Lack of effectiveness of 13-valent pneumococcal conjugate vaccination against pneumococcal carriage density in Papua New Guinean infants

BACKGROUND

Papua New Guinea (PNG) introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in 2014, with administration at 1, 2, and 3 months of age. PCV13 has reduced or eliminated carriage of vaccine types in populations with low pneumococcal carriage prevalence, carriage density and serotype diversity. This study investigated PCV13 impact on serotype-specific pneumococcal carriage prevalence, density, and serotype diversity in PNG infants, who have some of the highest reported rates of pneumococcal carriage and disease in the world.

METHODS

Nasopharyngeal swabs were collected at 1, 4 and 9 months of age from PCV13-vaccinated infants (n = 57) and age-/season-matched, unvaccinated infants (at approximately 1 month, n = 53; 4 months, n = 57; 9 months, n = 52). Serotype-specific pneumococcal carriage density and antimicrobial resistance genes were identified by qPCR and microarray.

RESULTS

Pneumococci were present in 89% of swabs, with 60 different serotypes and four non-encapsulated variants detected. Multiple serotype carriage was common (47% of swabs). Vaccine type carriage prevalence was similar between PCV13-vaccinated and unvaccinated infants at 4 and 9 months of age. The prevalence of non-vaccine type carriage was also similar between cohorts, with non-vaccine types present in three-quarters of samples (from both vaccinated and unvaccinated infants) by 4 months of age. The median pneumococcal carriage density was high and similar at each age group (~7.0 log₁₀genome equivalents/mL). PCV13 had no effect on overall pneumococcal carriage density, vaccine type density, non-vaccine type density, or the prevalence of antimicrobial resistance genes.

CONCLUSION

PNG infants experience dense and diverse pneumococcal colonisation with concurrent serotypes from 1 month of age. PCV13 had no impact on pneumococcal carriage density, even for vaccine serotypes. The low prevalence of vaccine serotypes, high pneumococcal carriage density and abundance of non-vaccine serotypes likely contribute to the lack of PCV13 impact on carriage in PNG infants. Indirect effects of the infant PCV programs are likely to be limited in PNG. Alternative vaccines with broader coverage should be considered.

Safety and Immunogenicity of Pneumococcal Conjugate Vaccines in a High-risk Population: A Randomized Controlled Trial of 10-Valent and 13-Valent Pneumococcal Conjugate Vaccine in Papua New Guinean Infants

Background

There are little data on the immunogenicity of PCV10 and PCV13 in the same high-risk population.

Methods

PCV10 and PCV13 were studied head-to-head in a randomized controlled trial in Papua New Guinea in which 262 infants received 3 doses of PCV10 or PCV13 at 1, 2, and 3 months of age. Serotype-specific immunoglobulin G (IgG) concentrations, and pneumococcal and nontypeable Haemophilus influenzae (NTHi) carriage were assessed prevaccination and at 4 and 9 months of age. Infants were followed up for safety until 9 months of age.

Results

One month after the third dose of PCV10 or PCV13, ˃80% of infants had IgG concentrations ≥0.35µg/mL for vaccine serotypes, and 6 months postvaccination IgG concentrations ≥0.35 µg/mL were maintained for 8/10 shared PCV serotypes in > 75% of children vaccinated with either PCV10 or PCV13. Children carried a total of 65 different pneumococcal serotypes (plus nonserotypeable). At 4 months of age, 92% (95% confidence interval [CI] 85–96) of children vaccinated with PCV10 and 81% (95% CI 72–88) vaccinated with PCV13 were pneumococcal carriers (P = .023), whereas no differences were seen at 9 months of age, or for NTHi carriage. Both vaccines were well tolerated and not associated with serious adverse events.

Conclusions

Infant vaccination with 3 doses of PCV10 or PCV13 is safe and immunogenic in a highly endemic setting; however, to significantly reduce pneumococcal disease in these settings, PCVs with broader serotype coverage and potency to reduce pneumococcal carriage are needed.

Clinical Trials Registration

NCT01619462.

