Development of a sensitive Luminex xMAP-based microsphere immunoassay for specific detection of Iris yellow spot virus

Development and evaluation of a bead-based Multiplexed Fluorescent ImmunoAssay (MFIA) for detection of antibodies to Salmonella enterica serogroup B and C1 in pigs

Background

Since 1995, a surveillance program for Salmonella has been applied in the Danish pig industry in order to reduce cases of human salmonellosis. The objective of this study was to develop a bead-based Multiplexed Fluorometric ImmunoAssay (MFIA) as an improved serological surveillance method compared to the Salmonella mix ELISA, which has been the national reference immunoassay in the Danish Salmonella surveillance program for about 20 years.

Results

An MFIA for detection of antibodies to Salmonella serogroup B and C₁ was developed and optimized with regard to coupling of beads with Salmonella lipopolysaccharide antigens and establishing suitable assay conditions. The Salmonella MFIA was validated by testing sera from experimentally infected pigs as well as field sera from non-infected and infected pig herds, and by comparing to results from the Salmonella mix ELISA, which was run in parallel. Sensitivity and specificity was evaluated using receiver operating curve analysis showing an area under curve for the serogroup B and C₁ MFIA of 0.984 and 0.998, respectively. The Salmonella MFIA was shown to detect more antibody-positive samples in seropositive herds compared to the Salmonella mix ELISA, and Bayesian statistics confirmed that the MFIA had a considerably higher sensitivity (94.5%) compared to the mix ELISA (75.1%). The assay specificity was slightly lower for the Salmonella MFIA (96.8%) compared to Salmonella mix ELISA (99.5%). Coupled beads were stable for at least 1 year at 4˚C, and MFIA reproducibility and repeatability of the Salmonella MFIA were acceptable. Results from proficiency tests also indicated that the Salmonella MFIA was more sensitive than the Salmonella mix ELISA and that they had similar specificity.

Conclusions

A bead-based MFIA for simultaneous detection of porcine serum antibodies to Salmonella enterica serogroup B and C₁ was developed and implemented in the Danish porcine serological Salmonella surveillance program in 2018. The Salmonella MFIA can distinguish, as opposed to the Salmonella mix ELISA, between antibodies to serogroup B and C₁ and the MFIA shows considerably better sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03362-w.

Comprehensive account of present techniques for in-field plant disease diagnosis

The early detection of plant pathogens is an appropriate preventive strategy for the management of crop yield and quality. For this reason, effective diagnostic techniques and tools, which are simple, specific, rapid and economic, are needed to be developed. Although several such technologies have been developed still most of them suffer one or the other limitation. Major limitations of the widely used diagnostic methods are requirement of trained staff and laboratory setup. Development of point-of-care diagnostic devices (handy portable devices) that require no specialized staff and can directly be used in fields is need of the hour. The aim of this review is to compile the information on current promising techniques that are in use for plant-pathogen diagnosis. Additionally, it focuses on the latest in-field pathogen diagnostic techniques with associated advantages and limitations.

Design and Evaluation of a Method for Testing Polymorphisms of Folate-Related Genes Using the Luminex Liquichip System

Purpose: The methylene tetrahydrofolate reductase (MTHFR) C677T, MTHFR A1298C, and the methionine synthase reductase (MTRR) A66G polymorphisms are the three most common folate metabolism-related loci in the Chinese population. They are associated with numerous birth defects or congenital diseases. To facilitate screening and genetic counseling, we established a method for the simultaneous detection of these three polymorphisms using the Luminex liquid suspension chip and multiple asymmetric polymerase chain reactions (PCRs). Materials and Methods: The three polymorphisms were amplified by multiplex PCR with biotinylated primers, followed by hybridization with six probe-linked magnetic microspheres. The mean fluorescent intensity value in each microsphere was detected by Luminex Magpix for polymorphism detection in 150 samples and confirmed by sequencing. Results: The consistency between the Luminex liquid suspension chip method and sequencing was 100%. Among the 150 randomized samples, the minor allele frequency (MAF) of MTHFR C677T was 0.41, which was the most common variant allele, followed by MTRR A66G (MAF = 0.24), and finally MTHFR A1298C (MAF = 0.19). Conclusion: The Luminex liquid suspension chip method can replace sequencing to analyze the MTHFR C677T, MTRR A1298C, and MTRR A66G loci simultaneously as a rapid, convenient, accurate, and stable method for large-scale testing.