ABSTRACT
Streptococcus suis causes diseases in pigs and has emerged as a zoonotic agent. When infected, the host develops an exacerbated inflammation that can lead to septic shock and meningitis. Although neutrophils greatly infiltrate the lesions, their dynamics during S. suis infection remain poorly described. Moreover, very few studies reported on the production and role of a key factor in the regulation of neutrophils: the colony-stimulating granulocyte factor (G-CSF). In this study, we characterized the G-CSF-neutrophil axis in the pathogenesis of S. suis induced disease. Using a mouse model of S. suis infection, we first evaluated the recruitment of neutrophils and their activation profile by flow cytometry. We found that infection provokes a massive neutrophil recruitment from the bone marrow to the blood and spleen. In both compartments, neutrophils displayed multiple activation markers. In parallel, we observed high systemic levels of G-CSF, with a peak of production coinciding with that of neutrophil recruitment. We then neutralized the effects of G-CSF and highlighted its role in the release of neutrophils from the bone marrow to the blood. However, it did not affect bacteremia nor the cytokine storm induced by S. suis. In conclusion, systemic G-CSF induces the release of neutrophils from the bone marrow to the blood, but its role in inflammation or bacterial clearance seems to be compensated by unknown factors. A better understanding of the role of neutrophils and inflammatory mediators could lead to better strategies for controlling the infection caused by S. suis.
Subject(s)
Granulocyte Colony-Stimulating Factor , Neutrophil Infiltration , Neutrophils , Streptococcal Infections , Streptococcus suis , Streptococcus suis/immunology , Animals , Granulocyte Colony-Stimulating Factor/metabolism , Streptococcal Infections/immunology , Mice , Neutrophils/immunology , Neutrophils/metabolism , Neutrophil Infiltration/immunology , Disease Models, Animal , Female , Mice, Inbred C57BLABSTRACT
The pathogenesis of anal sacculitis has not been extensively investigated, although atopic dogs seem to be predisposed to the disease. The aim of this study was therefore to characterize and compare the bacterial microbiota and pro-inflammatory cytokines in the anal sacs of dogs from three groups (healthy dogs, untreated atopic dogs and atopic dogs receiving antipruritic treatment or allergen-specific immunotherapy) in order to determine whether changes could be at the origin of anal sacculitis in atopic dogs. Bacterial populations of anal sac secretions from fifteen healthy dogs, fourteen untreated and six treated atopic dogs were characterized by sequencing the V4 region of the 16S rRNA gene using Illumina technology. Proinflammatory cytokines were analyzed with the Luminex multiplex test. Community membership and structure were significantly different between the anal sacs of healthy and untreated atopic dogs (P = 0.002 and P = 0.003, respectively) and between those of untreated and treated atopic dogs (P = 0.012 and P = 0.017, respectively). However, the community structure was similar in healthy and treated atopic dogs (P = 0.332). Among the proinflammatory cytokines assessed, there was no significant difference between groups, except for interleukin 8 which was higher in the anal sacs of untreated atopic dogs compared to treated atopic dogs (P = 0.02), and tumor necrosis factor-alpha which was lower in the anal sacs of healthy dogs compared to treated atopic dogs (P = 0.04). These results reveal a dysbiosis in the anal sacs of atopic dogs, which may partially explain the predisposition of atopic dogs to develop bacterial anal sacculitis. Treatments received by atopic dogs (oclacitinib, desloratadine and allergen-specific immunotherapy) shift the microbiota of the anal sacs towards that of healthy dogs. Further studies are required to identify significant cytokines contributing to anal sacculitis in atopic dogs.