Rationale and methods of a randomized controlled trial of immunogenicity, safety and impact on carriage of pneumococcal conjugate and polysaccharide vaccines in infants in Papua New Guinea

BACKGROUND

Children in third-world settings including Papua New Guinea (PNG) experience early onset of carriage with a broad range of pneumococcal serotypes, resulting in a high incidence of severe pneumococcal disease and deaths in the first 2 years of life. Vaccination trials in high endemicity settings are needed to provide evidence and guidance on optimal strategies to protect children in these settings against pneumococcal infections.

METHODS

This report describes the rationale, objectives, methods, study population, follow-up and specimen collection for a vaccination trial conducted in an endemic and logistically challenging setting in PNG. The trial aimed to determine whether currently available pneumococcal conjugate vaccines (PCV) are suitable for use under PNG's accelerated immunization schedule, and that a schedule including pneumococcal polysaccharide vaccine (PPV) in later infancy is safe and immunogenic in this high-risk population.

RESULTS

This open randomized-controlled trial was conducted between November 2011 and March 2016, enrolling 262 children aged 1 month between November 2011 and April 2014. The participants were randomly allocated (1:1) to receive 10-valent PCV (10vPCV) or 13-valent PCV (13vPCV) in a 1-2-3-month schedule, with further randomization to receive PPV or no PPV at age 9 months, followed by a 1/5th PPV challenge at age 23 months. A total of 1229 blood samples were collected to measure humoral and cellular immune responses and 1238 nasopharyngeal swabs to assess upper respiratory tract colonization and carriage load. Serious adverse events were monitored throughout the study. Of the 262 children enrolled, 87% received 3 doses of PCV, 79% were randomized to receive PPV or no PPV at age 9 months, and 67% completed the study at 24 months of age with appropriate immunization and challenge.

CONCLUSION

Laboratory testing of the many samples collected during this trial will determine the impact of the different vaccine schedules and formulations on nasopharyngeal carriage, antibody production and function, and immune memory. The final data will inform policy on pneumococcal vaccine schedules in countries with children at high risk of pneumococcal disease by providing direct comparison of an accelerated schedule of 10vPCV and 13vPCV and the potential advantages of PPV following PCV immunization.

TRIAL REGISTRATION

ClinicalTrials.gov CTN NCT01619462, retrospectively registered on May 28, 2012.

Structure-specificity relationships of an intracellular xylanase from Geobacillus stearothermophilus

Geobacillus stearothermophilus T-6 is a thermophilic Gram-positive bacterium that produces two selective family 10 xylanases which both take part in the complete degradation and utilization of the xylan polymer. The two xylanases exhibit significantly different substrate specificities. While the extracellular xylanase (XT6; MW 43.8 kDa) hydrolyzes the long and branched native xylan polymer, the intracellular xylanase (IXT6; MW 38.6 kDa) preferentially hydrolyzes only short xylo-oligosaccharides. In this study, the detailed three-dimensional structure of IXT6 is reported, as determined by X-ray crystallography. It was initially solved by molecular replacement and then refined at 1.45 A resolution to a final R factor of 15.0% and an R(free) of 19.0%. As expected, the structure forms the classical (alpha/beta)(8) fold, in which the two catalytic residues (Glu134 and Glu241) are located on the inner surface of the central cavity. The structure of IXT6 was compared with the highly homologous extracellular xylanase XT6, revealing a number of structural differences between the active sites of the two enzymes. In particular, structural differences derived from the unique subdomain in the carboxy-terminal region of XT6, which is completely absent in IXT6. These structural modifications may account for the significant differences in the substrate specificities of these otherwise very similar enzymes.

Insulin suppresses the increased activities of lysosomal cathepsins and ubiquitin conjugation system in burn-injured rats

BACKGROUND

Burn injury results in increased rate of skeletal muscle protein degradation. In vitro studies on incubated muscles indicate that increased rate of protein degradation is due to activation of multiple proteolytic systems, but the supporting evidence is of an indirect nature. The present study was carried out to investigate the role of various lysosomal cathepsins, ubiquitin conjugation, and proteasome systems in accelerated proteolysis, and the effect of insulin in burn-induced muscle wasting syndrome.

