Invasive Haemophilus influenzae Infections after 3 Decades of Hib Protein Conjugate Vaccine Use.

Haemophilus influenzae serotype b (Hib) was previously the most common cause of bacterial meningitis and an important etiologic agent of pneumonia in children aged <5 years. Its major virulence factor is the polyribosyl ribitol phosphate (PRP) polysaccharide capsule. In the 1980s, PRP-protein conjugate Hib vaccines were developed and are now included in almost all national immunization programs, achieving a sustained decline in invasive Hib infections. However, invasive Hib disease has not yet been eliminated in countries with low vaccine coverage, and sporadic outbreaks of Hib infection still occur occasionally in countries with high vaccine coverage. Over the past 2 decades, other capsulated serotypes have been recognized increasingly as causing invasive infections. H. influenzae serotype a (Hia) is now a major cause of invasive infection in Indigenous communities of North America, prompting a possible requirement for an Hia conjugate vaccine. H. influenzae serotypes e and f are now more common than serotype b in Europe. Significant year-to-year increases in nontypeable H. influenzae invasive infections have occurred in many regions of the world. Invasive H. influenzae infections are now seen predominantly in patients at the extremes of life and those with underlying comorbidities. This review provides a comprehensive and critical overview of the current global epidemiology of invasive H. influenzae infections in different geographic regions of the world. It discusses those now at risk of invasive Hib disease, describes the emergence of other severe invasive H. influenzae infections, and emphasizes the importance of long-term, comprehensive, clinical and microbiologic surveillance to monitor a vaccine's impact.

A review of invasive Haemophilus influenzae disease in the Indigenous populations of North America.

Historically, the highest incidence rates of invasive Haemophilus influenzae disease in the world were found in North American and Australian Indigenous children. Although immunization against H. influenzae type b (Hib) led to a marked decrease in invasive Hib disease in countries where it was implemented, this disease has not been eliminated and its rates in Indigenous communities remain higher than in the general North American population. In this literature review, we examined the epidemiology of invasive H. influenzae disease in the pre-Hib vaccine era, effect of carriage on disease epidemiology, immune response to H. influenzae infection and Hib vaccination in Indigenous and Caucasian children, and the changing epidemiology after Hib conjugate vaccine has been in use for more than two decades in North America. We also explored reasons behind the continued high rates of invasive H. influenzae disease in Indigenous populations in North America. H. influenzae type a (Hia) has emerged as a significant cause of severe disease in North American Indigenous communities. More research is needed to define the genotypic diversity of Hia and the disease burden that it causes in order to determine if a Hia vaccine is required to protect the vulnerable populations.

Proceedings of a workshop to discuss the epidemiology of invasive Haemophilus influenzae disease with emphasis on serotype a and b in the Americas, 2019.

On March 9, 2019, a one-day workshop titled "The current epidemiology of invasive Haemophilus influenzae disease in the Americas", jointly organized by the Public Health Agency of Canada (PHAC), the Canadian Institute of Health Research (CIHR), and the National Research Council Canada (NRC), brought together experts in the epidemiology and surveillance of invasive Haemophilus influenzae (Hi) disease from the Pan American Health Organization (PAHO) and its five regional reference laboratories in South America, USA, and Canada in Ottawa, Ontario, Canada. This workshop built upon recommendations of previous related workshops and incorporated updated data.

A case series evaluating the serological response of adult asthma patients to the 23-valent pneumococcal polysaccharide vaccine.

BACKGROUND: Asthma is an independent risk factor for invasive pneumococcal disease; however, the immune response of adult asthma patients to pneumococcal vaccination is unknown. We explore the serologic response of patients with moderate to severe asthma to the 23-valent pneumococcal polysaccharide vaccine (PPSV23). METHODS: Seventeen moderate to severe adult asthma patients that had not been vaccinated against pneumococcus over the 5 previous years were prospectively recruited from a tertiary care asthma clinic. Serum was analyzed for the presence of antibodies to five capsular polysaccharide (CP) antigens (6B, 9V, 19A, 19F, 23F) before and 4 weeks after PPSV23 vaccination. RESULTS: There was a wide variability in baseline anti-CP antibody concentrations. Other than for serotype 19A, our patients frequently have baseline anti-CP antibody concentrations below 1 µg/mL (35% for serotype 19F, 41% for serotypes 9V and 23F, and 59% for serotype 6B). All post-vaccination geometric mean antibody concentrations were significantly higher than baseline. In the 31 tests where the baseline antibody concentration was <1 µg/mL, 77.4% had at least a twofold increase post-vaccination. Despite this, a large proportion of post-vaccination anti-CP antibody concentrations remained <1 µg/mL (51.6% of tests). Nine patients had at least one anti-CP antibody concentration <1 µg/mL post-vaccination. There was no difference between these patients and the remaining eight patients in demographic or clinical variables. CONCLUSIONS: Patients with moderate to severe asthma have variable baseline and low post-vaccination antibody concentrations to common CP antigens included in the PPSV23 vaccine. The clinical relevance of these observations remains to be determined since the threshold concentration in adults required for clinical protection from invasive pneumococcal disease is uncertain.

