Human Opsonins Induced during Meningococcal Disease Recognize Transferrin Binding Protein Complexes

Abstract

Patient serum opsonins against transferrin binding protein A+B (TbpA+B) complexes from two Neisseria meningitidis strains (K454 and B16B6, with 85- and 68-kDa TbpB, respectively) were quantified by a functional phagocytosis and oxidative burst assay. TbpA+B complexes adsorbed to fluorescent beads were opsonized with individual acute and convalescent sera from 40 patients infected by a variety of meningococcal strains. Flow cytometric quantitation of leukocyte phagocytosis products (PP) demonstrated that disease-induced serum opsonins recognized TbpA+B, and the highest anti-TbpA+B serum opsonic activities were found between admission to hospital and 6 weeks later. The PP values obtained with TbpA+B from strain B16B6 (PPB16B6) were higher than those obtained with TbpA+B from strain K454 (PPK454), with both acute and convalescent sera (P < 0.0001), and correlated positively with higher immunoglobulin G enzyme-linked immunosorbent assay titers against TbpA+B from strain B16B6 than from strain K454 (P < 0.001). In spite of considerable variations between individuals, significant correlations were found between the PPB16B6 and PPK454 values, and the PP values did not depend on the variability of the TbpB proteins of the disease-causing strains. Simultaneously measured oxidative burst activity correlated closely with the PP values. We conclude that highly cross-reactive anti-TbpA+B serum opsonins are produced during meningococcal disease. The anti-TbpA+B opsonic activities were not affected by the variability of the TbpB proteins of the disease-causing strains, which further adds to the evidence for the vaccine potential of meningococcal TbpA+B complexes.

Neisseria meningitidis serogroup B: laboratory correlates of protection

“…FITC-labeling or heat-killing of bacteria might destroy epitope conformation and therefore not re£ect the epitope exposition on live bacteria [31]. Antigen-coated beads probably present antigens similar to the native conformation and have the advantage that antigen speci¢city of serum opsonic activity can be studied as well [22,32]. Serum opsonic activity has been shown to correlate with IgG titers against OMVs, PorA and PorB measured by enzyme-linked immunosorbent assay (ELISA) [22,33] and SBA [34].…”

Neisseria meningitidisserogroup B: laboratory correlates of protection

“…FITC‐labeling or heat‐killing of bacteria might destroy epitope conformation and therefore not reflect the epitope exposition on live bacteria [31]. Antigen‐coated beads probably present antigens similar to the native conformation and have the advantage that antigen specificity of serum opsonic activity can be studied as well [22,32]. Serum opsonic activity has been shown to correlate with IgG titers against OMVs, PorA and PorB measured by enzyme‐linked immunosorbent assay (ELISA) [22,33] and SBA [34].…”

Imunização Nasal Em Coelhos Com Neisseria Lactamica: Importância Dos Antígenos De Reatividade Cruzada

“…A bactéria coberta com FITC pode destruir a conformação do epítopo e, portanto, não refletir a exposição do epítopo sobre a bactéria viva (Michaelsen et al, 2001). No entanto antígenos cobertos com beads provavelmente apresentam serem similares à conformação nativa e tem a vantagem de poder se estudar melhor a especificidade da atividade opsonofagocítica do soro (Lehmann et al, 1999). A atividade opsonofagocítica do soro tem demonstrado correlação com títulos IgG contra OMVs, Por A e Por B medida por meio do ensaio de (ELISA) e pela atividade bactericida (SBA) (Aase et al, 1995).…”