECLIA and ELISA (k=0.357, p=0.001). Conclusion: The LFIA showed a higher sensitivity and specificity in comparison with ECLIA and ELISA. It might be due to fact that LFIA detect antibody against ncleocapsid and spike protein as well of SARS- COV-2 virus, while ECLIA and ELISA detects antibodies only against “N” Protein of SARS- COV-2 virus. Keywords: Convalescent plasma donors, Lateral flow Immunofluorescence assay, Electrochemiluminescence assay, Enzyme linked immunosorbent assay, Performance.

scholarly journals Immunodominant surface epitopes power immune evasion in the African trypanosome

2021 ◽  
Author(s):  
Anastasia Gkeka ◽  
Francisco Aresta-Branco ◽  
Gianna Triller ◽  
Evi P Vlachou ◽  
Mirjana Lilic ◽  
...  
Keyword(s):  
Immune Evasion ◽  
Antigenic Variation ◽  
Cross Reactivity ◽  
Surface Glycoprotein ◽  
Mammalian Host ◽  
African Trypanosome ◽  
Repetitive Nature ◽  
Variable Surface ◽  
Major Surface ◽  
Immunodominant Epitopes

The African trypanosome survives the immune response of its mammalian host by antigenic variation of its major surface antigen (the Variable Surface Glycoprotein, or VSG). Here we describe the antibody repertoires elicited by different VSGs. We show that the repertoires are highly restricted, directed predominantly to epitopes on the surface of the VSGs. They are also highly discriminatory: minor alterations within these exposed epitopes confer antigenically-distinct properties to these VSGs and elicit different repertoires. We propose that the patterned and repetitive nature of the VSG coat focuses host immunity to a restricted set of immunodominant epitopes per VSG, eliciting a highly stereotyped response, minimizing cross reactivity between different VSGs and facilitating prolonged immune evasion through epitope variation.

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