scholarly journals Detection of Toxoplasma gondii Infections using Virus-Like Particles Displaying T. gondii ROP4 Antigen

2021 ◽  
Vol 59 (6) ◽  
pp. 565-572
Author(s):  
Min-Ju Kim ◽  
Jie Mao ◽  
Hae-Ji Kang ◽  
Ki-Back Chu ◽  
Fu-Shi Quan
Keyword(s):  
Toxoplasma Gondii ◽  
Early Stage ◽  
Dependent Manner ◽  
Igg Antibody ◽  
Serological Tests ◽  
Virus Like Particles ◽  
Highly Sensitive ◽  
Infection Diagnostics ◽  
Tissue Lysate ◽  
Specific Igg

Toxoplasma gondii ME49 infections are typically diagnosed by serological tests. However, serological diagnosis of RH strain-induced toxoplasmosis remains unknown. In order to develop seradiagnosis of above 2 kinds of infections, we generated recombinant virus-like particles (VLPs) displaying the T. gondii rhoptry protein 4 (ROP4) and evaluated their potential in T. gondii ME49 or RH strain infection diagnostics. Mice were orally infected with either the tachyzoites of T. gondii (RH) or cysts of T. gondii (ME49) at various dosages, and sera were collected at regular intervals. ELISA-based serological tests were performed to assess IgG, IgM, and IgA antibody responses against ROP4 VLP antigen and tissue lysate antigen (TLA). Compared to TLA, IgG, IgM, and IgA levels to ROP4 VLP antigen were significantly higher in the sera of T. gondii RH-infected mice 1 and 2 week post-infection (PI). T. gondii-specific IgG antibody was detected at 1, 2, 4, and 8 week PI in the T. gondii ME49-infected mice with infection dose-dependent manner. These results indicated that the ROP4 VLP antigen was highly sensitive antigens detecting T. gondii RH and ME49 antibodies at an early stage.

scholarly journals Detection of Human Toxoplasma-Specific Immunoglobulins A, M, and G with a Recombinant Toxoplasma gondii Rop2 Protein

1998 ◽  
Vol 5 (5) ◽  
pp. 627-631 ◽  
Author(s):  
Valentina Martin ◽  
Miriam Arcavi ◽  
Graciela Santillan ◽  
Maria Regina R. Amendoeira ◽  
Elizabeth De Souza Neves ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Early Stage ◽  
Humoral Response ◽  
Enzyme Linked Immunosorbent Assay ◽  
Diagnostic Systems ◽  
Igg Antibody ◽  
Serological Tests ◽  
Antibody Reactivity ◽  
Group A ◽  
Group D

ABSTRACT The Toxoplasma gondii rhoptry protein Rop2 was expressed in Escherichia coli as a fusion protein containing 44 kDa of the 55-kDa mature Rop2, supplied with six histidyl residues at the N-terminal end (Rop2196–561). Humoral response during Toxoplasma infection of humans was analyzed by immunoglobulin G (IgG), IgA, and IgM enzyme-linked immunosorbent assay with Rop2196–561 as the antigen substrate. The analyzed sera were divided according to T. gondii-specific serological tests (IgG, IgA, or IgM indirect immunofluorescence and IgA or IgM immunosorbent agglutination assay) as group A (IgG+ IgA− IgM−;n = 35), group B (IgG+ IgA+IgM+; n = 21), group C (IgG+IgA+ IgM−; n = 5), and group D (IgG+ IgA− IgM+;n = 16). Twenty-six T. gondii-seronegative sera from individuals with other infections were also included (group E). Anti-Rop2 IgG antibodies were detected in 82.8% of group A sera and in 97.6% of the sera with acute-phase marker immunoglobulins (groups B, C, and D). The percentage of IgA antibody reactivity against Rop2196–561 was 17.1% in group A, 50% in group D, and 80.8% in groups B and C. The percentage of IgM antibody reactivity was 0% in groups A and C and 62% in groups B and D. Sera from group E failed to show IgA, IgM, or IgG antibody reactivity. Since T. gondii Rop2 elicits a strong humoral response from an early stage of infection, it is suggested that recombinant Rop2196–561 would be suitable for use in diagnostic systems, in combination with other T. gondii antigens, to detect specific IgG, IgA, and IgM antibodies.

scholarly journals Electrochemical Detection of Waterborne Bacteria Using Bi-Functional Magnetic Nanoparticle Conjugates

Biosensors ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 36
Author(s):  
Dharanivasan Gunasekaran ◽  
Yoram Gerchman ◽  
Sefi Vernick
Keyword(s):  
Electrochemical Detection ◽  
Electrochemical Method ◽  
Magnetic Nanoparticle ◽  
Specific Binding ◽  
Dependent Manner ◽  
Igg Antibody ◽  
E Coli ◽  
Amine Functionalized ◽  
Highly Sensitive ◽  
Dose Dependent

