Lymphomagenesis-related gene expression in B cells from sustained virological responders with occult hepatitis C virus infection.

The expression of activation-induced cytidine deaminase, B-aggressive lymphoma, cyclin D1 and serine/threonine kinase 15 genes, among others, is increased in B cells from patients with chronic hepatitis C virus (HCV) infection. It is unknown whether the level of expression of these genes in B cells is increased in patients with hepatitis C who have achieved a sustained virological response (SVR) but who have persistent, detectable HCV RNA, so-called occult infection. Eighty-three patients who achieved and SVR, 27 with detectable HCV and 56 without detectable HCV RNA, 28 chronic hepatitis C patients and 32 healthy controls were studied. RNA was extracted from B cells, and gene expression levels were measured by RT-PCR. Patients with chronic HCV and those who achieved an SVR (with and without persistent low-level HCV RNA) showed a statistically significant higher expression compared to healthy controls, of activation-induced cytidine deaminase (P = 0.004, P < 0.001 and P = 0.002, respectively), B-aggressive lymphoma (P < 0.001, P = 0.001 and P = 0.006) and cyclin D1 (P = 0.026, P = 0.001; P = 0.038). For activation-induced cytidine deaminase patients with an SVR and 'occult infection' had a statistically significantly higher expression level than patients with and SVR without 'occult infection' (P = 0.014). The higher expression levels found for activation-induced cytidine deaminase, together with other genes indicates that these B lymphomagenesis-related genes are upregulated following HCV therapy and this is more marked when HCV can be detected in PBMCs.

Cellular immune responses and occult infection in seronegative heterosexual partners of chronic hepatitis C patients.

It is unknown whether hepatitis C virus (HCV)-specific cellular immune responses can develop in seronegative sexual partners of chronically HCV-infected patients and whether they have occult infection. Thirty-one heterosexual partners of patients with chronic HCV were studied, fifteen of them with HCV transmission risks. Ten healthy individuals and 17 anti-HCV seropositive patients, without viremia, were used as controls. Virus-specific CD4+ and CD8+ T-cell responses were measured by flow cytometry against six HCV peptides, situated within the nonstructural (NS) proteins NS3, NS4 and NS5, through intracellular detection of gamma interferon (IFN-γ) or interleukin 4 (IL-4) production and CD69 expression. Sexual partners had a higher production of IFN-γ and IL-4 by CD4+ cells against NS3-p124 (P = 0.003), NS5b-p257 (P = 0.005) and NS5b-p294 (P = 0.012), and CD8+ cells against NS3-p124 (P = 0.002), NS4b-p177 (P = 0.001) and NS3-p294 (P = 0.004) as compared with healthy controls. We observed elevated IFN-γ production by CD4+ T cells against NS5b-p257 (P = 0.042) and NS5b-p294 (P = 0.009) in the sexual partners with HCV transmission risks (sexual, professional and familial altogether) than in those without risks. RNA was extracted from peripheral blood mononuclear cells (PBMC), and detection of HCV-RNA positive and replicative (negative) strands was performed by strand-specific real-time PCR. In four sexual partners, the presence of positive and negative HCV- RNA strands in PBMC was confirmed. Hence, we found an HCV-specific cellular immune response as well as occult HCV infection in seronegative and aviremic sexual partners of chronically HCV-infected patients.

Reducing noise in discretized time series.

We show that applying a noise-reduction algorithm to a discretized time series increases its average error, compared to the original series. We find that adding external noise comparable to the discretization step before noise reduction limits the increase of the average error and improves the estimation of Lyapunov exponents.