RESUMEN

BACKGROUND: Porcine small intestinal submucosa (SIS) is an acellular, naturally derived extracellular matrix (ECM) that has been used for tissue remodeling and repair in numerous xenotransplantations. Although a vigorous immune response to xenogeneic extracellular matrix biomaterials is expected, to date there has been evidence for only normal tissue regeneration without any accompanying rejection. The purpose of this study was to determine the reason for a lack of rejection. METHODS: Mice were implanted s.c. with xenogeneic tissue, syngeneic tissue, or SIS, and the graft site analyzed histologically for rejection or acceptance. Additionally, graft site cytokine levels were determined by reverse transcriptase polymerase chain reaction and SIS-specific serum antibody isotype levels were determined by ELISA. RESULTS: Xenogeneically implanted mice showed an acute inflammatory response followed by chronic inflammation and ultimately graft necrosis, consistent with rejection. Syngeneically or SIS implanted mice, however, showed an acute inflammatory response that diminished such that the graft ultimately became indistinguishable from native tissue, observations that are consistent with graft acceptance. Graft site cytokine analysis showed an increase in interleukin-4 and an absence of interferon-gamma. In addition, mice implanted with SIS produced a SIS-specific antibody response that was restricted to the IgG1 isotype. Reimplantation of SIS into mice led to a secondary anti-SIS antibody response that was still restricted to IgG1. Similar results were observed with porcine submucosa derived from urinary bladder. To determine if the observed immune responses were T cell dependent, T cell KO mice were implanted with SIS. These mice expressed neither interleukin-4 at the implant site nor anti-SIS-specific serum antibodies but they did accept the SIS graft. CONCLUSIONS: Porcine extracellular matrix elicits an immune response that is predominately Th2-like, consistent with a remodeling reaction rather than rejection.

Asunto(s)

Matriz Extracelular/trasplante , Células Th2/inmunología , Trasplante Heterólogo , Animales , Formación de Anticuerpos , Citocinas/genética , Matriz Extracelular/inmunología , Mucosa Intestinal/trasplante , Intestino Delgado/trasplante , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados/genética , Membrana Mucosa/trasplante , ARN Mensajero/metabolismo , Porcinos , Linfocitos T/inmunología , Linfocitos T/fisiología , Trasplante Isogénico/inmunología , Vejiga Urinaria/trasplante

RESUMEN

Interleukin-12 (IL-12) may be a beneficial adjuvant for augmenting vaccine efficacy against encapsulated bacteria such as Streptococcus pneumoniae and Neisseria meningitidis since it can stimulate production of interferon-gamma (IFN-gamma) and secretion of antibody isotypes that are efficient at mediating complement fixation and opsonophagocytosis. In this study, we demonstrate the ability of IL-12 to enhance murine antibody responses, particularly IgG2a levels, to both pneumococcal and meningococcal conjugate vaccines. Transfer of immune serum from mice immunized with the meningococcal conjugate vaccine and IL-12 resulted in increased survival times, whereas transfer of serum from mice immunized with the pneumococcal conjugate and IL-12 resulted in protection from death upon bacterial challenge. Although treatment with vaccine and IL-12 increased levels of IFN-gamma mRNA, IL-12-mediated enhancement of antibody responses still occurred in IFN-gamma(-/-) mice. The results demonstrate the effectiveness of IL-12 as an adjuvant for polysaccharide conjugate vaccines, especially the pneumococcal conjugate vaccine.

Asunto(s)

Interleucina-12/administración & dosificación , Vacunas Meningococicas/administración & dosificación , Vacunas Neumococicas/administración & dosificación , Animales , Anticuerpos Antibacterianos/biosíntesis , Secuencia de Bases , Cartilla de ADN/genética , Hipoxantina Fosforribosiltransferasa/genética , Inmunización Pasiva , Inmunoglobulina G/biosíntesis , Interferón gamma/deficiencia , Interferón gamma/genética , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Vacunas Conjugadas/administración & dosificación