Detection of microbial contamination in water is imperative to ensure water quality. We have developed an electrochemical method for the detection of E. coli using bi-functional magnetic nanoparticle (MNP) conjugates. The bi-functional MNP conjugates were prepared by terminal-specific conjugation of anti-E. coli IgG antibody and the electroactive marker ferrocene. The bi-functional MNP conjugate possesses both E. coli-specific binding and electroactive properties, which were studied in detail. The conjugation efficiency of ferrocene and IgG antibodies with amine-functionalized MNPs was investigated. Square-wave voltammetry enabled the detection of E. coli concentrations ranging from 101–107 cells/mL in a dose-dependent manner, as ferrocene-specific current signals were inversely dependent on E. coli concentrations, completely suppressed at concentrations higher than 107 cells/mL. The developed electrochemical method is highly sensitive (10 cells/mL) and, coupled to magnetic separation, provides specific signals within 1h. Overall, the bi-functional conjugates serve as ideal candidates for electrochemical detection of waterborne bacteria. This approach can be applied for the detection of other bacteria and viruses.

scholarly journals Reliability of serological tests for COVID-19: Comparison of three immunochromatography test kits for SARS-CoV-2 antibodies

2020 ◽  
Author(s):  
Hidetsugu Fujigaki ◽  
Masao Takemura ◽  
Michiko Osawa ◽  
Aki Sakurai ◽  
Kentaro Nakamoto ◽  
...  
Keyword(s):  
Early Stage ◽  
Serological Test ◽  
Entire Period ◽  
Serum Samples ◽  
Igg Antibody ◽  
Serological Tests ◽  
Igm Antibody ◽  
Potential Clinical Utility ◽  
Almost All ◽  
Positive Results

AbstractBackgroundSeveral immunochromatographic serological test kits have been developed to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibodies, but their relative performance and potential clinical utility is unclear.MethodsThree commercially available serological test kits were evaluated using 99 serum samples collected from 29 patients diagnosed with coronavirus disease 2019 (COVID-19).ResultsThe IgM antibody-positive rates of the three serological test kits for samples taken at the early stage of the disease (0–6 days after onset) were 19.0%, 23.8%, and 19.0%, respectively. The IgM antibody-positive rates over the entire period were 21.2%, 60.6%, and 15.2%, respectively. The IgG antibody-positive rates for samples taken after 13 days of onset were 100.0%, 97.6%, and 97.6%, respectively.ConclusionThere were large differences among the results of the three test kits. Only few cases showed positive results for IgM in the early stage of disease and the IgM antibody-positive rates over the entire period were low, suggesting that the kits used in this study were unsuitable for diagnosis of COVID-19. The IgG antibody was positive in almost all samples after 13 days of onset, suggesting that it may be useful for determining infections in the recent past.

scholarly journals Evaluating SARS-CoV-2 spike and nucleocapsid proteins as targets for IgG antibody detection in severe and mild COVID-19 cases using a Luminex bead-based assay

2020 ◽  
Author(s):  
Joachim Marien ◽  
Johan Michiels ◽  
Leo Heyndrickx ◽  
Karen Kerkhof ◽  
Nikki Foque ◽  
...  
Keyword(s):  
Large Scale ◽  
Detection Threshold ◽  
Neutralizing Antibody ◽  
Cost Effective ◽  
Antibody Detection ◽  
Igg Antibodies ◽  
Igg Antibody ◽  
Serological Tests ◽  
Specific Igg ◽  
Antibody Levels

Large-scale serosurveillance of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) will only be possible if serological tests are sufficiently reliable, rapid and inexpensive. Current assays are either labour-intensive and require specialised facilities (e.g. virus neutralization assays), or expensive with suboptimal specificity (e.g. commercial ELISAs). Bead-based assays offer a cost-effective alternative and allow for multiplexing to test for antibodies of other pathogens. Here, we compare the performance of four antigens for the detection of SARS-CoV-2 specific IgG antibodies in a panel of sera that includes both severe (n=40) and mild (n=52) cases, using a neutralization and a Luminex bead-based assay. While we show that neutralising antibody levels are significantly lower in mild than in severe cases, we demonstrate that a combination of recombinant nucleocapsid protein (NP), receptor-binding domain (RBD) and the whole spike protein (S1S2) results in a highly sensitive (96%) and specific (99%) bead-based assay that can detect IgG antibodies in both groups. Although S1-specific IgG levels correlate most strongly with neutralizing antibody levels, they fall below the detection threshold in 10% of the cases in our Luminex assay. In conclusion, our data supports the use of RBD, NP and S1S2 for the development of SARS-CoV-2 serological bead-based assays. Finally, we argue that low antibody levels in mild/asymptomatic cases might complicate the epidemiological assessment of large-scale surveillance studies.

