A new knockout human cell line has helped researchers make some huge leaps in the discovery of causative factors of some infectious diseases. The human cell line has been developed with only one copy of thousands of genes (chromosome 8 remained diploid), allowing for knockouts to be generated in which there isn't a second copy of the gene to compensate for the loss, through transcription of the encoded protein. The cell line, generated by a group from the Whitehead Institute for Biomedical Research, was used to study which genes are used by both viral and bacterial pathogens, one of which was the influenza virus. In a November 27 article in Science, the team describes which host factors (genes and gene products) are required for influenza infection and cytotoxic effects of several bacterial toxins.

Biosimilars are follow-on biopharmaceuticals, made by competitors of a branded drug, following expiry of the patent. By definition, they tend to be large molecules, as opposed to small molecule drugs or therapies, like siRNA. Being more complex, their production can also be a complicated process, and since the manufacturer might not have information such as exact culture fermentation conditions, or access to transgenic organisms used to produce the original product, biosimilar manufacturing processes are not identical. This gives rise to the potential for unprecedented and unpredictable problems such as immunogenic (allergic) reactions to impurities and breakdown products. Thus, unlike generic chemical drugs, the use of biosimilars can pose serious health risks.

The European Union has a system in place for approving biosimilars, but the USA has not yet followed suit. However, it is widely accepted that generic drug approval pathways are not appropriate for complex biologics, and a proposal for a pathway for biosimilars approval was made earlier this year.

From a business perspective, biosimilars may or may not be lucrative investments, depending on how safe they are, how easily they are approved and whether practitioners and the public are willing to accept them. For those working in this area of biopharmaceuticals, or interested in biosimilars, a comprehensive review of biosimilars regulation and market can be purchased online from Espicom Business Intelligence.

The internet is full of fun tools for enhancing your knowledge of biochemistry and biotechnology. One such resource is the Amino Acid Explorer, on the NCBI website. Students in introductory biotechnology courses might find the Structure and Chemistry button helpful for learning functional groups of amino acids and their properties. If you're in a more advanced program, check out the Amino Acids At Work button for the roles of different amino acids in the active sites of proteins, and the Mutation Analyzer button lets you look up the effects of mutations, or could be useful for investigating possible gene polymorphisms. The Amino Acids As Ligands button takes you to a library of 3-D pictures of protein-ligand complexes with links to the articles describing their role. For example, I checked out the role of a ligand containing valine in the biosynthesis of penicillin.

A number of global initiatives in recent years, including ICH and PAT, have encouraged the use of single-use systems in bioprocessing. A major benefit to adapting process systems in this way is the reduced risk of cross-contamination between batches. Traditionally, single-use systems may have been used in early stage development of a new product, but commercial production would be converted to the use of stainless steel, multiple-use systems. Improvements to culturing techniques and optimization of fermentation conditions have made it possible for companies to achieve better titers, and, thus, able to use smaller bioreactors, which has contributed to increased use of disposible equipment. Controversy is beginning to brew, however, over the use of single-use systems, since focus has begun to shift from how to design systems with disposibles to what the environmental impacts may be. If you're curious about who is using single-use systems, and for what purposes, BioProcess International has published the results of a survey on the Impact of Single-Use Technologies, online.

_{Source: McLeod, L. 2009. Advances in Bioprocessing. BioProcess International, May 2009.}