A241 CHARACTERIZING KUPFFER CELL-VIRUS INTERACTIONS IMMEDIATELY FOLLOWING VIRAL INVASION AND IN ACUTE HEPATITIS IN THE WOODCHUCK HEPATITIS VIRUS MODEL OF HEPATITIS B VIRUS INFECTIONS

Background

Hepatitis B virus (HBV) infections are one of the largest global infectious disease burdens, despite the availability of a preventative vaccine. The virus infects the liver which is a vital organ that plays a critical role in homeostasis due to its metabolic and immunoregulatory functions. Kupffer cells (KCs) are considered to be a first line of immune defense for protection of hepatocytes. Both woodchuck hepatitis virus (WHV) and HBV are members of Hepadnaviridae and demonstrate comparable infection outcomes and progression to hepatocellular carcinoma. North American woodchucks (Marmota monax) infected with WHV present a natural infection model for the assessment of acute and chronic hepadnaviral infections. We hypothesize that KC absence in acute viral hepatitis leads to chronic infections by impacting downstream virus processing and immune responses.

Purpose

We aim to uncover the early host-virus interactions in acute WHV infections to facilitate our understanding of the risk of progression to chronic infection and the immunopathogenic mechanisms involved in chronic hepatitis.

Method

We designed and optimized in-house WHV and woodchuck-specific assays to assess intrahepatic and systemic virus presence and anti-viral immune responses which occur following WHV invasion (<24 hours) and infection (4-6 weeks). A live imaging protocol was developed for capturing real-time events in a living host. Next, we optimized macrophage depletion in woodchucks to evaluate virus invasion and acute infection outcomes in the presence and absence of KCs. Using purified and fluorescently labelled WHV virions (concentrations exceeding 10¹⁰VGE copies/ml), we imaged host cell-hepadnaviral interactions and characterized immunological and virological differences between KC-depleted animals and non-depleted animals.

Result(s)

Ex vivo assessment of the consequences of KC depletion during invasion have been evaluated within 1- and at 24-hour post-virus injection. Intravital microscopy (IVM) revealed that the virus traffics to, and accumulates within, the liver 10 seconds following intravenous administration, demonstrating direct binding and capture by liver macrophages. In contrast, virus only begins to accumulate in the KC-non-depleted control minutes after infection in a randomized manner. Preliminary invasion results indicate that in both the KC-depleted and non-depleted animals, virus is most readily detectable in the blood within the first hour following viral administration. By 24-hours post-virus injection the highest viral load in non-depleted woodchucks was identified in the liver whereas in KC-depleted woodchucks, the highest viral loads were found in the spleen 24-hours post-injection.

Conclusion(s)

We have successfully captured the early host-virus interactions and continue to uncover the role of KCs in viral hepatitis infections. Tracking the initial interactions allows us to understand the events promoting viral dissemination and development of chronic hepatitis.

Disclosure of Interest

None Declared

Paravertebral catheter versus EPidural analgesia in Minimally invasive Esophageal resectioN: a randomized controlled multicenter trial (PEPMEN trial)

BACKGROUND

Thoracic epidural analgesia is the standard postoperative pain management strategy in esophageal cancer surgery. However, paravertebral block analgesia may achieve comparable pain control while inducing less side effects, which may be beneficial for postoperative recovery. This study primarily aims to compare the postoperative quality of recovery between paravertebral catheter versus thoracic epidural analgesia in patients undergoing minimally invasive esophagectomy.

METHODS

This study represents a randomized controlled superiority trial. A total of 192 patients will be randomized in 4 Dutch high-volume centers for esophageal cancer surgery. Patients are eligible for inclusion if they are at least 18 years old, able to provide written informed consent and complete questionnaires in Dutch, scheduled to undergo minimally invasive esophagectomy with two-field lymphadenectomy and an intrathoracic anastomosis, and have no contra-indications to either epidural or paravertebral analgesia. The primary outcome is the quality of postoperative recovery, as measured by the Quality of Recovery-40 (QoR-40) questionnaire on the morning of postoperative day 3. Secondary outcomes include the QoR-40 questionnaire score Area Under the Curve on postoperative days 1-3, the integrated pain and systemic opioid score and patient satisfaction and pain experience according to the International Pain Outcomes (IPO) questionnaire, and cost-effectiveness. Furthermore, the groups will be compared regarding the need for additional rescue medication on postoperative days 0-3, technical failure of the pain treatment, duration of anesthesia, duration of surgery, total postoperative fluid administration day 0-3, postoperative vasopressor and inotrope use, length of urinary catheter use, length of hospital stay, postoperative complications, chronic pain at six months after surgery, and other adverse effects.

