AAV-vectored expression of monospecific or bispecific monoclonal antibodies protects mice from lethal Pseudomonas aeruginosa pneumonia.

Pseudomonas aeruginosa poses a significant threat to immunocompromised individuals and those with cystic fibrosis. Treatment relies on antibiotics, but persistent infections occur due to intrinsic and acquired resistance of P. aeruginosa towards multiple classes of antibiotics. To date, there are no licensed vaccines for this pathogen, prompting the urgent need for novel treatment approaches to combat P. aeruginosa infection and persistence. Here we validated AAV vectored immunoprophylaxis as a strategy to generate long-term plasma and mucosal expression of highly protective monoclonal antibodies (mAbs) targeting the exopolysaccharide Psl (Cam-003) and the PcrV (V2L2MD) component of the type-III secretion system injectosome either as single mAbs or together as a bispecific mAb (MEDI3902) in a mouse model. When administered intramuscularly, AAV-αPcrV, AAV-αPsl, and AAV-MEDI3902 significantly protected mice challenged intranasally with a lethal dose of P. aeruginosa strains PAO1 and PA14 and reduced bacterial burden and dissemination to other organs. While all AAV-mAbs provided protection, AAV-αPcrV and AAV-MEDI3902 provided 100% and 87.5% protection from a lethal challenge with 4.47 × 107 CFU PAO1 and 87.5% and 75% protection from a lethal challenge with 3 × 107 CFU PA14, respectively. Serum concentrations of MEDI3902 were ~10× lower than that of αPcrV, but mice treated with this vector showed a greater reduction in bacterial dissemination to the liver, lung, spleen, and blood compared to other AAV-mAbs. These results support further investigation into the use of AAV vectored immunoprophylaxis to prevent and treat P. aeruginosa infections and other bacterial pathogens of public health concern for which current treatment strategies are limited.

High Prevalence of Non-typeable Haemophilus influenzae and Haemophilus haemolyticus Among Vaccinated Children with Community-Acquired Pneumonia in Vietnam.

Among 467 children under five hospitalized with community-acquired pneumonia, the prevalence of Haemophilus influenzae or Haemophilus haemolyticus was 60.8%, all cases were non-typable H. influenzae (NTHi) or H. haemolyticus. NTHi/H. haemolyticus PCR detection was associated with about twice the risk for severe disease. The results highlight the need for increased awareness and research efforts to investigate the role of NTHi/H. haemolyticus in severe CAP among children.

Community-acquired bacterial pneumonia in children: an update on antibiotic duration and immunization strategies.

PURPOSE OF REVIEW: This review is structured to update clinicians on the epidemiology, antibiotic treatment, and prevention of pediatric bacterial pneumonia. The review provides information regarding the current research on antibiotic management for bacterial pneumonia and the newest immunization recommendations to prevent pneumococcal pneumonia and other respiratory infections. RECENT FINDINGS: The recommended length of antibiotic therapy for bacterial pneumonia has been discrepant between low-income and high-income countries. Recently, randomized controlled trials conducted in high-income countries provided evidence to support a short antibiotic course (3-5 days) for uncomplicated bacterial pneumonia in otherwise healthy children. The negative impact of inaccurate penicillin allergy labels in children with pneumonia has emphasized the importance of prompt allergy de-labeling. Newer pneumococcal vaccines are recommended for children and are expected to have a significant impact on bacterial pneumonia rates. SUMMARY: Pediatric bacterial pneumonia is an important contributor to childhood morbidity and mortality. A short antibiotic course seems to be sufficient for the outpatient management of uncomplicated bacterial pneumonia; however, more studies are required in the inpatient setting. Future studies will inform the impact of recently introduced pneumococcal and respiratory syncytial virus vaccines on the epidemiology of bacterial pneumonia.

Manganese-Based Nanoparticle Vaccine for Combating Fatal Bacterial Pneumonia.

