Upper Respiratory Tract Of Humans Research Articles

Scientific Opinion on the substantiation of a health claim related to Bifidobacterium bifidum CNCM I‐3426 and defence against pathogens in the upper respiratory tract pursuant to Article 13(5) of Regulation (EC) No 1924/2006

Following an application from Lallemand Health Solutions, submitted pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of France, the Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to Bifidobacterium bifidum CNCM I-3426 and defence against pathogens in the upper respiratory tract. The food constituent that is the subject of the claim is B. bifidum CNCM I-3426. The Panel considers that B. bifidum CNCM I-3426 is sufficiently characterised. The Panel considers that defence against pathogens in the upper respiratory tract is a beneficial physiological effect. The applicant provided one published human intervention study, one unpublished human intervention study (which was published during the evaluation of the claim) and one in vitro study as pertinent to the claimed effect. The Panel considers that no conclusions can be drawn from either of the human studies for the scientific substantiation of the claim. In the absence of evidence of an effect of B. bifidum CNCM I3426 on defence against pathogens in the upper respiratory tract in humans, the results of the in vitro study submitted cannot be used as a source of data for the scientific substantiation of the claim. The Panel concludes that a cause and effect relationship has not been established between the consumption of B. bifidum CNCM I-3426 and defence against pathogens in the upper respiratory tract.

The capsule biosynthesis locus of Haemophilus influenzae shows conspicuous similarity to the corresponding locus in Haemophilus sputorum and may have been recruited from this species by horizontal gene transfer.

The newly described species Haemophilus sputorum has been cultured from the upper respiratory tract of humans and appears to have little pathogenic potential. The species encodes a capsular biosynthesis locus of approximately 12 kb composed of three distinct regions. Region I and III genes, involved in export and processing of the capsular material, show high similarity to the corresponding genes in capsulate lineages of the pathogenic species Haemophilus influenzae; indeed, standard bexA and bexB PCRs for detection of capsulated strains of H. influenzae give positive results with strains of H. sputorum. Three ORFs are present in region II of the sequenced strain of H. sputorum, of which a putative phosphotransferase showed homology with corresponding genes from H. influenzae serotype c and f. Phylogenetic analysis of housekeeping genes from 24 Pasteurellaceae species showed that H. sputorum was only distantly related to H. influenzae. In contrast to H. influenzae, the capsule locus in H. sputorum is not associated with transposases or other transposable elements. Our data suggest that the capsule locus of capsulate lineages of H. influenzae may have been recruited relatively recently from the commensal species H. sputorum by horizontal gene transfer.

Hydrogen Peroxide Contributes to the Epithelial Cell Death Induced by the Oral Mitis Group of Streptococci

Members of the mitis group of streptococci are normal inhabitants of the commensal flora of the oral cavity and upper respiratory tract of humans. Some mitis group species, such as Streptococcus oralis and Streptococcus sanguinis, are primary colonizers of the human oral cavity. Recently, we found that hydrogen peroxide (H2O2) produced by S. oralis is cytotoxic to human macrophages, suggesting that streptococcus-derived H2O2 may act as a cytotoxin. Since epithelial cells provide a physical barrier against pathogenic microbes, we investigated their susceptibility to infection by H2O2-producing streptococci in this study. Infection by S. oralis and S. sanguinis was found to stimulate cell death of Detroit 562, Calu-3 and HeLa epithelial cell lines at a multiplicity of infection greater than 100. Catalase, an enzyme that catalyzes the decomposition of H2O2, inhibited S. oralis cytotoxicity, and H2O2 alone was capable of eliciting epithelial cell death. Moreover, S. oralis mutants lacking the spxB gene encoding pyruvate oxidase, which are deficient in H2O2 production, exhibited reduced cytotoxicity toward Detroit 562 epithelial cells. In addition, enzyme-linked immunosorbent assays revealed that both S. oralis and H2O2 induced interleukin-6 production in Detroit 562 epithelial cells. These results suggest that streptococcal H2O2 is cytotoxic to epithelial cells, and promotes bacterial evasion of the host defense systems in the oral cavity and upper respiratory tracts.