RESUMEN

IgA is considered to be the principal Ab involved in defense against pathogens in the mucosal compartment. Using mice with a targeted disruption in IgA gene expression (IgA(-/-) mice), we have examined the precise role of IgA in protective anti-influenza responses after intranasal vaccination. IgA(-/-) mice immunized intranasally with soluble hemagglutinin (hemagglutinin subtype 1) and neuraminidase (neuraminidase subtype 1) vaccine in the absence of adjuvant were found to be more susceptible to influenza virus infection than IgA(+/+) mice (13 vs 75% survival after virus challenge). Inclusion of IL-12 during immunization restored the protective efficacy of the vaccine to that seen in IgA(+/+) animals. IgA(-/-) mice had no detectable IgA expression, but displayed enhanced serum and pulmonary IgM and IgG Ab levels after IL-12 treatment. Assessment of T cell function revealed markedly depressed splenic lymphoproliferative responses to PHA in IgA(-/-) animals compared with IgA(+/+) mice. Furthermore, IgA(-/-) animals displayed impaired T cell priming to the H1N1 subunit vaccine, with concomitant reduction in recall memory responses due to a defect in APC function. Collectively, these results provide evidence that a major role of IgA is to facilitate presentation of Ag to mucosal T cells. IL-12 treatment can overcome IgA deficiency by providing adequate T cell priming during vaccination.

Asunto(s)

Predisposición Genética a la Enfermedad , Deficiencia de IgA/genética , Deficiencia de IgA/inmunología , Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Infecciones por Orthomyxoviridae/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Administración Intranasal , Animales , Anticuerpos Antivirales/biosíntesis , Anticuerpos Antivirales/sangre , Células Cultivadas , Proteína HN/administración & dosificación , Proteína HN/inmunología , Deficiencia de IgA/virología , Inmunidad Innata/genética , Inmunoglobulina A/biosíntesis , Inmunoglobulina A/sangre , Memoria Inmunológica/genética , Vacunas contra la Influenza/administración & dosificación , Interleucina-12/uso terapéutico , Activación de Linfocitos/genética , Trastornos Linfoproliferativos/genética , Trastornos Linfoproliferativos/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Infecciones por Orthomyxoviridae/genética , Infecciones por Orthomyxoviridae/prevención & control , Linfocitos T Colaboradores-Inductores/metabolismo , Linfocitos T Colaboradores-Inductores/virología

RESUMEN

Administration of exogenous recombinant interleukin-12 (rIL-12) either prophylactically or therapeutically provides significant protection against lethal group A streptococcal skin infection in a mouse model. Treatment of mice with rIL-12 before infection with group A streptococci induced expression of interferon-gamma (IFN-gamma) at the infection site. In vivo neutralization of IFN-gamma increased susceptibility to lethal infection and completely abrogated the protective effects of rIL-12. IFN-gamma knockout mice were also more susceptible to lethal infection. Although IL-12 treatment provided protection, higher doses induced significantly elevated levels of IFN-gamma transcription that were associated with increased susceptibility to lethal infection. These results support the hypothesis that IFN-gamma at the infection site is critical for protection but suggest that increased systemic levels are detrimental to survival after infection with group A streptococci.

Asunto(s)

Interferón gamma/inmunología , Enfermedades Cutáneas Bacterianas/inmunología , Infecciones Estreptocócicas/inmunología , Streptococcus pyogenes , Animales , Interferón gamma/genética , Interferón gamma/metabolismo , Interleucina-12/inmunología , Interleucina-12/uso terapéutico , Ratones , Ratones Endogámicos C57BL , Pruebas de Neutralización , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/uso terapéutico , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Piel/inmunología , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Enfermedades Cutáneas Bacterianas/microbiología , Enfermedades Cutáneas Bacterianas/mortalidad , Bazo/inmunología , Infecciones Estreptocócicas/tratamiento farmacológico , Infecciones Estreptocócicas/microbiología , Infecciones Estreptocócicas/mortalidad