DISCUSSION

In this study, it is hypothesized that paravertebral analgesia achieves comparable pain control while causing less side-effects such as hypotension when compared to epidural analgesia, leading to shorter postoperative length of stay on a monitored ward and superior quality of recovery. If this hypothesis is confirmed, the results of this study can be used to update the relevant guidelines on postoperative pain management for patients undergoing minimally invasive esophagectomy.

TRIAL REGISTRATION

Netherlands Trial Registry, NL8037. Registered 19 September 2019.

Multicentre evaluation of significant bacteriuria among pregnant women in the cascade of referral healthcare system in North-western Tanzania: Bacterial pathogens, antimicrobial resistance profiles and predictors

OBJECTIVES

The aim of this multicentre study was to evaluate the magnitude of significant bacteriuria (SB) as well as the implicated bacterial pathogens, antimicrobial resistance (AMR) profiles and risk factors for SB among pregnant women attending different levels of healthcare facilities (HCFs) in Tanzania in order to guide antimicrobial therapy and preventive measures.

METHODS

Information on sociodemographic and clinical characteristics, midstream urine culture and antimicrobial susceptibility testing was collected from 1828 pregnant women between March 2016 and May 2017. Data were analysed using STATA v.13.0 software.

RESULTS

The prevalence of SB among pregnant women was 17.7% (323/1828; 95% CI 16.0-19.5%), with a predominance of Escherichia coli (164/323; 50.8%), Klebsiella spp. (55/323; 17.0%) and Staphylococcus aureus (28/323; 8.7%). Moreover, 37.5% (121/323) of bacteria were multidrug-resistant [84.3% (102/121) Gram-negative bacteria and 15.7% (19/121) in Gram-positive bacteria; P<0.001]. Third-generation cephalosporin resistance in E. coli, Klebsiella spp. and other Enterobacteriaceae was 13.4%, 21.8% and 27.5%, respectively, and was higher in strains from a tertiary hospital (OR=3.27, 95% CI 1.02-10.49; P=0.046) compared with lower HCFs. Predictors of SB among pregnant women were lack of formal occupation, current hospital admission and presence of co-morbidities.

CONCLUSIONS

The prevalence of SB among pregnant women in this study was high (17.7%) and was within the same range reported 10 years ago in a single-centre baseline study. However, there is an increase in AMR in the cascade of referral healthcare system, underscoring the need for health facility level-specific antimicrobial stewardship.

Nationwide screening of surface water toxicity to algae

According to the European Water Framework Directive (WFD), chemical water quality is assessed by monitoring 45 priority substances. However, observed toxic effects can often not be attributed to these priority substances, and therefore there is an urgent need for an effect-based monitoring strategy that employs bioassays to identify environmental risk. Algal photosynthesis is a sensitive process that can be applied to identify the presence of hazardous herbicides in surface water. Therefore, the aim of this study was to employ an algal photosynthesis bioassay to assess surface water toxicity to algae and to identify the compounds causing the observed effects. To this purpose, Raphidocelis subcapitata was exposed to surface water samples and after 4.5 h photosynthetic efficiency was determined using PAM fluorometry. In this rapid high throughput bioassay, algal photosynthesis was affected by surface water from only one of 39 locations. Single compounds toxicity confirmation elucidated that the observed effect could be solely attributed to the herbicide linuron, which occurred at 110 times the EQS concentration and which is not included in the WFD priority substances list. In conclusion, applying the algal photosynthesis bioassay enables more efficient and effective assessment of toxicity to primary producers because it: (i) identifies the presence of herbicides that would be overlooked by routine chemical WFD monitoring, and (ii) avoids redundant chemical analyses by focusing only on (non-)target screening in samples with demonstrated effects.

Bovine viral diarrhea virus genomic variation within persistently infected cattle

Bovine viral diarrhea virus (BVDV) is a single stranded RNA virus in the family Flaviviridae that causes a form of persistent infection. If a fetus is infected in utero during the first 120days of gestation the resulting calf will be immunotolerant to the infecting strain and maintain the virus for life. These animals are epidemiologically important in maintaining BVDV on farms, but also present a unique opportunity to study quasispecies in vivo in the absence of significant selection by the host adaptive immune response. We used deep sequencing and novel analytical methods to characterize the viral populations within the mesenteric lymph nodes of 10 persistently infected animals. Our results indicate that the pattern of variability across the viral genome from animal to animal is very consistent within BVDV subgenotypes. However, the individual mutations that constitute this variation are not necessarily the same in each animal. Even in the absence of significant immune selection the structural genes of BVDV vary more extensively than the non-structural genes. These findings could be useful for future vaccine design against BVDV as well as for measuring and understanding patterns of variation in other ssRNA viruses, especially those that belong to the family Flaviviridae.

