RESUMEN
The antibody response to Bartonella henselae has been studied in a number of mammals; however, the human response needs to be further studied. After natural infection, humans have antibody reactivity to a large number of B. henselae proteins. We used a proteomic approach to identify antigenic proteins of B. henselae to determine their capacity to elicit a human antibody response. Comparing patient sera by Western blot analysis demonstrated significant amounts of reactivity to B. henselae. The immunofluorescence assay (IFA)-positive sera identified several protein spots of interest. However, a consistent reactivity to a single spot by all sera was not observed. Three of these spots demonstrated reactivity in 71%, 64%, and 64% of positive sera tested with negligible reactivity to the negative sera. These proteins were identified as GroES, BepA, and GroEL. Most IFA-positive sera demonstrated reactivity to GroES, GroEL, and BepA. The usefulness of these proteins for a clinical serologic assay is discussed.
Asunto(s)
Angiomatosis Bacilar/inmunología , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Bartonella henselae/inmunología , Angiomatosis Bacilar/diagnóstico , Anticuerpos Antibacterianos/sangre , Antígenos Bacterianos/análisis , Proteínas Bacterianas/análisis , Electroforesis en Gel Bidimensional , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Proteómica , Pruebas SerológicasRESUMEN
Phosphorylcholine (ChoP) is an antigenic component on the cell surface of many commensal and pathogenic bacteria that reside in the upper airway. In the present study, human ChoP-specific antibody was affinity-purified from pooled serum gamma globulin. This naturally acquired antibody, which is primarily of the immunoglobulin (Ig) G2 subtype, recognized ChoP on the lipoteichoic acid of Streptococcus pneumoniae and on the lipopolysaccharide of Haemophilus influenzae, 2 of the leading etiologic agents of infection involving the human respiratory tract. In in vitro killing assays, anti-ChoP IgG2 was effective against some clinical isolates of nontypeable H. influenzae and against isolates of several common serotypes of S. pneumoniae. Moreover, passively administered human anti-ChoP antibody protected mice against lethal challenge with a transparent isolate of S. pneumoniae type 6A. The effectiveness of human antibody to this conserved bacterial structure suggests that, if it can be manipulated to broaden its activity, it could function as a single vaccine antigen that targets multiple pathogens.
Asunto(s)
Anticuerpos Antibacterianos/inmunología , Haemophilus influenzae/inmunología , Inmunoglobulina G/inmunología , Fosforilcolina/inmunología , Streptococcus pneumoniae/inmunología , Vacunas Bacterianas/inmunología , Reacciones Cruzadas , HumanosRESUMEN
Colonization is the first step in the interaction between Streptococcus pneumoniae and its human host. To better understand the mechanisms contributing to natural carriage, a mouse model of pneumococcal colonization was developed with a clinical isolate of S. pneumoniae previously characterized in experimental colonization of humans. Similar to carriage events in humans, colonization of mice was self-limited and there was no evidence of lower respiratory tract or invasive disease. Carriage induced a serum antibody response to whole pneumococci that was associated temporally with clearance of colonization in three inbred strains of mice. Individual mice, however, did not demonstrate a correlation between the density of colonization and amounts of serum or of mucosal antibodies, including antibodies of different isotypes and antigenic specificities. The role of antibody in the clearance of carriage was then examined in mice with genetic defects in humoral immunity. xid mice, which have deficient responses to polysaccharide antigens, cleared colonization at the same rate as the parent strain. Finally, we showed that microMT mice, which lack mature B cells and fail to produce antibody, were unaffected in the density or duration of colonization. These results demonstrate that antibody is not required for clearance of pneumococcal colonization in mice.
Asunto(s)
Anticuerpos Antibacterianos/inmunología , Modelos Animales de Enfermedad , Infecciones Neumocócicas/inmunología , Infecciones Neumocócicas/microbiología , Streptococcus pneumoniae/crecimiento & desarrollo , Streptococcus pneumoniae/inmunología , Animales , Formación de Anticuerpos/genética , Formación de Anticuerpos/inmunología , Especificidad de Anticuerpos , Antígenos Bacterianos/inmunología , Linfocitos B/citología , Linfocitos B/inmunología , Proteínas Bacterianas/inmunología , Ensayo de Inmunoadsorción Enzimática , Humanos , Sueros Inmunes/inmunología , Inmunidad Mucosa/inmunología , Isotipos de Inmunoglobulinas/inmunología , Ratones , Ratones Endogámicos , Infecciones Neumocócicas/prevención & control , Especificidad de la Especie , Streptococcus pneumoniae/clasificación , Streptococcus pneumoniae/fisiologíaRESUMEN
The immune response to pneumococcal surface structures during colonization was examined in a model of experimental human pneumococcal carriage. Healthy uncolonized adults were given a type 23F or 6B pneumococcus, and a portion of these subjects became colonized (6 of 14 with type 23F and 6 of 8 with type 6B). Sera from colonized and uncolonized subjects were used to determine the titer of antibody specific to pneumococcal surface components under consideration in development of noncapsular polysaccharide-based vaccines. These vaccine candidates included pneumococcal surface protein A (PspA), choline binding protein A (CbpA), lipoteichoic acid, immunoglobulin A1 (IgA1) protease, pneumolysin, proteinase maturation protein A, and pneumococcal surface adhesin A. Only the two related choline binding proteins, PspA and CbpA, were immunogenic in colonized subjects as determined by a statistically significant rise in the serum IgG titer. The serum IgG response to PspA was shown previously to correlate inversely with susceptibility to carriage and was localized to a region within the N-terminal portion of PspA. This region is highly variable in amino acid sequence between pneumococcal strains. Despite the sequence diversity in the immunodominant regions of both PspA and CbpA, a significant strain-to-strain cross-reactivity in the serum IgG response following experimental human carriage was observed. These findings support the need for further investigation of the human antibody response to PspA and CbpA and the potential use of one or both of these proteins as novel vaccine antigens for the prevention of pneumococcal colonization.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Antígenos Bacterianos/administración & dosificación , Inmunoglobulina G/sangre , Streptococcus pneumoniae/inmunología , Adulto , Secuencia de Aminoácidos , Antígenos Bacterianos/genética , Proteínas Bacterianas/administración & dosificación , Proteínas Bacterianas/genética , Proteínas Bacterianas/inmunología , Secuencia de Bases , Reacciones Cruzadas , ADN Bacteriano/genética , Humanos , Datos de Secuencia Molecular , Infecciones Neumocócicas/inmunología , Infecciones Neumocócicas/microbiología , Infecciones Neumocócicas/prevención & control , Vacunas Neumococicas/administración & dosificación , Vacunas Neumococicas/genética , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/crecimiento & desarrollo , Vacunas Sintéticas/administración & dosificación , Vacunas Sintéticas/genéticaRESUMEN
Colonization of the nasopharynx is the initial step in all infections caused by Streptococcus pneumoniae. The antibody response to carriage was examined in an experimental model of human colonization in healthy adults. Asymptomatic colonization was detected in 6/14 subjects and continued for up to 122 d. Susceptibility to carriage did not correlate with total serum immunoglobulin (Ig)G to the homotypic capsular polysaccharide. All of the colonized subjects, in contrast, developed a serum IgG and secretory IgA response to a 22 kD protein, whereas 7 of 8 subjects who did not become colonized had preexisting antibody to this protein. Analysis of the 22 kD protein identified it as the NH(2)-terminal region of pneumococcal surface protein A (PspA). Our findings provide evidence for the role of antibody to this protein fragment in preventing pneumococcal carriage by humans.