TLR-9 Contributes to the Antiviral Innate Immune Sensing of Rodent Parvoviruses MVMp and H-1PV by Normal Human Immune Cells

The oncotropism of Minute Virus of Mice (MVMp) is partially related to the stimulation of an antiviral response mediated by type-I interferons (IFNs) in normal but not in transformed mouse cells. The present work was undertaken to assess whether the oncotropism displayed against human cells by MVMp and its rat homolog H-1PV also depends on antiviral mechanisms and to identify the pattern recognition receptor (PRR) involved. Despite their low proliferation rate which represents a drawback for parvovirus multiplication, we used human peripheral blood mononuclear cells (hPBMCs) as normal model specifically because all known PRRs are functional in this mixed cell population and moreover because some of its subsets are among the main IFN producers upon infections in mammals. Human transformed models consisted in lines and tumor cells more or less permissive to both parvoviruses. Our results show that irrespective of their permissiveness, transformed cells do not produce IFNs nor develop an antiviral response upon parvovirus infection. However, MVMp- or H-1PV-infected hPBMCs trigger such defense mechanisms despite an absence of parvovirus replication and protein expression, pointing to the viral genome as the activating element. Substantial reduction of an inhibitory oligodeoxynucleotide (iODN) of the latter IFN production identified TLR-9 as a potential PRR for parvoviruses in hPBMCs. However, neither the iODN treatment nor an antibody-induced neutralization of the IFN-triggered effects restored parvovirus multiplication in these cells as expected by their weak proliferation in culture. Finally, given that a TLR-9 activation could also not be observed in parvovirus-infected human lines reported to be endowed with a functional TLR-9 pathway (Namalwa, Raji, and HEK293-TLR9^+/+), our data suggest that transformed human cells do not sense MVMp or H-1PV either because of an absence of PRR expression or an intrinsic, or virus-driven defect in the endosomal sensing of the parvovirus genomes by TLR-9.     

Oncolytic parvoviruses as cancer therapeutics

The experimental infectivity and excellent tolerance of some rodent autonomous parvoviruses in humans, together with their oncosuppressive effects in preclinical models, speak for the inclusion of these agents in the arsenal of oncolytic viruses under consideration for cancer therapy. In particular, wild-type parvovirus H-1PV can achieve a complete cure of various tumors in animal models and kill tumor cells that resist conventional anticancer treatments. There is growing evidence that H-1PV oncosuppression involves an immune component in addition to the direct viral oncolytic effect. This article summarizes the recent assessment of H-1PV antineoplastic activity in glioma, pancreatic ductal adenocarcinoma, and non-Hodgkin lymphoma models, laying the foundation for the present launch of a first phase I/IIa clinical trial on glioma patients.     

On Some Problems in Measuring Change on Ordinal Data

Two designs frequently occurring in biomedicine and social sciences are considered—the “experts”/“objects”—design consisting in ranking M fixed “objects” by each of N “experts” before and after an intervention, and the rating-scale-design in which N judges are asked to assign one of K given lables, constituting the rating-scale, before and after an intervention. Nonparametric test procedures are proposed for evaluating the treatment effect.     

Polymerase epsilon is required to maintain replicative senescence

Replicative senescence is a permanent cell cycle arrest in response to extensive telomere shortening. To understand the mechanisms behind a permanent arrest, we screened for factors affecting replicative senescence in budding yeast lacking telomere elongation pathways. Intriguingly, we found that DNA polymerase epsilon (Pol ε) acts synergistically with Exo1 nuclease to maintain replicative senescence. In contrast, the Pol ε-associated checkpoint and replication protein Mrc1 facilitates escape from senescence. To understand this paradox, in which DNA-synthesizing factors cooperate with DNA-degrading factors to maintain arrest, whereas a checkpoint protein opposes arrest, we analyzed the dynamics of double- and single-stranded DNA (ssDNA) at chromosome ends during senescence. We found evidence for cycles of DNA resection, followed by resynthesis. We propose that resection of the shortest telomere, activating a Rad24(Rad17)-dependent checkpoint pathway, alternates in time with an Mrc1-regulated Pol ε resynthesis of a short, double-stranded chromosome end, which in turn activates a Rad9(53BP1)-dependent checkpoint pathway. Therefore, instead of one type of DNA damage, different types (ssDNA and a double-strand break-like structure) alternate in a "vicious circle," each activating a different checkpoint sensor. Every time resection and resynthesis switches, a fresh signal initiates, thus preventing checkpoint adaptation and ensuring the permanent character of senescence.     

Disentangling Intervention and Temporal Effects in Longitudinal Designs Using Latent Curve Analysis

This article is concerned with an approach to disconfounding effects in repeated measure designs with multiple groups. An extension of latent curve analysis (MEREDITH and TISAK, 1990; RAO, 1958, 1965) is described. The method permits estimation and testing of intervention effects separately from temporal effects. It is based on restricted factor analysis of individual change profiles and utilizes basis curves representing group patterns of change. The approach is illustrated on data from a two-group intervention study.     

Initial Value Dependence: A Comparison of Two Methods For Its Study

This article is concerned with the comparison of slope estimator precision in regression analysis and the structural relationships approach (e.g., Humak, 1983, ch. 3; Kendall and Stuart, 1977), as it is relevant for their applications when testing for initial value dependence in biomedical and behavioral contexts of repeated assessments (e.g., Blomqvist, 1977; Wall, 1977). As a basis for the comparison of the two methods, the mean square error is adopted. In the general case, it is argued for an informed (data-dependent) choice between regression analysis and the structural relationships approach. For the apparent majority of biomedical and behavioral studies of the phenomenon of initial value depenence, this comparison suggests that structural relationships is the preferable approach leading to more trustworthy substantive conclusions.