Pseudomembranous colitis and Parabacteroides distasonis bacteraemia: a rare clinical presentation.

We present the case of a male with end-stage diabetic nephropathy on haemodialysis who initially presented with acute-on-chronic digital ulceration. While awaiting vascular intervention, he became septic with abdominal pain and diarrhoea. Flexible sigmoidoscopy confirmed pseudomembranous colitis secondary to Clostridium difficile. Blood cultures grew Parabacteroides distasonis, a Gram-negative gut anaerobe. Enterobacter cloacae, another Gram-negative anaerobic gut bacilli, was grown in colonic cultures and swabs of the digital ulcers. We hypothesise that the pseudomembranous colitis increased gut translocation and thus led to the systemic spread of both gut anaerobes. This is the first reported case of Parabacteroides distasonis bacteraemia in the context of Clostridium difficile infection. Our patient recovered with antibiotics and went on to have vascular intervention for his digital ulceration.

Clinical outcomes in COVID-19 and cirrhosis: a systematic review and meta-analysis of observational studies.

BACKGROUND: COVID-19 continues to pose a significant healthcare challenge throughout the world. Comorbidities including diabetes and hypertension are associated with a significantly higher mortality risk. However, the effect of cirrhosis on COVID-19 outcomes has yet to be systematically assessed. OBJECTIVES: To assess the reported clinical outcomes of patients with cirrhosis who develop COVID-19 infection. DESIGN/METHOD: PubMed and EMBASE databases were searched for studies included up to 3 February 2021. All English language primary research articles that reported clinical outcomes in patients with cirrhosis and COVID-19 were included. The study was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The risk of bias was assessed using the Quality In Prognostic Score (QUIPS) risk-of-bias assessment instrument for prognostic factor studies template. Meta-analysis was performed using Cochrane RevMan V.5.4 software using a random effects model. RESULTS: 63 studies were identified reporting clinical outcomes in patients with cirrhosis and concomitant COVID-19. Meta-analysis of cohort studies which report a non-cirrhotic comparator yielded a pooled mortality OR of 2.48 (95% CI: 2.02 to 3.04). Analysis of a subgroup of studies reporting OR for mortality in hospitalised patients adjusted for significant confounders found a pooled adjusted OR 1.81 (CI: 1.36 to 2.42). CONCLUSION: Cirrhosis is associated with an increased risk of all-cause mortality in COVID-19 infection compared to non-cirrhotic patients. Patients with cirrhosis should be considered for targeted public health interventions to prevent COVID-19 infection, such as shielding and prioritisation of vaccination.

Hb Penang [ß78(EF2)Leu→Pro, HBB: c.236T>C]: a Novel ß-Globin Variant.

We report a novel hemoglobin (Hb) variant with a ß chain amino acid substitution at codon 78 (CTG>CCG) (HBB: c.236T>C), detected through prenatal screening via capillary electrophoresis (CE) in an otherwise healthy and asymptomatic 38-year-old female of Southeast Asian ancestry. The variant, named Hb Penang after the proband's Malaysian city of origin, underwent further characterization through high performance liquid chromatography (HPLC), reversed phase HPLC, Sanger sequencing, isopropanol stability testing and isoelectric focusing (IEF).

Perivascular fibroblasts form the fibrotic scar after contusive spinal cord injury.

Injury to the CNS leads to formation of scar tissue, which is important in sealing the lesion and inhibiting axon regeneration. The fibrotic scar that comprises a dense extracellular matrix is thought to originate from meningeal cells surrounding the CNS. However, using transgenic mice, we demonstrate that perivascular collagen1α1 cells are the main source of the cellular composition of the fibrotic scar after contusive spinal cord injury in which the dura remains intact. Using genetic lineage tracing, light sheet fluorescent microscopy, and antigenic profiling, we identify collagen1α1 cells as perivascular fibroblasts that are distinct from pericytes. Our results identify collagen1α1 cells as a novel source of the fibrotic scar after spinal cord injury and shift the focus from the meninges to the vasculature during scar formation.

Tomato bushy stunt virus (TBSV), a versatile platform for polyvalent display of antigenic epitopes and vaccine design.