scholarly journals Insights on the mechanisms of the protective immunity in the brain from the studies on infection with an intracellular microorganism, Toxoplasma gondii

2021 ◽  
Vol 9 (11) ◽  
Author(s):  
Yasuhiro Suzuki
Keyword(s):  
T Cells ◽  
Toxoplasma Gondii ◽  
Cd8 T Cells ◽  
Protective Immunity ◽  
Early Stage ◽  
Cytotoxic T Cells ◽  
Host Cells ◽  
Protective Mechanism ◽  
Dependent Manner ◽  
The Brain

The immune system operates the protection against infections by selecting efficient pathways depending on the pathogen. Toxoplasma gondii, an obligate intracellular protozoan parasite, has two lifecycle stages, tachyzoite and cyst, in intermediate hosts including humans. Tachyzoite is the acute stage form that quickly proliferates within host cells. Cyst is the chronic stage form that can slowly grow into more than 100 mm in diameter by containing hundreds to thousands of bradyzoites. Our studies on the IFN-g-mediated protective immunity against cerebral tachyzoite growth revealed that IFN-g production by brain-resident cells is not only required for upregulation of the innate protective immunity to limit cerebral tachyzoite proliferation during the early stage of the tachyzoite growth but also crucial for recruiting immune T cells from the periphery and activation of the recruited T cells to ultimately prevent the tachyzoite growth. Since IFN-g is crucial for the protective immunity against various intracellular microorganisms in the brain, it is possible that IFN-gproduced by brain-resident cells plays a key first line defense role by orchestrating both the innate and T cell-mediated protective immunity to control not only T. gondii but also the other intracellular pathogens. Our studies on the protective immunity against T. gondii cysts uncovered the capability of cytotoxic T cells to penetrate into the target in a perforin-dependent manner for its elimination. After penetrating into the target, the cytotoxic T cells secrete granzyme B, which associates with an accumulation of phagocytes to eliminate the parasite. Since the presence of tumor-infiltrating CD8+ T cells in solid cancers is an indicator of positive prognosis of cancer patients, the perforin-mediated penetration of CD8+ T cells and an accumulation of phagocytes could function as a powerful protective mechanism against not only T. gondiicysts but also targets of large mass in general such as solid cancers.

scholarly journals Serine Protease Inhibitors Block Invasion of Host Cells by Toxoplasma gondii

1999 ◽  
Vol 43 (6) ◽  
pp. 1358-1361 ◽  
Author(s):  
V. Conseil ◽  
M. Soête ◽  
J. F. Dubremetz
Keyword(s):  
Toxoplasma Gondii ◽  
Serine Protease ◽  
Protease Inhibitors ◽  
Early Stage ◽  
Protozoan Parasite ◽  
Gliding Motility ◽  
Host Cells ◽  
Dependent Manner ◽  
Serine Protease Inhibitors ◽  
Experimental Conditions

ABSTRACT We investigated the effect of protease inhibitors on the asexual development of the protozoan parasite Toxoplasma gondii. Among the inhibitors tested only two irreversible serine protease inhibitors, 3,4-dichloroisocoumarin and 4-(2-aminoethyl)-benzenesulfonyl fluoride, clearly prevented invasion of the host cells by specifically affecting parasite targets in a dose-dependent manner, with 50% inhibitory concentrations between 1 and 5 and 50 and 100 μM, respectively. Neither compound significantly affected parasite morphology, basic metabolism, or gliding motility within the range of the experimental conditions in which inhibition of invasion was demonstrated. No partial invasion was observed, meaning that inhibition occurred at an early stage of the interaction. These results suggest that at least one serine protease of the parasite is involved in the invasive process of T. gondii.

scholarly journals Study on Toxoplasma gondii, Leptospira spp., Coxiella burnetii, and Echinococcus granulosus infection in veterinarians from Poland

2018 ◽  
Vol 62 (4) ◽  
pp. 477-483 ◽  
Author(s):  
Angelina Wójcik-Fatla ◽  
Jacek Sroka ◽  
Violetta Zając ◽  
Jacek Zwoliński ◽  
Anna Sawczyn-Domańska ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Echinococcus Granulosus ◽  
Coxiella Burnetii ◽  
Igg Antibodies ◽  
Serological Tests ◽  
Zoonotic Infections ◽  
Provinces Of Poland ◽  
Specific Igg ◽  
Positive Results ◽  
Specific Igg Antibodies

