Influence of three successive antiviral treatments on viral heterogeneity in nonresponder chronic hepatitis C patients.

The purpose of the present study was to assess the viral diversity of hepatitis C virus (HCV) in six nonresponder patients during three unsuccessful treatments. These patients were treated successively with IFN-alpha2a (IFN-alpha) at a posology of 3.10(6) units (MIU) three times a week, 10 MIU three times a week, and a combination of IFN-alpha (3 MIU) plus ribavirin (1,000 mg/day).

Individuality of Ag-selected and preimmune TCR repertoires.

We have combined flow cytometry and single-cell PCR to characterize the TCRBV repertoires selected by individual mice in a model CD8 response against a defined peptide/MHC complex (CW3 170-1 79/Kd). Ourresults established thatdifferent mice select individually distinct yet structurally similar CW3-specific repertoires. Repertoire selection appears to be flexible depending on the immunizing cell dose.

Comparative T cell receptor repertoire selection by antigen after adoptive transfer: a glimpse at an antigen-specific preimmune repertoire.

The low frequency of precursor cells specific for any particular antigen (Ag) makes it difficult to characterize preimmune T cell receptor (TCR) repertoires and to understand repertoire selection during an immune response. We have undertaken a combined adoptive transfer single-cell PCR approach to probe the Ag-specific preimmune repertoires of individual mice. Our strategy was to inject paired irradiated recipient mice with normal spleen cells prepared from individual donors and to compare the TCR repertoires subsequently selected during a CD8 response to a defined model Ag.

A quantitative, single-cell PCR analysis of an antigen-specific TCR repertoire selected during an in vivo CD8 response: direct evidence for a wide range of clone sizes with uniform tissue distribution.

The development of T cell effector and memory responses against foreign antigens (Ags) involves the activation, differentiation and proliferation of naive T cells expressing distinct Ag-specific TCRs. Understanding the complexity of Ag-selected TCR repertoires in individual responders in terms of the sequences selected and their relative frequencies may provide indications about how a repertoire is established and suggest ways to influence the outcome of an immune response. Most methods of repertoire analysis are unsuitable for calculating the relative in vivo frequencies of Ag-specific clones (expressing distinct TCRs) selected during an immune response, whereas sequence data obtained by single-cell PCR analysis directly reflect cell frequencies if a sufficiently large number of cells is sampled.