Bacterial pneumonia is the leading cause of death worldwide among all infectious diseases. However, currently available vaccines against fatal bacterial lung infections, e.g., pneumonic plague, are accompanied by limitations, including insufficient antigen-adjuvant co-delivery and inadequate immune stimulation. Therefore, there is an urgent requirement to develop next-generation vaccines to improve the interaction between antigen and adjuvant, as well as enhance the effects of immune stimulation. This study develops a novel amino-decorated mesoporous manganese silicate nanoparticle (AMMSN) loaded with rF1-V10 (rF1-V10@AMMSN) to prevent pneumonic plague. These results suggest that subcutaneous immunization with rF1-V10@AMMSN in a prime-boost strategy induces robust production of rF1-V10-specific IgG antibodies with a geometric mean titer of 315,844 at day 42 post-primary immunization, which confers complete protection to mice against 50 × LD50 of Yersinia pestis (Y. pestis) challenge via the aerosolized intratracheal route. Mechanistically, rF1-V10@AMMSN can be taken up by dendritic cells (DCs) and promote DCs maturation through activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway and production of type I interferon. This process results in enhanced antigen presentation and promotes rF1-V10-mediated protection against Y. pestis infection. This manganese-based nanoparticle vaccine represents a valuable strategy for combating fatal bacterial pneumonia.

Neumonía bacteriana en niños en Ecuador: una mirada al impacto de las vacunas / Bacterial pneumonia in children in Ecuador: a look at the impact of vaccines

INTRODUCCIÓN: La neumonía adquirida en la comunidad es una de las enfermedades con mayor prevalencia en la comunidad pediátrica en nuestro país. De las diferentes etiologías que pueden causarlas, la neumonía ocasionada por Streptococcus pneumoniae puede ser prevenida con el uso de inmunización. Actualmente se disponen de tres tipos de vacunas antineumocócicas conjugadas autorizadas de uso pediátrico de forma sistemática. OBJETIVO: Identificar la prevalencia de neumonía bacteriana en niños bajo 5 años de edad, que requirieron hospitalización comparando la vacuna neumocócica recibida: 10 valente (PCV10) versus 13 valente (PCV13). PACIENTES Y MÉTODOS: Estudio de descriptivo, retrospectivo. Se incluyeron pacientes hospitalizados bajo 5 años de edad, con diagnóstico de neumonía bacteriana mediante codificación CIE10 en un hospital de tercer nivel de la ciudad de Quito-Ecuador, durante el año 2019. RESULTADOS: Se estudiaron 175 pacientes de los cuales 74 cumplieron con criterios clínicos de neumonía, de estos 46 recibieron PCV10 y 28 recibieron vacuna PCV13. DISCUSIÓN Y CONCLUSIONES: La prevalencia de neumonía bacteriana fue mayor en los pacientes inmunizados con PCV10 lo que sugiere una relación de menor probabilidad de neumonía con el uso de la vacuna PCV13.

BACKGROUND: Community-acquired pneumonia is one of the most prevalent diseases in the pediatric community in our country, of the different etiologies that can cause them, pneumonia caused by Streptococcus pneumoniae can be prevented with the use of immunization. Currently there are three types of authorized pneumococcal conjugate vaccines for pediatric use in a systematic way. AIM: To identify the prevalence of bacterial pneumonia in children under 5 years of age who required hospitalization by comparing the pneumococcal vaccine received: 10 valent (PCV10) versus 13 valent (PCV13). METHODS: Descriptive, retrospective study. Hospitalized patients under 5 years of age with a diagnosis of bacterial pneumonia by ICD10 coding in a third level hospital in the city of Quito - Ecuador during 2019 were included. Results: 175 patients were studied, of which 74 patients met clinical criteria for pneumonia, of these 46 received PCV10 and 28 received PCV13 vaccine. DISCUSSION AND CONCLUSIONS: The prevalence of bacterial pneumonia was higher in patients immunized with PCV10, suggesting a relationship of lower probability of pneumonia with the use of the PCV13 vaccine.

Monoclonal antibodies against lipopolysaccharide protect against Pseudomonas aeruginosa challenge in mice.

