RESUMO
Bacterial acquisition of metals from a host is an essential attribute to facilitate survival and colonization within an infected organism. Staphylococcus aureus, a bacterial pathogen of medical importance, has evolved its strategies to acquire multiple metals, including iron, manganese, and zinc. Other important strategies for the colonization and infection of the host have been reported for staphylococci and include the expression of adhesins on the bacterial surface, as well as the acquisition of host plasminogen and complement regulatory proteins. Here we assess the ability of the zinc transport protein AdcA from Staphylococcus aureus, first characterized elsewhere as a zinc-binding protein of the ABC (ATP-binding cassette) transporters, to bind to host molecules. Like other staphylococcus ion-scavenging proteins, such as MntC, a manganese-binding protein, AdcA interacts with human plasminogen. Once activated, plasmin bound to AdcA cleaves fibrinogen and vitronectin. In addition, AdcA interacts with the human negative complement regulator factor H (FH). Plasminogen and FH have been shown to bind to distinct sites on the AdcA C-terminal portion. In conclusion, our in vitro data pave the way for future studies addressing the relevance of AdcA interactions with host molecules in vivo.
RESUMO
Infections caused by Staphylococcus aureus--particularly nosocomial infections--represent a great concern. Usually, the early stage of pathogenesis consists on asymptomatic nasopharynx colonization, which could result in dissemination to other mucosal niches or invasion of sterile sites, such as blood. This pathogenic route depends on scavenging of nutrients as well as binding to and disrupting extracellular matrix (ECM). Manganese transport protein C (MntC), a conserved manganese-binding protein, takes part in this infectious scenario as an ion-scavenging factor and surprisingly as an ECM and coagulation cascade binding protein, as revealed in this work. This study showed a marked ability of MntC to bind to several ECM and coagulation cascade components, including laminin, collagen type IV, cellular and plasma fibronectin, plasminogen and fibrinogen by ELISA. The MntC binding to plasminogen appears to be related to the presence of surface-exposed lysines, since previous incubation with an analogue of lysine residue, ε-aminocaproic acid, or increasing ionic strength affected the interaction between MntC and plasminogen. MntC-bound plasminogen was converted to active plasmin in the presence of urokinase plasminogen activator (uPA). The newly released plasmin, in turn, acted in the cleavage of the α and ß chains of fibrinogen. In conclusion, we describe a novel function for MntC that may help staphylococcal mucosal colonization and establishment of invasive disease, through the interaction with ECM and coagulation cascade host proteins. These data suggest that this potential virulence factor could be an adequate candidate to compose an anti-staphylococcal human vaccine formulation.
Assuntos
Proteínas de Bactérias/metabolismo , Matriz Extracelular/metabolismo , Plasminogênio/metabolismo , Staphylococcus aureus/metabolismo , Adesividade , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Coagulação Sanguínea , Sequência Conservada , Feminino , Fibrinogênio/metabolismo , Fibrinolisina/metabolismo , Humanos , Lisina , Camundongos , Concentração Osmolar , Ligação Proteica , ProteóliseRESUMO
More than 4 million deaths per year are due to respiratory diseases. Although licensed vaccines are available, bacteria, such as Streptococcus pneumoniae, Haemophilus influenzae, Mycobacterium tuberculosis, Bordetella pertussis and Neisseria meningiditis, among others, continue to be the major agents of diseases in young children, the elderly and/or immunocompromized individuals. Following respiratory tract infection, some microorganisms may also invade the epithelial tissue, achieving systemic circulation and/or other organs. Nasal administration of different antigen formulations has shown promising results in the induction of immune responses and the defeat of the pathogens at the site of infection. This review will focus on the main nasal vaccine strategies and technologies being investigated against the most common infections caused by respiratory bacteria.
