Waning Immunity and Microbial Vaccines-Workshop of the National Institute of Allergy and Infectious Diseases.

Since the middle of the 20th century, vaccines have made a significant public health impact by controlling infectious diseases globally. Although long-term protection has been achieved with some vaccines, immunity wanes over time with others, resulting in outbreaks or epidemics of infectious diseases. Long-term protection against infectious agents that have a complex life cycle and antigenic variation remains a key challenge.

Towards New Broader Spectrum Pneumococcal Vaccines: The Future of Pneumococcal Disease Prevention.

Seven-valent pneumococcal conjugate vaccine (PCV7) introduction and routine pediatric use has substantially reduced the burden of Streptococcus pneumoniae disease worldwide. However, a significant amount of disease burden, due to serotypes not contained in PCV7, still exists globally. A newly recognized serotype, 6C, was until recently, identified and reported as serotype 6A.

Late acyltransferase genes lpxX and lpxL jointly contribute to the biological activities of Moraxella catarrhalis.

Lipo-oligosaccharide (LOS) is a major surface component and virulence factor of the human respiratory pathogen Moraxella catarrhalis. Two late acyltransferase genes, lpxX and lpxL, have been identified involved in the incorporation of acyloxyacyl-linked secondary acyl chains into lipid A during M. catarrhalis LOS biosynthesis.

Moraxella catarrhalis activates murine macrophages through multiple toll like receptors and has reduced clearance in lungs from TLR4 mutant mice.

Moraxella catarrhalis is a gram negative bacterium and a leading causative agent of otitis media (OM) in children. Several recent reports have provided strong evidence for an association between toll like receptors and OM. It has been found that both Streptococcus pneumoniae and nontypeable Haemophilus influenzae activate host protective immune responses through toll like receptors (TLRs), however, the precise mechanism by which Moraxella catarrhalis initiates the host immune response is currently unknown.

Role of c-Jun N-terminal protein kinase 1/2 (JNK1/2) in macrophage-mediated MMP-9 production in response to Moraxella catarrhalis lipooligosaccharide (LOS).

Moraxella catarrhalis is a gram negative bacterium and a leading causative agent of otitis media (OM) in children. Recent reports have provided strong evidence for the presence of high levels of matrix metalloproteinase (MMPs) in effusion fluids from children suffering with OM, however, the precise mechanisms by which MMPs are generated are currently unknown. We hypothesized that MMPs are secreted from macrophages in the presence of M.

Characterization of extended co-culture of non-typeable Haemophilus influenzae with primary human respiratory tissues.

Non-typeable Haemophilus influenzae (NTHi) are human-adapted Gram-negative bacteria that comprise part of the normal flora of the human upper airway, but are also responsible for a number of mucosal infections such as otitis media and bronchitis. These infections often recur and can become chronic. To characterize the effect of long-term co-culture of NTHi with human tissues, we infected primary respiratory epithelial cells grown at the air-liquid interface with three NTHi strains over a range of 1-10 days.

Intranasal immunization of the combined lipooligosaccharide conjugates protects mice from the challenges with three serotypes of Moraxella catarrhalis.

Background: There are no licensed vaccines available against Moraxella catarrhalis, a significant human respiratory pathogen. Lipooligosaccharide (LOS) based conjugate vaccines derived from individual serotype M. catarrhalis only showed partial protection coverage.

Mutant lipooligosaccharide-based conjugate vaccine demonstrates a broad-spectrum effectiveness against Moraxella catarrhalis.

There is no licensed vaccine available against Moraxella catarrhalis, an exclusive human pathogen responsible for otitis media in children and respiratory infections in adults. We previously developed conjugate vaccine candidates based on lipooligosaccharides (LOSs) of M. catarrhalis serotypes A, B, and C, each of which was shown to cover a portion of the clinical strains.

Protection against nontypeable Haemophilus influenzae challenges by mucosal vaccination with a detoxified lipooligosaccharide conjugate in two chinchilla models.

Otitis media (OM) can occur following outset of upper respiratory tract infections. Inhibition of bacterial colonization in nasopharynx (NP) by mucosal vaccination may prevent OM by reducing bacterial invasion of the middle ears (MEs). In this study, 80 chinchillas were intranasally (i.

Identification of two late acyltransferase genes responsible for lipid A biosynthesis in Moraxella catarrhalis.

Lipid A is a biological component of the lipo-oligosaccharide of a human pathogen, Moraxella catarrhalis. No other acyltransferases except for UDP-GlcNAc acyltransferase, responsible for lipid A biosynthesis in M. catarrhalis, have been identified.

Galactose residues on the lipooligosaccharide of Moraxella catarrhalis 26404 form the epitope recognized by the bactericidal antiserum from conjugate vaccination.

Lipooligosaccharide (LOS) from Moraxella catarrhalis has the potential to elicit bactericidal antibodies against the pathogen. We generated LOS-based conjugate vaccines that elicited bactericidal antibodies in animal models. However, epitopes on the LOS recognized by the functional anti-LOS antibodies remain unidentified.

Moraxella catarrhalis lipooligosaccharide selectively upregulates ICAM-1 expression on human monocytes and stimulates adjacent naïve monocytes to produce TNF-alpha through cellular cross-talk.

To elucidate the role of Moraxella catarrhalis lipooligosaccharide (LOS) in otitis media with effusion (OME), the effects of LOS on adhesion antigens of human monocytes were investigated. M. catarrhalis LOS selectively enhanced intercellular adhesion molecule 1 (ICAM-1 or CD54) expression on human monocytes by significantly increasing both the surface expression intensity and the percentage of ICAM-1(+) cells.

Role of different moieties from the lipooligosaccharide molecule in biological activities of the Moraxella catarrhalis outer membrane.

