Monoclonal antibodies (MAbs) destined for use in drug-specific assays must meet specific binding criteria, and therefore require much more in the way of development than many protein-specific antibodies. This article describes one way to facilitate the development of well-characterized, high specificity MAbs. Essentially the same techniques have also been used for producing MAbs that are cancer markers and MAbs that are specific for infectious agents. Monoclonal antibody development, as in other endeavors, requires clearly defined goals and an examination of proposed methods to attain them. This has been succinctly stated by the phrase “Start with the end in mind.” Unfortunately, the vast majority of hybridoma development could be more appropriately described by Yogi Berra, “If you don’t know where you are going, you will wind up somewhere else.” In most laboratories, fusions are carried out with the goal of reducing the amount of cell culture and handling required and using the minimum amount of screening. Little or no consideration is given to ensuring that single clones are subjected to the screening tests. Under these conditions, it is little wonder that dozens of fusions can be carried out, each with the same result — no specific antibody found…
Tag: <span>screening</span>
Xenotransplantation has been defined by the US Public Health Service (PHS) as any procedure that involves the transplantation, implantation, or infusion into a human recipient of either (a) live cells, tissues, or organs from a nonhuman animal source, or (b) human body fluids, cells, tissues, or organs that have had ex vivo contact with live, nonhuman animal cells, tissues, or organs (PHS Guideline on Infectious Disease Issues in Xenotransplantation). In the US, several xenotransplantation clinical trials are in progress under US Food and Drug Administration (FDA) oversight. The PHS and the FDA have issued guidelines and guidance documents to address the potential for cross-species infection posed by the use of xenotransplantation products in humans. To minimize the infectious disease risk, these documents provide recommendations on how to screen and maintain source herds, individual source animals, and when possible, xenotransplantation products themselves. However, while precautions can be put in place to remove exogenous infectious agents, the endogenous retroviruses that a source species may carry cannot be removed…
Electron microscopy (EM) provides data for viral clearance studies, information on the presence and quantitation of endogenous retroviruses, and the detection and characterization of other potential contaminants. The technique is favored in this field because it is simple, reliable, and can give reliable quantitation for risk assessments. This article describes the main EM techniques currently used for testing cell cultures, culture supernatants, and bulk harvests. It also includes an in-depth description of a thin sectioning technique used to estimate virus titre in culture supernatants and bulk harvests…