Preliminary insights into the occurrence of similar clones of extended-spectrum beta-lactamase-producing bacteria in humans, animals and the environment in Tanzania: A systematic review and meta-analysis between 2005 and 2016

The emergence and spread of extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) are complex and of the public health concern across the globe. This review aimed at assessing the ESBL-PE clones circulating in humans, animals and the environment to provide evidence-based insights for combating ESBL-PE using One Health approach. Systematic search from Medline/PubMed, Google Scholar and African Journals Online was carried out and retrieved nine eligible articles (of 131) based on phenotypic and genotypic detection of ESBL-PE between 2005 and 2016 in Tanzania. Analysis was performed using STATA 11.0 software to delineate the prevalence of ESBL-PE, phenotypic resistance profiles and clones circulating in the three interfaces. The overall prevalence of ESBL-PE in the three interfaces was 22.6% (95% CI: 21.1-24.2) with the predominance of Escherichia coli (E. coli) strains (51.6%). The majority of ESBL-PE were resistant to the commonly used antimicrobials such as trimethoprim-sulfamethoxazole and tetracycline/doxycycline, 38%-55% were resistant to ciprofloxacin and all were sensitive to meropenem/imipenem. ESBL-PE infections were more associated with deaths compared to non-ESBL-PE infections. Strikingly, E. coli ST38, ST131 and ST2852 were found to intersect variably across the three interfaces. The predominant allele, bla_CTX-M-15, was found mostly in the conjugative IncF plasmids connoting transmission potential. The high prevalence of ESBL-PE and shared clones across the three interfaces, including the global E. coli ST131 clone, indicates wide and inter-compartmental spread that calls for One Health genomic-driven studies to track the resistome flow.

The influence of a user-adaptive prosthetic knee across varying walking speeds: A randomized cross-over trial

Previously conducted trials comparing the gait pattern of individuals with a transfemoral amputation using a user-adaptive and a non-microprocessor-controlled prosthetic knee (NMPK) found mixed and conflicting results. Few trials, however, have compared user-adaptive to non-adaptive prosthetic knees across different walking speeds. Because of the ability of variable damping, the effect of user-adaptive knees might be more pronounced at lower or higher walking speeds. Our aim was to compare the Rheo Knee II (a microprocessor-controlled prosthetic knee) with NMPKs across varying walking speeds. In addition, we studied compensatory mechanisms associated with non-optimal prosthetic knee kinematics, such as intact ankle vaulting and vertical acceleration of the pelvis. Nine persons with a transfemoral amputation or knee disarticulation were included and measured with their own NMPK and with the Rheo Knee II. Measurements were performed at three walking speeds: preferred walking speed, 70% preferred walking speed and 115% preferred walking speed. No differences on peak prosthetic knee flexion during swing were found between prosthetic knee conditions. In addition, prosthetic knee flexion increased significantly with walking speed for both prosthetic knee conditions. At 70% preferred walking speed we found that vaulting of the intact ankle was significantly decreased while walking with the Rheo Knee II compared to the NMPK condition (P=0.028). We did not find differences in peak vertical acceleration of the pelvis during initial and mid-swing of the prosthetic leg. In conclusion, comparison of walking with the Rheo Knee II to walking with a NMPK across different walking speeds showed limited differences in gait parameters.

Hepatitis B virus (HBV) variants fluctuate in paired plasma and peripheral blood mononuclear cells among patient cohorts during different chronic hepatitis B (CHB) disease phases

Hepatitis B virus is classically considered a hepatotropic virus but also infects peripheral blood mononuclear cells. Chronic hepatitis B has different disease phases modulated by host immunity. We compared HBV variability, drug resistance and immune escape mutations in the overlapping HBV polymerase/surface gene in plasma and peripheral blood mononuclear cells in different disease phases. Plasma and peripheral blood mononuclear cells were isolated from 22 treatment naïve patient cohorts (five inactive, six immune-active, nine HBeAg negative and two immune-tolerant). HBV was genotyped via line probe assay, hepatitis B surface antigen titres were determined by an in-house immunoassay, and HBV DNA was quantified by kinetic PCR. The HBV polymerase/surface region, including full genome in some, was PCR-amplified and cloned, and ~20 clones/sample were sequenced. The sequences were subjected to various mutational and phylogenetic analyses. Clonal sequencing showed that only three of 22 patients had identical HBV genotype profiles in both sites. In immune-active chronic hepatitis B, viral diversity in plasma was higher compared with peripheral blood mononuclear cells. Mutations at residues, in a minority of clones, associated with drug resistance, and/or immune escape were found in both compartments but were more common in plasma. Immune escape mutations were more often observed in the peripheral blood mononuclear cells of immune-active CHB carriers, compared with other disease phases. During all CHB disease phases, differences exist between HBV variants found in peripheral blood mononuclear cells and plasma. Moreover, these data indicate that HBV evolution occurs in a compartment and disease phase-specific fashion.