Pseudomonas aeruginosa is a common cause of hospital-acquired infections, including central line-associated bloodstream infections and ventilator-associated pneumonia. Unfortunately, effective control of these infections can be difficult, in part due to the prevalence of multi-drug resistant strains of P. aeruginosa. There remains a need for novel therapeutic interventions against P. aeruginosa, and the use of monoclonal antibodies (mAb) is a promising alternative strategy to current standard of care treatments such as antibiotics. To develop mAbs against P. aeruginosa, we utilized ammonium metavanadate, which induces cell envelope stress responses and upregulates polysaccharide expression. Mice were immunized with P. aeruginosa grown with ammonium metavanadate and we developed two IgG2b mAbs, WVDC-0357 and WVDC-0496, directed against the O-antigen lipopolysaccharide of P. aeruginosa. Functional assays revealed that WVDC-0357 and WVDC-0496 directly reduced the viability of P. aeruginosa and mediated bacterial agglutination. In a lethal sepsis model of infection, prophylactic treatment of mice with WVDC-0357 and WVDC-0496 at doses as low as 15 mg/kg conferred 100% survival against challenge. In both sepsis and acute pneumonia models of infection, treatment with WVDC-0357 and WVDC-0496 significantly reduced bacterial burden and inflammatory cytokine production post-challenge. Furthermore, histopathological examination of the lungs revealed that WVDC-0357 and WVDC-0496 reduced inflammatory cell infiltration. Overall, our results indicate that mAbs directed against lipopolysaccharide are a promising therapy for the treatment and prevention of P. aeruginosa infections.

Fall of viral and bacterial pneumonia hospitalizations following COVID-19 pandemic mitigation strategies: a central Italian Region retrospective study.

Community-Acquired Pneumonia (CAP) represents one of the first causes of hospitalization and death in the elderly all over the world and weighs heavily on public health system. Since the beginning of the COVID-19 (CoronaVirus Disease-19) pandemic, everybody's behavior was forced to change, as the result of a global lockdown strategy and the obligation of using personal protection equipment (PPE). We aimed to evaluate how the mitigation strategies adopted to fight SARS-CoV-2 (Severe Acute Respiratory Coronavirus Syndrome 2) infection have influenced hospitalizations due to CAP in two different Local Health Boards (LHBs) of central Italy. We considered two main periods of observation: before and after the national start of lockdown, in two Abruzzo's LHBs. We analyzed 19,558 hospital discharge records of bacterial and viral CAP. Excluding SARS-CoV2 infection, a significant decrease in CAP hospitalizations was observed. Through the analysis of Diagnosis Related Group (DRG) values, we highlighted a significant saving of founds for the Regional Health Service. The enactment of social distancing measures to contain COVID-19 spread, brought down admissions for bacterial and viral pneumonia. Our study emphasizes that costs for hospitalizations due to CAP could be drastically reduced by mask wearing and social distancing.

Transfusion of hyperimmune plasma for protecting foals against Rhodococcus equi pneumonia.

The bacterium Rhodococcus equi causes pneumonia in foals that is prevalent at breeding farms worldwide. In the absence of an effective vaccine, transfusion of commercial plasma from donor horses hyperimmunised against R. equi is used by many farms to reduce the incidence of pneumonia among foals at farms where the disease is endemic. The effectiveness of hyperimmune plasma for controlling R. equi pneumonia in foals has varied considerably among reports. The purposes of this narrative review are: (1) to review early studies that provided a foundational basis for the practice of transfusion of hyperimmune plasma that is widespread in the United States and in many other countries; (2) to summarise current knowledge of hyperimmune plasma for preventing R. equi pneumonia; (3) to provide an interpretive summary of probable explanations for the variable results among studies evaluating the effectiveness of transfusion of hyperimmune plasma for reducing the incidence of R. equi pneumonia; (4) to review mechanisms by which hyperimmune plasma might mediate protection; and (5) to consider risks of transfusing foals with hyperimmune plasma. Although the weight of evidence supports the practice of transfusing foals with hyperimmune plasma to prevent R. equi pneumonia, many important gaps in our knowledge of this topic remain including the volume/dose of hyperimmune plasma to be transfused, the timing(s) of transfusion, and the mechanism(s) by which hyperimmune plasma mediates protection. Transfusing foals with hyperimmune plasma is expensive, labour-intensive, and carries risks for foals; therefore, alternative approaches for passive and active immunisation to prevent R. equi pneumonia are greatly needed.

