scholarly journals Capsular Polysaccharide (CPS) Release by Serotype 3 Pneumococcal Strains Reduces the Protective Effect of Anti-Type 3 CPS Antibodies

2015 ◽  
Vol 23 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Eun Hwa Choi ◽  
Fan Zhang ◽  
Ying-Jie Lu ◽  
Richard Malley
Keyword(s):  
Capsular Polysaccharide ◽  
Culture Supernatant ◽  
Blood Concentrations ◽  
Passive Protection ◽  
Content Type ◽  
Sterile Culture ◽  
Covalently Linked ◽  
Opsonophagocytic Killing ◽  
Type 3

ABSTRACTThe efficacy of the serotype 3 (ST3) pneumococcal conjugate vaccine (PCV) remains unclear. While the synthesis of capsular polysaccharide (CPS) of most serotypes iswzydependent, the strains of two serotypes, 3 and 37, synthesize CPS by the synthase-dependent pathway, resulting in a polysaccharide that is not covalently linked to peptidoglycan and can be released during growth. We hypothesized that the release of CPS during growth reduces anti-type 3 CPS antibody-mediated protection and may explain the lower efficacy of the type 3 component of PCV than that of other PCVs. Thein vitro-released CPS concentrations per 107CFU of ST3 and ST37 strains were significantly higher than those for the ST1, ST4, ST6B, and ST14 strains. Following intraperitoneal (i.p.) injection in mice, blood concentrations of CPS were significantly higher for the ST3 than for the ST4/5 strains. The opsonophagocytic killing assay (OPKA) titer of anti-type 3 CPS antibody was significantly reduced by type 3 CPS, culture supernatant, or serum fromStreptococcus pneumoniaeST3 strain WU2-infected mice. Mice were injected with capsule-specific antibodies and challenged i.p. with or without the addition of sterile culture supernatant containing type-specific CPS. The addition of 0.2 μl of culture supernatant from WU2 inhibited passive protection, whereas 100-fold-more culture supernatant fromS. pneumoniaeST4 strain TIGR4 was required for the inhibition of protection. We conclude that released type 3 CPS interferes with antibody-mediated killing and protection by anti-CPS antibodies. The relative failure of ST3 PCV may be due to CPS release, suggesting that alternative immunization approaches for ST3 may be necessary.

scholarly journals Enzymatic Hydrolysis of Pneumococcal Capsular Polysaccharide Renders the Bacterium Vulnerable to Host Defense

2018 ◽  
Vol 86 (8) ◽  
Author(s):  
Dustin R. Middleton ◽  
Amy V. Paschall ◽  
Jeremy A. Duke ◽  
Fikri Y. Avci
Keyword(s):  
Enzymatic Hydrolysis ◽  
Capsular Polysaccharide ◽  
Protective Role ◽  
Pneumococcal Infections ◽  
Content Type ◽  
Drug Resistant Strains ◽  
Type 3 ◽  
Hydrolysis Of

ABSTRACTDespite a century of investigation,Streptococcus pneumoniaeremains a major human pathogen, causing a number of diseases, such as pneumonia, meningitis, and otitis media. Like many encapsulated pathogens, the capsular polysaccharide (CPS) ofS. pneumoniaeis a critical component for colonization and virulence in mammalian hosts. This study aimed to evaluate the protective role of a glycoside hydrolase, Pn3Pase, targeting the CPS of type 3S. pneumoniae, which is one of the most virulent serotypes. We have assessed the ability of Pn3Pase to degrade the capsule on a live type 3 strain. Throughin vitroassays, we observed that Pn3Pase treatment increases the bacterium's susceptibility to phagocytosis by macrophages and complement-mediated killing by neutrophils. We have demonstrated thatin vivoPn3Pase treatment reduces nasopharyngeal colonization and protects mice from sepsis caused by type 3S. pneumoniae. Due to the increasing shifts in serotype distribution, the rise in drug-resistant strains, and poor immune responses to vaccine-included serotypes, it is necessary to investigate approaches to combat pneumococcal infections. This study evaluates the interaction of pneumococcal CPS with the host at molecular, cellular, and systemic levels and offers an alternative therapeutic approach for diseases caused byS. pneumoniaethrough enzymatic hydrolysis of the CPS.

scholarly journals Antibodies to Staphylococcus aureus Serotype 8 Capsular Polysaccharide React with and Protect against Serotype 5 and 8 Isolates