RESUMEN

Passage in human blood of group A streptococcal isolate 64p was previously shown to result in the enhanced expression of M and M-related proteins. Similarly, when this isolate was injected into mice via an air sac model for skin infection, organisms recovered from the spleens showed both increased expression of M and M-related proteins and increased skin-invasive potential. We show that these phenotypic changes were not solely the result of increased transcription of the mRNAs encoding the M and M-related gene products. Rather, the altered expression was associated with posttranslational modifications of the M and M-related proteins that occur in this strain, based on the presence or absence of another virulence protein, the streptococcal cysteine protease SpeB. The phenotypic variability also correlates with colony size variation. Large colonies selected by both regimens expressed more hyaluronic acid, which may explain differences in colony morphology. All large-colony variants were SpeB negative and expressed three distinct immunoglobulin G (IgG)-binding proteins in the M and M-related protein family. Small-colony variants were SpeB positive and bound little IgG through their M and M-related proteins because these proteins, although made, were degraded or altered in profile by the SpeB protease. We conclude that passage in either human blood or a mouse selects for a stable, phase-varied strain of group A streptococci which is altered in many virulence properties.

Asunto(s)

Antígenos Bacterianos , Cápsulas Bacterianas/fisiología , Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/biosíntesis , Cisteína Endopeptidasas/biosíntesis , Streptococcus pyogenes/patogenicidad , Proteínas Portadoras/biosíntesis , Humanos , Peso Molecular , Fenotipo , Streptococcus pyogenes/metabolismo , Virulencia

RESUMEN

Previous studies of recent clinical isolates of serotype M1 group A streptococci indicated that they display two patterns of non-immune human IgG subclass binding reactivity associated with their M1 protein. One group reacted with all four IgG subclasses (type IIo), while the second group expressed an M1 protein reacting preferentially with human IgG3 (type IIb). In this study, we have demonstrated that a cysteine protease, SpeB, present in culture supernatants of M1 serotype group A streptococcal isolates expressing type IIb IgG binding protein, can convert a recombinant Emm1 protein from a type IIo functional profile to a type IIb profile by removal of 24 amino acids from the N-terminus of the mature M1 protein. Furthermore, SpeB can convert bacteria expressing IgG binding proteins of the type IIo phenotype into those expressing type IIb proteins. The role of the cysteine protease as the central bacterial enzyme in this posttranslational modification event was confirmed by generation of an isogenic SpeB-negative mutant.

Asunto(s)

Antígenos Bacterianos/metabolismo , Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/metabolismo , Proteínas Portadoras/metabolismo , Cisteína Endopeptidasas/metabolismo , Inmunoglobulina G/metabolismo , Streptococcus pyogenes/enzimología , Secuencia de Aminoácidos , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/química , Proteínas Bacterianas/inmunología , Proteínas Portadoras/química , Proteínas Portadoras/inmunología , Humanos , Inmunoglobulina G/inmunología , Datos de Secuencia Molecular , Peso Molecular , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Streptococcus pyogenes/inmunología

RESUMEN

The virulence of group A streptococcal isolate 64/14 and paired isogenic mutants in which either the emm or mrp gene had been insertionally inactivated was compared in mice. Loss of expression of the emm gene product resulted in a significant loss of virulence when the isolate was injected into the skin but had no significant difference when injected intraperitoneally. By contrast, inactivation of the mrp gene caused the organism to be more virulent in the skin, while having no significant effect intraperitoneally. An isogenic mutant, in which the mga gene was inactivated and neither the emm gene nor the mrp gene was expressed, demonstrated no significant difference in virulence from the wild type organism. Organisms recovered from the spleen of mice lethally infected with the mga mutant expressed all Mga-regulated IgG-binding gene products despite the presence of the spectinomycin-resistance cassette, which was used to inactivate the mga gene, in its original position.

Asunto(s)

Antígenos Bacterianos , Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/fisiología , Proteínas Portadoras , Enfermedades Cutáneas Bacterianas/genética , Infecciones Estreptocócicas/genética , Streptococcus pyogenes/genética , Streptococcus pyogenes/patogenicidad , Animales , Proteínas Bacterianas/genética , Western Blotting , ADN Bacteriano/genética , Farmacorresistencia Microbiana/genética , Expresión Génica , Inmunoglobulina G/metabolismo , Ratones , Mutagénesis Insercional , Reacción en Cadena de la Polimerasa , Espectinomicina/farmacología , Bazo/microbiología , Virulencia/genética