Chapter 30 - Neurologic aspects of influenza viruses

Although influenza A and B viruses are primarily known as respiratory viruses and mainly infected only the upper respiratory tract in humans, patients with influenza often develop signs and symptoms that are not due to the respiratory system. Frequently individuals with influenza develop headaches, meningismus, and even seizures in addition to their typical respiratory symptoms. In the past decades, influenza viruses have also been associated with serious non-respiratory signs. The famous 1918 strain of influenza was associated with von Economo's encephalitis lethargica and postencephalitic parkinsonism. In the 1960s influenza virus infections in children were associated with Reye's syndrome characterized often by fatty non-inflammatory hepatic disease and an encephalopathy with marked non-inflammatory cerebral edema. Intermittently children with influenza develop focal myalgia and myositis. Guillain–Barré syndrome was epidemiologically associated with the 1978 killed influenza vaccine but not subsequent vaccines. Although occasional children with influenza have developed encephalopathy, from 2000 through 2004 there was an increase in the number of serious cases of acute necrotizing encephalopathy accompanying infection with the influenza A 2009 strain. The current H5N1 strain of bird influenza occasionally infects humans with a high mortality rate and some appear to have central nervous signs. This chapter explores what is known about these influenza neurologic associations.

Protective Mechanisms of Respiratory Tract Streptococci against Streptococcus pyogenes Biofilm Formation and Epithelial Cell Infection

Streptococcus pyogenes (group A streptococci [GAS]) encounter many streptococcal species of the physiological microbial biome when entering the upper respiratory tract of humans, leading to the question how GAS interact with these bacteria in order to establish themselves at this anatomic site and initiate infection. Here we show that S. oralis and S. salivarius in direct contact assays inhibit growth of GAS in a strain-specific manner and that S. salivarius, most likely via bacteriocin secretion, also exerts this effect in transwell experiments. Utilizing scanning electron microscopy documentation, we identified the tested strains as potent biofilm producers except for GAS M49. In mixed-species biofilms, S. salivarius dominated the GAS strains, while S. oralis acted as initial colonizer, building the bottom layer in mixed biofilms and thereby allowing even GAS M49 to form substantial biofilms on top. With the exception of S. oralis, artificial saliva reduced single-species biofilms and allowed GAS to dominate in mixed biofilms, although the overall two-layer structure was unchanged. When covered by S. oralis and S. salivarius biofilms, epithelial cells were protected from GAS adherence, internalization, and cytotoxic effects. Apparently, these species can have probiotic effects. The use of Affymetrix array technology to assess HEp-2 cell transcription levels revealed modest changes after exposure to S. oralis and S. salivarius biofilms which could explain some of the protective effects against GAS attack. In summary, our study revealed a protection effect of respiratory tract bacteria against an important airway pathogen and allowed a first in vitro insight into local environmental processes after GAS enter the respiratory tract.

Comparison of sodA and 16S rDNA sequencing for accurate species-level identification of viridans group streptococci (VGS) isolated from patients with infective endocarditis

Background Viridans group streptococci (VGS) are commensal flora of the upper respiratory tract in humans and can cause serious infections, like infective endocarditis, septicemia, and meningitis. Accurate identification of VGS to the species level is difficult because they share many physiological characteristics. We report a study using sequencing of 16S ribosomal DNA (rDNA) gene and sodA gene to discriminate VGS up to species level.

Combat Pneumococcal Infections: Adhesins as Candidates for Protein- Based Vaccine Development

Streptococcus pneumoniae (pneumococcus) is an asymptomatic colonizer of the upper respiratory tract in humans. However, these apparently harmless bacteria have also a high virulence potential and are known as the etiologic agent of respiratory and life-threatening invasive diseases. Dissemination of pneumococci from the nasopharynx into the lungs or bloodstream leads to community-acquired pneumonia, septicaemia and meningitis. Traditionally, pneumococcal diseases are treated with antibiotics and prevented with polysaccharide-based vaccines. However, due to the dramatic increase in antibiotic resistance and limitations of the current available vaccines, the burden of diseases remains high. Thus, combating pneumococcal transmission and infections has emphasized the need for a new generation of protein-based vaccines. Interactions of pneumococci with soluble host proteins or cellular receptors are crucial for adherence, colonization, transmigration of host barriers and immune evasion. Therefore, surface-exposed proteins involved in these pathogenic processes and virtually expressed by all pneumococcal strains and serotypes are the prime potential targets for an immunogenic and highly protective pneumococcal-derived carrier protein of a vaccine. In this review, we will address the state of the art in deciphering, i). the conservation, distribution and pathogenic role of recently discovered pneumococcal adhesins in colonization and invasive diseases, ii). the interactions of these virulence factors with host-proteins and receptors, iii). the subversion of the host immune and cellular responses, and iv). the potential of pneumococcal adhesins as vaccine candidates.

