New highly sensitive sandwich ELISA system for soluble endoglin quantification in different biological fluids

Review detection of Newcastle disease virus

Newcastle disease (ND) is an acute and highly contagious disease caused by the Newcastle disease virus (NDV) infecting poultry, which has caused great harm to the poultry industry around the world. Rapid diagnosis of NDV is important to early treatment and early institution of control measures. In this review, we comprehensively summarize the most recent research into NDV, including historical overview, molecular structure, and infection mechanism. We then focus on detection strategies for NDV, including virus isolation, serological assays (such as hemagglutination and hemagglutination-inhibition tests, enzyme linked immunosorbent assay, reporter virus neutralization test, Immunofluorescence assay, and Immune colloidal gold technique), molecular assays (such as reverse transcription polymerase chain reaction, real-time quantitative PCR, and loop-mediated isothermal amplification) and other assays. The performance of the different serological and molecular biology assays currently available was also analyzed. To conclude, we examine the limitations of currently available strategies for the detection of NDV to lay the groundwork for new detection assays.

Prediction of preeclampsia based on maternal serum endoglin level in women with pregestational diabetes mellitus

PURPOSE

To evaluate the level of soluble endoglin (sEng) in pregnant women with pregestational diabetes mellitus (DM) and to assess its predictive value for preeclampsia development.

METHODS

Ninety pregnant women were enrolled in the study forming five comparison groups: type 1 DM (not planned, n = 20; planned, n = 20), type 2 DM (diet, n = 15; insulin therapy, n = 20), and the control group (n = 15). The primary outcome was clinically confirmed preeclampsia. Maternal serum concentrations of sEng were measured at 11+0-13+6 and 30+0-33+6 weeks.

RESULTS

sEng level was elevated in all patients with pregestational DM compared to the control group. Its plasma concentration increased with gestational age and in case of preeclampsia development. In patients with type 1 DM, serum sEng level did not depend on the presence of preeclampsia. This is evidence of severe metabolic disorder and endothelial dysfunction in these patients. The addition of sEng level to logistic models considering established risk factors (body mass index + age + HbA1c level) in the first and third trimesters significantly improved their performance for preeclampsia prediction.

CONCLUSIONS

Eng level may become an important marker for early prediction of preeclampsia in women with pregestational DM.

The role of endoglin and its soluble form in pathogenesis of preeclampsia

Preeclampsia remains till today a leading cause of maternal and fetal morbidity and mortality. Pathophysiology of the disease is not yet fully elucidated, though it is evident that it revolves around placenta. Cellular ischemia in the preeclamptic placenta creates an imbalance between angiogenic and anti-angiogenic factors in maternal circulation. Endoglin, a transmembrane co-receptor of transforming growth factor β (TGF-β) demonstrating angiogenic effects, is involved in a variety of angiogenesis-dependent diseases with endothelial dysfunction, including preeclampsia. Endoglin expression is up-regulated in preeclamptic placentas, through mechanisms mainly induced by hypoxia, oxidative stress and oxysterol-mediated activation of liver X receptors. Overexpression of endoglin results in an increase of its soluble form in maternal circulation. Soluble endoglin represents the extracellular domain of membrane endoglin, cleaved by the action of metalloproteinases, predominantly matrix metalloproteinase-14. Released in circulation, soluble endoglin interferes in TGF-β1 and activin receptor-like kinase 1 signaling pathways and inhibits endothelial nitric oxide synthase activation, consequently deranging angiogenesis and promoting vasoconstriction. Due to these properties, soluble endoglin actively contributes to the impaired placentation observed in preeclampsia, as well as to the pathogenesis and manifestation of its clinical signs and symptoms, especially hypertension and proteinuria. The significant role of endoglin and soluble endoglin in pathophysiology of preeclampsia could have prognostic, diagnostic and therapeutic perspectives. Further research is essential to extensively explore the potential use of these molecules in the management of preeclampsia in clinical settings.

Soluble endoglin concentration in maternal blood as a diagnostic biomarker of preeclampsia: A systematic review and meta-analysis

OBJECTIVE

Preeclampsia is a main cause of maternal and fetal morbidity and mortality. Research about maternal circulating diagnostic biomarkers is continuously performed, often with conflicting results that necessitate quantitative synthesis. Objective of this meta-analysis is to examine the value of soluble endoglin as predictor of preeclampsia separately at each pregnancy trimester, therefore exploring its potential usage as diagnostic biomarker in preeclampsia.