The emerging Haemophilus influenzae serotype a infection and a potential vaccine: Implementation science in action.

Haemophilus influenzae serotype b (Hib) was a major cause of meningitis in children until Hib conjugate vaccine was introduced into the routine infant immunization program and Hib disease in children was almost eliminated. In Alaska, northern Canada and other countries with Indigenous peoples, H. influenzae serotype a (Hia) has emerged as a significant cause of pneumonia, meningitis and septic arthritis especially in children under 24 months of age. A joint government initiative between the Public Health Agency of Canada (PHAC) and the National Research Council of Canada (NRC) was carried out to assess whether an Hia vaccine could be developed for the common good. The initiative included strategic partnerships with clinician researchers in Thunder Bay, Ontario who provide health services to Indigenous people and the Artic Investigations Program (AIP) of the United States Centers for Disease Control and Prevention (CDC) in Alaska. This government initiated and funded research identified that the development of an Hia vaccine is possible and ongoing surveillance that includes strain characterization is essential to understand the potential spread of Hia in North America and around the world.

Developing a vaccine for Haemophilus influenzae serotype a: Proceedings of a workshop.

Since the late 1990s there has been an emergence of Haemophilus influenzae serotype a (Hia) infections, especially in Indigenous communities in the northern regions of Canada and Alaska associated with significant morbidity and approximately a 10% mortality. A Hia vaccine could potentially prevent this disease and save the health care system millions of dollars in both acute and long-term care. On March 23-24, 2016, the National Research Council (NRC), the Public Health Agency of Canada (PHAC) and the Canadian Institutes of Health Research (CIHR) co-organized a meeting on H. influenzae serotype a (Hia) to examine the current state of disease epidemiology and a potential vaccine solution path. The meeting included representatives from academia, federal and territorial public health units, hospital laboratories, federal departments involved in Aboriginal health, advocacy organizations for Indigenous peoples and industry. Representatives from industry confirmed having the capacity and the interest to support preparation of clinical trial batches. Canadian regulatory authorities have expressed a willingness to help ensure appropriate measures are in place for licensure purposes. Furthermore, there is the capacity and interest in performing some clinical trials in Indigenous communities in both Canada and Alaska. Recommendations for next steps included: complete pre-clinical studies, improve epidemiological surveillance to better understand the extent of the disease in the rest of North America and globally, establish engagement mechanisms with national Indigenous organizations to ensure their peoples are fully involved in the process and explore funding opportunities to prepare clinical lots and undertake clinical trials.

The clonal antibody response to Pseudomonas aeruginosa heat shock protein is highly diverse in cystic fibrosis patients.

The GroEL protein of Pseudomonas aeruginosa belongs to the bacterial 60-65 kDa heat shock protein family. A strong antibody response to GroEL has been found in cystic fibrosis (CF) patients with chronic pulmonary infection caused by P. aeruginosa. Clonotypes of IgG1 and IgG2 antibodies against GroEL were studied in 60 consecutive sera from 18 CF patients with chronic P. aeruginosa infection using isoelectric focusing in combination with affinity immunoblotting. The persistent antigenic stimulation in CF patients with chronic P. aeruginosa infection induced numerous IgG1 and particularly IgG2 antibody clones against GroEL. The appearance of new clones with time reflected the long duration of the chronic infection. A striking addition of new clonotypes during the observation period occurred when a new unrelated bacterium (Burkholderia cepacia) had become established as a cause of the pulmonary infection, or when the P. aeruginosa infection became chronic.

[Antibodies to Streptococcus pneumoniae antigens in newborn infants]. / Antitela k nekotorym antigenam Streptococcus pneumoniae u novorozhdennykh detei.