MATERIALS AND METHODS

Fifteen to twenty percent total body surface area scald burn injury was inflicted on the shaved dorsum of young growing rats. Insulin-treated rats received a daily single subcutaneous injection for 3 days (0.25-1.0 U/day). The rate of ubiquitin conjugation to endogenous proteins and exogenously added (125)I-lysozyme and the activities of various proteases were measured in muscle homogenates.

RESULTS

Burn injury resulted in increased rate of ubiquitin conjugation to endogenous proteins and (125)I-lysozyme. Activities of cathepsins B, C, H, and L were also up-regulated following burn injury. When the burn-injured rats were treated with insulin, the increased rate of ubiquitin conjugation and cathepsin activities were suppressed to the control levels.

CONCLUSIONS

The increased ubiquitin conjugation and lysosomal cathepsins contribute to accelerated protein degradation in burn-injured rats and insulin suppresses the muscle protein degradation at least in part by suppressing the activities of lysosomal cathepsins and of ubiquitin conjugation system.

Ubiquitin conjugation by the N-end rule pathway and mRNAs for its components increase in muscles of diabetic rats

Insulin deficiency (e.g., in acute diabetes or fasting) is associated with enhanced protein breakdown in skeletal muscle leading to muscle wasting. Because recent studies have suggested that this increased proteolysis is due to activation of the ubiquitin-proteasome (Ub-proteasome) pathway, we investigated whether diabetes is associated with an increased rate of Ub conjugation to muscle protein. Muscle extracts from streptozotocin-induced insulin-deficient rats contained greater amounts of Ub-conjugated proteins than extracts from control animals and also 40-50% greater rates of conjugation of (125)I-Ub to endogenous muscle proteins. This enhanced Ub-conjugation occurred mainly through the N-end rule pathway that involves E2(14k) and E3alpha. A specific substrate of this pathway, alpha-lactalbumin, was ubiquitinated faster in the diabetic extracts, and a dominant negative form of E2(14k) inhibited this increase in ubiquitination rates. Both E2(14k) and E3alpha were shown to be rate-limiting for Ub conjugation because adding small amounts of either to extracts stimulated Ub conjugation. Furthermore, mRNA for E2(14k) and E3alpha (but not E1) were elevated 2-fold in muscles from diabetic rats, although no significant increase in E2(14k) and E3alpha content could be detected by immunoblot or activity assays. The simplest interpretation of these results is that small increases in both E2(14k) and E3alpha in muscles of insulin-deficient animals together accelerate Ub conjugation and protein degradation by the N-end rule pathway, the same pathway activated in cancer cachexia, sepsis, and hyperthyroidism.

Synthesis and preclinical pharmacology of 2-(2-aminopyrimidinio) ethylidene-1,1-bisphosphonic acid betaine (ISA-13-1)-a novel bisphosphonate

PURPOSE

To validate our hypothesis that a bisphosphonate (BP) having a nitrogen-containing heterocyclic ring on the side chain, and with no hydroxyl on the geminal carbon would possess increased activity, and better oral bioavailability due to enhanced solubility of its calcium complexes/salts and weaker Ca chelating properties.

METHODS

A novel BP, 2-(2-aminopyrimidinio)ethylidene-1, 1-bisphosphonic acid betaine (ISA-13-1) was synthesized. The physicochemical properties and permeability were studied in vitro. The effects on macrophages, bone resorption (young growing rat model), and tumor-induced osteolysis (Walker carcinosarcoma) were studied in comparison to clinically used BPs.

RESULTS

The solubility of the Ca salt of ISA-13-1 was higher, and the log beta(Ca:BP) stability constant and the affinity to hydroxyapatite were lower than those of alendronate and pamidronate. ISA-13-1 exhibited effects similar to those of alendronate on bone volume, on bone osteolysis, and on macrophages, following delivery by liposomes. ISA-13-1 was shown to have 1.5-1.7 times better oral absorption than the other BPs with no deleterious effects on the tight junctions of intestinal tissue.