RESUMEN

An association between the production of rheumatoid factor (RF)-like antibodies in animals immunized with bacterial immunoglobulin (Ig)G-binding proteins has been noted. Three potential explanations have been proposed: (1) altered host IgG due to binding of the immunogen; (2) B-cell superantigenic properties of the binding proteins; and (3) idiotype-anti-idiotype response leading to an antibody which acts as an antigen mimic. In order to distinguish among these possibilities, it is necessary to carry out studies in animals whose IgG does not react with the IgG-binding protein immunogen. Consequently, we have determined the effects of immunizing chickens with a purified group C streptococcal IgG-binding protein, FcRc, a bacterium expressing this protein, and appropriate control immunogens. The results of these studies provided evidence for production of specific antibodies to FcRc in groups of chickens immunized with either the pure protein or bacteria expressing the protein. No significant association with production of RF-like antibodies was noted, favouring the altered IgG-binding explanation for the association between RF-like antibodies and immunization with the bacterial IgG-binding proteins.

Asunto(s)

Proteínas Bacterianas/inmunología , Proteínas Bacterianas/farmacología , Factor Reumatoide/biosíntesis , Factor Reumatoide/inmunología , Animales , Especificidad de Anticuerpos , Pollos , Femenino , Inmunización Pasiva , Idiotipos de Inmunoglobulinas/sangre , Idiotipos de Inmunoglobulinas/inmunología , Ratones , Factor Reumatoide/sangre

RESUMEN

Epidemiological evidence implicates Streptococcus pyogenes (group A) infection as a common triggering stimulus for psoriasis. Unequivocal demonstration of streptococcal antigens in psoriatic skin has been difficult due to cross-reactive antigens in both normal human tissue and group A streptococci, which complicate immunohistological analysis. In this study cryostat sections of involved psoriatic skin were stained with monoclonal antibody 111-15504 to group A streptococci. The epitope recognized by this antibody was found to be specific for group A streptococci and is associated with class I M protein. Streptococcal antigens were found in the dermal papillae and epidermis of psoriatic skin lesions of 20 out 38 patients. These findings indicate that specific S. pyogenes antigen, associated with class I M protein, is often present in psoriatic lesions. Such an antigen, originating from focal infection elsewhere could be responsible for T-lymphocyte inflammatory responses triggering the development of psoriatic lesions.

Asunto(s)

Antígenos Bacterianos/análisis , Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/análisis , Proteínas Portadoras , Infección Focal/inmunología , Psoriasis/inmunología , Streptococcus pyogenes/inmunología , Anticuerpos Monoclonales/inmunología , Especificidad de Anticuerpos , Técnica del Anticuerpo Fluorescente Indirecta , Folículo Piloso/citología , Humanos , Microscopía Confocal , Psoriasis/microbiología

RESUMEN

Group A streptococci incubated in human plasma can acquire a plasmin-like enzymatic activity. This process involves at least two bacterial proteins and two human protein cofactors. In this study, the key bacterial proteins were identified by using a series of isogenic mutants of group A isolate, CS101. These studies confirm a key role for the secreted plasminogen activator, streptokinase, and identify the major surface fibrinogen-binding protein as the product of the mrp gene. The requirement for human fibrinogen and plasminogen as key cofactors was also confirmed.

Asunto(s)

Proteínas Bacterianas , Proteínas Portadoras/metabolismo , Fibrinógeno/metabolismo , Fibrinolisina , Proteínas de la Membrana/metabolismo , Plasminógeno/metabolismo , Streptococcus pyogenes/enzimología , Streptococcus pyogenes/genética , Estreptoquinasa/metabolismo , Proteínas Portadoras/biosíntesis , Proteínas Portadoras/química , Clonación Molecular , Cartilla de ADN , Genes Bacterianos , Humanos , Proteínas de la Membrana/biosíntesis , Proteínas de la Membrana/química , Mutagénesis Sitio-Dirigida , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/metabolismo , Streptococcus pyogenes/aislamiento & purificación , Estreptoquinasa/biosíntesis , Estreptoquinasa/genética