Assuntos
Bacteriemia/prevenção & controle , Infecções Bacterianas/prevenção & controle , Vacinas Bacterianas/administração & dosagem , Vacinas Bacterianas/imunologia , Infecções Respiratórias/prevenção & controle , Adjuvantes Imunológicos , Administração Intranasal , Animais , Infecções Bacterianas/imunologia , Proteínas de Bactérias/imunologia , Humanos , Imunidade nas Mucosas , Polissacarídeos Bacterianos/imunologia , Infecções Respiratórias/imunologia , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia , Vacinas de DNA/administração & dosagem , Vacinas de DNA/imunologiaRESUMO
Mucosal epithelia constitute the first barriers to be overcome by pathogens during infection. The induction of protective IgA in this location is important for the prevention of infection and can be achieved through different mucosal immunization strategies. Lactic acid bacteria have been tested in the last few years as live vectors for the delivery of antigens at mucosal sites, with promising results. In this work, Streptococcus pneumoniae PsaA antigen was expressed in different species of lactic acid bacteria, such as Lactococcus lactis, Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus helveticus. After nasal inoculation of C57Bl/6 mice, their ability to induce both systemic (IgG in serum) and mucosal (IgA in saliva, nasal and bronchial washes) anti-PsaA antibodies was determined. Immunization with L. lactis MG1363 induced very low levels of IgA and IgG, possibly by the low amount of PsaA expressed in this strain and its short persistence in the nasal mucosa. All three lactobacilli persisted in the nasal mucosa for 3 days and produced a similar amount of PsaA protein (150-250 ng per 10(9) CFU). However, L. plantarum NCDO1193 and L. helveticus ATCC15009 elicited the highest antibody response (IgA and IgG). Vaccination with recombinant lactobacilli but not with recombinant L. lactis led to a decrease in S. pneumoniae recovery from nasal mucosa upon a colonization challenge. Our results confirm that certain Lactobacillus strains have intrinsic properties that make them suitable candidates for mucosal vaccination experiments.
Assuntos
Adesinas Bacterianas/imunologia , Anticorpos Antibacterianos/análise , Aderência Bacteriana/imunologia , Lipoproteínas/imunologia , Infecções Pneumocócicas/imunologia , Infecções Pneumocócicas/prevenção & controle , Vacinas Pneumocócicas/administração & dosagem , Mucosa Respiratória/imunologia , Streptococcus pneumoniae/imunologia , Vacinação , Vacinas de DNA/administração & dosagem , Adesinas Bacterianas/biossíntese , Adesinas Bacterianas/genética , Administração Intranasal , Sequência de Aminoácidos , Animais , Anticorpos Antibacterianos/sangue , Aderência Bacteriana/genética , Proteínas de Bactérias/genética , Feminino , Imunoglobulina A/análise , Imunoglobulina G/sangue , Lactobacillus/genética , Lactobacillus/metabolismo , Lipoproteínas/biossíntese , Lipoproteínas/genética , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Sinais Direcionadores de Proteínas/genética , Saliva/imunologia , Especificidade da EspécieAssuntos
Proteínas de Bactérias/imunologia , Toxina da Cólera/imunologia , Infecções Pneumocócicas/prevenção & controle , Vacinas Pneumocócicas/imunologia , Proteínas Recombinantes de Fusão/imunologia , Vacinas Sintéticas/imunologia , Administração Cutânea , Animais , Feminino , Imunização , Camundongos , Camundongos Endogâmicos BALB C , Vacinas Pneumocócicas/administração & dosagem , Vacinas Sintéticas/administração & dosagemRESUMO
Cholera toxin B subunit (CTB) is responsible for CT holotoxin binding to the cell and has been described as a mucosal adjuvant for vaccines. In this work, the ctxB gene was genetically fused to the psaA gene from Streptococcus pneumoniae, a surface protein involved in its colonization in the host that is also considered a vaccine antigen candidate against this pathogen. The CTB-PsaA fusion protein was expressed in Escherichia coli, and the purified protein was used for intranasal immunization experiments in Balb/C mice. CTB-PsaA was able to induce both systemic and mucosal antibodies evaluated in serum, saliva, and in nasal and bronchial wash samples, showing that CTB-PsaA is a promising molecule to be investigated as S. pneumoniae vaccine antigen candidate.
Assuntos
Formação de Anticorpos/efeitos dos fármacos , Linfócitos B/imunologia , Proteínas de Bactérias/farmacologia , Toxina da Cólera/farmacologia , Proteínas Recombinantes de Fusão/farmacologia , Administração Intranasal , Animais , Antígenos de Bactérias/genética , Antígenos de Bactérias/farmacologia , Linfócitos B/efeitos dos fármacos , Proteínas de Bactérias/genética , Toxina da Cólera/genética , Escherichia coli/genética , Imunoglobulina A/análise , Imunoglobulina G/análise , CamundongosRESUMO
Intranasal challenge of C57BL/6 mice with Streptococcus pneumoniae serotypes 6B, 14, and 23F produced colonization of the middle ear and NP. Intranasal vaccination with ethanol-killed nonencapsulated cells with adjuvant protected both sites. Of four nontoxic adjuvants tested, the cholera toxin B subunit was most effective and least nonspecifically protective.