Ferguson D.,UK National Institute for Biological Standards and Control
AIDS | Year: 2016
OBJECTIVES:: Using simian models where SIV chronic viral loads are naturally controlled in the absence of potentially neurotoxic therapies we investigated the neuropathological events occurring during times of suppressed viremia and when these events were initiated. DESIGN:: Cynomolgus macaques were infected with SIV strains that are naturally controlled to low levels of chronic viremia. Study one; animals were maintained upto 300 days post inoculation and analysed for viral induced neuropathology following sustained suppression of chronic viral loads. Study two; initiation and development of pathology was examined following 3, 10, 21, or 125 days SIVmacC8 infection. METHODS:: Formalin fixed, paraffin embedded brain sections were analysed following immunohistochemical staining for SIV (KK41), blood brain barrier leakage (ZO-1, fibrinogen), apoptosis (active caspase 3), neuroinflammation (GFAP, COX-1, COX-2), microglia and macrophage (iba-1, CD68, CD16), oligodendrocytes (CNPase1), MHC class II expression and T cells (CD3, CD8). Replicating SIV was detected through in situ hybridisation. RESULTS:: Study one: Neuroinflammation was present despite prolonged suppressed viremia. Study two: Attenuated SIV entered the brain rapidly triggering acute phase neuroinflammatory responses. These did not return to naïve levels and GFAP and COX-2 responses continued to develop during a chronic phase with a suppressed viral load. CONCLUSIONS:: Neuroinflammatory responses similar to those in HIV neurocognitively impaired patients are present within macaque brains during prolonged periods of suppressed SIV viral load and in the absence of potentially neurotoxic antiretroviral drugs. These responses, initiated during acute infection, do not resolve despite the lack of on-going peripheral viremia to potentially re-seed the brain. Copyright © 2016 Wolters Kluwer Health, Inc.
Hubbard A.R.,UK National Institute for Biological Standards and Control
Seminars in Thrombosis and Hemostasis | Year: 2015
Various strategies to produce longer-lasting factor VIII and factor IX concentrates through chemical and genetic modifications are currently under evaluation. It is now clear that these new molecules are amenable to testing using conventional methods for biological activity (one-stage clotting and chromogenic) and there is a preference to maintain labeling in International Units (IU) traceable to the WHO International Standard Concentrates. This is an achievable goal; however, many of the new molecules are associated with potency discrepancies both between methods and also within methods, for instance, when different activated partial thromboplastin time reagents are used. In the interests of global harmonization, it is important for licensing authorities to reach agreement on the choice of the potency labeling method. This choice should be supported by a thorough characterization of product potency, both in vitro and in vivo, to anticipate future issues and with a view to maintaining equivalence of the IU compared with existing licensed products. In cases where the product potency is defined using specific reagents, the robustness of the manufacturer's product standard will be crucial for product consistency. The sensitivity of measured potency to different methodologies will require manufacturers to provide guidance to clinical laboratories on suitable postinfusion testing approaches.
Sesardic T.,UK National Institute for Biological Standards and Control
Current Opinion in Microbiology | Year: 2012
Bioassays play central role in evaluation of biological products and those derived from bacterial toxins often rely exclusively on in vivo models for assurance of safety and potency. This chapter reviews existing regulatory approved methods designed to provide information on potency and safety of complex biological medicines with an insight into strategies considered for alternative procedures. © 2012 Elsevier Ltd.
Thelwell C.,UK National Institute for Biological Standards and Control
Seminars in Thrombosis and Hemostasis | Year: 2014
Thrombolytic drugs are used for the treatment of thrombotic disorders such as acute myocardial infarction, acute ischemic stroke, and pulmonary embolism. Biological standards are used for potency assignment to the range of fibrinolytic proteins used in thrombolytic therapy. The World Health Organization (WHO) International Standards are primary reference materials, calibrated in arbitrary units (international unit), assigned by collaborative study using the range of assay methods available at the time. Provided the standard and test material are equivalent, adhering to the principle of measuring like versus like, the exact nature of the assay method is unimportant. This approach has been applied successfully for several decades since the advent of fibrinolytic treatment, ensuring consistency for potency labeling and the correct dosing of patients. The emergence of generic biosimilar products and new recombinant variants poses a challenge to this system, where functional differences impact on the relative biological activity in different assay systems. A more demanding system of standardization may therefore be required on the basis of international reference materials with associated reference methods. WHO recognizes this, and where possible and practical is seeking to incorporate concepts of traceability, uncertainty, and commutability to International Standards. However, some caution is needed because limitations on the characterization of many complex biologicals remain real, and a flexible approach is required on the basis of real-world needs. © 2014 by Thieme Medical Publishers, Inc.
Thorpe S.J.,UK National Institute for Biological Standards and Control
Transfusion | Year: 2015
Intravenous immunoglobulin (IVIG) products are generally safe and efficacious, although treatment-related adverse reactions can occur in recipients. Adverse reactions include hemolysis in non-blood group O recipients linked to the passive transfer of anti-A and/or anti-B present in the fractionated immunoglobulin product. In light of the recent increase in reported cases of severe hemolysis associated with anti-A and/or anti-B, this article traces the development of pharmacopoeial specifications, tests, and reference reagents to control their titers in IVIG products. © 2015 AABB.