AbstractIntroduction: Exposure to zoonotic factors in veterinary practice is closely related to the nature of the work. The main aim of the study was to determine the risk of selected zoonotic infections among the occupational group of veterinarians in Poland.Material and Methods: Blood samples of 373 veterinarians (162 males and 211 females) from 12 provinces of Poland were collected by the venipuncture of a forearm for serological tests. Commercial immunoenzymatic tests (ELISA) were used for detection of specific IgG antibodies to Echinococcus granulosus, IgM and IgG to Leptospira spp., and IgM, IgA, and I and II phase IgG to Coxiella burnetii. Enzyme-linked fluorescence assays (ELFA) were used to detect IgM and IgG antibodies to Toxoplasma gondii.Results: Positive results were found in 209 (56.0%) veterinarians for at least one of the examined diseases. The overall proportion of participants found to have specific Toxoplasma gondii antibodies in the IgM and/or IgG assays amounted to 44.5%. The presence of Coxiella burnetii antibodies was found in 16 (4.3%) subjects, while Leptospira spp. antibodies were detected in 63 (16.9%) veterinarians. Among the 373 veterinarians examined, no Echinococcus granulosus antibodies were found.Conclusion: Results of the study seem to indicate a slightly elevated risk of Toxoplasma gondii infection and a moderate risk of infection with Leptospira spp. and Coxiella burnetii in veterinarians.

scholarly journals Spiramycin Treatment of Toxoplasma gondii Infection in Pregnant Women Impairs the Production and the Avidity Maturation of T. gondii-Specific Immunoglobulin G Antibodies

2009 ◽  
Vol 16 (10) ◽  
pp. 1517-1520 ◽  
Author(s):  
V. Meroni ◽  
F. Genco ◽  
C. Tinelli ◽  
P. Lanzarini ◽  
L. Bollani ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Pregnant Women ◽  
Immunoglobulin G ◽  
Adult Patients ◽  
Control Group ◽  
Igg Antibody ◽  
Specific Immunoglobulin ◽  
Specific Igg ◽  
Toxoplasma Gondii Infection ◽  
Avidity Maturation

ABSTRACT The aim of the study was to evaluate the influence of treatment with spiramycin on the increase of immunoglobulin G (IgG) titers and IgG avidity indexes (AI) in pregnant women with seroconversion from the beginning of therapy until delivery and after delivery. This group was compared with adult patients with recently acquired untreated toxoplasmosis. One hundred four samples from 32 pregnant women with seroconversion for toxoplasmosis and/or very low IgG AI were followed from the beginning of therapy with spiramycin until delivery. Twenty-nine women were further followed some months after delivery and interruption of therapy. Thirty-eight samples from 16 untreated, nonpregnant patients were evaluated as the control group. The Toxoplasma gondii-specific IgG antibody and the T. gondii-specific IgG AI were significantly delayed in pregnant women receiving therapy compared to nonpregnant, untreated controls, and the findings were consistent with the results of assays from two different manufacturers. The T. gondii-specific IgG AI increased in pregnant women after they gave birth. Avidity maturation is delayed during pregnancy and treatment, and low-avidity antibodies in pregnant women within 3 to 4 months cannot be taken as a sign of infection.

Duffy antigen / receptor for chemokines correlates with inflammatory reaction in rats with venous hypertension: implication for the pathogenesis of primary chronic venous disease

VASA ◽  
2014 ◽  
Vol 43 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Weibin Huang ◽  
Weiwei Qin ◽  
Lei Lv ◽  
Haoyv Deng ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Early Stage ◽  
Antigen Receptor ◽  
Venous Hypertension ◽  
Skin Tissue ◽  
Chronic Venous Disease ◽  
Venous Disease ◽  
Dependent Manner ◽  
Time Points ◽  
Duffy Antigen

Background: Duffy antigen / receptor for chemokines (DARC) possesses high affinity for several chemokine subgroups of CC and CXC. Although DARC has been shown to play a role in many inflammatory diseases, its effect on chronic venous disease (CVD) remains unidentified. We explored whether the expression of DARC in skin tissue was activated under venous hypertension as well as the relationships between DARC and inflammation. Materials and methods: The inflammation in a rat model of venous hypertension caused by a femoral arterial-venous fistula (AVF) was studied. At specified intervals the pressure in the femoral veins was recorded within 42 days. Hindlimb skin specimens were harvested at different time points. The expressions of DARC, interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) in skin tissue were examined. Mononuclear cells infiltrated in skin tissue were detected. Results: Femoral venous pressures in AVF groups increased significantly at different time points (P < 0.01). DARC was expressed in skin tissue and its expression level increased significantly in AVF groups from the 7nd day on and was enhanced in a time-dependent manner within 42 days (P < 0.05). Meanwhile, both MCP-1 and IL-8 had higher levels, accompanied by increased mononuclear cells infiltrating into skin tissue (P < 0.05). Conclusions: A rat AVF model which can maintain venous hypertension for at least 42 days is competent for researching the pathogenesis of CVD. DARC, which plays a role in the inflammation of skin tissue under venous hypertension, may become a new molecular target for diagnosis and treatment of CVD at a very early stage.

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