Antibody response to outer membrane protein of nontypeable Haemophilus influenzae in otitis-prone children

Induction of Mucosal IgA-Mediated Protective Immunity Against Nontypeable Haemophilus influenzae Infection by a Cationic Nanogel-Based P6 Nasal Vaccine

Nontypeable Haemophilus influenzae (NTHi) strains form a major group of pathogenic bacteria that colonizes the nasopharynx and causes otitis media in young children. At present, there is no licensed vaccine for NTHi. Because NTHi colonizes the upper respiratory tract and forms biofilms that cause subsequent infectious events, a nasal vaccine that induces NTHi-specific secretory IgA capable of preventing biofilm formation in the respiratory tract is desirable. Here, we developed a cationic cholesteryl pullulan-based (cCHP nanogel) nasal vaccine containing the NTHi surface antigen P6 (cCHP-P6) as a universal vaccine antigen, because P6 expression is conserved among 90% of NTHi strains. Nasal immunization of mice with cCHP-P6 effectively induced P6-specific IgA in mucosal fluids, including nasal and middle ear washes. The vaccine-induced P6-specific IgA showed direct binding to the NTHi via the surface P6 proteins, resulting in the inhibition of NTHi biofilm formation. cCHP-P6 nasal vaccine thus protected mice from intranasal NTHi challenge by reducing NTHi colonization of nasal tissues and eventually eliminated the bacteria. In addition, the vaccine-induced IgA bound to different NTHi clinical isolates from patients with otitis media and inhibited NTHi attachment in a three-dimensional in vitro model of the human nasal epithelial surface. Therefore, the cCHP-P6 nanogel nasal vaccine induced effective protection in the airway mucosa, making it a strong vaccine candidate for preventing NTHi-induced infectious diseases, such as otitis media, sinusitis, and pneumonia.

The Peptidoglycan-associated lipoprotein Pal contributes to the virulence of Burkholderia mallei and provides protection against lethal aerosol challenge

BURKHOLDERIA MALLEI

is a highly pathogenic bacterium that causes the fatal zoonosis glanders. The organism specifies multiple membrane proteins, which represent prime targets for the development of countermeasures given their location at the host-pathogen interface. We investigated one of these proteins, Pal, and discovered that it is involved in the ability of B. mallei to resist complement-mediated killing and replicate inside host cells in vitro, is expressed in vivo and induces antibodies during the course of infection, and contributes to virulence in a mouse model of aerosol infection. A mutant in the pal gene of the B. mallei wild-type strain ATCC 23344 was found to be especially attenuated, as BALB/c mice challenged with the equivalent of 5,350 LD50 completely cleared infection. Based on these findings, we tested the hypothesis that a vaccine containing the Pal protein elicits protective immunity against aerosol challenge. To achieve this, the pal gene was cloned in the vaccine vector Parainfluenza Virus 5 (PIV5) and mice immunized with the virus were infected with a lethal dose of B. mallei. These experiments revealed that a single dose of PIV5 expressing Pal provided 80% survival over a period of 40 days post-challenge. In contrast, only 10% of mice vaccinated with a PIV5 control virus construct survived infection. Taken together, our data establish that the Peptidoglycan-associated lipoprotein Pal is a critical virulence determinant of B. mallei and effective target for developing a glanders vaccine.

Clinical practice guidelines for the diagnosis and management of acute otitis media in children-2018 update

OBJECTIVE

"Clinical Practice Guidelines for the Diagnosis and Management of Acute Otitis Media in Children-2018 update (2018 Guidelines)" aim to provide appropriate recommendations about the diagnosis and management of children with acute otitis media (AOM), including recurrent acute otitis media (recurrent AOM), in children under 15 years of age. These evidence-based recommendations were created with the consensus of the subcommittee members, taking into consideration unique characteristics of bacteriology and antimicrobial susceptibilities of AOM pathogens in Japan, as well as global advances in vaccines.

METHODS

The subcommittee re-evaluated key clinical issues based on SCOPE (a master plan of the guidelines) and created clinical questions (CQ) about the diagnosis and management of AOM patients. A literature search of the publications from 2013 to 2016 were added to the Guidelines 2013, not only to assess the evidence on the effectiveness of vaccines, but also to provide up to date information of the bacteriology and antimicrobial susceptibilities of AOM causative pathogens in Japan.

RESULTS

We have proposed guidelines for disease severity-based management of AOM patients, after classifying AOM severity into mild, moderate, and severe, based on age, clinical manifestations, and otoscopic findings.

CONCLUSIONS

Precise otoscopic findings are essential for judging AOM severity, which can lead to appropriate management of AOM patients.

Recombinant truncated E protein as a new vaccine candidate against nontypeable H. influenzae: Its expression and immunogenic evaluation

Protein E (PE) is a conserved entity observed in both nontypeable Haemophilus influenzae (NTHi) and encapsulated H. influenzae. This is a small surface lipoprotein, consisting of only 160 amino acids, involved in the adhesion of H. influenzae to various types of epithelial cells. A 384-bp-long fragment from NTHi PE was cloned into the prokaryotic expression vector pBAD-gIIIA. The recombinant protein was expressed with arabinose and then purified by affinity purification on an Ni-NTA agarose matrix. BALB/c mice were immunized by subcutaneous injection with purified recombinant truncated PE mixed with an alum adjuvant. Serum antibody response and the functional activity of antibodies were evaluated by enzyme-linked immunosorbent assay (ELISA) and serum bactericidal assay (SBA), respectively. Colony PCR, double digestion, and sequencing were used to verify successful cloning of truncated PE. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blot analyses indicated the presence of a ∼15-kDa recombinant protein. Serum IgG, IgG1, and IgG2a levels were significantly higher in the group immunized by recombinant truncated PE mixed with an alum adjuvant, compared to the non-vaccinated control group. Development of a strong bactericidal effect against NTHi was observed in the serum samples from immunized animals. Our findings suggest that recombinant truncated PE is a potential vaccine candidate for NTHi.

Australian Aboriginal Children with Otitis Media Have Reduced Antibody Titers to Specific Nontypeable Haemophilus influenzae Vaccine Antigens

Indigenous populations experience high rates of otitis media (OM), with increased chronicity and severity, compared to those experienced by their nonindigenous counterparts. Data on immune responses to otopathogenic bacteria in these high-risk populations are lacking. Nontypeable Haemophilus influenzae (NTHi) is the predominant otopathogen in Australia. No vaccines are currently licensed to target NTHi; however, protein D (PD) from NTHi is included as a carrier protein in the 10-valent pneumococcal polysaccharide conjugate vaccine (PHiD10-CV), and other promising protein vaccine candidates exist, including outer membrane protein 4 (P4) and protein 6 (P6). We measured the levels of serum and salivary IgA and IgG against PD, P4, and P6 in Aboriginal and non-Aboriginal children with chronic OM who were undergoing surgery and compared the levels with those in healthy non-Aboriginal children (controls). We found that Aboriginal cases had lower serum IgG titers to all NTHi proteins assessed, particularly PD. In contrast, serum IgA and salivary IgA and IgG titers to each of these 3 proteins were equivalent to or higher than those in both non-Aboriginal cases and healthy controls. While serum antibody levels increased with age in healthy controls, no changes in titers were observed with age in non-Aboriginal cases, and a trend toward decreasing titers with age was observed in Aboriginal cases. This suggests that decreased serum IgG responses to NTHi outer membrane proteins may contribute to the development of chronic and severe OM in Australian Aboriginal children and other indigenous populations. These data are important for understanding the potential benefits of PHiD10-CV implementation and the development of NTHi protein-based vaccines for indigenous populations.