STUDY DESIGN

This systematic review and meta-analysis adhered to PRISMA and MOOSE guidelines. MEDLINE, SCOPUS, Cochrane CENTRAL and ClinicalTrials.gov were searched up to April 20, 2020. Included studies were those comparing soluble endoglin levels in maternal serum or plasma at any pregnancy trimester, between women who subsequently developed preeclampsia and normotensive pregnant women being low-risk for preeclampsia development. Primary outcome was development of preeclampsia, while soluble endoglin levels in 1 st, 2nd and 3rd trimester of pregnancy were examined as possible predictors of preeclampsia. Subgroup analysis was performed regarding time of preeclampsia onset (early, late). Methodological quality of included studies was assessed using Newcastle-Ottawa scale. Overall quality of evidence for primary and secondary outcomes was evaluated using GRADEpro GD tool.

RESULTS

There were overall 20 studies included in meta-analysis, enrolling 1146 preeclamptic and 1675 normotensive pregnant women. Soluble endoglin concentration (ng/mL) was significantly higher in preeclamptic women during 2nd (8 studies, MD:5.554, 95 %CI:2.671-8.436, P < .001, I² = 97 %) and 3rd trimester (12 studies, MD:31.006, 95 %CI:24.734-37.278, P < .001, I² = 98 %). Levels were also higher during 1st trimester; however, the difference was marginally not significant (MD:1.105, 95 %CI: -0.071 to 2.282, P = .06, I² = 64 %). Furthermore, levels were significantly higher both in early-onset and late-onset preeclamptic vs normotensive pregnancies, (4 studies, MD:51.611, 95 %CI:2.250-100.972, P = .04, I² = 97 %), (5 studies, MD:12.426, 95 %CI:7.863-16.989, P < .001, I² = 98 %) respectively. However, when comparing directly early and late-onset preeclamptic women, no significant difference was detected (3 studies, MD:20.725, 95 %CI: -11.601 to 53.052, P = .209, I² = 93 %).

CONCLUSIONS

Soluble endoglin levels were consistently higher in preeclamptic compared to normotensive pregnant women almost throughout pregnancy. Our results firmly indicate soluble endoglin's potential use as predictor of preeclampsia. Further studies are required to support the use of soluble endoglin as a diagnostic tool for preeclampsia in clinical settings.

Fenobody and RANbody-based sandwich enzyme-linked immunosorbent assay to detect Newcastle disease virus

BACKGROUND

Traditional sandwich enzyme-linked immunosorbent assay (ELISA) using polyclonal and monoclonal antibodies as reagents presents several drawbacks, including limited amounts, difficulty in permanent storage, and required use of a secondary antibody. Nanobodies can be easily expressed with different systems and fused with several tags in their tertiary structure by recombinant technology, thus offering an effective detection method for diagnostic purposes. Recently, the fenobody (ferritin-fused nanobody) and RANbody (nanobody-fused reporter) have been designed and derived from the nanobody for developing the diagnostic immunoassays. However, there was no report about developing the sandwich ELISA using the fenobody and RANbody as pairing reagents.

RESULTS

A platform for developing a sandwich ELISA utilizing fenobody as the capture antibody and RANbody as the detection antibody was firstly designed in the study. Newcastle disease virus (NDV) was selected as the antigen, from which 13 NDV-specific nanobodies were screened from an immunized Bactrian camel. Then, 5 nanobodies were selected to produce fenobodies and RANbodies. The best pairing of fenobodies (NDV-fenobody-4, 800 ng/well) and RANbodies (NDV-RANbody-49, 1:10) was determined to develop the sandwich ELISA for detecting NDV. The detection limits of the assay were determined to be 2² of hemagglutination (HA) titers and 10 ng of purified NDV particles. Compared with two commercial assays, the developed assay shows higher sensitivity and specificity. Meanwhile, it exhibits 98.7% agreement with the HA test and can detect the reference NDV strains belonging to Class II but not Class I.

CONCLUSIONS

In the presented study, the 13 anti-NDV nanobodies binding the NDV particles were first produced. Then, for the first time, the sandwich ELISA to detect the NDV in the different samples has been developed using the fenobody and RANbody as reagents derived from the nanobodies. Considering the rapidly increasing generation of nanobodies, the platform can reduce the cost of production for the sandwich ELISA and be universally used to develop assays for detecting other antigens.