A verified multiplexed immunoassay for detecting antibodies against infectious pathogens

Baseline screening  of population groups at increased risk of developing infectious diseases (ID) includes a number of ELISA-based analyses, thereby accounting for high cost laborious and time-consuming examination. Earlier wedeveloped a cheap multiplex assay allowing to quickly perform a complex initial testing. Here, we would like to describe a novel kit designed to simultaneously detect antibodies against the six ID pathogens in blood products (plasma, serum etc.): human immunodeficiency virus, hepatitis B and C viruses, cytomegalovirus, Treponema pallidum and Toxoplasma gondii. The kit is based on multiplex dot-immunoassay over flat protein arrays (immune chips) utilizing colloidal gold conjugates and silver development. It allows carrying out complex analysis at room temperature within 70 minutes and does not require highly-qualified personnel. In this article, the results of laboratory tests of the experimental sample of a multiplex kit are compared with commercial ELISA kits from five Russian manufacturers using an array of 240 blood product samples including 200 clinical serum (plasma) samples from patients with ID and 40 plasma samples from donors. It was shown that the multiplex test analysis has a sensitivity and specificity of at least 95%, and optical signals of the dot-assay correlate well with the optical density values obtained using commercial ELISA kits and allow a semiquantitative evaluation of the content of specific antibodies in the sample. Furthermore, multiplex analysis is quicker and cheaper compared to ELISA and can be carried out in field. The kit for multiplex dot-immunoassay of antibodies can provide a complex approach to the diagnosis of ID, significantly simplify initial testing, make it faster, more efficient and affordable for patients.