CONCLUSIONS

The similar potency to clinically used BPs, the increased oral absorption as well as the lack of effect on tissue tight junction of ISA-13-1 warrant its further consideration as a potential drug for bone diseases.

A new model of cancer cachexia: contribution of the ubiquitin-proteasome pathway

A new model of cachexia is described in which muscle protein metabolism related to the ubiquitin-proteasome pathway was investigated. Cloning of the colon-26 tumor produced a cell line, termed R-1, which induced cytokine (noninterleukin-1beta, interleukin-6 and tumor necrosis factor-alpha)-independent cachexia. Implantation of R-1 cells in mice elicited significant (20-30%) weight loss and decreased blood glucose by 70%, and adipose tissue levels declined by 95% and muscle weights decreased by 20-25%. Food intake was unaffected. The decrease in muscle weight reflected a decline in insoluble, but not soluble, muscle protein that was associated with a significant increase in net protein degradation. The rate of ubiquitin conjugation of proteins was significantly elevated in muscles of cachectic mice. Furthermore, the proteasome inhibitor lactacystin blocked the increase in protein breakdown but had no significant effect on proteolysis. Several markers of the ubiquitin-proteasome pathway, E2(14k) mRNA and E2(14k) protein and ubiquitin-protein conjugates, were not elevated. Future investigations with this new model should gain further insights into the mechanisms of cachexia and provide a background to evaluate novel and more efficacious therapies.

Rates of ubiquitin conjugation increase when muscles atrophy, largely through activation of the N-end rule pathway

The rapid loss of muscle mass that accompanies many disease states, such as cancer or sepsis, is primarily a result of increased protein breakdown in muscle, and several observations have suggested an activation of the ubiquitin-proteasome system. Accordingly, in extracts of atrophying muscles from tumor-bearing or septic rats, rates of 125I-ubiquitin conjugation to endogenous proteins were found to be higher than in control extracts. On the other hand, in extracts of muscles from hypothyroid rats, where overall proteolysis is reduced below normal, the conjugation of 125I-ubiquitin to soluble proteins decreased by 50%, and treatment with triiodothyronine (T3) restored ubiquitination to control levels. Surprisingly, the N-end rule pathway, which selectively degrades proteins with basic or large hydrophobic N-terminal residues, was found to be responsible for most of these changes in ubiquitin conjugation. Competitive inhibitors of this pathway that specifically block the ubiquitin ligase, E3alpha, suppressed most of the increased ubiquitin conjugation in the muscle extracts from tumor-bearing and septic rats. These inhibitors also suppressed ubiquitination in normal extracts toward levels in hypothyroid extracts, which showed little E3alpha-dependent ubiquitination. Thus, the inhibitors eliminated most of the differences in ubiquitination under these different pathological conditions. Moreover, 125I-lysozyme, a model N-end rule substrate, was ubiquitinated more rapidly in extracts from tumor-bearing and septic rats, and more slowly in those from hypothyroid rats, than in controls. Thus, the rate of ubiquitin conjugation increases in atrophying muscles, and these hormone- and cytokine-dependent responses are in large part due to activation of the N-end rule pathway.

The N-end rule pathway catalyzes a major fraction of the protein degradation in skeletal muscle

In skeletal muscle, overall protein degradation involves the ubiquitin-proteasome system. One property of a protein that leads to rapid ubiquitin-dependent degradation is the presence of a basic, acidic, or bulky hydrophobic residue at its N terminus. However, in normal cells, substrates for this N-end rule pathway, which involves ubiquitin carrier protein (E2) E214k and ubiquitin-protein ligase (E3) E3alpha, have remained unclear. Surprisingly, in soluble extracts of rabbit muscle, we found that competitive inhibitors of E3alpha markedly inhibited the 125I-ubiquitin conjugation and ATP-dependent degradation of endogenous proteins. These inhibitors appear to selectively inhibit E3alpha, since they blocked degradation of 125I-lysozyme, a model N-end rule substrate, but did not affect the degradation of proteins whose ubiquitination involved other E3s. The addition of several E2s or E3alpha to the muscle extracts stimulated overall proteolysis and ubiquitination, but only the stimulation by E3alpha or E214k was sensitive to these inhibitors. A similar general inhibition of ubiquitin conjugation to endogenous proteins was observed with a dominant negative inhibitor of E214k. Certain substrates of the N-end rule pathway are degraded after their tRNA-dependent arginylation. We found that adding RNase A to muscle extracts reduced the ATP-dependent proteolysis of endogenous proteins, and supplying tRNA partially restored this process. Finally, although in muscle extracts the N-end rule pathway catalyzes most ubiquitin conjugation, it makes only a minor contribution to overall protein ubiquitination in HeLa cell extracts.