Subject(s)
Anal Sacs , Cytokines , Dog Diseases , Animals , Dogs , Cytokines/metabolism , Dog Diseases/microbiology , Dog Diseases/immunology , Dog Diseases/drug therapy , Anal Sacs/microbiology , Male , Microbiota , Female , RNA, Ribosomal, 16S/genetics , Dermatitis, Atopic/veterinary , Dermatitis, Atopic/microbiology , Dermatitis, Atopic/drug therapy , Dermatitis, Atopic/immunology , Case-Control Studies , Bacteria/classification , Bacteria/geneticsABSTRACT
Streptococcus suis is a bacterial pathogen that causes important economic losses to the swine industry worldwide. Since there are no current commercial vaccines, the use of autogenous vaccines applied to gilts/sows to enhance transfer of passive immunity is an attractive alternative to protect weaned piglets. However, there is no universal standardization in the production of autogenous vaccines and the vaccine formulation may be highly different among licenced manufacturing laboratories. In the present study, an autogenous vaccine that included S. suis serotypes 2, 1/2, 5, 7 and 14 was prepared by a licensed laboratory and administrated to gilts using a three-dose program prior to farrowing. The antibody response in gilts as well as the passive transfer of antibodies to piglets was then evaluated. In divergence with previously published data with an autogenous vaccine produced by a different company, the increased response seen in gilts was sufficient to improve maternal antibody transfer to piglets up to 5 weeks of age. However, piglets would still remain susceptible to S. suis disease which often appears during the second part of the nursery period. Vaccination did not affect the shedding of S. suis (as well as that of the specific S. suis serotypes included in the vaccine) by either gilts or piglets. Although all antibiotic treatments were absent during the trial, the clinical protective effect of the vaccination program with the autogenous vaccine could not be evaluated, since limited S. suis cases were present during the trial, confirming the need for a complete evaluation of the clinical protection that must include laboratory confirmation of the aetiological agent involved in the presence of S. suis-associated clinical signs. Further studies to evaluate the usefulness of gilt/sow vaccination with autogenous vaccines to protect nursery piglets should be done.
Subject(s)
Autovaccines , Streptococcal Infections , Streptococcus suis , Swine Diseases , Animals , Streptococcus suis/immunology , Swine , Swine Diseases/prevention & control , Swine Diseases/microbiology , Swine Diseases/immunology , Streptococcal Infections/veterinary , Streptococcal Infections/prevention & control , Streptococcal Infections/immunology , Female , Immunity, Maternally-Acquired , Streptococcal Vaccines/immunology , Streptococcal Vaccines/administration & dosage , Serogroup , Vaccination/veterinaryABSTRACT
Streptococcus suis serotype 2 is a major swine pathogen and a zoonotic agent, causing meningitis in both swine and humans, responsible for substantial economic losses to the swine industry worldwide. The pathogenesis of infection and the role of bacterial cell wall components in virulence have not been fully elucidated. Lipoproteins, peptidoglycan, as well as lipoteichoic acids (LTA) have all been proposed to contribute to virulence. In the present study, the role of the LTA in the pathogenesis of the infection was evaluated through the characterisation of a mutant of the S. suis serotype 2 strain P1/7 lacking the LtaS enzyme, which mediates the polymerization of the LTA poly-glycerolphosphate chain. The ltaS mutant was confirmed to completely lack LTA and displayed significant morphological defects. Although the bacterial growth of this mutant was not affected, further results showed that LTA is involved in maintaining S. suis bacterial fitness. However, its role in the pathogenesis of the infection appears limited. Indeed, LTA presence reduces self-agglutination, biofilm formation and even dendritic cell activation, which are important aspects of the pathogenesis of the infection caused by S. suis. In addition, it does not seem to play a critical role in virulence using a systemic mouse model of infection.
