Detection of Parechovirus (P) and Enterovirus (E) Among Infants Evaluated for Late-Onset Sepsis in the Neonatal Intensive Care Unit (NICU): The VIRIoN-P-E Study

Background: Limited data exist on the role of human parechoviruses (HPeV) and enteroviruses (EV) as causes of late-onset sepsis (LOS) in the NICU. Objective: To determine the frequency of detection of parechoviruses and enteroviruses among infants >72 hr of age who were evaluated for LOS in 2 academic NICUs (Parkland Memorial Hospital [PMH], Dallas -shared bays; Women & Infants Hospital [W&I], RI -single patient rooms) Design/Methods: Prospective cohort study of inborn infants hospitalized in the NICU at PMH and WIH from 1/2012 to 1/2013 and were enrolled in the Viral Respiratory Infections in the Neonatal Intensive Care Unit (VIRIoN-I; J Pediatr 2014:165:690). Eligible subjects were infants of all gestational ages (GA) and birth weights (BW) who were >72 hrs of age, remained in the NICU since birth, and underwent evaluation with initiation of antibiotic therapy for suspected LOS. Nasopharyngeal specimens were obtained within 72 hrs of the sepsis evaluation using flexible flocked nylon swabs that were placed in universal transport medium and frozen at -80\ub0C until tested for parechovirus and enterovirus RNA by polymerase chain reaction (PCR) assay (Virology Laboratory, Nationwide Children\u2019s Hospital, Columbus, OH). Demographic, clinical, laboratory, and radiographic data were obtained. Results: Of the 100 infants enrolled in the VIRIoN-I study, nasopharyngeal specimens were available from 65 (59, PMH; 6, WIH) for parechovirus and enterovirus PCR testing. These 65 infants (38, male; 27, female; 49, Hispanic; 6, white; 9, Black; 1, unknown) had a mean \ub1SD gestational age of 30 \ub1 5 wks and birth weight of 1619 \ub1 929 g, and received empirical antibiotics for possible LOS. Infants had a total of 94 sepsis evaluations (65, 1 evaluation; 16, 2; 8, 3; 4, 4) at a mean age of 20 days. Reasons for the sepsis evaluations included fever (9), hypothermia (65), apnea (50),feeding intolerance (51), seizure (1), irritabilitiy (5), emesis (20), diarrhea (1), bloody stool (5), rhinorrhea/congestion/cough (6), and lethargy (9). Four infants died. None of the infants had parechovirus or enterovirus detected in nasopharygeal specimens either at the first or subsequent sepsis evaluations. Conclusion(s): The burden of disease due to parechovirus and enteroviruses among inborn infants who remain in the NICU since birth appears to be low in those evaluated for LOS. Larger, prospective studies are needed to fully determine their contribution to \u201cculture-negative\u201d sepsis in the NICU. Publication Number: 3860.53

High-Dose Mannose-Binding Lectin Therapy for Ebola Virus Infection

Mannose-binding lectin (MBL) targets diverse microorganisms for phagocytosis and complement-mediated lysis by binding specific surface glycans. Although recombinant human MBL (rhMBL) trials have focused on reconstitution therapy, safety studies have identified no barriers to its use at higher levels. Ebola viruses cause fatal hemorrhagic fevers for which no treatment exists and that are feared as potential biothreat agents. We found that mice whose rhMBL serum concentrations were increased ≥7-fold above average human levels survived otherwise fatal Ebola virus infections and became immune to virus rechallenge. Because Ebola glycoproteins potentially model other glycosylated viruses, rhMBL may offer a novel broad-spectrum antiviral approach

Lectin-Dependent Enhancement of Ebola Virus Infection via Soluble and Transmembrane C-type Lectin Receptors