Decoding the Distribution of Glycan Receptors for Human-Adapted Influenza A Viruses in Ferret Respiratory Tract

Ferrets are widely used as animal models for studying influenza A viral pathogenesis and transmissibility. Human-adapted influenza A viruses primarily target the upper respiratory tract in humans (infection of the lower respiratory tract is observed less frequently), while in ferrets, upon intranasal inoculation both upper and lower respiratory tract are targeted. Viral tropism is governed by distribution of complex sialylated glycan receptors in various cells/tissues of the host that are specifically recognized by influenza A virus hemagglutinin (HA), a glycoprotein on viral surface. It is generally known that upper respiratory tract of humans and ferrets predominantly express α2→6 sialylated glycan receptors. However much less is known about the fine structure of these glycan receptors and their distribution in different regions of the ferret respiratory tract. In this study, we characterize distribution of glycan receptors going beyond terminal sialic acid linkage in the cranial and caudal regions of the ferret trachea (upper respiratory tract) and lung hilar region (lower respiratory tract) by multiplexing use of various plant lectins and human-adapted HAs to stain these tissue sections. Our findings show that the sialylated glycan receptors recognized by human-adapted HAs are predominantly distributed in submucosal gland of lung hilar region as a part of O-linked glycans. Our study has implications in understanding influenza A viral pathogenesis in ferrets and also in employing ferrets as animal models for developing therapeutic strategies against influenza.

Structural studies of the lipopolysaccharide from Haemophilus parainfluenzae strain 20

Haemophilus parainfluenzae is a Gram-negative bacterium that colonizes the upper respiratory tract of humans and is a part of normal flora. In this study, we investigated the lipopolysaccharide (LPS) expressed by H. parainfluenzae strain 20. Using NMR and MS techniques on LPS, oligosaccharide samples and lipid A, the structures for O-antigen, core oligosaccharide and lipid A could be established. It was found that the biological repeating unit of the O-antigen is →4)-α- d-Gal pNAc-(1→ P→6)-β- d-Glc p-(1→3)-α- d-Fuc pNAc4N-(1→, in which d-Fuc pNAc4N is 2-acetamido-4-amino-2,4,6-trideoxy- d-galactose. This sugar is in β-configuration when linked to O-4 of the glucose residue of β- d-Gal p-(1→2)- l-α- d-Hep p-(1→2)-[ PEtn→6]- l-α- d-Hep p-(1→3)-[β- d-Glc p-(1→4)]- l-α- d-Hep p-(1→5)-[ PPEtn→4]-α-Kdo-(2→6)-lipid A. LPS from a wbaP mutant of H. parainfluenzae strain 20 did not contain an O-antigen, consistent with the wbaP gene product being required for expression of O-antigen in fully extended LPS.

Tyrannobdella rex n. gen. n. sp. and the evolutionary origins of mucosal leech infestations.

BackgroundLeeches have gained a fearsome reputation by feeding externally on blood, often from human hosts. Orificial hirudiniasis is a condition in which a leech enters a body orifice, most often the nasopharyngeal region, but there are many cases of leeches infesting the eyes, urethra, vagina, or rectum. Several leech species particularly in Africa and Asia are well-known for their propensity to afflict humans. Because there has not previously been any data suggesting a close relationship for such geographically disparate species, this unnerving tendency to be invasive has been regarded only as a loathsome oddity and not a unifying character for a group of related organisms.Principal FindingsA new genus and species of leech from Perú was found feeding from the nasopharynx of humans. Unlike any other leech previously described, this new taxon has but a single jaw with very large teeth. Phylogenetic analyses of nuclear and mitochondrial genes using parsimony and Bayesian inference demonstrate that the new species belongs among a larger, global clade of leeches, all of which feed from the mucosal surfaces of mammals.ConclusionsThis new species, found feeding from the upper respiratory tract of humans in Perú, clarifies an expansion of the family Praobdellidae to include the new species Tyrannobdella rex n. gen. n.sp., along with others in the genera Dinobdella, Myxobdella, Praobdella and Pintobdella. Moreover, the results clarify a single evolutionary origin of a group of leeches that specializes on mucous membranes, thus, posing a distinct threat to human health.