The levels of antibodies to capsular polysaccharide antigens of pneumococci (serotypes 1, 3, 6B, 8, 9N, 15F, 23F), C-polysaccharide and protein antigen of pneumococci in the blood sera of 38 newborn infants at the moment of their birth (umbilical blood) and on the 5th or 6th day of their life, in their mothers' blood sera, as well as in the colostrum and milk of 48 nursing women, have been studied by means of the enzyme immunoassay. The study showed that in the normal course of pregnancy antibodies to pneumococci were transferred transplacentally from the mother to the fetus. Though in most cases their content in the blood of newborn infants was lower than that in maternal blood, it exceeded the average level of antipneumococcal antibodies in children aged 3-12 months. In the milk of nursing mothers considerable amount of IgA antibodies to pneumococci was detected, which might be an additional protective factor with respect to pneumococcal infection in infants.

[Determination of pneumococcus antibodies in secretions in acute pneumonia in children]. / Opredelenie antitel k pnevmokokku v sekretakh pri ostroi pnevmonii u detei.

IgA-antibodies to pneumococcal antigens were measured by enzyme immunoassay in saliva and nasal washings, obtained from 32 children aged 6 months to 14 years with acute pneumonia and from 25 healthy children aged 2.5-11 years. In the secretions of children with acute pneumonia an essential increase in the levels of IgA-antibodies in comparison with those observed in healthy children was detected. The levels of antibodies to pneumococci in saliva and in nasal washings were in direct correlation. These data are indicative of a protective role played, probably, by secretory antibodies at the portals of infection in pneumococcal pneumonia.

[An immunoenzyme system for determining antibodies to Streptococcus pneumoniae polysaccharides in biological fluids]. / Immunofermentnaia sistema dlia opredeleniia antitel k polisakharidam Streptococcus pneumoniae v biologicheskikh zhidkostiakh.

The enzyme immunoassay (EIA) system for the determination of antibodies to capsular polysaccharides of pneumococci, serotypes 1, 3, 6B, 8, 9N, 15F, 23F, and C-polysaccharide has been developed on the basis of poly-L-lysin-modified antigens. The use of isotype-specific conjugates in this system permits the detection of IgG and IgA antibodies in different biological fluids: blood serum, pleural fluid, saliva, milk. Samples obtained from children with pneumococcal infection and from nursing mothers have been studied. As shown in this study, the EIA system can be used for the evaluation of the dynamics of pneumococcal infection in children.

[The indices of antipneumococcal immunity in children with chronic pneumonia]. / Pokazateli protivopnevmokokkovogo immuniteta u detei, bol'nykh khronicheskoi pnevmoniei.

In 76 children with chronic pneumonia the levels of serum antibodies to pneumococcal capsular polysaccharide antigens (serotypes 1, 3, 6B, 8, 9N, 15F, 23F), O-polysaccharide and pneumococcal protein somatic antigens were determined by ELISA techniques. The study showed that in sick children the content of antipneumococcal antibodies in the blood increased with age. No correlation between the content of total immunoglobulins and that of antipneumococcal antibodies in the blood of the patients was established, but a sharp decrease in the concentration of antibodies was registered in a child with hypoglobulinemia. No increase in the level of antibodies to pneumococcal antigens was observed in cases of the exacerbation of Pneumococcus-induced inflammatory process in the lungs.

[The periodic and regional characteristics of the pneumococcal serotype spectrum in children with respiratory diseases and in healthy carriers]. / Peridodicheskie i regional'nye osobennosti serotipovogo spektra pnevmokokkov u detei s respiratornymi zabolevaniiami i zdorovykh nositelei.

The aim of the work was the comparative study Streptococcus pneumoniae serotypes, isolated from healthy carriers and acute pneumonia patients in different regions of the CIS; in Moscow observations were carried out for 10 years. Specific antibodies to different S.pneumoniae capsular polysaccharide antigens were determined in blood serum samples by the method of heterogeneous enzyme immunoassay. The study revealed that S.pneumoniae serotype spectra in healthy children and in children with acute respiratory viral diseases were similar, while from pneumonia patients with complications of pleuritis caused by S.pneumoniae serotypes 1, 3, 5 and 14, were more frequently isolated. During 10 years of observations changes in the occurrence of individual serotypes were noted both in carriers and in patients. Differences in the serotype spectra of S.pneumoniae isolated in different regions were established. S.pneumoniae serotype 5 caused 70% of pleuritis cases in Tashkent, while rarely occurring in regions with the moderate climate. S.pneumoniae serotype 14, formerly causing complicated forms of pneumonia, lately became more widespread, but at the same time caused fewer cases of pneumonia with complications. High occurrence of pneumonia among children aged 1-3 years correlated with a low level of specific antibodies in the child population.