Bisphosphonates and tetracycline: experimental models for their evaluation in calcium-related disorders

PURPOSE

This work was aimed at synthesizing novel bisphosphonates (BPs) and examining them in comparison to clinically used BPs such as pamidronate and alendronate, and to tetracycline, in order to evaluate their potential as anticalcification and antiresorption agents. The correlation between the various models was examined in order to establish facile experimental models for pre-screening of potential compounds.

METHODS

Nitrogen-containing heterocyclic, novel BPs such as 2-(3-methylimidazolio) ethylidene-1,1-bisphosphonic acid betaine (VS-5b), 2-(2-dimethylamino-4-pyrazinio)ethylidene-1,1-bisphosphonic acid betaine (VS-6b), and 2-(2-alpha-pyridylethylthio) ethylidene-1,1-bisphosphonic acid (ISA-225), were synthesized and evaluated in comparison to clinically used BPs, in various experimental models of resorption and calcification.

RESULTS

The physicochemical properties of the novel compounds are slightly different than the BPs in clinical use: the pKa values are lower, the affinity for hydroxyapatite is lower and the solubilities of the calcium salts are higher. The anticalcification potencies of the novel compounds were high and ranked as follows: alendronate = pamidronate > VS-6b = VS-5b = ISA-225 > tetracycline. The in vivo antiresorption activity of VS-5b and VS-6b in comparison to that of the clinically employed, pamidronate, was shown to be similar and higher, respectively.

CONCLUSIONS

The anticalcification activity of the novel compounds as well as that of tetracycline was lower than that of alendronate. The antiresorption activity of VS-6b was similar to that of pamidronate. A good correlation between the different models was found, enabling the facile screening of novel compounds. The activities of tetracycline and EDTA highlight the distinct behavior of BPs as "crystal poison." In addition, tetracycline was found to be a potent anticalcification agent in the ectopic calcification model.

Structurally different bisphosphonates exert opposing effects on alkaline phosphatase and mineralization in marrow osteoprogenitors

Bisphosphonates (BPs) are inhibitors of bone resorption and soft tissue calcification. The biological effects of the BPs in calcium-related disorders are attributed mainly to their incorporation in bone, enabling direct interaction with osteoclasts and/or osteoblasts through a variety of biochemical pathways. Structural differences account for the considerable differences in the pharmacological activity of BPs. We compared the effects of two structurally different compounds, alendronate and 2-(3'-dimethylaminopyrazinio)ethylidene-1,1-bisphosphonic acid betaine (VS-6), in an osteoprogenitor differentiation system. The BPs were examined in a bone marrow stromal-cell culture system, which normally results in osteoprogenitor differentiation. The drugs were present in the cultures from days 2 to 11 of osteogenic stimulation, a period estimated as being comparable to the end of proliferation and the matrix-maturation stages. We found that the two different BPs have opposing effects on specific alkaline phosphatase (ALP) activity, on stromal-cell proliferation, and on cell-mediated mineralization. These BPs differentially interact with cell-associated phosphohydrolysis, particularly at a concentration of 10(-2) of ALP Km, in which alendronate inhibits whereas VS-6 did not inhibit phosphatase activity. VS-6 treatment resulted in similar and significantly increased mineralization at 10 and 1 microM drug concentrations, respectively. In contrast, mineralization was similar to control, and significantly decreased at 10 and 1 microM drug concentrations, respectively, under alendronate treatment.