Influenza Virus Receptor Specificity: Disease and Transmission

Influenza Virus Receptor Specificity: Disease and Transmission

The human H5N1 influenza A virus polymerase complex is active in vitro over a broad range of temperatures, in contrast to the WSN complex, and this property can be attributed to the PB2 subunit

Influenza A virus (IAV) replicates in the upper respiratory tract of humans at 33 °C and in the intestinal tract of birds at close to 41 °C. The viral RNA polymerase complex comprises three subunits (PA, PB1 and PB2) and plays an important role in host adaptation. We therefore developed an in vitro system to examine the temperature sensitivity of IAV RNA polymerase complexes from different origins. Complexes were prepared from human lung epithelial cells (A549) using a novel adenoviral expression system. Affinity-purified complexes were generated that contained either all three subunits (PA/PB1/PB2) from the A/Viet/1203/04 H5N1 virus (H/H/H) or the A/WSN/33 H1N1 strain (W/W/W). We also prepared chimeric complexes in which the PB2 subunit was exchanged (H/H/W, W/W/H) or substituted with an avian PB2 from the A/chicken/Nanchang/3-120/01 H3N2 strain (W/W/N). All complexes were functional in transcription, cap-binding and endonucleolytic activity. Complexes containing the H5N1 or Nanchang PB2 protein retained transcriptional activity over a broad temperature range (30–42 °C). In contrast, complexes containing the WSN PB2 protein lost activity at elevated temperatures (39 °C or higher). The E627K mutation in the avian PB2 was not required for this effect. Finally, the avian PB2 subunit was shown to confer enhanced stability to the WSN 3P complex. These results show that PB2 plays an important role in regulating the temperature optimum for IAV RNA polymerase activity, possibly due to effects on the functional stability of the 3P complex.

Evaluation of Trigeminal Sensitivity to Ammonia in Asthmatics and Healthy Human Volunteers

Asthmatics often report the triggering or exacerbation of respiratory symptoms following exposure to airborne irritants, which in some cases may result from stimulation of irritant receptors in the upper airways inducing reflexive bronchoconstriction. Ammonia (NH3) is a common constituent of commercially available household products, and in high concentration has the potential to elicit sensory irritation in the eyes and upper respiratory tract of humans. The goal of the present study was to evaluate the irritation potential of ammonia in asthmatics and healthy volunteers and to determine whether differences in nasal or ocular irritant sensitivity to ammonia between these two groups could account for the exacerbation of symptoms reported by asthmatics following exposure to an irritant. Twenty-five healthy and 15 mild/moderate persistent asthmatic volunteers, with reported sensitivity to household cleaning products, were evaluated for their sensitivity to the ocular and nasal irritancy of NH3. Lung function was evaluated at baseline and multiple time points following exposure. Irritation thresholds did not differ between asthmatics and healthy controls, nor did ratings of odor intensity, annoyance, and irritancy following exposure to NH3 concentrations at and above the irritant threshold for longer periods of time (30 s). Importantly, no changes in lung function occurred following exposure to NH3 for any individuals in either group. Thus, despite heightened symptom reports to environmental irritants among asthmatics, the ocular and nasal trigeminal system of mild to moderate asthmatics does not appear to be more sensitive or more reactive than that of nonasthmatics, nor does short-duration exposure to ammonia at irritant levels induce changes in lung function. At least in brief exposures, the basis for some asthmatics to experience adverse responses to volatile compounds in everyday life may arise from factors other than trigeminally mediated reflexes.