Randomized controlled trial of juzen-taiho-to in children with recurrent acute otitis media

OBJECTIVE

Recurrent acute otitis media (AOM) in young children is rapidly increasing worldwide. Repeated antibiotic use leads to antibiotic-resistant pathogen development. Complementary and alternative medicine approaches have been suggested as a supplemental treatment option to conventional antimicrobial medicine. This randomized, parallel-group, open-label, non-herbal medicine controlled trial assessed the efficacy of a traditional Japanese herbal medicine, juzen-taiho-to (JTT) for AOM prevention in otitis-prone children.

METHODS

Children prone to recurrent AOM aged 6-48 months were recruited from 26 otolaryngology clinics in Japan and received conventional AOM treatment based on Japanese guidelines with or without 2 daily oral doses of JTT (0.10-0.25g/kg/day). The mean number of AOM episodes, coryza episodes, and duration of total antibiotic administration per month were compared during 3-month intervention.

RESULTS

At least one episode of AOM was diagnosed in 71% of JTT-group and 92% of control participants during follow-up. JTT administration reduced the frequency of AOM episodes by 57% compared with children who received conventional treatment alone (0.61±0.54 vs. 1.07±0.72 AOM instances/month; P=0.005) and also significantly decreased number of coryza episodes (P=0.015) and total antibiotic administration (P=0.024).

CONCLUSIONS

This is the first report of recurrent AOM prevention by herbal medication. JTT appears to effectively prevent recurrent AOM in children. Subsequent double-blind studies are needed to confirm the beneficial effects of JTT on recurrent AOM and upper respiratory tract infections.

Recombinant C-terminal 311 amino acids of HapS adhesin as a vaccine candidate for nontypeable Haemophilus influenzae: A study on immunoreactivity in Balb/C mouse

Hap, an auto-transporter protein, is an antigenically conserved adhesion protein which is present on both typeable and nontypeable Haemophilus influenzae. This protein has central role in bacterial attachment to respiratory tract epithelial cells. A 1000bp C-terminal fragment of Hap passenger domain (HapS) from nontypeable Haemophilus influenzae was cloned into a prokaryotic expression vector, pET-24a. BALB/c mice were immunized subcutaneously with purified rC-HapS. Serum IgG responses to purified rC-HapS, serum IgG subclasses were determined by ELISA and functional activity of antibodies was examined by Serum Bactericidal Assay. The output of rC-HapS was approximately 62% of the total bacterial proteins. Serum IgG responses were significantly increased in immunized group with rC-HapS mixed with Freund's adjuvant in comparison with control groups. Analysis of the serum IgG subclasses showed that the IgG1 subclass was predominant after subcutaneous immunization in BALB/c mice (IgG2a/IgG1 < 1). The sera from rC-HapS immunized animals were strongly bactericidal against nontypeable Haemophilus influenzae. These results suggest that rC-HapS may be a potential vaccine candidate for nontypeable Haemophilus influenzae.

Developing a vaccine to prevent otitis media caused by nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is a predominant organism of the upper respiratory nasopharyngeal microbiota. Its disease spectrum includes otitis media, sinusitis, non-bacteremic pneumonia and invasive infections. Protein-based vaccines to prevent NTHi infections are needed to alleviate these infections in children and vulnerable populations such as the elderly and those with chronic obstructive pulmonary disease (COPD). One NTHi protein is included in a pneumococcal conjugate vaccine and has been shown to provide efficacy. Our lab has been interested in understanding the immunogenicity of NTHi vaccine candidates P6, protein D and OMP26 for preventing acute otitis media in young children. We expect that continued investigation and progress in the development of an efficacious protein based vaccine against NTHi infections is achievable in the near future.

Serum Concentrations of Antibodies against Outer Membrane Protein P6, Protein D, and T- and B-Cell Combined Antigenic Epitopes of Nontypeable Haemophilus influenzae in Children and Adults of Different Ages

Nontypeable Haemophilus influenzae (NTHi) is one of the most common etiologies of acute otitis media, rhinosinusitis, and pneumonia. Outer membrane proteins (OMPs) are the main focus in new vaccine development against NTHi, as the H. influenzae type b (Hib) vaccine does not cover noncapsulated NTHi. The OMPs P6 and protein D are the most promising candidate antigens for an NTHi vaccine, and low antibody levels against them in serum may be correlated with infection caused by NTHi. In the current study, we measured the antibody titers against P6, protein D, and their T- and B-cell combined peptide epitopes in healthy individuals of different ages. We found that children <1 month old had the lowest antibody levels against NTHi P6, protein D, and their T- and B-cell combined antigenic epitopes. Antibody titers increased at ages 1 to 6 months, peaked at 7 months to 3 years, and remained high at 4 to 6 years. The antibody titers started to decrease after 6 years and were the lowest in the 21- to 30-year group. The geometric mean titers (GMTs) of T- and B-cell combined antigenic epitopes in P6 and protein D were positively correlated with those of the protein antigens. Among 12 peptides tested, P6-61, P6-123, and protein D-167 epitopes were better recognized than others in human serum. These findings might contribute to the development of an effective serotype-independent vaccine for H. influenzae.

Middle Ear and Eustachian Tube Mucosal Immunology

Mucosal immune responses within the middle ear and eustachian tube generally provide an effective and efficient response to the presence of microbial pathogens, with approximately 80% of clinically recognizable middle ear infections resolved within 7 days. Particularly for young children aged less than 3 years of age, the proximity and direct connection of the middle ear, via the eustachian tube, to the nasopharynx provide increased risk of commensal bacteria and upper respiratory tract viruses infecting the middle ear. Mucosal immunological defense in the middle ear and eustachian tube utilizes a number of mechanisms, including physicochemical barriers of mucus and the mucosal epithelial cells and innate immune responses such as inflammation, cellular infiltration, effusion, and antimicrobial protein secretions, in addition to adaptive host immune responses. Recent advances in otopathogen recognition via microbial pattern recognition receptors and elucidation of complex signaling cascades have improved understanding of the coordination and regulation of the middle ear mucosal response. These advances support vaccine development aiming to reduce the risk of otitis media in children.

IgG responses to Pneumococcal and Haemophilus influenzae protein antigens are not impaired in children with a history of recurrent acute otitis media

Background

Vaccines including conserved antigens from Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) have the potential to reduce the burden of acute otitis media. Little is known about the antibody response to such antigens in young children with recurrent acute otitis media, however, it has been suggested antibody production may be impaired in these children.

Methods

We measured serum IgG levels against 4 pneumococcal (PspA1, PspA 2, CbpA and Ply) and 3 NTHi (P4, P6 and PD) proteins in a cross-sectional study of 172 children under 3 years of age with a history of recurrent acute otitis media (median 7 episodes, requiring ventilation tube insertion) and 63 healthy age-matched controls, using a newly developed multiplex bead assay.

Results

Children with a history of recurrent acute otitis media had significantly higher geometric mean serum IgG levels against NTHi proteins P4, P6 and PD compared with healthy controls, whereas there was no difference in antibody levels against pneumococcal protein antigens. In both children with and without a history of acute otitis media, antibody levels increased with age and were significantly higher in children colonised with S. pneumoniae or NTHi compared with children that were not colonised.

Conclusions

Proteins from S. pneumoniae and NTHi induce serum IgG in children with a history of acute otitis media. The mechanisms in which proteins induce immunity and potential protection requires further investigation but the dogma of impaired antibody responses in children with recurrent acute otitis media should be reconsidered.