The application of cluster nursing to prevent bacterial pneumonia in stroke patients in neurology department.

The research aims to explore the intervention effect of cluster nursing methods on bacterial pneumonia in stroke patients in neurology. A retrospective analysis is conducted on 120 patients diagnosed with stroke in the hospital from 2020 to 2022, who are diagnosed as stroke patients in the neurology department by doctors. 120 patients are randomly separated into a control group (CG) and a research group (RG) for the experiment, with 60 people in each group. The CG receive normal nursing; The RG adopt cluster nursing methods. Comparison have done in the general information, nursing satisfaction, physical improvement after intervention, and oral hygiene indicators of the 2 groups of patients, and the intervention effect of the 2 nursing methods on patients suffering from bacterial pneumonia is evaluated. When the time reached the 7th day, the nutritional risk screening scores of both groups were (9.53 ± 2.29) and (8.10 ± 2.12), respectively. The serum albumin levels were (36.46 ± 4.80) g/L and (34.16 ± 3.69) g/L, respectively. After simultaneous nursing intervention, there were P < .005 in respiratory rates in the 2nd and 4th months of intervention, as well as after the completion of nursing intervention. The respiratory rates of the RG patients improved toward a larger range of normal respiratory rates, with significant statistical significance (P < .005). As time passed, the number of people with shortness of breath in the CG increased sharply to 46, while those in the RG was only 27, indicating P < .05 between the 2 groups. At the beginning of the 3rd month, the satisfaction rates of the RG and the CG were (92.33 ± 1.17)% and (78.18 ± 1.07)%, respectively, and there was P < .0.05 between the 2 groups of data. The cluster nursing strategy has a significant relieving effect on bacterial pneumonia in stroke patients in the neurology department, which can effectively reduce the probability of pneumonia, improve their physical condition, and enhance their quality of life. It has certain clinical application value.

Rhodococcus equi foal pneumonia: Update on epidemiology, immunity, treatment and prevention.

Pneumonia in foals caused by the bacterium Rhodococcus equi has a worldwide distribution and is a common cause of disease and death for foals. The purpose of this narrative review was to summarise recent developments pertaining to the epidemiology, immune responses, treatment, and prevention of rhodococcal pneumonia of foals. Screening tests have been used to implement earlier detection and treatment of foals with presumed subclinical R. equi pneumonia to reduce mortality and severity of disease. Unfortunately, this practice has been linked to the emergence of antimicrobial-resistant R. equi in North America. Correlates of protective immunity for R. equi infections of foals remain elusive, but recent evidence indicates that innate immune responses are important both for mediating killing and orchestrating adaptive immune responses. A macrolide antimicrobial in combination with rifampin remains the recommended treatment for foals with R. equi pneumonia. Great need exists to identify which antimicrobial combination is most effective for treating foals with R. equi pneumonia and to limit emergence of antimicrobial-resistant strains. In the absence of an effective vaccine against R. equi, passive immunisation remains the only commercially available method for effectively reducing the incidence of R. equi pneumonia. Because passive immunisation is expensive, labour-intensive and carries risks for foals, great need exists to develop alternative approaches for passive and active immunisation.

Evaluation of the indirect impact of the 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine in a cluster-randomised trial.