Subject(s)
Rodent Diseases , Streptococcal Infections , Streptococcus suis , Swine Diseases , Humans , Mice , Animals , Swine , Serogroup , Cell Shape , Virulence , Streptococcal Infections/veterinary , Streptococcal Infections/microbiologyABSTRACT
The porcine pathogen and zoonotic agent Streptococcus suis induces an exacerbated inflammation in the infected hosts that leads to sepsis, meningitis, and sudden death. Several virulence factors were described for S. suis of which the capsular polysaccharide (CPS) conceals it from the immune system, and the suilysin exhibits cytotoxic activity. Although neutrophils are recruited rapidly upon S. suis infection, their microbicidal functions appear to be poorly activated against the bacteria. However, during disease, the inflammatory environment could promote neutrophil activation as mediators such as the granulocyte colony-stimulating factor granulocyte (G-CSF) and the granulocyte-macrophages colony-stimulating factor (GM-CSF) prime neutrophils and enhance their responsiveness to bacterial detection. Thus, we hypothesized that CPS and suilysin prevent an efficient activation of neutrophils by S. suis, but that G-CSF and GM-CSF rescue neutrophil activation, leading to S. suis elimination. We evaluated the functions of porcine neutrophils in vitro in response to S. suis and investigated the role of the CPS and suilysin on cell activation using isogenic mutants of the bacteria. We also studied the influence of G-CSF and GM-CSF on neutrophil response to S. suis by priming the cells with recombinant proteins. Our study confirmed that CPS prevents S. suis-induced activation of most neutrophil functions but participates in the release of neutrophil-extracellular traps (NETs). Priming with G-CSF did not influence cell activation, but GM-CSF strongly promote IL-8 release, indicating its involvement in immunomodulation. However, priming did not enhance microbicidal functions. Studying the interaction between S. suis and neutrophils-first responders in host defense-remains fundamental to understand the immunopathogenesis of the infection and to develop therapeutical strategies related to neutrophils' defense against this bacterium.
Subject(s)
Colony-Stimulating Factors , Streptococcus suis , Animals , Swine , Granulocyte-Macrophage Colony-Stimulating Factor , Neutrophils , Granulocyte Colony-Stimulating FactorABSTRACT
Streptococcus suis serotype 2 is an important encapsulated bacterial swine pathogen and zoonotic agent for which no effective vaccine exists. The interaction with B cells and the humoral response against S. suis are poorly understood despite their likely relevance for a potential vaccine. We evaluated germinal center (GC) B cell kinetics, as well as the production and role of S. suis-specific antibodies following infections in a mouse model. We found that mice infected with S. suis developed GC that peaked 13-21 days post-infection. GC further increased and persisted upon periodic reinfection that mimics real life conditions in swine farms. Anti-S. suis IgM and several IgG subclasses were produced, but antibodies against the S. suis capsular polysaccharide (CPS) were largely IgM. Interestingly, depletion of total IgG from the wild-type mice sera had no effect on bacterial killing by opsonophagocytosis in vitro. Somatic hypermutation and isotype switching were dispensable for controlling the infection or anti-CPS IgM production. However, T cell-deficient (Tcrb-/-) mice were unable to control bacteremia, produce optimal anti-CPS IgM titers, or elicit antibodies with opsonophagocytic activity. SAP deficiency, which prevents GC formation but not extrafollicular B cell responses, ablated anti S. suis-IgG production but maintained IgM production and eliminated the infection. In contrast, B cell deficient mice were unable to control bacteremia. Collectively, our results indicate that the antibody response plays a large role in immunity against S. suis, with GC-independent but T cell-dependent germline IgM being the major effective antibody specificities. Our results further highlight the importance IgM, and potentially anti-CPS antibodies, in clearing S. suis infections and provide insight for future development of S. suis vaccines.
Subject(s)
Bacteremia , Streptococcal Infections , Streptococcus suis , Vaccines , Animals , Mice , Swine , Streptococcus suis/genetics , Antibodies, Bacterial , Immunoglobulin G , Immunoglobulin M , T-Lymphocytes , Streptococcal Infections/microbiologyABSTRACT
Streptococcus suis is a causative agent of swine and human infections. Genomic analysis indicated that eight S. suis serotype 5 strains recovered from human patients and pigs carried many virulence-associated genes and markers defining pathogenic pathotypes. The strains were sequence types diverse and clustered within either minimum core genome group 3 (MCG-3) or MCG-7-3. Almost all the serotype 5 strains were non-susceptible to penicillin, ceftriaxone, erythromycin, and levofloxacin. Resistance to tetracycline and clindamycin was observed in all strains. The antimicrobial resistance genes tet(O), tet(O/W/32/O), tet(W), tet(44), erm(B), ant(6)-Ia, lsaE, and lnuB were found in these strains. Moderate-to-large numbers of substitutions were observed in three penicillin-binding proteins (PBP)-PBP1A, PBP2B, and PBP2X-in the penicillin-non-susceptible serotype 5 isolates that were involved in ß-lactam-non-susceptibility. Comparative genomics between the serotype 5 and 2 strains revealed that only 15 genes absent from the serotype 2 strains were shared by all the serotype 5 strains. However, some additional genes were present only in some of the serotype 5 strains. This study highlighted the pathogenic potential of virulent serotype 5 strains in humans and pigs and the need for increased monitoring of penicillin-non-susceptibility in S. suis serotypes other than for serotype 2.
