Viral ecogenomics across the Porifera

BackgroundViruses directly affect the most important biological processes in the ocean via their regulation of prokaryotic and eukaryotic populations. Marine sponges form stable symbiotic partnerships with a wide diversity of microorganisms and this high symbiont complexity makes them an ideal model for studying viral ecology. Here, we used morphological and molecular approaches to illuminate the diversity and function of viruses inhabiting nine sponge species from the Great Barrier Reef and seven from the Red Sea.ResultsViromic sequencing revealed host-specific and site-specific patterns in the viral assemblages, with all sponge species dominated by the bacteriophage order Caudovirales but also containing variable representation from the nucleocytoplasmic large DNA virus families Mimiviridae, Marseilleviridae, Phycodnaviridae, Ascoviridae, Iridoviridae, Asfarviridae and Poxviridae. Whilst core viral functions related to replication, infection and structure were largely consistent across the sponge viromes, functional profiles varied significantly between species and sites largely due to differential representation of putative auxiliary metabolic genes (AMGs) and accessory genes, including those associated with herbicide resistance, heavy metal resistance and nylon degradation. Furthermore, putative AMGs varied with the composition and abundance of the sponge-associated microbiome. For instance, genes associated with antimicrobial activity were enriched in low microbial abundance sponges, genes associated with nitrogen metabolism were enriched in high microbial abundance sponges and genes related to cellulose biosynthesis were enriched in species that host photosynthetic symbionts.ConclusionsOur results highlight the diverse functional roles that viruses can play in marine sponges and are consistent with our current understanding of sponge ecology. Differential representation of putative viral AMGs and accessory genes across sponge species illustrate the diverse suite of beneficial roles viruses can play in the functional ecology of these complex reef holobionts

The portal hypertension syndrome: etiology, classification, relevance, and animal models

BACKGROUND Portal hypertension is a key complication of portal hypertension, which is responsible for the development of varices, ascites, bleeding, and hepatic encephalopathy, which, in turn, cause a high mortality and requirement for liver transplantation. AIM This review deals with the present day state-of-the-art preventative treatments of portal hypertension in cirrhosis according to disease stage. Two main disease stages are considered, compensated and decompensated cirrhosis, the first having good prognosis and being mostly asymptomatic, and the second being heralded by the appearance of bleeding or non-bleeding complications of portal hypertension. RESULTS The aim of treatment in compensated cirrhosis is preventing clinical decompensation, the more frequent event being ascites, followed by variceal bleeding and hepatic encephalopathy. Complications are mainly driven by an increase of hepatic vein pressure gradient (HVPG) to values ≥10 mmHg (defining the presence of Clinically Significant Portal Hypertension, CSPH). Before CSPH, the treatment is limited to etiologic treatment of cirrhosis and healthy life style (abstain from alcohol, avoid/correct obesity…). When CSPH is present, association of a non-selective beta-blocker (NSBB), including carvedilol should be considered. NSBBs are mandatory if moderate/large varices are present. Patients should also enter a screening program for hepatocellular carcinoma. In decompensated patients, the goal is to prevent further bleeding if the only manifestation of decompensation was a bleeding episode, but to prevent liver transplantation and death in the common scenario where patients have manifested first non-bleeding complications. Treatment is based on the same principles (healthy life style..) associated with administration of NSBBs in combination if possible with endoscopic band ligation if there has been variceal bleeding, and complemented with simvastatin administration (20-40 mg per day in Child-Pugh A/B, 10-20 mg in Child C). Recurrence shall be treated with TIPS. TIPS might be indicated earlier in patients with: 1) Difficult/refractory ascites, who are not the best candidates for NSBBs, 2) patients having bleed under NSBBs or showing no HVPG response (decrease in HVPG of at least 20% of baseline or to values equal or below 12 mmHg). Decompensated patients shall all be considered as potential candidates for liver transplantation. CONCLUSION Treatment of portal hypertension has markedly improved in recent years. The present day therapy is based on accurate risk stratification according to disease stage