BACKGROUND: In the nation-wide double-blind cluster-randomised Finnish Invasive Pneumococcal disease trial (FinIP, ClinicalTrials.gov NCT00861380, NCT00839254), we assessed the indirect impact of the 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) against five pneumococcal disease syndromes. METHODS: Children 6 weeks to 18 months received PHiD-CV10 in 48 clusters or hepatitis B/A-vaccine as control in 24 clusters according to infant 3+1/2+1 or catch-up schedules in years 2009-2011. Outcome data were collected from national health registers and included laboratory-confirmed and clinically suspected invasive pneumococcal disease (IPD), hospital-diagnosed pneumonia, tympanostomy tube placements (TTP) and outpatient antimicrobial prescriptions. Incidence rates in the unvaccinated population in years 2010-2015 were compared between PHiD-CV10 and control clusters in age groups <5 and ≥5 years (5-7 years for TTP and outpatient antimicrobial prescriptions), and in infants <3 months. PHiD-CV10 was introduced into the Finnish National Vaccination Programme (PCV-NVP) for 3-month-old infants without catch-up in 9/2010. RESULTS: From 2/2009 to 10/2010, 45398 children were enrolled. Vaccination coverage varied from 29 to 61% in PHiD-CV10 clusters. We detected no clear differences in the incidence rates between the unvaccinated cohorts of the treatment arms, except in single years. For example, the rates of vaccine-type IPD, non-laboratory-confirmed IPD and empyema were lower in PHiD-CV10 clusters compared to control clusters in 2012, 2015 and 2011, respectively, in the age-group ≥5 years. CONCLUSIONS: This is the first report from a clinical trial evaluating the indirect impact of a PCV against clinical outcomes in an unvaccinated population. We did not observe consistent indirect effects in the PHiD-CV10 clusters compared to the control clusters. We consider that the sub-optimal trial vaccination coverage did not allow the development of detectable indirect effects and that the supervening PCV-NVP significantly diminished the differences in PHiD-CV10 vaccination coverage between the treatment arms.

Exploring Klebsiella pneumoniae capsule polysaccharide proteins to design multiepitope subunit vaccine to fight against pneumonia.

BACKGROUND: Klebsiella pneumoniae is an emerging human pathogen causing neonatal lung disease, catheter-associated infections, and nosocomial outbreaks with high fatality rates. Capsular polysaccharide (CPS) protein plays a major determinant in virulence and is considered as a promising target for vaccine development. RESEARCH DESIGN AND METHODS: In this study, we used immunoinformatic approaches to design a multi-peptide vaccine against K. pneumonia. The epitopes were selected through several immune filters, such as antigenicity, conservancy, nontoxicity, non-allergenicity, binding affinity to HLA alleles, overlapping epitopes, and peptides having common epitopes. RESULTS: Finally, a construct comprising 2 B-Cell, 8 CTL, 2 HTL epitopes, along with adjuvant, linkers was designed. Peptide-HLA interaction analysis showed strong binding of these epitopes with several common HLA molecules. The in silico immune simulation and population coverage analysis of the vaccine showed its potential to evoke strong immune responses.. Further, the interaction between vaccine and immune was evaluated by docking and simulation, revealing high affinity and complex stability. Codon adaptation and in silico cloning revealed higher expression of vaccine in E. coli K12 expression system. CONCLUSIONS: Conclusively, the findings of the present study suggest that the designed novel multi-epitopic vaccine holds potential for further experimental validation against the pathogen.

Randomized, controlled trial comparing Rhodococcus equi and poly-N-acetyl glucosamine hyperimmune plasma to prevent R equi pneumonia in foals.

BACKGROUND: Hyperimmune plasma raised against ß-1→6-poly-N-acetyl glucosamine (PNAG HIP) mediates more opsonophagocytic killing of Rhodococcus equi (R equi) than does R equi hyperimmune plasma (RE HIP) in vitro. The relative efficacy of PNAG HIP and RE HIP to protect foals against R equi pneumonia, however, has not been evaluated. HYPOTHESIS: Transfusion with PNAG HIP will be superior to RE HIP in foals for protection against R equi pneumonia in a randomized, controlled, blinded clinical trial. ANIMALS: Four hundred sixty Quarter Horse and Thoroughbred foals at 5 large breeding farms in the United States. METHODS: A randomized, controlled, blinded clinical trial was conducted in which foals were transfused within 24 hours after birth with 2 L of either RE HIP or PNAG HIP. Study foals were monitored through weaning for clinical signs of pneumonia by farm veterinarians. The primary outcome was the proportion of foals that developed pneumonia after receiving each type of plasma. RESULTS: The proportion of foals that developed pneumonia was the same between foals transfused with RE HIP (14%; 32/228) and PNAG HIP (14%; 30/215). CONCLUSIONS AND CLINICAL IMPORTANCE: Results indicate that PNAG HIP was not superior to a commercially available, United States Department of Agriculture-licensed RE HIP product for protecting foals against R equi pneumonia under field conditions.

