Linear extension sums as valuations on cones

33 pagesInternational audienceThe geometric and algebraic theory of valuations on cones is applied to understand identities involving summing certain rational functions over the set of linear extensions of a poset

Genetic Clustering of Hepatitis C Virus Strains and Severity of Recurrent Hepatitis after Liver Transplantation

The influence of viral factors on the severity of hepatitis C virus (HCV)-related liver disease is controversial. We studied 68 liver transplant patients with recurrent hepatitis C, of whom 53 were infected by genotype 1 strains. Relationships between core sequences, serum HCV RNA levels, and fibrosis scores for each patient were analyzed in pairwise fashion 5 years after transplantation. We used Mantel's test, a matrix correlation method, to evaluate the correspondence between measured genetic distances and observed phenotypic differences. No clear relationship was found when all 68 patients were analyzed. In contrast, when the 53 patients infected by genotype 1 strains were analyzed, a strong positive relationship was found between genetic distance and differences in 5-year fibrosis scores (P = 0.001) and differences in virus load (P = 0.009). In other words, the smaller the genetic distance between two patients' viral core sequences, the smaller the difference between the two patients' fibrosis scores and viral replication levels. No relationship was found between genetic distance and differences in age, sex, or immunosuppression. In multivariate analysis, the degree of fibrosis was negatively related to the virus load (r = −0.68; P = 0.003). In the particular setting of liver transplantation, and among strains with closely related phylogenetic backgrounds (genotype 1), this study points to a correlation between the HCV genetic sequence and the variability of disease expression

European collaborative study on factors influencing outcome after liver transplantation for hepatitis C

Background & Aims: Liver transplantation for hepatitis C virus (HCV)-related liver disease is characterized by frequent graft infection by HCV. The prognosis and risk factors for morbidity and mortality in this condition were determined. Methods: A retrospective study of 652 consecutive anti-HCV-positive patients undergoing liver transplantation between 1984 and 1995 in 15 European centers was conducted; 102 patients coinfected with hepatitis B virus (HBV) received immunoglobulin prophylaxis for antibody to hepatitis B surface antigen. Results: Overall, 5-year survival was 72%. Five-year actuarial rates of hepatitis and cirrhosis were 80% and 10%. Genotypes 1b, 1a, and 2 were detected in 214 (80%), 24 (9%), and 24 (9%) of 268 patients analyzed. The only discriminant factor for patient or graft survival was hepatocellular carcinoma as primary indication. Independent risk factors for recurrent hepatitis included the absence of HBV coinfection before transplantation (relative risk [RR], 1.7; 95% confidence interval [CI], 1.2-2.6; P = 0.005), genotype Ib (RR, 2; 95% CI, 1.3-2.9; P = 0.01), and age > 49 years (RR, 1.4; 95% CI, 1.1-1.8; P = 0.01). Conclusions: The results of transplantation for HCV-related disease are compromised by a significant risk of cirrhosis, although 5-year survival is satisfactory. Genotype 1b, age, and absence of pretransplantation coinfection by HBV are risk factors for recurrent HCV

In Vitro and In Vivo Infectivity and Pathogenicity of the Lymphoid Cell-Derived Woodchuck Hepatitis Virus

Woodchuck hepatitis virus (WHV) and human hepatitis B virus are closely related, highly hepatotropic mammalian DNA viruses that also replicate in the lymphatic system. The infectivity and pathogenicity of hepadnaviruses propagating in lymphoid cells are under debate. In this study, hepato- and lymphotropism of WHV produced by naturally infected lymphoid cells was examined in specifically established woodchuck hepatocyte and lymphoid cell cultures and coculture systems, and virus pathogenicity was tested in susceptible animals. Applying PCR-based assays discriminating between the total pool of WHV genomes and covalently closed circular DNA (cccDNA), combined with enzymatic elimination of extracellular viral sequences potentially associated with the cell surface, our study documents that virus replicating in woodchuck lymphoid cells is infectious to homologous hepatocytes and lymphoid cells in vitro. The productive replication of WHV from lymphoid cells in cultured hepatocytes was evidenced by the appearance of virus-specific DNA, cccDNA, and antigens, transmissibility of the virus through multiple passages in hepatocyte cultures, and the ability of the passaged virus to infect virus-naive animals. The data also revealed that WHV from lymphoid cells can initiate classical acute viral hepatitis in susceptible animals, albeit small quantities (∼10(3) virions) caused immunovirologically undetectable (occult) WHV infection that engaged the lymphatic system but not the liver. Our results provide direct in vitro and in vivo evidence that lymphoid cells in the infected host support propagation of infectious hepadnavirus that has the potential to induce hepatitis. They also emphasize a principal role of the lymphatic system in the maintenance and dissemination of hepadnavirus infection, particularly when infection is induced by low virus doses