ABSTRACT
Streptococcus suis serotype 2 is an important swine bacterial pathogen causing sudden death, septic shock, and meningitis. However, serotype 2 strains are phenotypically and genotypically heterogeneous and composed of a multitude of sequence types (STs) whose distributions greatly vary worldwide. It has been previously shown that the lipoprotein (LPP) maturation enzymes diacylglyceryl transferase (Lgt) and signal peptidase (Lsp) significantly modulate the inflammatory host response and play a differential role in virulence depending on the genetic background of the strain. Differently from Eurasian ST1/ST7 strains, the capsular polysaccharide of a North American S. suis serotype 2 ST25 representative strain only partially masks sub-capsular domains and bacterial wall components. Thus, our hypothesis is that since LPPs would be more surface exposed in ST25 strains than in their ST1 or ST7 counterparts, the maturation enzymes would play a more important role in the pathogenesis of the infection caused by the North American strain. Using isogenic Δlgt and Δlsp mutants derived from the wild-type ST25 strain, our studies suggest that these enzymes do not seem to play a role in the interaction between S. suis and epithelial and endothelial cells, regardless of the genetics background of the strain used. However, a role in the formation of biofilms (also independently of the STs) has been demonstrated. Moreover, the involvement of LPP dendritic cell activation in vitro seems to be somehow more pronounced with the ST25 strain. Finally, the Lgt enzyme seems to play a more important role in the virulence of the ST25 strain. Although some differences between STs could be observed, our original hypothesis that LPPs would be significantly more important in ST25 strains due to a better bacterial surface exposition could not be confirmed.
ABSTRACT
Avian necrotic enteritis is an enteric disease of broiler chickens caused by certain pathogenic strains of Clostridium perfringens in combination with predisposing factors. A vaccine offering complete protection against the disease has not yet been commercialized. In a previous study, we produced five recombinant proteins predicted to be surface-exposed and unique to necrotic enteritis-causing C. perfringens and the immunogenicity of these potential vaccine candidates was assessed in broiler chickens. In the current work, the relative contribution of the antibodies raised by these putative antigens to protect broiler chickens was evaluated using an experimental necrotic enteritis induction model. Additionally, the link between the immune response elicited and the gut microbiota profiles in immunized birds subjected to infection with virulent C. perfringens was studied. The ELISA results showed that the IgY antibody titers in vaccinated birds on days 21 and 33 were significantly higher than those on days 7 and 14 and those in birds receiving the adjuvant alone, while the relative contribution of the specific immunity attributed to these antibodies could not be precisely determined using this experimental necrotic enteritis induction model. In addition, 16S rRNA gene amplicon sequencing showed that immunization of birds with recombinant proteins had a low impact on the chicken caecal microbiota.