2014 ◽  
Vol 82 (12) ◽  
pp. 5049-5055 ◽  
Author(s):  
Saeyoung Park ◽  
Sabina Gerber ◽  
Jean C. Lee
Keyword(s):  
Staphylococcus Aureus ◽  
Conjugate Vaccine ◽  
Rational Design ◽  
Capsular Polysaccharide ◽  
Passive Immunization ◽  
Reactive Material ◽  
Content Type ◽  
Serotype 5 ◽  
Opsonophagocytic Killing

ABSTRACTMostStaphylococcus aureusisolates produce either a serotype 5 (CP5) or 8 (CP8) capsular polysaccharide, and the CP antigens are targets for vaccine development. Since CP5 and CP8 have similar trisaccharide repeating units, it is important to identify an epitope shared by both CP5 and CP8. To characterize cross-reactivity between CP5 and CP8, the immunogenicity of CP5 and CP8 conjugate vaccines in mice and rabbits was evaluated by serological assays. Immune sera were also tested for functional activity byin vitroopsonophagocytic-killing assays and a murine bacteremia model. Antibodies to the CP5-cross-reactive material 197 (CRM197) conjugate vaccine bound only to purified CP5. In contrast, antibodies to the CP8-CRM conjugate vaccine reacted with CP8 and (to a lesser extent) CP5. De-O-acetylation of CP5 increased its reactivity with CP8 antibodies. Moreover, CP8 antibodies bound toPseudomonas aeruginosaO11 lipopolysaccharide, which has a trisaccharide repeating unit similar to that of theS. aureusCPs. CP8-CRM antibodies mediatedin vitroopsonophagocytic killing ofS. aureusexpressing CP5 or CP8, whereas CP5-CRM antibodies were serotype specific. Passive immunization with antiserum to CP5-CRM or CP8-CRM protected mice against bacteremia induced by a serotype 5S. aureusisolate, suggesting that CP8-CRM elicits antibodies cross-reactive to CP5. The identification of epitopes shared by CP5 and CP8 may inform the rational design of a vaccine to protect against infections caused by CP5- or CP8-producing strains ofS. aureus.

scholarly journals L-Ficolin and Capsular Polysaccharide-Specific IgG in Cord Serum Contribute Synergistically to Opsonophagocytic Killing of Serotype III and V Group B Streptococci

2012 ◽  
Vol 80 (6) ◽  
pp. 2053-2060 ◽  
Author(s):  
Mioko Fujieda ◽  
Youko Aoyagi ◽  
Kousaku Matsubara ◽  
Yasuhito Takeuchi ◽  
Wakae Fujimaki ◽  
...  
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Capsular Polysaccharide ◽  
Lectin Pathway ◽  
Group B Streptococci ◽  
Igg Antibody ◽  
Content Type ◽  
Specific Igg ◽  
Group B ◽  
Opsonophagocytic Killing

ABSTRACTGroup B streptococci (GBS;Streptococcus agalactiae) are the most common cause of neonatal sepsis and meningitis. Serotype-specific IgG antibody is known to protect neonates against GBS infections by promoting opsonophagocytosis. The L-ficolin-mediated lectin pathway of the complement is also a potential mechanism for opsonization of GBS, because L-ficolin activates the complement after binding to serotype Ib, III, V, VI, and VIII GBS. In the present study, we investigated how L-ficolin and serotype-specific IgG in cord sera contribute to opsonophagocytic killing of GBS. Neither L-ficolin nor serotype-specific IgG concentrations correlated with C3b deposition on serotype Ib and VI GBS, suggesting L-ficolin- and serotype-specific IgG-independent mechanisms of complement activation. The percentage of serotype VIII GBS killed was high regardless of the concentration of L-ficolin and IgG. In contrast, L-ficolin and serotype-specific IgG can each initiate C3b deposition on serotype III and V GBS and promote phagocytosis by polymorphonuclear leukocytes, but L-ficolin and serotype-specific IgG together promote opsonophagocytic killing to a greater extent than does either alonein vitro. This synergy was observed when serotype III-specific IgG concentrations were between 1 and 6 μg/ml and when serotype V-specific IgG concentrations were between 2 and 5 μg/ml. Concentrations of serotype III-specific IgG in cord blood above 7 μg/ml are considered protective for neonates colonized with GBS, but most neonates with IgG levels of less than 7 μg/ml do not develop GBS infections. The data presented here suggest that L-ficolin enhances opsonophagocytosis of serotype III and V GBS when serotype-specific IgG alone is suboptimal for protection.