Bactericidal antibody response against P6, protein D, and OMP26 of nontypeable Haemophilus influenzae after acute otitis media in otitis-prone children

The bactericidal antibody response to three nontypeable Haemophilus influenzae (NTHi) outer membrane proteins (D, P6, and OMP26) was studied in 24 otitis-prone children (aged 7-28 months) after an acute otitis media (AOM) caused by NTHi. The study was carried out to understand the contribution of antigen-specific bactericidal antibody responses in the class of children who are most vulnerable to recurrent otitis media infections. Levels of protein D (P = 0.005) and P6 (P = 0.026) but not OMP26 antibodies were higher in bactericidal sera compared with nonbactericidal sera. For five (24%) and 16 (76%) of 21 bactericidal sera tested, removal of anti-protein D and P6 antibody, respectively, resulted in a two- to fourfold drop in bactericidal antibody. Antibodies to OMP26 did not make any contribution to the overall bactericidal activity in any serum samples. Eleven of 21 sera (52%) had bactericidal activity against a heterologous NTHi (86-028 NP) strain but the titers were significantly lower (P < 0.05) as compared to the homologous strains. Future studies of protein D, P6, OMP26, and other potential NTHi vaccine antigens should include studies of bactericidal antibody in children who are otitis prone as a possible correlate of protection.

Maternal immunization with pneumococcal surface protein A protects against pneumococcal infections among derived offspring

Pathogen-specific antibody plays an important role in protection against pneumococcal carriage and infections. However, neonates and infants exhibit impaired innate and adaptive immune responses, which result in their high susceptibility to pneumococci. To protect neonates and infants against pneumococcal infection it is important to elicit specific protective immune responses at very young ages. In this study, we investigated the protective immunity against pneumococcal carriage, pneumonia, and sepsis induced by maternal immunization with pneumococcal surface protein A (PspA). Mother mice were intranasally immunized with recombinant PspA (rPspA) and cholera toxin B subunit (CTB) prior to being mated. Anti-PspA specific IgG, predominantly IgG1, was present at a high level in the serum and milk of immunized mothers and in the sera of their pups. The pneumococcal densities in washed nasal tissues and in lung homogenate were significantly reduced in pups delivered from and/or breast-fed by PspA-immunized mothers. Survival after fatal systemic infections with various types of pneumococci was significantly extended in the pups, which had received anti-PspA antibody via the placenta or through their milk. The current findings strongly suggest that maternal immunization with PspA is an attractive strategy against pneumococcal infections during early childhood. (191 words)

Serum antibody response to five Streptococcus pneumoniae proteins during acute otitis media in otitis-prone and non-otitis-prone children

BACKGROUND

Streptococcus pneumoniae (Spn) is one of the common bacteria responsible for episodic acute otitis media (AOM; non-otitis-prone), recurrent AOM (otitis-prone), and AOM treatment failure (AOMTF) in children.

OBJECTIVE

From a population of 268 children, we sought to compare the serum IgG antibody titers of 5 different Spn proteins (PhtD, LytB, PcpA, PhtE, and Ply) that are vaccine candidates in children with episodic AOM (n = 34), who were otitis prone (n = 35) and who had AOMTF (n = 25) caused by Spn.

METHODS

Antibody was quantitated by enzyme-linked immunosorbent assay.

RESULTS

At their AOM visit, anti-PhtD, -LytB, -PhtE, and -Ply IgG antibody titers in otitis-prone children were significantly lower compared with non-otitis-prone children (P < 0.05) and children with AOMTF (P < 0.05). On comparing acute to convalescent geometric mean IgG antibody titers after AOM against the 5 proteins we found that otitis-prone, AOMTF, and non-otitis-prone children had no significant change in titers (except for PhtE in children with AOMTF), but detailed analysis showed that about one-third of the children in each cohort had a 2-fold rise in antibody to the studied antigens. Although non-otitis-prone children had significant increases (P < 0.001) between 6 and 24 months of age in anti-PhtD, PcpA, PhtE, and Ply IgG antibody titers as a consequence of nasopharyngeal colonization and AOM, otitis-prone children either failed to show rises or the rises were significantly less than the non-otitis-prone children.

CONCLUSION

Otitis-prone and AOMTF children mount less of an IgG serum antibody response as compared with non-otitis-prone children to Spn proteins after AOM and nasopharyngeal colonization.

Serum antibody response to three non-typeable Haemophilus influenzae outer membrane proteins during acute otitis media and nasopharyngeal colonization in otitis prone and non-otitis prone children

Non-typeable Haemophilus influenzae (NTHi) is the most common bacteria responsible for episodic acute otitis media (AOM; non-otitis prone), recurrent AOM (rAOM; otitis prone) and AOM treatment failure (AOMTF) in children. In this 3.5 years of prospective study, we measured the serum antibody response to outer membrane proteins D, P6 and OMP26 of NTHi in children with AOM (n=26), rAOM (n=32), AOMTF (n=27). The geometric mean titers (GMTs) of IgG at their acute AOM visit against Protein D in otitis prone children were significantly lower compared to AOMTF (p value<0.01) and non-otitis prone (p value<0.03) children; otitis prone children had significantly lower IgG levels to P6 compared to AOMTF children (p value<0.02); otitis prone children had significantly lower IgG levels to OMP26 compared to AOMTF children (p value<0.04). Comparing acute to convalescent titers after AOM, otitis prone and AOMTF children had no significant change in total IgG against all the three proteins, while non-otitis prone children had significant increases to Protein D. Anti-protein D, P6 and OMP26 antibody levels measured longitudinally during NP colonization between age 6 and 24 months in 10 otitis prone children and 150 non-otitis prone children showed <2-fold increases over time in otitis prone children compared to >4 fold increases in the non-otitis prone children (p value<0.001). We conclude that otitis prone children mount less of an IgG serum antibody response toward Protein D, P6 and OMP26 after AOM which may account for recurrent infections. The data on acute sera of otitis prone vs non-otitis prone children and the acute-to-convalescence response in non-otitis prone children point to a possible link of anti-PD to protection. Moreover, the data suggest that otitis prone children should be evaluated for their responses to Protein D, P6 and OMP26 vaccine antigens of NTHi.

Antibody response to Haemophilus influenzae outer membrane protein D, P6, and OMP26 after nasopharyngeal colonization and acute otitis media in children

Development of natural antibodies to 3 nontypeable Haemophilus influenzae (NTHi) outer membrane proteins (D, P6 and OMP26) was prospectively studied in 130 children 6-30 months of age during NP colonization and acute otitis media (AOM). IgG antibody to protein D, P6 and OMP26 increased with age (p<0.001). Serum IgG responses to NP colonization were different for the 3 proteins: protein D responses occurred at a later age than P6, and OMP26 responses were minimal. For all 3 proteins serum antibody levels in the convalescent phase of AOM infection were not as high as after NP colonization. Antibodies to protein D and P6 but not OMP26 were bactericidal.

Epitope mapping immunodominant regions of the PilA protein of nontypeable Haemophilus influenzae (NTHI) to facilitate the design of two novel chimeric vaccine candidates

We designed and tested three PilA-derived vaccine candidates in a chinchilla model of ascending nontypeable Haemophilus influenzae (NTHI)-induced otitis media (OM). Delivery of antiserum directed against each immunogen conferred varying degrees of protection. Presentation of a B-cell epitope derived from the OMP P5 adhesin at the N-terminus of recombinant soluble PilA protein (as opposed to the C-terminus), resulted in a protective chimeric immunogen that combined epitopes from two distinct NTHI adhesins (type IV pili and OMP P5). Incorporating protective epitopes derived from two NTHI adhesins/virulence determinants into a single pediatric vaccine candidate to prevent OM has multiple potential inherent advantages.

