Mitigating the risk of Zika virus contamination of raw materials and cell lines in the manufacture of biologicals.

Ensuring the virological safety of biologicals is challenging due to the risk of viral contamination of raw materials and cell banks, and exposure during in-process handling to known and/or emerging viral pathogens. Viruses may contaminate raw materials and biologicals intended for human or veterinary use and remain undetected until appropriate testing measures are employed. The outbreak and expansive spread of the mosquito-borne flavivirus Zika virus (ZIKV) poses challenges to screening human- and animal -derived products used in the manufacture of biologicals. Here, we report the results of an in vitro study where detector cell lines were challenged with African and Asian lineages of ZIKV. We demonstrate that this pathogen is robustly detectable by in vitro assay, thereby providing assurance of detection of ZIKV, and in turn underpinning the robustness of in vitro virology assays in safety testing of biologicals.

Spatial p21 expression profile in the mid-term mouse embryo.

Throughout development cells make the decision to proliferate, arrest or die. Control of this process is essential for normal development, with unrestrained cell proliferation and cell death underlying the origin and progression of disease. The cell-cycle is tightly regulated by a number of factors including the cyclin-dependent kinase inhibitor 1A (Cdkn1a), termed p21 (or Cip1 or WAF1). p21 acts as a negative regulator of cell-cycle progression by binding and inhibiting complexes formed between the cyclin-dependent kinases and their catalytic partners the cyclins. In this report we identify the temporal spatial expression profile of p21 in the developing mid-term mouse embryo using a p21-LacZ reporter mouse line. Expression of p21 was restricted to specific regions with a correspondence to both areas of terminal differentiation and active remodelling. A complex temporal and spatial relationship between p21 expression and regions of apoptosis was evident. A protective role with regard to apoptosis for p21 is proposed.

p21-LacZ reporter mice reflect p53-dependent toxic insult.

There is an urgent need to discover less toxic and more selective drugs to treat disease. The use of transgenic mice that report on toxic insult-induced transcription can provide a valuable tool in this regard. To exemplify this strategy, we have generated transgenic mice carrying a p21-LacZ transgene. Transgene activity reflected endogenous p21 gene activation in various tissues, displayed compound-specific spatial expression signatures in the brain and immune tissues and enabled p53-dependent and p53-independent responses to be identified. We discuss the application of these mice in delineating the molecular events in normal cellular growth and disease and for the evaluation of drug toxicity.

CD4(+)CD25(+) immunoregulatory T Cells: new therapeutics for graft-versus-host disease.

CD4(+)CD25(+) immunoregulatory T cells play a pivotal role in preventing organ-specific autoimmune diseases and in tolerance induction to allogeneic organ transplants. We investigated whether these cells could also control graft-versus-host disease (GVHD), the main complication after allogeneic hematopoietic stem cell transplantation (HSCT). Here, we show that the few CD4(+)CD25(+) T cells naturally present in the transplant regulate GVHD because their removal from the graft dramatically accelerates this disease. Furthermore, the addition of freshly isolated CD4(+)CD25(+) T cells at time of grafting significantly delays or even prevents GVHD. Ex vivo-expanded CD4(+)CD25(+) regulatory T cells obtained after stimulation by allogeneic recipient-type antigen-presenting cells can also modulate GVHD. Thus, CD4(+)CD25(+) regulatory T cells represent a new therapeutic tool for controlling GVHD in allogeneic HSCT. More generally, these results outline the tremendous potential of regulatory T cells as therapeutics.