Importance of the ATP-ubiquitin-proteasome pathway in the degradation of soluble and myofibrillar proteins in rabbit muscle extracts

Recent studies have suggested that activation of the ubiquitin-proteasome pathway is primarily responsible for the rapid loss of muscle proteins in various types of atrophy. The present studies were undertaken to test if different classes of muscle proteins are degraded by this pathway. In extracts of rabbit psoas muscle, the complete degradation of soluble proteins to amino acids was stimulated up to 6-fold by ATP. Peptide aldehyde inhibitors of the proteasome or the removal of proteasomes markedly inhibited only the ATP-dependent process. Addition of purified myosin, actin, troponin, or tropomyosin to these extracts showed that these proteins served as substrates for the ubiquitin-proteasome pathway. By contrast, degradation of myoglobin did not require ATP, proteasomes, or any known proteases in muscles. When myosin, actin, and troponin were added as actomyosin complexes or as intact myofibrils to these extracts, they were not hydrolyzed at a significant rate, probably because in these multicomponent complexes, these proteins are protected from degradation. Accordingly, actin (but not albumin or troponin) inhibited the degradation of 125I-myosin, and actin was found to selectively inhibit ubiquitin conjugation to 125I-myosin. Also, the presence of tropomyosin inhibited the degradation of 125I-troponin. However, neither actin nor tropomyosin inhibited the degradation of 125I-lysozyme or soluble muscle proteins. Thus, specific interactions between the myofibrillar proteins appear to protect them from ubiquitin-dependent degradation, and the rate-limiting step in their degradation is probably their dissociation from the myofibril.

Pulpal anesthesia efficacy of four lidocaine solutions injected with an intraligamentary syringe

Four lidocaine solutions that differed in concentration or vasoconstrictor composition were compared for efficacy of pulpal anesthesia. These drugs were injected in a double-blind manner with the use of an intraligamentary syringe to the periodontal ligament of maxillary lateral incisors. These teeth were subjected to electric pulp test stimulation that yielded absolute sensation threshold values. It was found that there was no dose response relationship between the local anesthetic concentration and the efficacy of pulpal anesthesia. Lidocaine 2% with vasopressin 25 IU% and noradrenaline bitartrate produced a noticeably shorter duration of pulpal anesthesia in comparison with the other three drugs. The results indicated that the nature of vasoconstrictors when added to the local anesthetic can affect the efficacy of pulpal anesthesia using the intraligamentary model.

Pseudothrombocytopenia masking true thrombocytopenia

Pseudothrombocytopenia owing to platelet clumping is usually associated with blood specimens anticoagulated with EDTA. It may also be seen if specimens possessing IgM cold agglutinins are processed at room temperature. A patient with a temperature-independent, EDTA-independent agglutinin is reported whose pseudothrombocytopenia was masking true thrombocytopenia. A technique for blood collection when evaluating similar cases is described.

Differential diagnosis of the multiple personality

The diagnosis of multiple personality is difficult and complicated. The differential diagnosis includes temporal lobe epilepsy, schizophrenia, borderline personality disorder, malingering, and other dissociative disorders. Psychometric research is needed to sharpen detection of multiple personality.

Electron microscopic localization of factor-VIII-related antigen in adult human blood vessels

We have localized factor-VIII-related antigen, using immunofluorescence and electron microscopy, in adult human blood vessels. In addition to its presence in endothelial cells, the antigen was localized within subendothelium and the layers of elastic lamina closest to the lumen. Also, we provide the first morphological evidence that factor-VIII-related antigen is associated with collagen fibrils within the vessel wall. These studies suggest that this subendothelial factor-VIII-related antigen may play a role in the adhesion of platelets to subendothelial components following endothelial injury.

Localization of factor-VIII-related antigen in human vascular subendothelium

Factor-VIII-related antigen has previously been shown to be synthesized by vascular endothelial cells. Using both an immunofluorescent staining technique and electron microscopy, we have demonstrated the presence of factor-VIII-related antigen in human vascular subendothelium. This finding may have implications in the mechanism of platelet adhesion to deendothelialized blood vessel surfaces.