PubMed · 16111201
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Hideyuki Shimazaki, Seiichi Tamai. 2005. [Immunologic tests: Circulating immune complex].. https://pubmed.ncbi.nlm.nih.gov/16111201/
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BACKGROUND: The aim of this study was to determine the clinical benefit of a new combined antigen-antibody immunoenzymatic assay (Monolisa HCV Ag-Ab Ultra, Biorad) in the setting of acute HCV infection in HIV infected patients. PATIENTS AND METHODS: The performance of this assay was first evaluated in 160 HIV positive samples from uninfected and chronically HCV infected patients. To assess the performance of the Ag-Ab assay in the context of acute hepatitis C, 94 stored frozen serums from 20 recently diagnosed cases were retrospectively tested for HCV-RNA and presence of anti-HCV antibodies, in parallel with the new assay. RESULTS: In HIV infected patients, the sensitivity and specificity of the Ultra assay was 100% with a strong discrimination between positive and negative samples. In HCV acutely infected patients, the Ag-Ab assay significantly reduced the seronegative period, allowing an earlier diagnosis compared to a 3rd generation ELISA in 65% of the cases. The combined assay became positive on the same bleed as the first HCV-RNA detection for 13 patients out of 20. Nevertheless, in one case, characterized by an absence of seroconversion over one year but a continuous viral replication above 1 million IU/ml, the combined assay did not improve HCV infection diagnosis. CONCLUSION: Use of this new assay as a first line screening would significantly reduce the long seronegative window period seen in HCV infection allowing earlier HCV diagnosis and rapid clinical management. However, in case of clinical acute hepatitis C, sensitive HCV-RNA detection should remain the gold standard.
The performance of polyclonal monospecific rabbit anti-sera raised against synthetic peptides derived from conserved HCV sequences of genotype 4 was evaluated for efficient detection of viral core and E1 antigens in circulating immune complexes (ICs) precipitated from 65 serum samples of HCV patients. The infection was established in those patients by the presence of HCV RNA in their sera. A novel enzyme-linked immunosorbent assay (ELISA) was developed for the detection of HCV core and E1 antigen in serum samples. Western blot analyses were used to demonstrate the presence of the core and E1 target antigen in serum samples. The mean OD readings of both core and E1 antigens were significantly higher (P < 0.05) among the viremic patients when compared to controls. Also a significant positive correlation (P < 0.05, r = 0.98) between the values of both core and E1 was recorded. Western blot analysis based on monospecific antibodies against core and E1 recognized the 38-kDa and 88 -kDa bands respectively in the sera of all infected patients. No specific reaction was observed with the sera from uninfected individuals. Interestingly the results of core and E1 antigen levels displayed no positive correlation with the HCV copy number as measured by bDNA. Liver enzymes (ALT and AST) showed a moderate positive correlation (r = 0.44 and 0.47 respectively) with the viral core antigens level. The same trend holds true for E1 (r = 0.43 and 0.64 for ALT and AST respectively). HCV load in infected patients revealed extremely poor correlation with serum ALT and AST levels (r = 0.022 and 0.002 respectively). In conclusion we present a new combination of serological tools correlating with liver enzyme levels that could be utilized as supplemental tests to viral load testing. Also, a sensitive and specific immunoassay was developed for the detection of HCV core and E1 in human serum. This test can be applied for laboratory diagnosis of HCV infection.
The reaction kinetics of antigen-antibody binding in the electrokinetically controlled microfluidic heterogeneous immunoassays has been investigated by numerical simulations. A two-dimensional computational model was employed to include the mass transport (convection and diffusion) and binding reaction between the antigen in the bulk flow and the immobilized antibody at the channel surface. The influence of the bulk velocity, the concentrations of the antibody and antigen, and the geometry of the microchips was studied for a variation of conditions and the guidance for designing of microfluidic immunoassay was provided. The model also shows that electrokinetically driven immunoassays have better reaction kinetics than pressure-driven ones, resulting from the plug-like velocity profile. Finally, a multi-patch immunoassay chip was analyzed and the reaction kinetics was optimized by rearranging the reaction patches at the channel surfaces.