RESUMEN

An M2 streptococcal isolate and isogenic mutants in which either the emm or mrp gene was insertionally inactivated were tested for virulence using either a mouse model or a chicken embryo model. The results of the studies using the mouse model demonstrated that neither the emm nor mrp gene products had a significant effect on virulence when mice were challenged via the i.p. route. However, when the bacteria were injected into the skin the emm gene product was identified as a virulence factor. In parallel studies in the chicken embryo model the mrp gene product was found to be a major virulence factor, while a minor contribution to virulence could also be attributed to the emm gene product. The importance of these gene products to virulence was noted when the chicken embryo were injected either i.v or when the bacteria were placed on top of the chorioallantoic membrane. The direct comparison of a single wild type group A organism and its paired isogenic mutants in two animal models suggests that different combinations of bacterial factors are required to overcome host defense strategies associated with different animal species.

Asunto(s)

Antígenos Bacterianos , Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/fisiología , Proteínas Portadoras/fisiología , Proteínas de la Membrana/fisiología , Regulón , Enfermedades Cutáneas Bacterianas/microbiología , Streptococcus pyogenes/genética , Streptococcus pyogenes/patogenicidad , Animales , Proteínas Bacterianas/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Embrión de Pollo , ADN Bacteriano , Fibrinógeno/metabolismo , Inmunoglobulina A/metabolismo , Inmunoglobulina G/metabolismo , Inyecciones Intraperitoneales , Inyecciones Subcutáneas , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Ratones , Mutación , Albúmina Sérica/metabolismo , Enfermedades Cutáneas Bacterianas/genética , Infecciones Estreptocócicas/genética , Tasa de Supervivencia , Virulencia

RESUMEN

Recent clinical Streptococcus pyogenes isolates of the M1 serotype can be grouped according to the IgG-binding properties of their M proteins. One group expressed an IgG-binding M1 protein reactive with human IgG1, IgG2, IgG3, and IgG4 (type IIo); the other expressed a protein with predominant reactivity with human IgG3 alone (type IIb). Both IgG-binding protein phenotypes were equally resistant to phagocytosis in human blood; however, when they were injected into a skin air sac on outbred CD1 mice, all mice injected with M1 isolates of the type IIo phenotype were dead within 70 h, while only 40% of those injected with M1 isolates of the type IIb phenotype died within the same period. Bacteria recovered from the spleens of animals that died after injection with type IIb phenotype isolates demonstrated a change in their IgG-binding profile and were indistinguishable, in vitro or in vivo, from isolates displaying the type IIo phenotype.

Asunto(s)

Proteínas Bacterianas/metabolismo , Piel/microbiología , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/patogenicidad , Animales , Proteínas Bacterianas/inmunología , Humanos , Ratones , Proteínas Opsoninas/inmunología , Fagocitosis , Bazo/inmunología , Infecciones Estreptocócicas/inmunología , Streptococcus pyogenes/inmunología

RESUMEN

Invasive group A streptococcal isolates collected as part of a Centers for Disease Control and Prevention surveillance study were analyzed for expression of immunoglobulin G (IgG)-binding proteins. Two IgG-binding phenotypes of group A isolates of the M1 serotype were identified. The first group expressed a surface protein that bound all four human IgG subclasses (type IIo) and was recognized by rabbit anti-serotype M1-specific antiserum but not by normal rabbit serum. The second group expressed an IgG-binding protein that was also recognized by the anti-serotype M1 antiserum but demonstrated significant nonimmune reactivity only with human IgG3 (type IIb). Analysis of extracts of the isolates for reactivity with human IgA, fibrinogen, and albumin was also performed. The importance of the binding of human plasma proteins to pathogenic group A streptococci remains to be established.

Asunto(s)

Proteínas Bacterianas/análisis , Inmunoglobulina G/química , Streptococcus pyogenes/patogenicidad , Antígenos Bacterianos/análisis , Western Blotting , Unión Proteica/inmunología , Streptococcus pyogenes/química , Streptococcus pyogenes/clasificación