ABSTRACT
Streptococcus suis (S. suis) is an endemic zoonotic pathogen still lacking adequate prevention in pigs. The present case study looked back to the occurrence and consequences of S. suis outbreaks in our swine research facilities in search of new metabolic and physiological insight. From a series of outbreaks, a dataset was created including 56 pigs sampled during disease detection based on clinical signs. Pigs suspected with S. suis infection were defined as diseased (nâ =â 28) and included pigs defined as neurologically diseased (nâ =â 20) when severe neurological signs (central nervous system dysfunctions, i.e., opisthotonos, ataxia, and generalized tremor) were observed. Another set of 28 pigs included respective pen mates from each case and were defined as control. Representative deaths were confirmed to be caused by S. suis. Tonsillar swabs were collected and analyzed by quantitative polymerase chain reaction (qPCR) for total bacteria, total S. suis, and S. suis serotypes (SS) 2 (and/or 1/2) and 9. Blood and sera were analyzed to quantify blood gases, minerals, and S. suis reactive immunoglobulins against current isolates. Data collected included litter sibling associations, birth and weaning body weight (BW), and average daily gain (ADG) 7 d after the disease detection. In general, the disease increased pH, sO2 and the incidence of alkalosis, but reduced pCO2, glucose, Ca, P, Mg, K, and Na in blood/serum compared to control. The SS2 (and/or SS1/2) prevalence was significantly (Pâ <â 0.05) increased in neurologically diseased pigs and its relative abundance tended (Pâ <â 0.10) to increase in tonsils. In contrast, the relative abundance of total S. suis was lower (Pâ >â 0.05) in diseased pigs than control pigs. Levels of S. suis reactive IgG2 were lower, but IgM were higher (Pâ <â 0.03) in neurologically affected pigs compared to control. Furthermore, there was an increased proportion of sibling pigs that were diseased compared to control. In conclusion, our results evidence that naturally affected pigs were associated to average performing pigs without any predisease trait to highlight but a sow/litter effect. Besides, neurologically affected pigs had increased S. suis (SS2 and/or 1/2) prevalence and relative abundance, a respiratory alkalosis profile, and mineral loss.
ABSTRACT
Streptococcus suis is an encapsulated bacterium causing severe diseases in swine. Here, we compared the protective properties of the capsular polysaccharide (CPS) of different S. suis serotypes by using serotype-switched mutants in a mouse model of infection. CPS structure influenced bacterial survival in mice, antibody binding, and antibody-mediated bacterial killing. The CPS of serotypes 3, 4 and 14 allowed more antibody binding and bacterial elimination than the CPS of serotypes 2, 7 and 9. Results suggest that the different CPS structures of S. suis provide varying levels of protection by influencing antigen availability and elimination by the host immune system.
Subject(s)
Streptococcal Infections , Streptococcus suis , Animals , Mice , Swine , Polysaccharides, Bacterial , Streptococcus suis/metabolism , Bacterial Capsules , Serogroup , Antibodies , Streptococcal Infections/microbiology , Antibodies, BacterialABSTRACT
Bacterial and/or viral co-infections are very common in swine production and cause severe economic losses. Mycoplasma hyopneumoniae, Mycoplasma hyorhinis and Streptococcus suis are pathogenic bacteria that may be found simultaneously in the respiratory tracts of pigs. In the present study, the interactions of S. suis with epithelial and phagocytic cells in the presence or absence of a pre-infection with M. hyopneumoniae and/or M. hyorhinis were studied. Results showed relatively limited interactions between these pathogens. A previous infection with one or both mycoplasmas did not influence the adhesion or invasion properties of S. suis in epithelial cells or its resistance to phagocytosis (including intracellular survival) by macrophages and dendritic cells. The most important effect observed during the co-infection was a clear increment in toxicity for the cells. An increase in the relative expression of the pro-inflammatory cytokines IL-6 and CXCL8 was also observed; however, this was the consequence of an additive effect due to the presence of different pathogens rather than a synergic effect. It may be hypothesized that if one or both mycoplasmas are present along with S. suis in the lower respiratory tract at the same time, then increased damage to epithelial cells and phagocytes, as well as an increased release of pro-inflammatory cytokines, may eventually enhance the invasive properties of S. suis. However, more studies should be carried out to confirm this hypothesis.