Mannose-binding lectin (MBL) is a key soluble effector of the innate immune system that recognizes pathogen-specific surface glycans. Surprisingly, low-producing MBL genetic variants that may predispose children and immunocompromised individuals to infectious diseases are more common than would be expected in human populations. Since certain immune defense molecules, such as immunoglobulins, can be exploited by invasive pathogens, we hypothesized that MBL might also enhance infections in some circumstances. Consequently, the low and intermediate MBL levels commonly found in human populations might be the result of balancing selection. Using model infection systems with pseudotyped and authentic glycosylated viruses, we demonstrated that MBL indeed enhances infection of Ebola, Hendra, Nipah and West Nile viruses in low complement conditions. Mechanistic studies with Ebola virus (EBOV) glycoprotein pseudotyped lentiviruses confirmed that MBL binds to N-linked glycan epitopes on viral surfaces in a specific manner via the MBL carbohydrate recognition domain, which is necessary for enhanced infection. MBL mediates lipid-raft-dependent macropinocytosis of EBOV via a pathway that appears to require less actin or early endosomal processing compared with the filovirus canonical endocytic pathway. Using a validated RNA interference screen, we identified C1QBP (gC1qR) as a candidate surface receptor that mediates MBL-dependent enhancement of EBOV infection. We also identified dectin-2 (CLEC6A) as a potentially novel candidate attachment factor for EBOV. Our findings support the concept of an innate immune haplotype that represents critical interactions between MBL and complement component C4 genes and that may modify susceptibility or resistance to certain glycosylated pathogens. Therefore, higher levels of native or exogenous MBL could be deleterious in the setting of relative hypocomplementemia which can occur genetically or because of immunodepletion during active infections. Our findings confirm our hypothesis that the pressure of infectious diseases may have contributed in part to evolutionary selection of MBL mutant haplotypes

Successive influenza virus infection and Streptococcus pneumoniae stimulation alter human dendritic cell function

Background: Influenza virus is a major cause of respiratory disease worldwide and Streptococcus pneumoniae infection associated with influenza often leads to severe complications. Dendritic cells are key antigen presenting cells but its role in such co-infection is unclear.Methods: In this study, human monocyte derived-dentritic cells were either concurrently or successively challenged with the combination of live influenza virus and heat killed pneumococcus to mimic the viral pneumococcal infection. Dendritic cell viability, phenotypic maturation and cytokine production were then examined.Results: The challenge of influenza virus and pneumococcus altered dendritic cell functions dependent on the time interval between the successive challenge of influenza virus and pneumococcus, as well as the doses of pneumococcus. When dendritic cells were exposed to pneumococcus at 6 hr, but not 0 hr nor 24 hr after influenza virus infection, both virus and pneumococcus treated dendritic cells had greater cell apoptosis and expressed higher CD83 and CD86 than dendritic cells infected with influenza virus alone. Dendritic cells produced pro-inflammatory cytokines: TNF-α, IL-12 and IFN-γ synergistically to the successive viral and pneumococcal challenge. Whereas prior influenza virus infection suppressed the IL-10 response independent of the timing of the subsequent pneumococcal stimulation.Conclusions: Our results demonstrated that successive challenge of dendritic cells with influenza virus and pneumococcus resulted in synergistic up-regulation of pro-inflammatory cytokines with simultaneous down-regulation of anti-inflammatory cytokine, which may explain the immuno-pathogenesis of this important co-infection. © 2011 Wu et al; licensee BioMed Central Ltd.published_or_final_versio

Intestinal carriage of Staphylococcus aureus: How does its frequency compare with that of nasal carriage and what is its clinical impact?

The bacterial species Staphylococcus aureus, including its methicillin-resistant variant (MRSA), finds its primary ecological niche in the human nose, but is also able to colonize the intestines and the perineal region. Intestinal carriage has not been widely investigated despite its potential clinical impact. This review summarizes literature on the topic and sketches the current state of affairs from a microbiological and infectious diseases' perspective. Major findings are that the average reported detection rate of intestinal carriage in healthy individuals and patients is 20% for S. aureus and 9% for MRSA, which is approximately half of that for nasal carriage. Nasal carriage seems to predispose to intestinal carriage, but sole intestinal carriage occurs relatively frequently and is observed in 1 out of 3 intestinal carriers, which provides a rationale to include intestinal screening for surveillance or in outbreak settings. Colonization of the intestinal tract with S. aureus at a young age occurs at a high frequency and may affect the host's immune system. The frequency of intestinal carriage is generally underestimated and may significantly contribute to bacterial dissemination and subsequent risk of infections. Whether intestinal rather than nasal S. aureus carriage is a primary predictor for infections is still ill-defined