Viruses-like particles (VLPs) are frequently being used as platforms for polyvalent display of foreign epitopes of interest on their capsid surface to improve their presentation enhancing the antigenicity and host immune response. In the present study, we used the VLPs of Tomato bushy stunt virus (TBSV), an icosahedral plant virus, as a platform to display 180 copies of 16 amino acid epitopes of ricin toxin fused to the C-terminal end of a modified TBSV capsid protein (NDelta52). Expression of the chimeric recombinant protein in insect cells resulted in spontaneous assembly of VLPs displaying the ricin epitope. Cryo-electron microscopy and image reconstruction of the chimeric VLPs at 22 A resolution revealed the locations and orientation of the ricin epitope exposed on the TBSV capsid surface. Furthermore, injection of chimeric VLPs into mice generated antisera that detected the native ricin toxin. The ease of fusing of short peptides of 15-20 residues and their ability to form two kinds (T=1, T=3) of bio-nanoparticles that result in the display of 60 or 180 copies of less constrained and highly exposed antigenic epitopes makes TBSV an attractive and versatile display platform for vaccine design.

Characterization of polymorphism displayed by the coat protein mutants of tomato bushy stunt virus.

Expression of full-length and N-terminal deletion mutants of the coat protein (CP) of tomato bushy stunt virus (TBSV) using the recombinant baculovirus system resulted in spontaneously assembled virus-like particles (VLPs). Deletion of the majority of the R-domain sequence of the CP, residues 1-52 (CP-NDelta52) and 1-62 (CP-NDelta62), produced capsids similar to wild-type VLPs. Interestingly, the CP-NDelta62 mutant that retains the last 3 residues of R-domain is capable of forming both the T = 1 and T = 3 particles. However, between the two types of VLPs, formation of the T = 1 capsids appears to be preferred. Another mutant, CP-NDelta72, in which R-domain (residues 1-65) was completely removed but contains most of the beta-annulus and extended arm (betaA) regions exclusively formed T = 1 particles. These results suggest that as few as 3 residues (63-65) of the R-domain, which includes 2 basic amino acids together with the arm (betaA) and beta-annulus regions, may be sufficient for the formation of T = 3 particles. However, anywhere between 4 to 13 residues of the R-domain may be required for proper positioning of betaA and beta-annulus structural elements of the C-type subunits to facilitate an error free assembly of T = 3 capsids.

In vitro dendritic cell infection by pseudotyped adenoviral vectors does not correlate with their in vivo immunogenicity.

Expression of antigens in dendritic cells (DC) can stimulate protective immunity against both viral infection and tumor growth, making them important targets for gene therapy. In-vitro-generated DC are commonly used in gene delivery studies with the assumption that the results will correlate with in vivo activity. Adenovirus Type 5 (Ad5) vectors have been widely used with DC, but these cells lack the primary receptor (CAR) used by Ad5 and are poorly infected. We investigated the use of Ad5 vector particles pseudotyped with fibers from other Ad serotypes in DC targeting. Several fiber proteins, including those from Ad16 (Subgroup B) and Ad37 (Subgroup D), conferred dramatically increased in vitro infection. Surprisingly, neither dendritic cell infection nor the immune response to an Ad-delivered antigen was improved when the modified viruses were tested in vivo. These results underscore the importance of using appropriate animal models in gene delivery studies.

Adenoviral serotype 5 vectors pseudotyped with fibers from subgroup D show modified tropism in vitro and in vivo.

Adenovirus (Ad5) serotype 5 vectors are commonly used for gene transfer. Preclinical studies have shown that their application to systemic gene delivery, however, is limited by their highly efficient uptake in the liver, principally mediated by receptor-binding sites on the fiber shaft and knob domain. Using Ad to target other sites in vivo requires vectors that lack hepatic tropism. We therefore sought to exploit Ad family diversity to isolate vectors that possessed poor hepatic tropism. We pseudotyped the fibers from Ad16 (subgroup B; Ad5/16), Ad19p (subgroup D; Ad5/19p), and Ad37 (subgroup D; Ad5/37) onto Ad5 capsids and assessed infectivity profiles in vitro in multiple cell types and in vivo in rats. In rat, mouse, and human hepatocytes, Ad5/19p and Ad5/37 both possessed a striking lack of hepatic cell infectivity compared with Ad5. Both vectors were, however, able to transduce human vascular endothelial and smooth muscle cells with efficiencies equal to or greater than that of nonmodified Ad5. We evaluated liver uptake in 12-week-old male rats after intravenous injection. In contrast to a vector with the wild-type Ad5 fiber, Ad5, both Ad5/19p and Ad5/37 produced significantly less virion accumulation (measured at 1 hr and 5 days) and transgene expression in the liver. Thus, Ad5/19p and Ad5/37 may be useful platforms for the development of targeted Ad vectors.