Evaluationof the New Outer Membrane Protein A Epitope-based Vaccines for Mice Model of Acinetobacter baumannii Associated Pneumonia and Sepsis Infection.

Nosocomial infections caused by Acinetobacter baumannii (A. baumannii) nosocomial infections caused by Acinetobacter baumannii (A. baumannii) are considered as a global serious problem in hospitalized patients because of emerging antibiotic resistance. Immunotherapy approaches are promising to prevent such infections. In our previous study, five antigenic epitopes of outer membrane protein A (OmpA), as the most dangerous virulence molecule in A. baumanii, were predicted in silico. In this study, the investigators evaluated some immunological aspects of the peptides. Five peptides were separately injected into C5BL/6 mice; then the cytokine production (interleukin-4 and interferon-gamma) of splenocytes and opsonophagocytic activity of immunized serum were assessed. To identify the protective function of the peptides, animal models of sepsis and pneumonia infections were actively and passively immunized with selected peptides and pooled sera of immunized mice, respectively. Then, survival rates of them were compared with the non-infected controls. Based on the results, activated spleen cells in P127 peptide-immunized mice exhibited an increase level of IFN-γ compared with the other experimental groups, but not about the IL-4 concentration. The results of opsonophagocytic assay revealed an appropriate killing activity of produced antibodies against A. baumannii in a dose-dependent manner. Further, the survival rates of the mice under passive immunization with the immunized sera or active immunization with P127 peptide were significantly more than those in the control group. Moreover, the survival rate of the P127 peptide immunized group was considerably higher than that among the other peptide-immunized group. In conclusion, findings indicated that peptides derived from outer membrane protein-A can be used as a promising tool for designing the epitope-based vaccines against infections caused by A. baumannii.

Vaccination induces rapid protection against bacterial pneumonia via training alveolar macrophage in mice.

Vaccination strategies for rapid protection against multidrug-resistant bacterial infection are very important, especially for hospitalized patients who have high risk of exposure to these bacteria. However, few such vaccination strategies exist due to a shortage of knowledge supporting their rapid effect. Here, we demonstrated that a single intranasal immunization of inactivated whole cell of Acinetobacter baumannii elicits rapid protection against broad A. baumannii-infected pneumonia via training of innate immune response in Rag1-/- mice. Immunization-trained alveolar macrophages (AMs) showed enhanced TNF-α production upon restimulation. Adoptive transfer of immunization-trained AMs into naive mice mediated rapid protection against infection. Elevated TLR4 expression on vaccination-trained AMs contributed to rapid protection. Moreover, immunization-induced rapid protection was also seen in Pseudomonas aeruginosa and Klebsiella pneumoniae pneumonia models, but not in Staphylococcus aureus and Streptococcus pneumoniae model. Our data reveal that a single intranasal immunization induces rapid and efficient protection against certain Gram-negative bacterial pneumonia via training AMs response, which highlights the importance and the possibility of harnessing trained immunity of AMs to design rapid-effecting vaccine.

Myricetin protects mice against MRSA-related lethal pneumonia by targeting ClpP.

Methicillin-resistant Staphylococcus aureus is one of the leading causes of community and nosocomial infections, which has created the urgent need for innovative anti-infective agents to control MRSA-associated infections. A conserved serine protease, caseinolytic peptidase P (ClpP) in Staphylococcus aureus is highly associated with pathogenicity and has been claimed to be a novel antimicrobial target. We aim to search suitable inhibitors of ClpP to attenuate the virulence of MRSA and combat their infections in vivo. Over 500 natural compounds were pre-screened via fluorescence resonance energy transfer using the Suc-LY-AMC substrate. The binding of myricetin to ClpP was determined and the mechanism of action was elucidated by thermal shift assay, surface plasmon resonance, and molecular dynamics simulations. The therapeutic effects of myricetin on S. aureus infection were further investigated using a S. aureus-induced pneumonia model. We revealed that myricetin could effectively block the activity of ClpP without disturbing the growth of the bacteria and the Gln-47 and Met-31 residues were necessary for myricetin binding to ClpP. Importantly, myricetin attenuated the pathogenicity of S. aureus in vivo, while improving the efficacy of the traditional antibiotic oxacillin against MRSA infection and protecting mice from fatal lung infections caused by MRSA. These findings indicate that myricetin has the potential to be applied in the pharmaceutical industry as a promising therapeutic agent.