scholarly journals Inhibition of LpxC Protects Mice from Resistant Acinetobacter baumannii by Modulating Inflammation and Enhancing Phagocytosis

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Lin Lin ◽  
Brandon Tan ◽  
Paul Pantapalangkoor ◽  
Tiffany Ho ◽  
Beverlie Baquir ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Gram Negative ◽  
Content Type ◽  
Novel Treatments ◽  
New Class ◽  
Virulent Strains ◽  
Lethal Infection ◽  
Tlr4 Activation ◽  
Opsonophagocytic Killing

ABSTRACT New treatments are needed for extensively drug-resistant (XDR) Gram-negative bacilli (GNB), such as Acinetobacter baumannii. Toll-like receptor 4 (TLR4) was previously reported to enhance bacterial clearance of GNB, including A. baumannii. However, here we have shown that 100% of wild-type mice versus 0% of TLR4-deficient mice died of septic shock due to A. baumannii infection, despite having similar tissue bacterial burdens. The strain lipopolysaccharide (LPS) content and TLR4 activation by extracted LPS did not correlate with in vivo virulence, nor did colistin resistance due to LPS phosphoethanolamine modification. However, more-virulent strains shed more LPS during growth than less-virulent strains, resulting in enhanced TLR4 activation. Due to the role of LPS in A. baumannii virulence, an LpxC inhibitor (which affects lipid A biosynthesis) antibiotic was tested. The LpxC inhibitor did not inhibit growth of the bacterium (MIC > 512 µg/ml) but suppressed A. baumannii LPS-mediated activation of TLR4. Treatment of infected mice with the LpxC inhibitor enhanced clearance of the bacteria by enhancing opsonophagocytic killing, reduced serum LPS concentrations and inflammation, and completely protected the mice from lethal infection. These results identify a previously unappreciated potential for the new class of LpxC inhibitor antibiotics to treat XDR A. baumannii infections. Furthermore, they have far-reaching implications for pathogenesis and treatment of infections caused by GNB and for the discovery of novel antibiotics not detected by standard in vitro screens. IMPORTANCE Novel treatments are needed for infections caused by Acinetobacter baumannii, a Gram-negative bacterium that is extremely antibiotic resistant. The current study was undertaken to understand the immunopathogenesis of these infections, as a basis for defining novel treatments. The primary strain characteristic that differentiated virulent from less-virulent strains was shedding of Gram-negative lipopolysaccharide (LPS) during growth. A novel class of antibiotics, called LpxC inhibitors, block LPS synthesis, but these drugs do not demonstrate the ability to kill A. baumannii in vitro. We found that an LpxC inhibitor blocked the ability of bacteria to activate the sepsis cascade, enhanced opsonophagocytic killing of the bacteria, and protected mice from lethal infection. Thus, an entire new class of antibiotics which is already in development has heretofore-unrecognized potential to treat A. baumannii infections. Furthermore, standard antibiotic screens based on in vitro killing failed to detect this treatment potential of LpxC inhibitors for A. baumannii infections.

scholarly journals USA300 and USA500 Clonal Lineages of Staphylococcus aureus Do Not Produce a Capsular Polysaccharide Due to Conserved Mutations in the cap5 Locus

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Xue Li ◽  
Md Tauqeer Alam ◽  
Timothy D. Read ◽  
Julia Sieth ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
The United States ◽  
Whole Genome Sequence ◽  
Content Type ◽  
Capsule Production ◽  
Usa300 Strain