[Changes in the drug resistance of Haemophilus influenzae and Streptococcus pneumoniae isolated between 1997 and 2006]

We studied changes in the drug resistance of 606 strains of Haemophilus influenzae (H. influenzae) and 502 strains of Streptococcus pneumoniae (S. pneumoniae) isolated from our patients between 1997 and 2006. The incidence of beta-lactamase nonproducing ampicillin-susceptible H. influenzae (BLNAS) in 1997-1998 and 1999-2000 was 72.0 and 69.6%, respectively. In 2005-2006, the incidence of BLNAS decreased to 31.0%, while that of beta-lactamase nonproducing ampicillin-resistant H. influenzae (BLNAR) and intermediate-resistant H. influenzae increased to 65.5%. Remarkably early development of BLNAR and intermediate-resistant H. influenzae was found in patients younger than 3 years, as compared to patients older than 3 years. The proportion of penicillin-susceptible S. pneumoniae (PSSP) in 1999-2000 was 18.4%. In 2005-2006, the proportions of penicillin-resistant S. pneumoniae (PRSP) and penicillin-intermediate S. pneumoniae (PISP) were lower, while that of PSSP increased to 38.2%. An early increase in the proportion of PSSP was found in patients older than 3 years, as compared to patients younger than 3 years. The difference between age groups may be attributed to entrance into nursery school, frequent administration of antibiotics, and the immature immunological state of patients younger than 3 years. Therefore, changes in the drug resistance of H. influenzae and S. pneumoniae should be investigated separately, depending on the age of the patients. The minimum inhibitory concentrations of antibiotics, including cefditoren and cefcapene, against BLNAR and PRSP did not increase. The marked increase in intermediate-resistant H. influenzae and BLNAR mandates a re-evaluation of the directions for antibacterial agents.

Effects of Japanese herbal medicine, Juzen-taiho-to, in otitis-prone children--a preliminary study

CONCLUSION

Juzen-taiho-to (JTT, TJ-48), a Japanese herbal medicine that improves immune function, was found to be effective in otitis-prone in children.

OBJECTIVE

To evaluate the efficacy of JTT against intractable and recurrent infections in immature immune systems, we administered JTT to otitis-prone infants and investigated clinical changes before and during JTT administration.

SUBJECTS AND METHODS

Twenty-four otitis-prone infants were administered JTT at 0.10-0.14 g/kg/day twice a day for 3 months. We compared clinical course, such as frequency of acute otitis media (AOM), duration of fever and antibiotics administration, and hospital visits for the periods before and during JTT administration.

RESULTS

Medication compliance rate was 87.5%, and administration of JTT led to remission in 95.2% patients. No apparent side effects were observed. The frequency of AOM decreased significantly (Wilcoxon signed rank test, p=0.000) with JTT. The duration of fever (p=0.000) and administration of antibiotics (p=0.001), as well as the number of hospital visits (p=0.001) and emergent hospital visits (p=0.000) showed significant decreases after JTT administration. After the end of the JTT period, 14 of 21 (66.7%) patients started to take it again, as they experienced purulent otitis media and/or other infections after discontinuation. The frequency of AOM increased significantly after stopping JTT (p=0.004) and decreased again with JTT resumption (p=0.005).

Promiscuous peptides on the nontypeable Haemophilus influenzae P6 outer membrane protein

INTRODUCTION

P6 outer membrane protein is one of the candidates for a vaccine formulation against nontypeable Haemophilus influenzae (NTHi) infection. As otitis-prone children who have recurrent episodes of acute otitis media because of NTHi show an impaired immune response to P6, an innovative approach to vaccination is required to augment their immune response.

RESULTS AND DISCUSSION

We previously identified human HLA-DR9-restricted T cell epitope peptide and highly immunogenic analog peptides on P6 for peptide vaccine candidates. To develop a vaccine formulation effective in the general population, we identified promiscuous T cell epitope peptides (p41-55, p71-85) on P6. In addition to stimulating with potentially promiscuous peptides (p30-44, p45-59) selected using a computer algorithm, we established peptide-specific T cell lines which respond to P6.

CONCLUSION

Our present results indicate that these peptides would be candidates for a widely applicable peptide vaccine formulation.

Study of nasopharyngeal bacterial flora. Variations in nasopharyngeal bacterial flora in schoolchildren and adults when administered antimicrobial agents

Changes in nasopharyngeal bacterial flora in adults with acute upper respiratory tract infection on administration of antimicrobial agents were investigated, and how these changes contrasted with those in children. Many patients with acute sinusitis due to allergies, and patients with malignancy and diabetes mellitus were included in the investigation. The detection rates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, the major bacteria of acute otitis media (AOM), were 22%, 10%, and 7% respectively, which were significantly lower than those for children. Gram stain examination of nasopharyngeal swab samples showed a significant relation between leukocyte infiltration and the detection amount of S. pneumoniae (P = 0.0086). A significant relation (P = 0.0134) was also observed when H. influenzae was simultaneously detected. No significant change in the three major AOM bacteria present in nasopharyngeal bacterial flora after administration of antimicrobial agents was observed. However, all S. pneumoniae and H. influenzae detected after antimicrobial agent administration had the beta-lactam-resistance gene. It was observed that a significant improvement in leukocyte infiltration occurred 6 to 10 days after antimicrobial agent administration. In contrast, a significant improvement in children was observed at 2 to 5 days. In the adult subjects, this improvement was probably due to spontaneous remission rather than the effect of the antimicrobial agents. Although investigation of the long-term administration of antimicrobial agents was also conducted, its benefits for the patients were not elucidated.

Colonization and turnover of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in otitis-prone children

Recurrent otitis media are frequently intractable during childhood. It is unclear whether recurrent otitis media is caused by etiological bacteria colonization or by new infections. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were isolated from the nasopharynx of 7 otitisprone and 2 non-prone children with recurrent otitis media. Plural bacterial species and strains were found in all children while affected by otitis media. The same strain was repeatedly isolated from all otitisprone children even after administration of antibiotics but was not from the non-prone children. Antibiotic susceptibility did not differ significantly among the same repeatedly isolated strains. This pilot study suggests that the etiological bacteria tend to colonize and is hard to eliminate in otitis-prone children.

Acute otitis media in children aged less than 2 years: drug treatment issues

The management of acute otitis media (AOM) in childhood has evolved considerably during recent years as a result of the new insights provided by publication (in 2004) of the American Academy of Pediatrics and the American Academy of Family Physicians guidelines for the treatment of AOM. The new treatment guidelines establish a clear hierarchy among the various antibacterials used in the treatment of this disease and also the use of an age-stratified approach to AOM by recommending an observation strategy ('watchful waiting') without the use of antibacterials for some groups of patients with AOM. Infants and young children aged <2 years represent a target population characterized by a high incidence of AOM (and in particular of recurrent disease), lack of anatomic and physiologic maturity of airways, age-related immune humoral and cellular deficiencies, the presence of antibacterial-resistant pathogens, and a less efficient response to antibacterial treatment. Presently, the evidence accumulated in the literature is not sufficient to conclude that the role of antibacterials is only minimal in the management of AOM and that the watchful waiting policy is the most appropriate choice for patients aged <2 years with a certain AOM diagnosis. However, adherence to such a policy in patients with an uncertain or questionable AOM diagnosis and/or mild-to-moderate symptoms, in addition to its implementation in patients aged >2 years, could reduce substantially the use of antibacterials in children and play a major role in the strategy of decreasing antibacterial resistance.

Mathematical model comparisons of potential non-typeable Haemophilus influenzae vaccine effects

Vaccines to prevent acute otitis media (AOM) caused by non-typeable Haemophilus influenzae (NTHi) are under development. Because NTHi is highly variable and colonization rates are high, special vaccine characteristics and trial designs might be needed. We examined in mathematical models the equilibrium NTHi-caused AOM rate given hypothetical vaccines that generated immunity identical to corresponding maximal naturally acquired immunity. Vaccines were examined with single effects and combinations of immunity affecting (1) AOM rates given colonization (pathogenicity), (2) susceptibility to colonization, and (3) contagiousness given colonization. Percent reductions in AOM across all preschool children were (1) 34%, (2) 31%, (3) 9%, (1 and 2) 57%, (2 and 3) 50%, and (1, 2, and 3) 75%. Effects on children in daycare vs. not in daycare were (1) 18 vs. 48%, (2) -1 vs. 57%, (3) 13 vs. 5%, (1 and 2) 30 vs. 79%, (2 and 3) 33 vs. 60%, and (1, 2, and 3) 64 vs. 85%. Pure pathogenicity effects (1 alone) will need to be supplemented by transmission effects. The effects of susceptibility (2 alone) are diminished or negative because children protected against colonization have lower levels of immunity to (1) and (3) than unvaccinated children. For trials to predict population effects, both colonization and AOM outcomes must be studied and all three effects must be evaluated. This need arises because, unlike H. influenzae type B, high NTHi exposure diminishes cumulative vaccine effects and high colonization rates generate rapid accumulation of natural immunity that alters the indirect effects of vaccine immunity on transmission differently by age and daycare status.