RESUMEN

Analysis of immunoglobulin G (IgG)-binding-protein expression by invasive group A streptococcal isolates of the M1 serotype collected as part of a Centers for Disease Control and Prevention surveillance study revealed two distinct phenotypes. One group of type M1 isolates expressed a surface protein reactive with all four human IgG subclasses (type IIo), while a second group expressed a surface protein demonstrating significant reactivity only with human IgG3 (type IIb). The functional forms of IgG-binding protein were antigenically related, and both were recognized by a rabbit polyclonal antiserum to serotype M1 but not by normal rabbit serum. While the quantities of antigenic M1 protein present in the extracts of representative isolates displaying each phenotype differed, the functional differences were found to be qualitative and not solely quantitative. The IgG-binding properties of these antigenically related M1 proteins could be readily distinguished from those of another IgG-binding protein, protein H. Type M1 isolates of the IIb phenotype differed from those of the IIo phenotype by secreting larger amounts of a casein-hydrolyzing protease into culture supernatants.

Asunto(s)

Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/análisis , Inmunoglobulina G/química , Streptococcus pyogenes/patogenicidad , Antígenos Bacterianos/análisis , Western Blotting , Proteínas Portadoras/análisis , Electroforesis en Gel de Poliacrilamida , Endopeptidasas/biosíntesis , Ensayo de Inmunoadsorción Enzimática , Humanos , Proteínas de la Membrana/análisis , Unión Proteica/inmunología , Serotipificación , Streptococcus pyogenes/clasificación , Streptococcus pyogenes/enzimología

RESUMEN

Two antigenic classes of non-immune IgG-binding proteins can be expressed by group A streptococci. One antigenic group of proteins is recognized by an antibody prepared against the product of a cloned fcrA gene (anti-FcRA). In this study, the immunogen used to prepare the antibody that defines the second antigenic class was shown to be the product of the emm-like (emmL) gene of M serotype 55 group A isolate, A928. The emmL55 gene expressed in E. coli produced an M(r) approximately 58,000 molecule which bound human IgG1, IgG2, IgG3 and IgG4, as well as horse, rabbit and pig IgG in a non-immune fashion. These properties are characteristic of the previously described type IIo IgG-binding protein isolated from this strain. In addition, the recombinant protein was reactive with human serum albumin and fibrinogen. The emmL 55 gene sequence was analysed and found to have the organization and sequence characteristics of a typical class I emm-like gene.

Asunto(s)

Proteínas de la Membrana Bacteriana Externa , Proteínas Bacterianas/genética , Genes Bacterianos/genética , Inmunoglobulina G/metabolismo , Streptococcus pyogenes/genética , Secuencia de Aminoácidos , Animales , Antígenos Bacterianos/genética , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Secuencia de Bases , Clonación Molecular , Humanos , Isotipos de Inmunoglobulinas/metabolismo , Datos de Secuencia Molecular , Streptococcus pyogenes/inmunología

RESUMEN

It has been shown that interleukin (IL)-12 induces cell-mediated immunity and provides significant protection against intracellular organisms. The ability of this cytokine to enhance immunity in a mouse model of group A streptococcal skin infection was studied. Outbred CD1 mice were injected for 3 consecutive days with 0.1 microgram of recombinant murine IL-12 before or after challenge with strain 64/14 group A streptococci. In both cases, in vivo IL-12 treatment significantly decreased the rate of death after infection and increased survival over the period of experimental observation. Thus, IL-12 may be useful for treatment of gram-positive bacterial infections. The time course of the experiments suggests that IL-12 is acting in this model system to enhance natural, rather than acquired, immunity.

Asunto(s)

Interleucina-12/administración & dosificación , Enfermedades de la Piel/tratamiento farmacológico , Enfermedades de la Piel/prevención & control , Infecciones Estreptocócicas/tratamiento farmacológico , Infecciones Estreptocócicas/prevención & control , Animales , Esquema de Medicación , Ratones , Streptococcus pyogenes , Análisis de Supervivencia

RESUMEN

Analysis of group A streptococcal immunoglobulin G (IgG)-binding protein reactivity with different human IgG3-myeloma proteins provided evidence for at least two functional forms of these molecules. Representative IgG3-binding molecules were isolated, biotinylated, and used as tracers in competitive binding assays. Cross-inhibition studies demonstrated the existence of two distinct patterns of IgG3-binding activity. Proteins of one form could be inhibited from binding to an IgG3-myeloma protein by streptococcal protein G while binding of the second form was not inhibited. These studies further underscore the extent of heterogeneity among immunoglobulin-binding proteins expressed by group A streptococci.