Antibody against Haemophilus influenzae protein D in patients with chronic conditions causing secondary immunodeficiency.

Prevalence of non-typeable Haemophilus influenzae (NTHi) in the etiology of invasive infections in immunocompromised individuals is increasing. Serum IgG antibody levels to H. influenzae protein D (PD) were significantly lower in adults suffering from chronic conditions causing secondary immunodeficiency (COPD, cancer, chronic renal failure, and diabetes) compared to age-matched healthy controls. A lack of naturally acquired antibody against this highly conserved antigen may contribute to an increased susceptibility to invasive NTHi disease. As COPD patients frequently infected with NTHi during disease exacerbations were unable to develop antibody response to PD, such defect could potentially contribute to the pathogenesis. Considering that pediatric PD-containing vaccines show protective effect against NTHi-caused otitis media, our data suggest the possibility of improving the defense against NTHi in COPD patients using immunization against PD. Although more research on the role of anti-PD antibody in protection against invasive NTHi disease is warranted, development of adult formulations of PD-based vaccines may be advantageous for prevention of severe infections in immunocompromised individuals.

Expression of idiotypic antibodies-1 and -2 and breastfeeding in relation to antibody levels against Haemophilus influenzae type B in children.

The aim of the study was to determine the concentrations of serum antibodies against Haemophilus influenzae type b in preschool children in relation to the distribution of idiotypic antibodies 1 and 2 (Id-1 and Id-2) and the exposure to breastfeeding in infancy. Sera were obtained from 74 control children recruited in an earlier case-control study before the introduction of general Hib vaccination. Duration of breastfeeding was monitored, and prevalence of noninvasive infections was registered. Concentrations of IgG1 and IgG2 anti-Hib, as well as of total Id-1 and Id-2, were determined in ELISA. The expression of Id-1 antibodies increased with age in contrast to the Id-2 antibodies that were found only in children up to 24 months of age. Expression of Id-1 antibodies was positively correlated with higher anti-Hib levels of both the IgG1 and IgG2 isotype. Children expressing Id-2 antibodies showed higher IgG2 anti-Hib concentrations than those who did not have Id-2 (P = 0.001). The concentrations of neither Id-1 nor Id-2 antibodies were related to the duration of breastfeeding. Duration of breastfeeding was related to increased anti-Hib IgG2 in healthy children above 18 months of age. These study shows that the expression of idiotype-1 and idiotype-2 antibodies was associated with higher IgG2 anti-Hib concentration and that breastfeeding could enhance the anti-Hib IgG2 production in children.

[The role of Pneumococcus in the development of acute bronchitis in young children]. / O roli pnevmokokka v razvitii ostrogo bronkhita u detei rannego vozrasta.

To study the etiological role of Streptococcus pneumoniae in bronchial inflammation, 49 children with acute bronchitis and 21 children with acute nasopharyngitis were examined. The given patients' groups manifested no significant differences in the microflora of the upper respiratory tract, serotype landscape of pneumococcus, the level and dynamics of the immunologic characteristics. The growth of the titer of pneumococcal antibodies in the saliva in the early times of the disease as well as the lack of its changes in blood serum suggest that interaction of pneumococcus with the host is restricted in the given case by the bronchial lumen.

Invasive Haemophilus influenzae type b (Hib) infection in an adult patient with a selective deficiency of antibody to the Hib capsular polysaccharide.

A 31-year-old woman without any underlying disease contracted severe invasive Haemophilus influenzae type b (Hib) infection but developed no antibodies to the Hib capsular polysaccharide. Serum immunoglobulin levels were normal, but she had an isolated deficiency of antibody to Hib. Subsequently, immunization with a tetanus toxoid-conjugated Hib vaccine induced only a minimal response. However, she had a protective level of antibody (> 1 microgram/mL) after the fifth vaccination.

The Common vaccine adjuvant aluminum hydroxide up-regulates accessory properties of human monocytes via an interleukin-4-dependent mechanism.