Construction of a mutant and characterization of the role of the vaccine antigen P6 in outer membrane integrity of nontypeable Haemophilus influenzae

Outer membrane protein P6 is the subject of investigation as a vaccine antigen to prevent infections caused by nontypeable Haemophilus influenzae, which causes otitis media in children and respiratory tract infections in adults with chronic lung disease. P6 induces protective immune responses in animal models and is the target of potentially protective immune responses in humans. P6 is a 16-kDa lipoprotein that shares homology with the peptidoglycan-associated lipoproteins of gram-negative bacteria and is highly conserved among strains of H. influenzae. To characterize the function of P6, an isogenic mutant was constructed by replacing the P6 gene with a chloramphenicol resistance cassette. The P6 mutant showed altered colony morphology and slower growth in vitro than that of the parent strain. By electron microscopy, the P6 mutant cells demonstrated increased size, variability in size, vesicle formation, and fragility compared to the parent cells. The P6 mutant showed hypersensitivity to selected antibiotics with different mechanisms of action, indicating increased accessibility of the agents to their targets. The P6 mutant was more sensitive to complement-mediated killing by normal human serum. Complementation of the mutation in trans completely or partially restored the phenotypes. We concluded that P6 plays a structural role in maintaining the integrity of the outer membrane by anchoring the outer membrane to the cell wall. The observation that the absence of expression of P6 is detrimental to the cell is a highly desirable feature for a vaccine antigen, supporting further investigation of P6 as a vaccine candidate for H. influenzae.

Identification of human T-cell epitopes and highly immunogenic analog peptides on the non-typeable Haemophilus influenzae P6 outer membrane protein

P6 outer membrane protein is one of the candidates for a vaccine formulation against non-typeable Haemophilus influenzae (NTHi) infection. However, otitis-prone children who have recurrent episodes of acute otitis media due to NTHi fail to respond adequately to P6. An innovative approach to vaccination is therefore required to augment such children's immune response. To develop an effective peptide vaccine, we established P6-specific CD4(+) T-cell lines (TCLs) restricted by the human histocompatibility leukocyte antigen (HLA)-DR9 molecule, and revealed a human T-cell epitope on P6 and its core peptide sequence (p77-85; EYNIALGQR). Furthermore, we found that 3 analog peptides, E77D (the substitution of E at position 77 with D), N79G, and R85K, induced high proliferative responses as well as marked cytokine production when compared to the T-cell epitope peptide. These peptides may be candidates for a peptide vaccine formulation effective against NTHi infections, even in otitis-prone children.

High frequency of Alloiococcus otitidis in the nasopharynx and in the middle ear cavity of otitis-prone children

OBJECTIVE

Colonization of middle ear pathogens is facilitated in the nasopharynx of otitis-prone children, and is associated with the development of otitis media. Recently, a new species of bacterium, Alloiococcus otitidis, is considered as one of the major middle ear pathogens. However, as far as we know, no study has been reported concerning the prevalence of A. otitidis in the nasopharynx of otitis-prone children. And, no study has been conducted on the association of A. otitidis in the nasopharynx with otitis media.

METHODS

The frequency of A. otitidis in 83 middle ear effusions (MEE) and 56 nasopharyngeal swab (NPS) specimens from 56 children with otitis media was investigated by culture and polymerase chain reaction (PCR).

RESULTS

A. otitidis was detected in 24 (28.9%) of MEE and in 6 (10.7%) of NPS specimens. When the frequency was investigated in relation to proneness to otitis media, A. otitidis was detected in 16 (64%) of 25 MEE and in 5 (29.4%) of 17 NPS specimens from otitis-prone children, whereas it was detected in 8 (13.8%) of 58 MEE and in 1 (2.6%) of 39 NPS specimens from non-otitis-prone children. The frequency of A. otitidis in both NPS and MEE specimens was significantly higher in otitis-prone than in non-otitis-prone children.

CONCLUSIONS

Our results suggest that colonization of A. otitidis is facilitated in the nasopharynx of otitis-prone children. And, nasopharyngeal colonization of A. otitidis may be associated with the frequency of otitis media.

Maternal intranasal immunization with outer membrane protein P6 maintains specific antibody level of derived offspring

Acute otitis media is one of the most common infectious diseases in children younger than 2 years of age. Immunological studies in young children have revealed that immature antibody-responses to major pathogens, such as S. pneumoniae, H.influenzae, would cause the vulnerability to upper respiratory tract infections. Thus, it is very important to induce effective protective immunity among children younger than 2 years of age. In this study, we evaluated the capacity of maternal immunization with P6 of H. influenzae to evoke specific antibody to P6 and to transfer it to offspring. We intranasally immunized mother mice with P6 and investigated the induction of specific antibody in sera and breast milk. The specific antibody among offspring delivered by immunized mother was also investigated according to the nursing status to evaluate the importance of breast feedings by immunized mothers. Anti-P6 specific IgG in sera were high at delivery and maintained during nursing periods among P6-immunized mother mice. Anti-P6 specific IgG were predominantly induced in breast milk. IgG subclass induced in sera and breast milk from P6-immunized mother mice were IgG2b, followed by IgG1 and IgG2a subclass. Offspring delivered by P6-immunized mothers had anti-P6 specific IgG in sera at the birth. The levels of anti-P6 specific IgG in sera from offspring breast-fed by P6-immunized mothers were then increased until day 14 and then decreased on day 21. The anti-P6 specific IgG in sera from offspring breast-fed by sham-immunized mothers were rapidly decreased after birth. The current findings strongly suggest that maternal intranasal immunization with P6 would be an attractive strategy against NTHi infections during early childhood. It can supply protective antibodies via transplacental transfer during pregnancy and via breast milk after birth.

Characterization of salivary immunoglobulin A responses in children heavily exposed to the oral bacterium Streptococcus mutans: influence of specific antigen recognition in infection

The initial infection of children by Streptococcus mutans, the main pathogen of dental caries, depends on the ability of S. mutans to adhere and accumulate on tooth surfaces. These processes involve the adhesin antigen I/II (AgI/II), glucosyltransferases (GTF) and glucan-binding protein B (GbpB), each a target for anticaries vaccines. The salivary immunoglobulin A (IgA) antibody responses to S. mutans antigens (Ags) were characterized in 21 pairs of 5- to 13-month-old children. Pairs were constructed with one early S. mutans-infected and one noninfected child matched by age, racial background, number of teeth, and salivary levels of IgA. Specific salivary IgA antibody response and S. mutans infection levels were then measured during a 1-year follow-up. Robust responses to S. mutans were detected from 6 months of age. Salivary IgA antibody to AgI/II and GTF was commonly detected in salivas of all 42 children. However, GbpB-specific IgA antibody was seldom detected in the subset of infected children (38.1% at baseline). In contrast, most of the subset of noninfected children (76.2%) showed GbpB-reactive IgA antibody during the same period. Frequencies of GbpB responses increased with age, but differences in intensities of GbpB-IgA antibody reactions were sustained between the subsets. At baseline, GbpB-reactive IgA antibody accounted for at least half of the total salivary IgA S. mutans-reactive antibody in 33.3 and 9.5% of noninfected and infected children, respectively. This study provides evidence that a robust natural response to S. mutans Ags can be achieved by 1 year of age and that IgA antibody specificities may be critical in modulating initial S. mutans infection.