ABSTRACTThe surface capsular polysaccharide (CP) is a virulence factor that has been used as an antigen in several successful vaccines against bacterial pathogens. A vaccine has not yet been licensed againstStaphylococcus aureus, although two multicomponent vaccines that contain CP antigens are in clinical trials. In this study, we evaluated CP production in USA300 methicillin-resistantS. aureus(MRSA) isolates that have become the predominant community-associated MRSA clones in the United States. We found that all 167 USA300 MRSA and 50 USA300 methicillin-susceptibleS. aureus(MSSA) isolates were CP negative (CP−). Moreover, all 16 USA500 isolates, which have been postulated to be the progenitor lineage of USA300, were also CP−. Whole-genome sequence analysis of 146 CP−USA300 MRSA isolates revealed they all carry acap5locus with 4 conserved mutations compared with strain Newman. Genetic complementation experiments revealed that three of these mutations (in thecap5promoter,cap5Dnucleotide 994, andcap5Enucleotide 223) ablated CP production in USA300 and that Cap5E75 Asp, located in the coenzyme-binding domain, is essential for capsule production. All but three USA300 MSSA isolates had the same fourcap5mutations found in USA300 MRSA isolates. Most isolates with a USA500 pulsotype carried three of these four USA300-specific mutations, suggesting the fourth mutation occurred in the USA300 lineage. Phylogenetic analysis of thecaploci of our USA300 isolates as well as publicly available genomes from 41 other sequence types revealed that the USA300-specificcap5mutations arose sequentially inS. aureusin a common ancestor of USA300 and USA500 isolates.IMPORTANCEThe USA300 MRSA clone emerged as a community-associated pathogen in the United States nearly 20 years ago. Since then, it has rapidly disseminated and now causes health care-associated infections. This study shows that the CP-negative (CP−) phenotype has persisted among USA300 isolates and is a universal and characteristic trait of this highly successful MRSA lineage. It is important to note that a vaccine consisting solely of CP antigens would not likely demonstrate high efficacy in the U.S. population, where about half of MRSA isolates comprise USA300. Moreover, conversion of a USA300 strain to a CP-positive (CP+) phenotype is unlikelyin vivoorin vitrosince it would require the reversion of 3 mutations. We have also established that USA300 MSSA isolates and USA500 isolates are CP−and provide new insight into the evolution of the USA300 and USA500 lineages.

scholarly journals Toll-Like Receptor 4 Agonistic Antibody Promotes Host Defense against Chronic Pseudomonas aeruginosa Lung Infection in Mice

2016 ◽  
Vol 84 (7) ◽  
pp. 1986-1993 ◽  
Author(s):  
Shigeki Nakamura ◽  
Naoki Iwanaga ◽  
Masafumi Seki ◽  
Kenji Fukudome ◽  
Kazuhiro Oshima ◽  
...  
Keyword(s):  
Immune Response ◽  
Pseudomonas Aeruginosa ◽  
Neutrophil Recruitment ◽  
Dependent Manner ◽  
Bacterial Clearance ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Content Type ◽  
Opsonophagocytic Killing

Chronic lower respiratory tract infection withPseudomonas aeruginosais difficult to treat due to enhanced antibiotic resistance and decreased efficacy of drug delivery to destroyed lung tissue. To determine the potential for restorative immunomodulation therapies, we evaluated the effect of Toll-like receptor 4 (TLR4) stimulation on the host immune response toPseudomonasinfection in mice. We implanted sterile plastic tubes precoated withP. aeruginosain the bronchi of mice, administered the TLR4/MD2 agonistic monoclonal antibody UT12 intraperitoneally every week, and subsequently analyzed the numbers of viable bacteria and inflammatory cells and the levels of cytokines. We also performed flow cytometry-based phagocytosis and opsonophagocytic killing assaysin vitrousing UT12-treated murine peritoneal neutrophils. UT12-treated mice showed significantly enhanced bacterial clearance, increased numbers of Ly6G+neutrophils, and increased concentrations of macrophage inflammatory protein 2 (MIP-2) in the lungs (P< 0.05). Depletion of CD4+T cells eliminated the ability of the UT12 treatment to improve bacterial clearance and promote neutrophil recruitment and MIP-2 production. Additionally, UT12-pretreated peritoneal neutrophils exhibited increased opsonophagocytic killing activity via activation of the serine protease pathway, specifically neutrophil elastase activity, in a TLR4-dependent manner. These data indicated that UT12 administration significantly augmented the innate immune response against chronic bacterial infection, in part by promoting neutrophil recruitment and bactericidal function.

scholarly journals Regulation by ToxR-Like Proteins Converges onvttRBExpression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae

2016 ◽  
Vol 198 (11) ◽  
pp. 1675-1682 ◽  
Author(s):  
Kelly A. Miller ◽  
Madeline K. Sofia ◽  
Jacob W. A. Weaver ◽  
Christopher H. Seward ◽  
Michelle Dziejman
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Vibrio Cholerae ◽  
Secretion System ◽  
Content Type ◽  
Transcriptional Regulatory ◽  
Type 3 Secretion System ◽  
Type 3