Aluminum adjuvants are widely used in human vaccines based on their ability to enhance antibody production. However, the mechanisms underlying these effects remain unknown. In the present study we assessed the direct in vitro effect of aluminum hydroxide on human peripheral blood monocytes, specifically with regard to its impact on the phenotype and functional properties of this cell population. Our results revealed significant changes in the accessory properties of monocytes following short-term exposure of cultured cells to aluminum hydroxide. Thus, flow cytometry analyses showed an increase in the expression of major histocompatibility complex (MHC) class II, CD40, CD54, CD58, CD83, and CD86 molecules on the monocytes. In addition, many cells in the cultures containing aluminum hydroxide acquired typical dendritic morphology. Increased synthesis of interleukin-4 (IL-4) mRNA, but not gamma interferon mRNA, was also noted after exposure to aluminum hydroxide. The increase in cell surface expression of MHC class II did not occur in the presence of neutralizing IL-4 antibody or in cultures of highly purified monocytes or CD4-depleted mononuclear cells. Our findings suggest that aluminum hydroxide directly stimulates monocytes to produce proinflammatory cytokines activating T cells. Activated Th2 cells release IL-4, which in turn can induce an increase in the expression of MHC class II molecules on monocytes. The increase in the expression of antigen-presenting and costimulatory molecules leads to enhanced accessory functions of monocytes. These properties of aluminum hydroxide observed in vitro may explain its potent in vivo adjuvant effect.

Expression of Haemophilus influenzae type b idiotype 1 on naturally acquired antibodies.

The Chinese population in Hong Kong has a low incidence of invasive Haemophilus influenzae type b(Hib) disease, as well as carriage of the microorganism. Likely stimuli for the natural antibodies to Hib, which might protect against Hib infection, are cross-reactive antigens of bacteria like Escherichia coli K 100. Our aim was to determine the isotype and idiotype distribution and cross-reactivity of natural antibodies against Hib capsular polysaccharide (CP) in healthy Hong Kong Chinese. Titration of 20 sera by ELISA showed IgG antibodies reacting with Hib CP in all individuals. The antibodies were mainly IgG2, and their avidity index ranged widely. Isoelectric focusing (IEF) combined with immunoblotting showed patterns of IgG2 antibody clones against the CP of Hib and E. coli K 100 which were similar in 10 cases. Absorption with Hib CP only eliminated some bands in two sera. Absorption with K 100 CP did not remove any anti-Hib CP bands. In three sera additional clones of antibodies reacting to K 100 CP only, disappeared after absorption with this CP. Spectrotypic analyses of IgG antibodies reacting with anti-Hib idiotype 1 (Id-1) revealed stronger IEF patterns with bands in differing locations compared with anti-Hib CP antibodies. The strong reactivity of serum IgG, IgA and IgM antibodies with monoclonal anti-Hib Id-1 was confirmed by ELISA. This reactivity was not abolished after absorption of the sera with either Hib CP, or K 100 CP. The data indicate a high prevalence of Id-1 among Hong Kong Chinese. However, only one individual had Id-1 antibodies specific for Hib CP, judging from absorption experiments. Others had much lower activity of Id-1 anti-Hib CP antibodies compared with the total IgG Id-1, suggesting that Hong Kong subjects have Id-1-positive antibodies in their serum which are not specific for Hib CP. This is consistent with the nature of Id-1, which is a marker of A2VL region usage rather than a marker of a Hib CP paratope. We suggest that natural antibodies reacting with Hib CP in healthy Hong Kong Chinese are the product of exposure to some cross-reactive antigen(s), different from both Hib and E. coli K 100 CP.

Antigen-specific regulation of CD1 expression in humans.

During the last decade the CD1 family of cell surface glycoproteins has been implicated in the presentation of nonpeptide antigens in man. Recent findings by our group indicate that CD1 molecules also can be involved in the presentation of certain bacterial proteins. However, CD1a, b, and c (group 1 CD1 molecules) are not present at significant levels on circulating monocytes unless their expression is induced by cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF). In this study we investigated the cell surface expression of CD1 molecules following the antigenic stimulation in vivo via immunization of healthy volunteers with tetanus toxoid vaccine and in vitro cell cultures using the same antigen. Both the in vivo and in vitro studies demonstrated clear up-regulation of the surface expression of CD1a, b, and c on monocytes as a result of antigenic stimulation with tetanus toxoid, supporting the idea that CD1 molecules participate in the presentation of this protein antigen in man. In vitro, antigen-triggered expression of these molecules was mediated by GM-CSF, since neutralization of this cytokine with specific antibody totally abrogated CD1a, b, and c expression. In contrast to the group 1 CD1 molecules, CD1d was found to be constitutively expressed on the majority of circulating monocytes and B lymphocytes prior to immunization. There was no effect of antigenic stimulation with tetanus toxoid on the cell surface expression of CD1d, suggesting major differences in regulation of the expression and function of the different CD1 molecules in humans. Altogether our results point to antigen-driven up-regulation of CD1a, b, and c expression on human monocytes that is mediated by GM-CSF and no effect on CD1d expression.