Eustachian tube possesses immunological characteristics as a mucosal effector site and responds to P6 outer membrane protein of nontypeable Haemophilus influenzae

The eustachian tube (ET) plays an important role in the pathogenesis of otitis media (OM). To better understand its biology and to develop a nasal vaccine for preventing OM, mucosal lymphocytes in the ET were analyzed, and the ET's immunological function was investigated. Mononuclear cells were isolated from murine ET, and lymphocyte subsets were analyzed by flow cytometry. Antibody-producing cells were determined by enzyme-linked immunospot assay. The expression of cytokine mRNA in ET CD4(+) T cells was determined by RT-PCR. Results in naive mice showed that the ET contained many immunocompetent cells, including a relative large number of IgA-producing cells and Th2 cytokine-expressing T cells. Next, we investigated antigen-specific immune responses in the ET. Mice were immunized intranasally with the P6 outer membrane of nontypeable Haemophilus influenzae (NTHi) and cholera toxin (CT), and P6-specific immune responses in the ET were examined. P6-specific IgA producing cells markedly increased in the ET. Moreover, in vitro stimulation with P6 of purified CD4(+) T cells from immunized mice resulted in the proliferation of CD4(+) T cells that expressed Th2 cytokine mRNA. These results indicate that the ET might be characterized as a mucosal effector site and that antigen-specific IgA and Th2 immune responses could be induced in the ET by intranasal immunization. These findings suggest that the ET might be a key immunological organ in the pathogenesis of OM, and in the development of a nasal vaccine.

Role of an immunodominant T cell epitope of the P6 protein of nontypeable Haemophilus influenzae in murine protective immunity

Nontypeable Haemophilus influenzae (NTHI) is a common cause of otitis media in children and lower respiratory tract infection in adults with chronic lung disease. The highly conserved P6 protein of NTHI infection is under evaluation as a vaccine antigen in several animal models. To elucidate the role of cellular immune response to P6 in protective immunity, the goal of this study was to identify and characterize T cell epitope(s) on P6 and to investigate the role of these epitope(s) in eliciting antigen specific antibody responses and in mediating pulmonary clearance of NTHI. We report that T cells from BALB/c immunized with P6 recognize a single, immunodominant region, represented by 15 amino acids (residues 41-55) of the P6 protein. To verify the ability of this epitope to elicit T cell responses to the P6 protein, mice were immunized with a synthetic peptide corresponding to the sequence of dominant peptide. T cells isolated from mice primed in vivo with the peptide responded following in vitro stimulation with either the peptide or with the whole P6 molecule. Substitution of single amino acids and N or C terminal truncations of the dominant peptide resulted in complete abrogation of the response, implicating their importance to the T cell response. Furthermore, mucosal immunization of mice with a chimeric peptide that encompassed the dominant T cell epitope and a putative B cell epitope resulted in enhanced bacterial clearance following pulmonary challenge with NTHI. Collectively, these results establish that, in a mouse model, P6 contains a single immunodominant T cell epitope and this epitope plays an important role in protective immune responses induced by immunization with P6.

[Recurrent respiratory tract infections: how should we investigate and treat?]

Recurrent respiratory tract infections are a common reason for visits to primary care practitioners or hospital physicians. They are placed at the junction of several medical specialities: paediatrics, ENT, pneumology, allergology, immunology, infectiology. The great diversity of the laboratory tests requested and on the other hand the proposed treatments, are the consequences of the diversity of the patients encountered and the paucity of the evidence based-medicine studies in this setting. The dilemma is how to identify the child for which recurrent respiratory tract infections are the witness of underlying condition, without performing repeated medical examinations, laboratory tests and treatments for normal children for which immunologic development occurs normally. The essential tools are the history analysis, physical examination and few laboratory tests. The other questions are how to include, for these patients, influenza and pneumococcal vaccines in the immunization program and how to assess the benefit/risk ratio and the cost of surgical treatments. This paper presents the thought of an expert group trying to define the situations where biological tests or treatments are useful.

Interference of outer membrane protein PalA with protective immunity against Actinobacillus pleuropneumoniae infections in vaccinated pigs

The role of antibodies to the outer membrane protein PalA of Actinobacillus pleuropneumoniae in protective immunity was studied in pigs vaccinated with purified PalA alone and PalA in combination with toxoids of the RTX toxins ApxI and ApxII using an established challenge model with the virulent serotype 1 of A. pleuropneumoniae. Pigs that developed antibody titers against PalA after immunization were more significantly affected by challenge with A. pleuropneumoniae serotype 1. Following challenge, pigs that were immunized with PalA showed more severe respiratory symptoms, had a higher mortality rate and died faster. They also displayed much more severe lung lesions after necropsy than animals not immunized with PalA. Pigs that were immunized with toxoids of the two cytotoxins ApxI and ApxII were protected against challenge with A. pleuropneumoniae. In contrast, the protective efficacy of the ApxI and ApxII vaccine was completely lost when it was supplemented with PalA. Hence, antibodies induced against the outer membrane protein PalA of A. pleuropneumoniae aggravated the consequences of infection and counteracted the protective effect of anti-ApxI and anti-ApxII antibodies. Due to the high similarity between protein analogues of PalA from various bacteria of the Pasteurellaceae family such as P6 of Haemophilus influenzae or 16kDa Omp of Pasteurella multocida, this deleterious effect of PalA in vaccination should be taken into consideration in the development of vaccines against infections with other Pasteurellaceae.

T cell cytokine responses to outer membrane proteins of Haemophilus influenzae and the house dust mite allergens Der p 1 in allergic and non-allergic subjects

BACKGROUND

Haemophilus influenzae are ubiquitous colonizers of the nasopharynx, Little is known about the T cell cytokine responses to the antigens of these bacteria and whether or not the responses may interact with responses to aeroallergen.

OBJECTIVE

To measure the T cell cytokine responses to conserved outer membrane protein antigens of Haemophilus influenzae and to house dust mite allergen of subjects allergic to the house dust mite and of subjects without allergic sensitization.

METHODS

T cell responses were measured by in vitro proliferation and cytokine release from peripheral blood monocytes (PBMC). The allergen used was Der p 1 and outer membrane proteins were recombinant polypeptides representing the OMP6 and D15 antigens.

RESULTS

The PBMC of most subjects had proliferative responses to OMP6 and D15, which were highly correlated. The pattern of cytokine release was Th1 biased with high levels of IFN-gamma and usually little IL-5 or IL-13 although PBMC from a few subjects did release IL-5 independent of allergic status. IL-10 release was readily detected. There was no difference in the anti-OMP cytokine response of PBMC from subjects without any known allergy and the responses of PBMC from subjects who were highly allergic to house dust mite. The responses to the Der p 1 allergen showed the expected Th2 cytokine release.

CONCLUSION

The outer membrane protein antigens of the ubiquitous colonizing bacteria Haemophilus influenzae induce Th1 cytokine responses which are similar for PBMC from non-allergic individuals and subjects with a high degree of allergy to the perennial house dust mite allergen and strong Th2 responses to Der p 1.

Effect of 23 valent pneumococcal polysaccharide and Haemophilus influenza conjugated vaccines on the clinical course of otitis media with effusion

OBJECTIVE

To determine if there is any clinical effect of 23-valent pneumococcal and type B conjugate vaccine on prognosis of otitis media with effusion.