ABSTRACT
Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. Herein, we performed genomic analysis of seven S. suis serotype 4 strains belonging to clonal complex (CC) 94 that were recovered from a human patient or from diseased and clinically healthy pigs. Genomic exploration and comparisons, as well as in vitro cytotoxicity tests, indicated that S. suis CC94 serotype 4 strains are potentially virulent. Genomic analysis revealed that all seven strains clustered within minimum core genome group 3 (MCG-3) and had a high number of virulence-associated genes similar to those of virulent serotype 2 strains. Cytotoxicity assays showed that both the human lung adenocarcinoma cell line and HeLa cells rapidly lost viability following incubation for 4 h with the strains at a concentration of 106 bacterial cells. The human serotype 4 strain (ID36054) decreased cell viability profoundly and similarly to the control serotype 2 strain P1/7. In addition, strain ST1689 (ID34572), isolated from a clinically healthy pig, presented similar behaviour in an adenocarcinoma cell line and HeLa cells. The antimicrobial resistance genes tet(O) and ermB that confer resistance to tetracyclines, macrolides, and lincosamides were commonly found in the strains. However, aminoglycoside and streptothricin resistance genes were found only in certain strains in this study. Our results indicate that S. suis CC94 serotype 4 strains are potentially pathogenic and virulent and should be monitored.
Subject(s)
Streptococcal Infections , Streptococcus suis , Swine Diseases , Swine , Humans , Animals , Serogroup , Virulence/genetics , HeLa Cells , Genomics , Anti-Bacterial Agents , Streptococcal Infections/veterinary , Streptococcal Infections/microbiology , Swine Diseases/microbiologyABSTRACT
Since the ban or reduction on the use of antibiotic growth promoters (AGPs) in commercial broiler chickens in many countries, avian necrotic enteritis (NE) caused by Clostridium perfringens has re-emerged as one of the biggest threats for the poultry industry worldwide. While the toolbox for controlling NE in the absence of antibiotics consists of a limited number of alternatives for which the overall effectiveness has yet proven to be suboptimal, an effective vaccine would represent the best control strategy for this often-deadly disease. Using a comparative and subtractive reverse vaccinology approach, we previously identified 14 putative antigenic proteins unique to NE-causing strains of C. perfringens. In the current work, the in silico findings were confirmed by PCR and sequencing, and five vaccine candidate proteins were produced and purified subsequently. Among them, two candidates were hypothetical proteins, two candidates were prepilin proteins which are predicted to form the subunits of a pilus structure, and one candidate was a non-heme iron protein. Western blotting and ELISA results showed that immunization of broiler chickens with five of these proteins raised antibodies which can specifically recognize both the recombinant and native forms of the protein in pathogenic C. perfringens.
Subject(s)
Clostridium Infections , Enteritis , Poultry Diseases , Animals , Clostridium perfringens/genetics , Chickens , Clostridium Infections/prevention & control , Clostridium Infections/veterinary , Enteritis/pathology , Vaccination , Fimbriae Proteins , NecrosisABSTRACT
Streptococcus suis serotype 2 is an important bacterial pathogen of swine, responsible for substantial economic losses to the swine industry worldwide. The knowledge on the pathogenesis of the infection caused by S. suis is still poorly known. It has been previously described that S. suis possesses at least one lipoprotein with double laminin and zinc (Zn)-binding properties, which was described in the literature as either laminin-binding protein (Lmb, as in the current study), lipoprotein 103, CDS 0330 or AdcAII. In the present study, the role of the Lmb in the pathogenesis of the infection caused by S. suis serotype 2 was dissected. Using isogenic mutants, results showed that Lmb does not play an important role in the laminin-binding activity of S. suis, even when clearly exposed at the bacterial surface. In addition, the presence of this lipoprotein does not influence bacterial adhesion to and invasion of porcine respiratory epithelial and brain endothelial cells and it does not increase the susceptibility of S. suis to phagocytosis. On the other hand, the Lmb was shown to play an important role as cytokine activator when tested in vitro with dendritic cells. Finally, this lipoprotein plays a critical role in Zn acquisition from the host environment allowing bacteria to grow in vivo. The significant lower virulence of the Lmb defective mutant may be related to a combination of a lower bacterial survival due to the incapacity to acquire Zn from their surrounding milieu and a reduced cytokine activation.
