A rapid method for quantitation of antiviral antibodies

Fluorescence immunoassay for detecting periodontal bacterial pathogens in plaque

A particle concentration fluorescence immunoassay has been modified into a bacterial concentration fluorescence immunoassay (BCFIA) to rapidly detect periodontopathic bacteria in human plaque samples. The BCFIA utilizes fluorescently tagged monoclonal antibodies (MAbs) directed against the lipopolysaccharide of selected gram-negative plaque bacteria. Microorganisms closely associated with periodontal disease that can be identified in plaque with the BCFIA include Porphyromonas gingivalis, Bacteroides intermedius, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, and Eikenella corrodens. Briefly, the procedure involved mixing a patient's plaque sample or other bacterial preparation with a species-specific fluorescein isothiocyanate-labeled MAb in a specialized microtiter plate. This mixture was incubated to allow binding of the MAb to its homologous bacteria. The bound and unbound fluorescent tagged MAbs were separated by filtration in the modified microtiter plate, and the total bacterial bound fluorescence was determined with a fluorimeter. The number of a specific bacterial species in a given plaque sample or other bacterial suspension was estimated by reference to a primary standard carried through the BCFIA. The lower detection limit of the BCFIA was 10(3) to 10(4) bacterial cells from single cultures of bacteria or 10(4) bacterial cells in mixed cultures. The coefficient of variation within and between plates for each of the five bacterium-specific MAbs in screening plaque for the periodontal pathogens was less than 10%. These results demonstrate that microbes in plaque can be used as the solid phase in the BCFIA to detect and quantitate MAbs associated with specific bacteria quickly and reliably.

Bacteria as solid phase in a concentration fluorescence immunoassay analysis of antibodies to surface antigens

A modified solid-phase fluorescence immunoassay was developed using bacterial cells as the solid phase to screen antibodies produced against surface antigens from a clinical isolate of Escherichia coli, strain 1-149. The bacterial solid phase was used to analyze both polyclonal and monoclonal antibodies. The bacterial concentration fluorescence immunoassay (BCFIA) showed up to 50-fold greater sensitivity in bacterial cell detection as compared to ELISA (enzyme-linked immunosorbent assay). Moreover, BCFIA was considerably faster than ELISA with uniform reproducibility. This paper demonstrates the utility of using bacteria and their surface antigens as solid-phase matrices for antibody characterization in a FIA.

Rapid biotin-avidin method for quantitation of antiviral antibody isotypes

A rapid and efficient method is described for isotype quantitation of antiviral antibodies in mice infected with Theiler's murine encephalomyelitis virus (TMEV). Serum antibodies were reacted with fluorochrome-labeled TMEV in a modified fluid-phase particle concentration fluorescence immunoassay (PCFIA). Biotin and avidin were used to attach anti-immunoglobulin isotype antibodies to polystyrene particles by the separate incubation of biotinylated goat anti-mouse isotypes (IgG1-, IgG2a-, IgG2b-, IgG3-, or IgM-specific) with avidin coupled polystyrene particles. These anti-isotype particles captured the virus-antibody complexes. Mouse myeloma proteins were used to quantitate and standardize isotype profiles of normal mouse serum using fluorescein isothiocyanate (FITC)-labeled, goat anti-mouse isotypes and polystyrene particles coated with goat anti-mouse. These assays quantitated the affinity-purified mouse serum antiviral antibodies for the standardization of antiviral isotype assays. Immunoglobulin of all serum isotypes as well as the amount of virus-specific isotypes can be quantitated rapidly and accurately.

Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. III. Failure of neuroantigen-specific immune tolerance to affect the clinical course of demyelination

Intracerebral inoculation of Theiler's murine encephalomyelitis virus (TMEV) into susceptible mouse strains produces a chronic demyelinating disease in which mononuclear cell-rich infiltrates in the central nervous system (CNS) are prominent. Current evidence strongly supports an immune-mediated basis for myelin breakdown, with an effector role proposed for TMEV-specific, major histocompatibility complex (MHC) class II-restricted delayed-type hypersensitivity (DTH) responses in which lymphokine-activated macrophages mediate bystander demyelination. The present study examined the possibility that concomitant or later-appearing neuroantigen-specific autoimmune T cell responses, such as those demonstrated in chronic-relapsing experimental allergic encephalomyelitis (R-EAE), may contribute to the demyelinating process following TMEV infection. T cell responses against intact, purified major myelin proteins (myelin basic protein (MBP) and proteolipid protein (PLP], and against altered myelin constituents were readily demonstrable in SJL/J mice with R-EAE, but were not detectable in SJL/J mice with TMEV-induced demyelinating disease. TMEV-infected mice also did not display T cell responses against the peptide fragments of MBP(91-104) and PLP(139-151) recently shown to be encephalitogenic in SJL/J mice. In addition, induction of neuroantigen-specific tolerance to a heterogeneous mixture of CNS antigens, via the i.v. injection of syngeneic SJL/J splenocytes covalently coupled with mouse spinal cord homogenate, resulted in significant suppression of clinical and histologic signs of R-EAE and the accompanying MBP- and PLP-specific DTH responses. In contrast, neuroantigen-specific tolerance failed to alter the development of clinical and histologic signs of TMEV-induced demyelinating disease or the accompanying virus-specific DTH and humoral immune responses. These findings demonstrate that TMEV-induced demyelinating disease can occur in the apparent absence of neuroantigen-specific autoimmune responses. The relationship of the present results to the immunopathology of multiple sclerosis is discussed.