Glycan topology determines human adaptation of avian H5N1 virus hemagglutinin

A switch in specificity of avian influenza A viruses' hemagglutinin (HA) from avian-like (alpha2-3 sialylated glycans) to human-like (alpha2-6 sialylated glycans) receptors is believed to be associated with their adaptation to infect humans. We show that a characteristic structural topology--and not the alpha2-6 linkage itself--enables specific binding of HA to alpha2-6 sialylated glycans and that recognition of this topology may be critical for adaptation of HA to bind glycans in the upper respiratory tract of humans. An integrated biochemical, analytical and data mining approach demonstrates that HAs from the human-adapted H1N1 and H3N2 viruses, but not H5N1 (bird flu) viruses, specifically bind to long alpha2-6 sialylated glycans with this topology. This could explain why H5N1 viruses have not yet gained a foothold in the human population. Our findings will enable the development of additional strategies for effective surveillance and potential therapeutic interventions for H5N1 and possibly other influenza A viruses.

Viral Tropism and the Pathogenesis of Influenza in the Mammalian Host

Influenza viruses, single-stranded negative-sense RNA viruses within the family Orthomyxoviridae, remain an important cause of human morbidity and mortality worldwide. Despite effective vaccines, more than 200,000 individuals in the United States are hospitalized each year for influenza, and approximately 35,000 succumb to disease.1 Seasonal epidemics arise through antigenic variation and recombination events from existing and currently circulating human strains, which initially target the upper respiratory tract with extension to a bronchointerstitial pneumonia in a subset of affected individuals. Disease is often more severe in older and debilitated patients, producing a characteristic distribution in age-related mortality within the affected population.2 In contrast to seasonal epidemics, pandemics arise when antigenically novel viruses emerge and are readily transmissible within the naive human population. Such events are rare and occur after zoonotic transmission of viruses through recombination events between established human and avian strains or possibly through direct adaptation of avian strains for efficient human to human transmission.3 Concerns over an avian influenza pandemic have risen since 1997 with the recognition of H5N1 as a cause of fulminant disease in humans.4,5 Pathologically fatal H5N1 causes diffuse alveolar damage and progression to multiple organ dysfunction with a case fatality rate estimated at more than 50%. Although H5N1 disease is severe, transmission rates have been low, and viral adaptation to efficient human to human transmission has not occurred. Understanding viral and host barriers that prevent transmission may be critical in establishing rational control measures as well as predicting and stratifying risk for individual strains of influenza. In this issue of The American Journal of Pathology, van Riel et al6 examine the viral binding distribution in pulmonary tissue of a number of avian and human influenza strains to elucidate the role of tropism in transmission and pathogenesis.

The OxyR Regulon in Nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is a gram-negative bacterium and a common commensal organism of the upper respiratory tract in humans. NTHi causes a number of diseases, including otitis media, sinusitis, conjunctivitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. During the course of colonization and infection, NTHi must withstand oxidative stress generated by insult due to multiple reactive oxygen species produced endogenously by other copathogens and by host cells. Using an NTHi-specific microarray containing oligonucleotides representing the 1821 open reading frames of the recently sequenced NTHi isolate 86-028NP, we have identified 40 genes in strain 86-028NP that are upregulated after induction of oxidative stress due to hydrogen peroxide. Further comparisons between the parent and an isogenic oxyR mutant identified a subset of 11 genes that were transcriptionally regulated by OxyR, a global regulator of oxidative stress. Interestingly, hydrogen peroxide induced the OxyR-independent upregulation of expression of the genes encoding components of multiple iron utilization systems. This finding suggested that careful balancing of levels of intracellular iron was important for minimizing the effects of oxidative stress during NTHi colonization and infection and that there are additional regulatory pathways involved in iron utilization.