Cannabis use and age at onset of symptoms in subjects at clinical high risk for psychosis

OBJECTIVE

Numerous studies have found a robust association between cannabis use and the onset of psychosis. Nevertheless, the relationship between cannabis use and the onset of early (or, in retrospect, prodromal) symptoms of psychosis remains unclear. The study focused on investigating the relationship between cannabis use and early and high-risk symptoms in subjects at clinical high risk for psychosis.

METHOD

Prospective multicenter, naturalistic field study with an 18-month follow-up period in 245 help-seeking individuals clinically at high risk. The Composite International Diagnostic Interview was used to assess their cannabis use. Age at onset of high risk or certain early symptoms was assessed retrospectively with the Interview for the Retrospective Assessment of the Onset of Schizophrenia.

RESULTS

Younger age at onset of cannabis use or a cannabis use disorder was significantly related to younger age at onset of six symptoms (0.33 < r(s) < 0.83, 0.004 < P < 0.001). Onset of cannabis use preceded symptoms in most participants.

CONCLUSION

Our results provide support that cannabis use plays an important role in the development of psychosis in vulnerable individuals. Cannabis use in early adolescence should be discouraged.

Estimation of fractal dimension in radiographs

In the last decade, the fractal dimension has become a popular parameter to characterize image textures. Also in radiographs, various procedures have been used to estimate the fractal dimension. However, certain characteristics of the radiographic process, e.g., noise and blurring, interfere with the straightforward application of these estimation methods. In this study, the influence of quantum noise and image blur on several estimation methods was quantified by simulating the effect of quantum noise and the effect of modulation transfer functions, corresponding with different screen-film combinations, on computer generated fractal images. The results are extrapolated to explain the effect of film-grain noise on fractal dimension estimation. The effect of noise is that, irrespective of the noise source, the fractal dimension is overestimated, especially for lower fractal dimensions. On the other hand, blurring results in an underestimation of the dimensions. The effect of blurring is dependent on the estimation method used; the dimension estimates by the power spectrum method are lowered with a constant value, whereas the underestimation by the methods working in the spatial domain is dependent on the given dimension. The influence of the MTF and noise on fractal dimension estimation seriously limits the comparability of fractal dimensions estimated from radiographs which differ in noise content or MTF. Only when the power spectrum method is used, it is possible to correct for the influence of different MTFs of screen-film combinations. It is concluded that only when using the same object-focus distance, the same exposure conditions, the same digitizer at the same resolution, can fractal dimensions as estimated in radiographs be reliably compared.

Tubular structures involved in movement of cowpea mosaic virus are also formed in infected cowpea protoplasts

In cowpea plant cells infected with cowpea mosaic virus, tubular structures containing virus particles are formed in the plasmodesmata between adjacent cells; these structures are supposedly involved in cell-to-cell spread of the virus. Here we show that similar tubular structures are also formed in cowpea protoplasts, from which the cell wall and plasmodesmata are absent. Between 12 and 21 h post-inoculation, tubule formation starts in the periphery of the protoplast at the level of the plasma membrane. Upon assembly, the virus-containing tubule is enveloped by the plasma membrane and extends into the culture medium. This suggests that the tubule has functional polarity and makes it likely that a tubule 'grows' into a neighbouring cell in vivo. On average, 75% of infected protoplasts were shown to possess tubular structures extending from their surface. The tubule wall was 3 to 4 nm thick and they were up to 20 microns in length, as shown by fluorescent light microscopy and negative staining electron microscopy. By analogy to infected plant cells, both the viral 58K/48K movement and capsid proteins were located in these tubules, as determined by immunofluorescent staining and immunogold labelling using specific antisera against these proteins. These results demonstrate that the formation of tubules is not necessarily dependent on the presence of plasmodesmata or the cell wall, and that they are composed, at least in part, of virus-encoded components.