ABSTRACTGenes carried on the type 3 secretion system (T3SS) pathogenicity island ofVibrio choleraenon-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affectingin vitrocell death, including bacterial load and the role of three transmembrane transcriptional regulatory proteins, VttRA, VttRB, and ToxR. VttRAand VttRBare encoded on the horizontally acquired T3SS genomic island, whereas ToxR is encoded on the ancestral chromosome. While strains carrying deletions in any one of the three transcriptional regulatory genes are unable to cause eukaryotic cell death, the results of complementation studies point to a hierarchy of regulatory control that converges onvttRBexpression. The data suggest both that ToxR and VttRAact upstream of VttRBand that modifying the level of eithervttRAorvttRBexpression can strongly influence T3SS gene expression. We therefore propose a model whereby T3SS activity and, hence,in vitrocytotoxicity are ultimately regulated byvttRBexpression.IMPORTANCEIn contrast to O1 and O139 serogroupV. choleraestrains that cause cholera using two main virulence factors (toxin-coregulated pilus [TCP] and cholera toxin [CT]), O39 serogroup strain AM-19226 uses a type 3 secretion system as its principal virulence mechanism. Although the regulatory network governing TCP and CT expression is well understood, the factors influencing T3SS-associated virulence are not. Using anin vitromammalian cell model to investigate the role of three ToxR-like transmembrane transcriptional activators in causing T3SS-dependent cytotoxicity, we found that expression levels and a hierarchical organization were important for promoting T3SS gene expression. Furthermore, our results suggest that horizontally acquired, ToxR-like proteins act in concert with the ancestral ToxR protein to orchestrate T3SS-mediated pathogenicity.

scholarly journals Serum Antibody Responses against Carbapenem-Resistant Klebsiella pneumoniae in Infected Patients

mSphere ◽  
2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Kasturi Banerjee ◽  
Michael P. Motley ◽  
Elizabeth Diago-Navarro ◽  
Bettina C. Fries
Keyword(s):  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Serum Antibody ◽  
Antibody Responses ◽  
Capsular Polysaccharides ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Reactive Properties

ABSTRACT Capsular polysaccharide (CPS) heterogeneity within carbapenem-resistant Klebsiella pneumoniae (CR-Kp) strain sequence type 258 (ST258) must be considered when developing CPS-based vaccines. Here, we sought to characterize CPS-specific antibody responses elicited by CR-Kp-infected patients. Plasma and bacterial isolates were collected from 33 hospital patients with positive CR-Kp cultures. Isolate capsules were typed by wzi sequencing. Reactivity and measures of efficacy of patient antibodies were studied against 3 prevalent CR-Kp CPS types (wzi29, wzi154, and wzi50). High IgG titers against wzi154 and wzi50 CPS were documented in 79% of infected patients. Patient-derived (PD) IgGs agglutinated CR-Kp and limited growth better than naive IgG and promoted phagocytosis of strains across the serotype isolated from their donors. Additionally, poly-IgG from wzi50 and wzi154 patients promoted phagocytosis of nonconcordant CR-Kp serotypes. Such effects were lost when poly-IgG was depleted of CPS-specific IgG. Additionally, mice infected with wzi50, wzi154, and wzi29 CR-Kp strains preopsonized with wzi50 patient-derived IgG exhibited lower lung CFU than controls. Depletion of wzi50 antibodies (Abs) reversed this effect in wzi50 and wzi154 infections, whereas wzi154 Ab depletion reduced poly-IgG efficacy against wzi29 CR-Kp. We are the first to report cross-reactive properties of CPS-specific Abs from CR-Kp patients through both in vitro and in vivo models. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae is a rapidly emerging public health threat that can cause fatal infections in up to 50% of affected patients. Due to its resistance to nearly all antimicrobials, development of alternate therapies like antibodies and vaccines is urgently needed. Capsular polysaccharides constitute important targets, as they are crucial for Klebsiella pneumoniae pathogenesis. Capsular polysaccharides are very diverse and, therefore, studying the host’s capsule-type specific antibodies is crucial to develop effective anti-CPS immunotherapies. In this study, we are the first to characterize humoral responses in infected patients against carbapenem-resistant Klebsiella pneumoniae expressing different wzi capsule types. This study is the first to report the efficacy of cross-reactive properties of CPS-specific Abs in both in vitro and in vivo models.

scholarly journals Type III Group B Streptococcal Polysaccharide Induces Antibodies That Cross-React with Streptococcus pneumoniae Type 14