The survival of pathogens in soil treated with wastewater sludge and in potatoes grown in such soil

The prevalence of pathogens on potatoes (Solanum tuberosum) grown in soil amended with a pathogen rich wastewater sludge was investigated. Bacteria of the family Enterobacteriaceae are important pathogens causing intestinal and systemic illness of humans and other animals. Type B sludge was used. Sludges investigated are the high metal and the low metal sludges. Microorganisms in the sludge-amended soil were using culture-based technique. Salmonella and E. coli were observed in tested soil samples. No microorganisms were isolated from control samples taken throughout the process of the experiment. At harvest time, some of the potato samples from LMS soil were contaminated. These potatoes were subjected to further investigation using molecular techniques (polymerase chain reaction) with fD1 and rP2 as primers. Organisms identified from the sequenced potato peel samples with the BLAST search tool included Enterobacter agglomerans (Pantoea agglomerans), several Buttiauxella spp., Pectobacterium spp., Erwinia spp. and a few Pantoea spp. Other than the E. agglomerans, which is commonly found in the gut and upper respiratory tract of humans and in the environment, all the other species identified were found to be mainly either plant or soil pathogens. The E. agglomerans are not primary pathogens but secondary opportunistic pathogens particularly in immunocompromised individuals. These results suggest that growing high risk crops using wastewater sludge contaminated soil may lead to limited infestation of produce with primary pathogens. It appears that the use of HMS due to early pathogen die-off provides less risk of infection than the LMS. However, proper treatment of wastewater sludge to reduce pathogen load is essential prior to its use as soil conditioner.

Crystallization of recombinantHaemophilus influenzaee(P4) acid phosphatase

Haemophilus influenzae infects the upper respiratory tract of humans and can cause infections of the middle ear, sinuses and bronchi. The virulence of the pathogen is thought to involve a group of surface-localized macromolecular components that mediate interactions at the host-pathogen interface. One of these components is lipoprotein e (P4), which is a class C acid phosphatase and a potential vaccine candidate for nontypeable H. influenzae infections. This paper reports the crystallization of recombinant e (P4) and the acquisition of a 1.7 angstroms resolution native X-ray diffraction data set. The space group is P4(2)2(1)2, with unit-cell parameters a = 65.6, c = 101.4 angstroms, one protein molecule per asymmetric unit and 37% solvent content. This is the first report of the crystallization of a class C acid phosphatase.

Influenza virus receptors in the human air way

Avian influenza A (H5N1) virus infections have resulted in more than 100 human deaths; yet, human-to-human transmission is rare. We demonstrated that the epithelial cells in the upper respiratory tract of humans mainly possess sialic acid linked to galactose by alpha 2,6 linkages (SA alpha 2,6Gal), a molecule preferentially recognized by human viruses. However, many cells in the respiratory bronchioles and alveoli possess SA alpha 2,3Gal, which is preferentially recognized by avian viruses. These facts are consistent with the observation that H5N1 viruses can be directly transmitted from birds to humans and cause serious lower respiratory tract damage in humans. Furthermore, this anatomical difference in receptor prevalence may explain why the spread of H5N1 viruses among humans is limited. However, since some H5N1 viruses isolated from humans recognize human virus receptors, additional changes must be required for these viruses to acquire the ability for efficient human-to-human transmission.

Growth Characteristics of and Virulence Factor Production by Group A Streptococcus during Cultivation in Human Saliva

Group A Streptococcus (GAS) commonly infects the human oropharynx, but the initial molecular events governing this process are poorly understood. Saliva is a major component of the innate and acquired immune defense in this anatomic site. Although landmark studies were done more than 60 years ago, investigation of GAS-saliva interaction has not been addressed extensively in recent years. Serotype M1 GAS strain MGAS5005 cultured in human saliva grew to approximately 10(7) CFU/ml and, remarkably, maintained this density for up to 28 days. Strains of several other M-protein serotypes had similar initial growth patterns but did not maintain as high a CFU count during prolonged culture. As revealed by analysis of the growth of isogenic mutant strains, the ability of GAS to maintain high numbers of CFU/ml during the prolonged stationary phase in saliva was dependent on production of streptococcal inhibitor of complement (Sic) and streptococcal pyrogenic exotoxin B (SpeB). During cultivation in human saliva, GAS had growth-phase-dependent production of multiple proven and putative extracellular virulence factors, including Sic, SpeB, streptococcal pyrogenic exotoxin A, Mac protein, and streptococcal phospholipase A(2). Our results clearly show that GAS responds in a complex fashion to growth in human saliva, suggesting that the molecular processes that enhance colonization and survival in the upper respiratory tract of humans are well under way before the organism reaches the epithelial cell surface.