Antibody activities in hyperimmune plasma against the Rhodococcus equi virulence -associated protein A or poly-N-acetyl glucosamine are associated with protection of foals against rhodococcal pneumonia.

The efficacy of transfusion with hyperimmune plasma (HIP) for preventing pneumonia caused by Rhodococcus equi remains ill-defined. Quarter Horse foals at 2 large breeding farms were randomly assigned to be transfused with 2 L of HIP from adult donors hyperimmunized either with R. equi (RE HIP) or a conjugate vaccine eliciting antibody to the surface polysaccharide ß-1→6-poly-N-acetyl glucosamine (PNAG HIP) within 24 hours of birth. Antibody activities against PNAG and the rhodococcal virulence-associated protein A (VapA), and to deposition of complement component 1q (C՛1q) onto PNAG were determined by ELISA, and then associated with either clinical pneumonia at Farm A (n = 119) or subclinical pneumonia at Farm B (n = 114). Data were analyzed using multivariable logistic regression. Among RE HIP-transfused foals, the odds of pneumonia were approximately 6-fold higher (P = 0.0005) among foals with VapA antibody activity ≤ the population median. Among PNAG HIP-transfused foals, the odds of pneumonia were approximately 3-fold (P = 0.0347) and 11-fold (P = 0.0034) higher for foals with antibody activities ≤ the population median for PNAG or C՛1q deposition, respectively. Results indicated that levels of activity of antibodies against R. equi antigens are correlates of protection against both subclinical and clinical R. equi pneumonia in field settings. Among PNAG HIP-transfused foals, activity of antibodies with C՛1q deposition (an indicator of functional antibodies) were a stronger predictor of protection than was PNAG antibody activity alone. Collectively, these findings suggest that the amount and activity of antibodies in HIP (i.e., plasma volume and/or antibody activity) is positively associated with protection against R. equi pneumonia in foals.

Orientin mediates protection against MRSA-induced pneumonia by inhibiting Sortase A.

Drug-resistant pathogenic Staphylococcus aureus (S. aureus) has severely threatened human health and arouses widespread concern. Sortase A (SrtA) is an essential virulence factor of S. aureus, which is responsible for the covalent anchoring of a variety of virulence-related proteins to the cell wall. SrtA has always been regarded as an ideal pharmacological target against S. aureus infections. In this research, we have determined that orientin, a natural compound isolated from various medicinal plants, can effectively inhibit the activity of SrtA with an IC50 of 50.44 ± 0.51 µM. We further demonstrated that orientin inhibited the binding of S. aureus to fibrinogen and diminished biofilm formation and the attaching of Staphylococcal protein A (SpA) to the cell wall in vitro. Using the fluorescence quenching assay, we demonstrated a direct interaction between orientin and SrtA. Further mechanistic studies revealed that the residues Glu-105, Thr-93, and Cys-184 were the key sites for the binding of SrtA to orientin. Importantly, we demonstrated that treatment with orientin attenuated S. aureus virulence of in vivo and protected mice against S. aureus-induced lethal pneumonia. These findings indicate that orientin is a potential drug to counter S. aureus infections and limit the development of drug resistance.

Lianhuaqingwen capsule inhibits influenza-induced bacterial adhesion to respiratory epithelial cells through down-regulation of cell adhesion molecules.