Subject(s)
Streptococcal Infections , Streptococcus suis , Swine Diseases , Animals , Swine , Laminin/genetics , Laminin/metabolism , Serogroup , Cytokines/metabolism , Endothelial Cells , Zinc/metabolism , Streptococcal Infections/veterinary , Streptococcal Infections/microbiology , Swine Diseases/microbiologyABSTRACT
Group B Streptococcus (GBS) is one of the most common bacteria isolated in human chorioamnionitis. Placental infection due to GBS is a major risk factor for fetal organ injuries, preterm birth, perinatal morbidity and mortality, and life-long multiorgan morbidities. Preclinical and clinical studies have shown that GBS-induced infection drives polymorphonuclear (PMN) cell infiltration within the placenta, the hallmark of human chorioamnionitis. In preclinical and clinical studies, the upregulation of interleukin(IL)-1ß in the placenta and maternal/fetal blood was associated with a high risk of neurodevelopmental impairments in the progeny. We hypothesized that targeted IL-1 blockade administered to the dam alleviates GBS-induced chorioamnionitis and the downstream fetal inflammatory response syndrome (FIRS). IL-1 receptor antagonist (IL-1Ra) improved the gestational weight gain of GBS-infected dams and did not worsen the infectious manifestations. IL-1Ra reduced the IL-1ß titer in the maternal sera of GBS-infected dams. IL-1Ra decreased the levels of IL-1ß, IL-6, chemokine (C-X-C motif) ligand 1 (CXCL1), and polymorphonuclear (PMN) infiltration in GBS-infected placenta. IL-1Ra treatment reduced the IL-1ß titer in the fetal sera of GBS-exposed fetuses. IL-1 blockade also alleviated GBS-induced FIRS and subsequent neurobehavioral impairments of the offspring without worsening the outcome of GBS infection. Altogether, these results showed that IL-1 plays a key role in the physiopathology of live GBS-induced chorioamnionitis and consequent neurobehavioral impairments.
Subject(s)
Chorioamnionitis , Premature Birth , Streptococcal Infections , Chorioamnionitis/drug therapy , Chorioamnionitis/microbiology , Female , Fetal Diseases , Humans , Infant, Newborn , Interleukin 1 Receptor Antagonist Protein/pharmacology , Placenta/microbiology , Pregnancy , Streptococcal Infections/complications , Streptococcal Infections/drug therapy , Streptococcal Infections/microbiology , Streptococcus agalactiae , Systemic Inflammatory Response SyndromeABSTRACT
The public health systems of Southeast Asian countries are financially challenged by a comparatively higher incidence of human S. suis infections than other geographical areas. Efforts to improve practices in production settings, including improved meat inspection regulations, prevention of the slaughtering of non-healthy pigs, and enhanced hygiene practices at processing facilities, along with improvements in the pork supply chain, all appear promising for reducing food cross-contamination with S. suis. However, opportunities for intervention at the societal level are also needed to effect changes, as population behaviors such as the consumption of raw pork, blood, and offal products are important contributors to the increased incidence of human S. suis disease in Southeast Asia. A plethora of factors are associated with the consumption of these high-risk dishes, including traditional culture and knowledge, shared beliefs, socio-economic level, and personal attitudes associated with gender and/or marital status. Education and intervention in behavioral attitudes that are sensible to cultural practices and traditions may provide additional means to reduce the burden of S. suis human disease in Southeast Asia.
ABSTRACT
Group B Streptococcus (GBS) is a leading cause of placental infection, termed chorioamnionitis. Chorioamnionitis is associated with an increased risk of neurobehavioral impairments, such as autism spectrum disorders, which are more prominent in males than in female offspring. In a pre-clinical model of chorioamnionitis, a greater inflammatory response was observed in placenta associated with male rather than female fetuses, correlating with the severity of subsequent neurobehavioral impairments. The reason for this sex difference is not understood. Our hypothesis is that androgens upregulate the placental innate immune response in male fetuses. Lewis dams were injected daily from gestational day (G) 18 to 21 with corn oil (vehicle) or an androgen receptor antagonist (flutamide). On G 19, dams were injected with saline (control) or GBS. Maternal, fetal sera and placentas were collected for protein assays and in situ analyses. Our results showed that while flutamide alone had no effect, a decrease in placental concentration of pro-inflammatory cytokines and infiltration of polymorphonuclear cells was observed in flutamide/infected compared to vehicle/infected groups. These results show that androgens upregulate the placental innate immune response and thus may contribute to the skewed sex ratio towards males observed in several developmental impairments resulting from perinatal infection/inflammation.