2002 ◽  
Vol 70 (4) ◽  
pp. 1724-1738 ◽  
Author(s):  
Hilde-Kari Guttormsen ◽  
Carol J. Baker ◽  
Moon H. Nahm ◽  
Lawrence C. Paoletti ◽  
Susu M. Zughaier ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Bacterial Infections ◽  
Capsular Polysaccharide ◽  
Sialic Acid Residue ◽  
Coating Antigen ◽  
Type Iii ◽  
Young Infants ◽  
Covalently Linked ◽  
Group B

ABSTRACT Covalent linkage of a bacterial polysaccharide to a protein greatly enhances the carbohydrate's immunogenicity and its binding to solid surfaces in immunoassays. These findings have spurred the development of glycoconjugate vaccines to prevent serious bacterial infections as well as the use of glycoconjugates as coating antigens in bioassays. We evaluated sera from women immunized with unconjugated group B streptococcal (GBS) type III (GBS III) polysaccharide (IIIPS) or with IIIPS covalently linked to tetanus toxoid to assess specificity, sensitivity, and parallelism in dilution curves in two GBS III enzyme-linked immunosorbent assays (ELISAs). One assay used IIIPS mixed with methylated human serum albumin (IIIPS + mHSA) as the coating antigen, and the other used IIIPS covalently linked to HSA (III-HSA). Each coating antigen was associated with a highly specific GBS III bioassay. The sensitivity was higher in the III-HSA ELISA, in which conjugated IIIPS is bound to the plates. Parallelism in titration curves was observed in the III-HSA but not in the IIIPS + mHSA ELISA. The excellent correlation between the concentrations of GBS IIIPS-specific immunoglobulin G (IgG) and the opsonophagocytic activity of these antibodies indicated that the III-HSA assay can predict functionality of vaccine-induced IgG against GBS III disease. The structure of the repeating unit of the capsular polysaccharide of GBS III differs from that of Streptococcus pneumoniae type 14 (Pn14 PS) only by the presence on GBS III of a sialic acid residue at the end of the side chain. The majority of healthy adults responding to GBS III vaccines with a fourfold or greater increase in GBS III-specific IgG antibodies developed antibodies cross-reacting with Pn14 PS (i.e., desialylated GBS IIIPS). The proportion of GBS vaccine responders who developed IgG to the desialylated IIIPS did not depend on whether IIIPS was given in the unconjugated or conjugated form. When present, these vaccine-induced cross-reacting antibodies conferred in vitro antibody-mediated opsonophagocytosis and killing of both GBS III and Pn14, two pathogens that cause invasive disease in young infants.

scholarly journals Phenotypically Adapted Mycobacterium tuberculosis Populations from Sputum Are Tolerant to First-Line Drugs

2016 ◽  
Vol 60 (4) ◽  
pp. 2476-2483 ◽  
Author(s):  
Obolbek Turapov ◽  
Benjamin D. O'Connor ◽  
Asel A. Sarybaeva ◽  
Caroline Williams ◽  
Hemu Patel ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Liquid Medium ◽  
Culture Supernatant ◽  
Ex Vivo ◽  
First Line ◽  
Content Type ◽  
Host Environment ◽  
Solid Media ◽  
Bactericidal Effects

ABSTRACTTuberculous sputum contains multipleMycobacterium tuberculosispopulations with different requirements for isolationin vitro. These include cells that form colonies on solid media (plateableM. tuberculosis), cells requiring standard liquid medium for growth (nonplateableM. tuberculosis), and cells requiring supplementation of liquid medium with culture supernatant (SN) for growth (SN-dependentM. tuberculosis). Here, we describe protocols for the cryopreservation and direct assessment of antimicrobial tolerance of theseM. tuberculosispopulations within sputum. Our results show that first-line drugs achieved only modest bactericidal effects on all three populations over 7 days (1 to 2.5 log10reductions), and SN-dependentM. tuberculosiswas more tolerant to streptomycin and isoniazid than the plateable and nonplateableM. tuberculosisstrains. Susceptibility of plateableM. tuberculosisto bactericidal drugs was significantly increased after passagein vitro; thus, tolerance observed in the sputum samples from the population groups was likely associated with mycobacterial adaptation to the host environment at some time prior to expectoration. Our findings support the use of a simpleex vivosystem for testing drug efficacies against mycobacteria that have phenotypically adapted during tuberculosis infection.

Sign in / Sign up

Export Citation Format

Share Document