A Single-Step Gold Nanoparticle–Blood Serum Interaction Assay Reveals Humoral Immunity Development and Immune Status of Animals from Neonates to Adults

Abstract

A well-developed, functional immune system is paramount to combat harmful attacks from pathogenic organisms and prevent infectious diseases. Newborn animals and humans have only limited immunity upon birth, but their immune functions are expected to develop within weeks to months and eventually to reach a maturity that will provide full protection. Despite the importance of immune activity in animal and human health management, there is no convenient test available that allows for rapid assessment of the state of immune function in nonlaboratory settings. Here we report an extremely simple and rapid blood test that may be used in point-of-care clinics or field settings to evaluate the humoral immune status of animals. The test detects a cooperative interaction between a gold nanoparticle and arguably the three most important proteins involved in the immune system: immunoglobulin M (IgM), immunoglobulin G (IgG), and at least one complement protein, C3, in the blood serum. Such interactions cause the gold nanoparticles to form clusters and aggregates. The average particle size of the gold nanoparticle−serum mixture, measured by dynamic light scattering, corresponds positively to the immune status and activity of the subject. Our study demonstrates that the test may be used not only for monitoring the immune function development from neonates to adults, but also for detecting active immune responses during infection. Although data reported here are largely based on murine and bovine models, it is likely that this test will be applicable to humans as well.

A Rapid Blood Test to Monitor the Immune Status Change of Dairy Cows and to Evaluate their Disease Risk during the Periparturient Period

“…Once IgG and IgM are bound to the nanoparticle, the entire structure will be recognized by the complement system as an antibody-coated pathogen particle, and a cascade of reactions and interactions will follow between the blood proteins and the IgG or IgM-bound nanoparticle. As we demonstrated in our previous studies [21], the D2Dx™ immunity test response is determined by the collective effect of IgG, IgM, complements, and possibly other proteins in the blood. In our current study, we further con rmed that a change of IgG1/IgG2 ratio in the blood will lead to a change of the D2Dx™ immunity test response.…”

“…Even though the test was designed to detect bovine IgG1/IgG2 relative quantity change, the test result is not an absolute quantity measurement of the IgG1/IgG2 ratio. In our previously published study [21], we explained in details the mechanism of this test. Brie y, the test uses a nanoparticle "pseudo" pathogen to probe the humoral immune status of a blood sample.…”

“…Although laboratory tools and tests are available to measure and evaluate different cellular and molecular components of the immune system, these are typically not suitable for on-site farm testing. Here we report the use of a newly developed, D2Dx™ immunity test, to monitor the immune status change in dairy cows during the transition period [20,21]. This is a single-step test requiring only the mixing of a testing reagent with a small volume of un-diluted and un-treated blood serum or plasma providing a test result within 30 seconds.…”

Specific immunological areactivity formation during gestation period in pregnant sows

“…Chronic carrier of pathogens in animals and their influence on the spread of the infectious process is an urgent problem of modern veterinary medicine. The possibility of vaccination in newborns is limited by the presence of maternal antibodies that have an immunosuppressive effect [4][5][6][7][8][9][10][11].…”

“…The purpose of this study is to obtain additional information about changes in some parameters of immunological areactivity induction in animals of various degrees of antigenic load [4,6,7,9].…”