Asunto(s)

Proteínas Bacterianas/análisis , Inmunoglobulina G/metabolismo , Receptores de IgG/análisis , Streptococcus pyogenes/química , Animales , Proteínas Bacterianas/fisiología , Humanos , Proteínas de Mieloma/metabolismo

RESUMEN

An emm-like gene (emmL) and a fcrA gene from group A streptococcal strain 64/14 (emmL64/14 and fcrA64/14) were amplified by PCR and force cloned into the heat-inducible expression vector pJLA 602. The emmL gene encoded a recombinant protein that bound human IgG1, IgG2, and IgG4 in a nonimmune fashion. This is the reactivity profile of a type IIa IgG-binding protein. The emmL64/14 gene product was antigenically similar to the previously identified high-molecular-weight type IIa IgG-binding protein of strain 64/14 and had an N-terminal sequence identical to that of the wild-type protein. The fcrA gene also encoded a recombinant protein with type IIa functional activity. This protein was similar to the lower-molecular-weight type IIa IgG-binding protein previously isolated from strain 64/14 and was antigenically distinct from the higher-molecular-weight type IIa protein encoded by the emmL64/14 gene. The sequences for both genes including the intervening regions are presented. The emmL gene demonstrates significant homology to other class I emm and emmL genes expressed by opacity factor-negative group A streptococcal isolates. The fcrA gene was found to be homologous to other fcrA genes normally present in opacity factor-positive group A isolates. The sequence upstream of the fcrA gene and the intervening sequence between the end of the fcrA gene and the start of the emmL gene were similar to those reported for other fcrA genes.

Asunto(s)

Proteínas Bacterianas/genética , Genes Bacterianos , Receptores de IgG/genética , Streptococcus pyogenes/genética , Secuencia de Aminoácidos , Animales , Proteínas Bacterianas/química , Proteínas Bacterianas/fisiología , Secuencia de Bases , Pollos , Clonación Molecular , Humanos , Datos de Secuencia Molecular , Peso Molecular , Reacción en Cadena de la Polimerasa

RESUMEN

Expression of immunoglobulin G (IgG)-binding proteins on group A streptococcus strain 64 was monitored on bacteria subjected to sequential passage in human blood. After approximately 10 cycles through human blood, strain 64 demonstrated enhanced levels of IgG-binding protein, including the expression of a type IIa binding molecule with an M(r) of approximately 47,000 present only at very low levels on the parent isolate. Changes in the expression of IgG-binding proteins after passage in human blood were similar to those observed when the same organism was passaged sequentially intraperitoneally in mice. Strain 64, passaged in human blood 23 times, was found to be more virulent than the parent isolate when used to infect mice either intraperitoneally or in a skin air sac. These findings suggest that the expression of IgG-binding proteins may be a common response of group A organisms to pressures exerted by distinct host defense mechanisms.

Asunto(s)

Proteínas Bacterianas/análisis , Sangre/microbiología , Proteínas Portadoras/análisis , Inmunoglobulina G/metabolismo , Streptococcus pyogenes/química , Animales , Humanos , Ratones , Peso Molecular , Streptococcus pyogenes/patogenicidad , Streptococcus pyogenes/fisiología , Virulencia

RESUMEN

In this study, we developed a mouse model of skin infection to test the association between expression of immunoglobulin-binding proteins by and infectivity of group A streptococci. Group A streptococci capable of crossing tissue barriers and establishing a lethal systemic infection in mice showed a higher level of immunoglobulin-binding protein expression. The group A streptococci recovered from the spleen of a mouse that died following a skin infection were found to be more virulent when injected into the skin of naive mice. Together, these results suggest that immunoglobulin-binding protein expression by group A streptococci correlates with their ability to establish invasive skin infections.

Asunto(s)

Proteínas Bacterianas/metabolismo , Enfermedades de la Piel/inmunología , Infecciones Estreptocócicas/inmunología , Streptococcus pyogenes/inmunología , Streptococcus pyogenes/patogenicidad , Animales , Ratones , Enfermedades de la Piel/microbiología