ETHNOPHARMACOLOGICAL RELEVANCE: Influenza virus infection is widely believed to cause mild symptoms, but can lead to high mortality and severe disease complicated by secondary bacterial pneumonia. Traditional Chinese medicine (TCM) has been proposed as a promising agent to treat respiratory viral infections. A herbal formula Lianhuaqingwen capsule (LHQW) comprising two prescriptions: Maxing Shigan decoction and Yinqiao San, has been used clinically to treat respiratory infection with immune regulatory effects. However, little is known about the capacity of LHQW against influenza-induced secondary bacterial pneumonia. AIM OF STUDY: This study aimed to evaluate the efficacy and underlying mechanism of LHQW on influenza A virus A/PR/8/34 (PR8) secondary methicillin-resistant Staphy-lococcus aureus (MRSA) infection. METHODS: The anti-adhesion activity of LHQW against PR8-induced MRSA infection was assessed in human lung epithelial (A549) cells and the effect of LHQW on the expression of intracellular adhesion molecule 1 (ICAM-1) was detected. Also, the mRNA expression levels of inflammatory cytokines upon lipopolysaccharide (LPS) stimulation in PR8-infected A549 cells were determined. The body weight change, survivals, viral titers, colonies and the pathological parameters after LHQW treatment in severe pneumonia model have all been systematically determined. RESULTS: LHQW significantly reduced the adhesion of MRSA to PR8-infected A549 cells in a dose-dependent manner by suppressing the up-regulation of bacterial receptors. LHQW also markedly declined the overexpression of IL-6, IL-8, and TNF-α induced by LPS stimulated-A549 cells following influenza virus infection. Furthermore, the abnormal changes of lung index in dual-infection mice were relieved after administered with LHQW in preventive and therapeutic mode, but with no significantly difference (P > 0.05). LHQW could not effectively improve survival rate or prolong the survival time of mice (P > 0.05). LHQW (1000 mg/kg/d) administered prophylactically significantly decreased the lung viral titers (P < 0.05), slightly downregulated IL-6 but TNF-α, IL-1ß levels and improved lung pathological inflammation including neutrophil infiltration, necrosis, which is consistent with the expression of inflammatory factors. CONCLUSIONS: LHQW inhibited influenza-induced bacterial adhesion by down-regulating the adhesion molecules with the improvement trend on severe pneumonia, indicating that it can be used as an adjuvant medication in severe viral-bacterial pneumonia therapy rather than as a single medication.

Bacterial Membrane Vesicles in Pneumonia: From Mediators of Virulence to Innovative Vaccine Candidates.

Pneumonia due to respiratory infection with most prominently bacteria, but also viruses, fungi, or parasites is the leading cause of death worldwide among all infectious disease in both adults and infants. The introduction of modern antibiotic treatment regimens and vaccine strategies has helped to lower the burden of bacterial pneumonia, yet due to the unavailability or refusal of vaccines and antimicrobials in parts of the global population, the rise of multidrug resistant pathogens, and high fatality rates even in patients treated with appropriate antibiotics pneumonia remains a global threat. As such, a better understanding of pathogen virulence on the one, and the development of innovative vaccine strategies on the other hand are once again in dire need in the perennial fight of men against microbes. Recent data show that the secretome of bacteria consists not only of soluble mediators of virulence but also to a significant proportion of extracellular vesicles-lipid bilayer-delimited particles that form integral mediators of intercellular communication. Extracellular vesicles are released from cells of all kinds of organisms, including both Gram-negative and Gram-positive bacteria in which case they are commonly termed outer membrane vesicles (OMVs) and membrane vesicles (MVs), respectively. (O)MVs can trigger inflammatory responses to specific pathogens including S. pneumonia, P. aeruginosa, and L. pneumophila and as such, mediate bacterial virulence in pneumonia by challenging the host respiratory epithelium and cellular and humoral immunity. In parallel, however, (O)MVs have recently emerged as auspicious vaccine candidates due to their natural antigenicity and favorable biochemical properties. First studies highlight the efficacy of such vaccines in animal models exposed to (O)MVs from B. pertussis, S. pneumoniae, A. baumannii, and K. pneumoniae. An advanced and balanced recognition of both the detrimental effects of (O)MVs and their immunogenic potential could pave the way to novel treatment strategies in pneumonia and effective preventive approaches.