Lipooligosaccharide (LOS), a major component of the outer membrane of Moraxella catarrhalis, consists of two major moieties: a lipid A and a core oligosaccharide (OS). The core OS can be dissected into a linker and three OS chains. To gain an insight into the biological activities of the LOS molecules of M.

Biological and immunological characteristics of lipooligosaccharide-based conjugate vaccines for serotype C Moraxella catarrhalis.

Moraxella catarrhalis is an important bacterial cause of otitis media in children and respiratory tract infections in the elderly. Lipooligosaccharide (LOS), a major surface antigen of this bacterium, is a potential vaccine component against the organism. There are three major LOS serotypes (serotypes A, B, and C) in clinical isolates of M.

Kinetics of mouse antibody and lymphocyte responses during intranasal vaccination with a lipooligosaccharide-based conjugate vaccine.

We investigated the kinetics of humoral immunity and its related cellular immune responses to intranasal (IN) immunization with a detoxified lipooligosaccharide (dLOS)-tetanus toxoid (TT) conjugate against nontypeable Haemophilus influenzae (NTHi) in mice. IN vaccination with dLOS-TT elicited high titers of LOS-specific IgA in nasal washes and IgG in sera during a course of 4 inoculations while high titers of TT-specific IgA and IgG were found in sera. A significant increase of LOS-specific IgA antibody forming cells (AFCs) was observed in nasopharyngeal-associated lymphoid tissue (NALT) and nasal passages.

Moraxella catarrhalis bacterium without endotoxin, a potential vaccine candidate.

Lipooligosaccharide (LOS) is a major surface component of Moraxella catarrhalis and a possible virulence factor in the pathogenesis of human infections caused by this organism. The presence of LOS on the bacterium is an obstacle to the development of vaccines derived from whole cells or outer membrane components of the bacterium. An lpxA gene encoding UDP-N-acetylglucosamine acyltransferase responsible for the first step of lipid A biosynthesis was identified by the construction and characterization of an isogenic M.

Mucosal immunity induced by pneumococcal glycoconjugate.

Host defenses against Streptococcus pneumoniae involve opsonophagocytosis mediated by antibodies and complement. Because the pneumococcus is a respiratory pathogen, mucosal immunity may play an important role in the defense against infection. The mechanism for protection in mucosal immunity consists of induction of immunity by the activation of lymphocytes within the mucosal-associated lymphoid tissues, transport of antigen-specific B and T cells from inductive sites through bloodstream and distribute to distant mucosal effector sites.

Investigation of non-typeable Haemophilus influenzae outer membrane protein P6 as a new carrier for lipooligosaccharide conjugate vaccines.

Non-typeable Haemophilus influenzae (NTHi) outer membrane protein P6 was used as a new protein carrier for NTHi detoxified lipooligosaccharide (dLOS) conjugates due to its conservation and potential to elicit bactericidal antibodies. P6 was covalently conjugated to dLOS of strain 9274 through adipic acid dihydrazide with different ratios of dLOS to P6, which resulted in two conjugate formulations with weight ratios of dLOS to P6 of 3.7 for dLOS-P6 (I) and 1.

Roles of 3-deoxy-D-manno-2-octulosonic acid transferase from Moraxella catarrhalis in lipooligosaccharide biosynthesis and virulence.

Lipooligosaccharide (LOS), a major outer membrane component of Moraxella catarrhalis, is a possible virulence factor in the pathogenesis of human infections caused by the organism. However, information about the roles of the oligosaccharide chain from LOS in bacterial infection remains limited. Here, a kdtA gene encoding 3-deoxy-D-manno-2-octulosonic acid (Kdo) transferase, which is responsible for adding Kdo residues to the lipid A portion of the LOS, was identified by transposon mutagenesis and construction of an isogenic kdtA mutant in strain O35E.

Synthesis and characterization of lipooligosaccharide-based conjugate vaccines for serotype B Moraxella catarrhalis.

Moraxella catarrhalis is an important cause of otitis media in children and respiratory tract infections in the elderly. Lipooligosaccharide (LOS) is a major surface antigen of the bacterium that elicits bactericidal antibodies. Serological studies show that three major LOS types (A, B, and C) have been identified among clinical isolates.

Nontypeable Haemophilus influenzae lipoprotein P6 induces MUC5AC mucin transcription via TLR2-TAK1-dependent p38 MAPK-AP1 and IKKbeta-IkappaBalpha-NF-kappaB signaling pathways.

Mucin overproduction is a hallmark of nontypeable Haemophilus influenzae (NTHi) infections. The molecular mechanisms underlying up-regulation of mucin in NTHi infections especially during the initial phase remain unknown. Here we show that P6, a 16-kDa outer membrane lipoprotein well conserved in NTHi, up-regulates MUC5AC mucin gene transcription in vitro and in vivo.

[Detection of LOS-specific antibody-secreting cells by ELISPOT assay].

Aim: To detect dynamically the response of specific antibody-secreting cells elicited by a detoxified-lipooligosaccharide-cross-reactive mutant (dLOS-CRM) of diphtheria toxin conjugate vaccine for Moraxella catarrhalis (M.cat).

Methods: BALB/c mice were intranasally immunized with dLOS-CRM conjugate vaccine.

Exploration of Moraxella catarrhalis outer membrane proteins, CD and UspA, as new carriers for lipooligosaccharide-based conjugates.

Moraxella catarrhalis outer membrane proteins, CD and ubiquitous surface protein A (UspA), were used as carriers for M. catarrhalis detoxified lipooligosaccharide (dLOS)-based conjugates. Our study was designed to investigate the feasibility of CD and UspA as protein carriers for dLOS-based conjugates and their possible synergic effects on protection from both anti-LOS and anti-CD or anti-UspA antibody responses.