Subject(s)
Chorioamnionitis , Streptococcal Infections , Androgens/metabolism , Androgens/pharmacology , Chorioamnionitis/metabolism , Female , Flutamide/pharmacology , Humans , Immunity, Innate , Male , Placenta/metabolism , Pregnancy , Streptococcal Infections/complications , Streptococcus agalactiaeABSTRACT
Streptococcus suis is a zoonotic pathogen affecting pigs and humans. This bacterium causes severe economic losses in the swine industry and poses a serious threat to public health and food safety. There is no effective commercial vaccine available for pigs or humans. In this study, we applied the biopolymer particle (BP) vaccine technology to incorporate seven conserved S. suis antigens (38 kDa protein (38), enolase (Enol), SSU1915, SSU1355, SSU0185, SSU1215, and SSU1773 (SSU1 and SSU2)). Two combinations of these antigens (38 and Enol; all SSU antigens designated as SSU1 and SSU2) were engineered to mediate production of BPs coated with either antigens 38 and Enol or SSU1 and SSU2 inside recombinant Escherichia coli. The isolated and purified empty BPs, 38-BP-Enol and SSU1-BP-SSU2, showed size ranges of 312-428 nm and 292-344 nm with and without the QuilA® adjuvant, respectively, and all showed a negative surface charge. Further characterization of purified BPs confirmed the presence of the expected antigen-comprising fusion proteins as assessed by tryptic peptide fingerprinting analysis using quadrupole time-of-flight mass spectrometry and immunoblotting. Vaccination with 38-BP-Enol and SSU1-BP-SSU2 formulated with and without QuilA® adjuvant induced significant antigen-specific humoral immune responses in mice. Antigen-coated BPs induced significant and specific Ig (IgM + IgG) and IgG immune responses (1.0 × 106-1.0 × 107) when compared with mice vaccinated with empty BPs. Functionality of the immune response was confirmed in challenge experiments using an acute murine S. suis infection model, which showed 100% survival of the 38-BP-Enol and SSU1-BP-SSU2 vaccinated mice compared to 70% survival when vaccinated with empty BPs. Overall, our data suggest that S. suis antigen-coated BPs could be developed into particulate vaccines that induce protective immunity against S. suis infections.
ABSTRACT
Streptococcus suis is a zoonotic pathogen of swine involved in arthritis, polyserositis, and meningitis. Colonization of piglets by S. suis is very common and occurs early in life. The clinical outcome of infection is influenced by the virulence of the S. suis strains and the immunity of the animals. Here, the role of innate immunity was studied in cesarean-derived colostrum-deprived piglets inoculated intranasally with either virulent S. suis strain 10 (S10) or non-virulent S. suis strain T15. Colonization of the inoculated piglets was confirmed at the end of the study by PCR and immunohistochemistry. Fever (≥40.5 °C) was more prevalent in piglets inoculated with S10 compared to T15 at 4 h after inoculation. During the 3 days of monitoring, no other major clinical signs were detected. Accordingly, only small changes in transcription of genes associated with the antibacterial innate immune response were observed at systemic sites, with S10 inducing an earlier response than T15 in blood. Local inflammatory response to the inoculation, evaluated by transcriptional analysis of selected genes in nasal swabs, was more sustained in piglets inoculated with the virulent S10, as demonstrated by transcription of inflammation-related genes, such as IL1B, IL1A, and IRF7. In contrast, most of the gene expression changes in trachea, lungs, and associated lymph nodes were observed in response to the non-virulent T15 strain. Thus, S. suis colonization in the absence of systemic infection induces an innate immune response in piglets that appears to be related to the virulence potential of the colonizing strain.