METHOD

All children who have middle ear effusion despite long-standing antibiotherapy with a beta lactamase stable agent were offered for tympanostomy tube insertion between February 1999 and December 2001. Patients who accepted the surgical intervention were operated under general anesthesia and a Shepard grommet-type tympanostomy tube was inserted. Those who refused the surgical intervention were vaccinated with 23-valent pneumococcal and type B conjugate vaccine. State of the middle ear effusion was evaluated at the end of the 12th month in the vaccine group and 1 month after the myringotomy site was healed in the tympanostomy tube insertion group.

RESULTS

Twenty-six children in the vaccine group and 37 children in the tympanostomy tube insertion group proved the inclusion criteria at the end of study. Complete or partial resolution of middle ear effusion was observed in 73.1% of 26 children in the vaccine group and 59.5% of children in the tympanostomy tube insertion group. There was no significant difference between the two groups.

CONCLUSION

Vaccination against and type b seems to aid resolution of middle ear effusion in children with otitis media with effusion.

Intranasal immunization with recombinant outer membrane protein P6 induces specific immune responses against nontypeable Haemophilus influenzae

OBJECTIVE

Nontypeable Haemophilus influenzae (NTHi) is one of the leading causative pathogens for otitis media. The outer membrane protein P6 of NTHi is highly conserved among the strains and is an attractive candidate for a preventive vaccine. However, for the production of a relatively small amount P6 containing lipopolysaccharides, the development of a recombinant version of this protein is required. This study was designed to investigate the specific mucosal immunity induced by intranasal immunization of recombinant P6 (rP6) with cholera toxin (CT).

METHODS

BALB/c mice were immunized with of rP6 (30 microg) and CT (2 microg) intranasally every 2 days for 2 weeks. Anti-rP6 specific IgG, IgA and IgM antibodies and the subclass of anti-rP6 specific IgG antibody were determined by enzyme linked immunosorbent assay (ELISA). Anti-rP6 specific IgA in nasopharyngeal washings were also determined by ELISA. Nasopharyngeal clearance of inoculated NTHi after the intranasal immunization were assessed. All statistical differences between the two groups were assessed by ANOVA parametric test.

RESULTS

Intranasal immunization with rP6 and CT evoked rP6-specific mucosal IgA immune response as well as the systemic IgG immune response against rP6 and enhanced nasopharyngeal clearance of inoculated live NTHi.

CONCLUSION

These results indicate the good immunogenicities of rP6 to induce specific immune responses against NTHi. Intranasal immunization with rP6 will be an effective approach to protect infections of NTHi.

Decreased serum and pharyngeal antibody levels specific to streptococcal lipoteichoic acid in children with recurrent tonsillitis

OBJECTIVE

Streptococcus (S.) pyogenes is a common cause of primary as well as recurrent tonsillitis (RT). Lipoteichoic acid (LTA) has been proposed as a possible candidate for vaccine formulation against streptococcal infections, because LTA is a common constituent of streptococci and the antibody to LTA inhibits bacterial attachment to epithelial cells in vitro. Streptolysin-O and streptococcal whole cell body are highly immunogenic and the antibodies to these antigens are reported to be better parameters for streptococcal infections The objective of the present study is to investigate how systemic and local immune activities against S. pyogenes may be associated with RT.

METHODS

Sera from 178 children with or without RT aged 1-15 years with a median age of 5 years were investigated for the levels of total immunoglobulins and antibodies specific to streptococcal antigens such as whole cell body, LTA, and streptolysin-O. Pharyngeal secretions from 67 children with or without RT aged 2-14 years with a median age of 6 years were subjects to secretory IgA (SIgA) antibody levels to streptococcal LTA. The antibodies to whole cell body and LTA were measured by enzyme-linked immunosorbent assay. Total immunoglobins and the anti-streptolysin-O antibody were assayed by nephelometry.

RESULTS

An age-matched comparison revealed that either levels of serum IgG antibody or pharyngeal SIgA antibody to streptococcal LTA at 2-5 years of age were significantly lower in RT children than in non-RT children (1.39 vs. 5.14 microg/ml, P=0.001; 10.6 vs. 29.9 units/ng/ml total SIgA, P=0.015; respectively) and correlated inversely to episodes of tonsillitis (r=-0.242, P=0.024; r=-0.3, P=0.024; respectively). Either serum total immunoglobulin levels of IgG or IgA correlated positively to episodes of tonsillitis in children aged 2-5 years (r=0.293, P=0.011; r=0.361, P=0.002; respectively). No difference was found on either serum levels of IgG antibody to streptococcal whole cell body or antibody to streptolysin-O between RT and non-RT children in any age-matched comparisons. High serum antibody levels to whole cell body was associated with high antibody levels to streptococcal LTA in non-RT children (r=0.198, P<0.05), but no association was found between these antibody levels in RT children.

CONCLUSIONS

Selective immunologic failure in systemic and pharyngeal antibody response to streptococcal LTA may be a potential cause of RT in young children.

Intranasal immunization with lipoteichoic acid and cholera toxin evokes specific pharyngeal IgA and systemic IgG responses and inhibits streptococcal adherence to pharyngeal epithelial cells in mice

OBJECTIVE

Streptococcus (S.) pyogenes is common cause of acute tonsillitis. Lipoteichoic acid (LTA), which is a common constitute of the cell surface of most gram positive bacteria, is known to act as a substance of bacterial site for adherence to epithelium and antiserum to LTA is reported to inhibit bacterial attachment to epithelial cells in vitro. Cholera toxin subunit B (CT-B) is known to be a mucosal adjuvant. The purpose of this study is to investigate whether intranasal immunization with LTA and CT-B may be a possible candidate for vaccine formulation.

METHODS

Six-week-old male BALB/c mice were assigned to three experimental groups, mice immunized with LTA and CT-B, with LTA alone and with phosphate buffered saline (PBS) as a control. Immunizations were performed intranasally every 2 days for 2 weeks in every group. At the 21 days after immunization, sera, pharyngeal washings and pharyngeal epithelial cells were taken. The levels of serum IgG and pharyngeal IgA antibodies to LTA were measured by enzyme-linked immunosorbent assay (ELISA). The adherence rates of S. pyogenes pretreated by pharyngeal washings to pharyngeal epithelial cells from the mice were determined by in vitro adherence assay.

RESULTS

The serum anti-LTA IgG antibody levels of either mice immunized with LTA and CT-B or mice immunized with LTA alone were significantly higher than those of mice administered with PBS alone. The pharyngeal anti-LTA IgA antibody levels of the mice immunized with LTA and CT-B were significantly higher than those of either mice with LTA alone or mice with PBS alone. The streptococcal adherence rates to pharyngeal epithelial cells were significantly decreased by pretreatment with pharyngeal washings from the mice immunized with LTA and CT-B as compared with pretreatment with those from either mice with PBS or mice with LTA alone.

CONCLUSIONS

These data shows that intranasal immunization with LTA and CT-B evokes a good pharyngeal IgA response as well as systemic IgG response to LTA and inhibits streptococcal adherence to pharyngeal epithelial cells, suggesting that intranasal immunization with LTA and CT-B may be an effective approach to prevent streptococcal tonsillitis.

Lymphocyte proliferative response to P6 of Haemophilus influenzae is associated with relative protection from exacerbations of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by periodic exacerbations, some of which are caused by nontypeable Haemophilus influenzae (NTHI). P6 is an outer membrane lipoprotein that is highly conserved among strains of NTHI. We hypothesized that lymphocytes from patients with COPD who have exacerbations due to NTHI have a decreased ability to recognize P6. The in vitro lymphocyte proliferative response to P6 in 36 patients with COPD and 12 healthy control subjects was studied. Ten patients who had exacerbations due to NTHI in the previous 12 months showed statistically significant lower proliferation to P6 (stimulation index, log transformed mean +/- standard error 0.82 +/- 0.17) compared with 26 patients who had no exacerbations due to NTHI in the previous 12 months (1.42 +/- 0.13) and to 12 healthy control subjects (1.61 +/- 0.16). These three groups had no significant difference in the lymphocyte proliferative response to tetanus toxoid. There was no difference in serum antibody levels to P6 in the two groups with COPD. These results indicate that decreased proliferation of T cells to P6 is associated with exacerbations of COPD and suggest that the ability of T cells to recognize P6 is associated with relative protection from exacerbations due to NTHI.

Vaccine prevention of acute otitis media

The incidence of acute otitis media (AOM) in infants and young children has increased dramatically in recent years in the United States. AOM often follows upper respiratory tract infections due to pathogens such as respiratory syncytial virus (RSV), influenza virus, and parainfluenza virus (PIV). These viruses cause eustachian tube dysfunction that is critical to the pathogenesis of AOM. Vaccines against these viruses would likely reduce the incidence of AOM. In three previous studies, influenza virus vaccines reduced the incidence of AOM by 30% to 36%. Vaccines to prevent infections with RSV and PIV type 3 are undergoing clinical testing at this time. Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis are the three most common AOM pathogens. Heptavalent pneumococcal conjugate vaccine is effective in preventing invasive disease and AOM caused by serotypes contained in the vaccine. Vaccine candidates for NTHi and M. catarrhalis are under development.

Bacteriology of acute otitis media in a cohort of Finnish children followed for the first two years of life

BACKGROUND

Timely information on the bacteriology of primary, noncomplicated acute otitis media (AOM) may today be needed more than ever, because of the increasing antimicrobial resistance of its major bacterial causes and because of the potential of new pneumococcal and other bacterial vaccines for prevention of AOM.

METHODS

The study followed 329 children from 2 to 24 months of age at scheduled healthy visits and sick visits at the study clinic. Whenever AOM was diagnosed during the follow-up, myringotomy was performed and middle ear fluid was aspirated for bacterial culture.

RESULTS

At least one middle ear fluid sample was available from 772 AOM events; Streptococcus pneumoniae (Pnc) was isolated in 201 (26%), Moraxella catarrhalis (Mc) in 177 (23%) and Haemophilus influenzae (Hi) in 174 events (23%). The incidence of Pnc AOM peaked at 12 months of age, whereas the incidence of Mc AOM showed the first peak at 6 months and Hi AOM at 20 months. Pnc AOM showed less prominent seasonality in occurrence than Mc and Hi AOM. Hi was a rare cause of the first 2 AOM episodes (13%) but became increasingly common from the third episode on (32% on average).

CONCLUSIONS

Pnc, Mc and Hi were almost equally common findings in AOM. Pnc seems to be the most pathogenic of these three, the role of Mc is increasing and Hi is clearly associated with recurrent AOM.

The nasopharynx and the middle ear. Inflammatory reactions in middle ear disease

The host-parasite interactions in the nasopharynx with bacterial colonization and antigen uptake in the lymphoid tissue, the adenoid, has an impact on the maturation of local and systemic immunity. The adenoid is a part of mucosa associated lymphoid tissue and is responsible for both effector and inductor functions in the nasopharynx. Increasing evidence supports the role of serum antibody in protecting the middle ear cavity from disease. There is evidence for a minor immunologic defect in a number of children with recurrent episodes of AOM.

Stimulation of adenoidal lymphocytes by Alloiococcus otitidis

Otitis media with effusion (OME) is characterized by persistent effusion in the middle ear cavity and by chronic inflammation in the middle ear mucosa. Alloiococcus otitidis, a gram-positive aerobic bacterium, has been isolated in middle ear effusion, and by means of sensitive polymerase chain reaction detection assays it has been detected in as many as 20% of middle ear aspirates of patients with OME. Because A otitidis may freely interact with leukocytes in the middle ear effusion, it may potentially modulate the inflammatory reaction in OME. To study the nature of these interactions, we applied an in vitro assay in which killed A otitidis bacteria were incubated with peripheral blood and adenoidal mononuclear cells. The expression of the proliferation-associated surface marker CD69 was then measured in B lymphocytes and in CD4+ helper and CD8+ cytotoxic-suppressor T lymphocytes by means of multicolor flow cytometry. Alloiococcus otitidis induced the expression of CD69 in both peripheral blood and adenoidal T and B cells. Among the T cells, the cytotoxic-suppressor T lymphocytes were preferentially activated. It was also tested whether A otitidis would have an effect in another cytotoxic and immunoregulatory system, namely, the induction of natural killer cell activity in peripheral blood mononuclear cells. However, the effect was minimal compared with that of Salmonella minnesota or Staphylococcus aureus. The results show that A otitidis has a unique immunostimulatory capacity in vitro that is mainly confined to CD8+ T lymphocytes.

Immune responses to specific antigens of Streptococcus pneumoniae and Moraxella catarrhalis in the respiratory tract

Streptococcus pneumoniae and Moraxella catarrhalis are two common respiratory pathogens, colonizing as many as 54 and 72% of children, respectively, by 1 year of age. The immune responses to surface protein A of S. pneumoniae (PspA) and the high-molecular-weight outer membrane protein of M. catarrhalis (UspA) in the sera of various age groups in the general population and in the nasopharynges of 30 children monitored from birth through 1 year of age were evaluated. Immunoglobulin G (IgG) was the dominant serum antibody to PspA and UspA. Whereas the serum antibody response to PspA peaked in childhood, the antibody response to UspA peaked in adulthood. In the first 2 years of life, comparable amounts of IgM and IgG antibodies to both proteins were observed. In older persons, IgG antibodies to both antigens predominated over IgM antibodies. The levels of IgA antibody to these antigens in serum remained low during the first 2 years of life. The levels of IgM antibody to the two antigens in serum exceeded the levels of IgA antibody to the same two antigens throughout life. Although IgA was the dominant antibody to PspA and UspA in airway secretions, it was detected in a minority of the children (3 of 15 for PspA and 0 of 15 for UspA). Even the majority of the children previously colonized with these pathogens lacked antibody to them in their secretions.

Antibody responses to the outer membrane protein P6 of non-typeable Haemophilus influenzae and pneumococcal capsular polysaccharides in otitis-prone children

Acute otitis media (AOM) is a common infectious disease in children. Some children experience recurrent episodes of AOM. Recent investigations demonstrate antigen-specific immunological deficiencies in children prone to AOM. In the present study, the immune responses to non-typeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae (S. pneumoniae) were further investigated in otitis-prone children and normal children. Forty-eight percent of otitis-prone children exhibited reduced IgG2 levels to S. pneumoniae and 55% exhibited reduced IgG levels to NTHi. These data suggest that otitis proneness appears to be related to numerous immunological derangements. Pathogen-specific antibodies are a reliable measure of otitis proneness.

Purification and characterization of outer membrane protein P6, a vaccine antigen of non-typeable Haemophilus influenzae

Outer membrane protein P6 is a promising vaccine antigen with potential to prevent infections caused by non-typeable Haemophilus influenzae. A convenient and reliable method for the purification of P6 and an assessment of the purity, yield, protein structure, antigenicity and immunogenicity of the purified protein are described. The method begins with intact H. influenzae and utilizes a series of incubations and centrifugations using a single buffer to remove all cell components with the exception of the peptidoglycan to which the P6 is associated. P6 is dissociated from the complex with heat and the insoluble peptidoglycan is removed by centrifugation. The procedure yields highly purified P6. Contamination with lipooligosaccharide is less than 0.025 endotoxin U per microgr P6. The yield of P6 is approximately 2 mg of P6 per l H. influenzae culture. The purified P6 retains both the secondary and tertiary structure as measured by circular dichroism and analysis with monoclonal antibodies. The purified P6 is immunogenic in animals. A convenient method for purifying P6 which retains antigenicity and immunogenicity will be an important tool for future studies of the vaccine potential of P6.