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Volume 13 Issue 4

Integrated Testing Strategies for Skin Sensitization: Focus on Direct Peptide Reactivity Assay (DPRA)

A common characteristic of skin sensitizers is their reactivity with skin proteins. The Direct Peptide Reactivity Assay (DPRA) measures a chemical's ability to react with proteins which is a key upstream event in the mechanism of skin sensitization. In the DPRA, the test chemical is incubated with two small model peptides which contain nucleophilic residues, cysteine or lysine, for 24 hours. Following this reaction period, peptide depletion is analyzed by HPLC-UV. Data have demonstrated significant peptide depletion by skin sensitizers.


Developed at the Procter & Gamble Company by Frank Gerberick and colleagues, the DPRA has proven to be an effective tool to screen a chemical's ability to induce skin sensitization. The assay has been evaluated for transferability, reproducibility, and accuracy, and following successful inter-laboratory investigations has reached an advanced stage of pre-validation with ECVAM. EURL ECVAM has endorsed the DPRA as part of an integrated testing strategy to assess skin sensitization potential, and an OECD test guideline for the assay is being drafted (read more on this in the box to the right).


IIVS is currently in the process of transferring the DPRA to our laboratory. Given the complex cascade of events leading to skin sensitization, it is generally thought that an integrated testing approach combining multiple assays will be needed to replace the animal based methods. As described during a recent IIVS hosted webinar on Integrated Strategies for Skin Sensitization, there is a significant effort underway to ascertain how the non-animal assays may be combined most effectively to assess skin sensitization potential. At IIVS, we plan to add the DPRA as a complement to the currently offered KeratinoSens skin sensitization assay. For more information on the DPRA, please contact Dr. Kimberly Norman at


University of Maryland Bioengineering Society Workshop

On the 23rd of November, IIVS hosted 20 students from the Bioengineering Society of the University of Maryland to participate in an introductory in vitro toxicology course.  Through a combination of lectures and hands-on laboratory sessions, the students were exposed to how bioengineers could work together with toxicologists to develop in vitro testing strategies. This is the second time that IIVS has partnered with the University of Maryland to provide the course and we look forward to continuing this partnership in the future. 


IIVS Biologist Elizabeth Sly demonstrates the Bovine Corneal Opacity and Permeability Assay to UMD students.
Chinese National Toxicological Congress 2013   

IIVS' Hans Raabe and Quanshun Zhang attended the 6th Chinese National Toxicological Congress of the Chinese Society of Toxicology in Guangzhou on November 13-15. This activity was supported by the European Partnership for Alternative Approaches to Animal Testing (EPAA). IIVS presented a poster outlining the structure of the EPAA and introduced the attendees to the mission and activities of the group. In addition to this poster, IIVS presented recent work on the successful validation of the skin sensitization assay, KeratinoSens. This poster announced the successful validation of the assay and outlined the validation approach taken, including some valuable lessons learned. The meeting, with over 2,000 attendees, provided valuable networking with Chinese scientists and regulators.

Technical Training in Non-Animal Safety Methods Held in China 


IIVS Study Director Allison Hilberer speaks with scientists from China's NIFDC during the training. 

IIVS, with support from its Industry Council for the Advancement of Regulatory Acceptance of Alternatives (ICARAA), conducted a training course on September 23-27 for in vitro safety testing methods for scientists from China's NIFDC (National Institutes for Food and Drug Control), a division of the China Food and Drug Administration.


The training was held at the Institute for Food and Cosmetic Control (IFCC) of the National Institutes for Food and Drug Control (NIFDC) in Beijing. The goal of the training was to familiarize NIFDC scientists with the biological relevance, critical techniques and data interpretation of in vitro (non-animal) methods for safety testing. Twenty-eight participants from 18 provincial Institutes for Food and Drug Control, Institutes for Medical Device Control and Institute for Food and Drug Safety Evaluation of NIFDC attended. Lectures and hands-on laboratory sessions focused on methods for eye irritation, skin irritation and sensitization.


Wang Youchun, Vice Director-General of NIFDC spoke at the opening ceremony and emphasized that it is "very necessary to expedite training and research of in vitro cosmetic safety evaluation methods and promote in vitro safety evaluation technology application and academic exchanges in Food and Drug Control systems in order to adapt to the international cosmetics testing technology development and to meet the requirements for actual inspection work." To read the full press release, follow this link to the IIVS website.   


Upcoming Events
Congratulations to the 2013 LUSH Prize Recipients

The 2nd Annual Lush Prize was awarded in November in London, UK. Recognizing efforts to reduce the use of animals in experimentation, the prize is given in each of 5 categories including training, lobbying and research. IIVS was honored to be the recipient of the 1st Annual Lush Training Award in 2012 and was among the groups short-listed for the training prize again this year. Please visit the LUSH prize website for a full list of nominees and recipients from 2012 and 2013 awards.

Prof. Bas Blaauboer was presented with the Willy van Heumen Prize by the Alternatives for Laboratory Animals Stimulus Fund Foundation. Presented every two years, the prize is awarded to individuals or institutions which have made outstanding achievements in limiting the use of laboratory animals tests and promoting the use of alternatives to animal testing. As Professor of Alternatives to Animal Testing in Toxicological Risk Assessment at Utrecht University's Institute for Risk Assessment Sciences, Dr. Blaauboer received the prize for his entire body of work involving the 3Rs of laboratory animal testing - Refinement, Reduction, and Replacement.  

Society of Toxicology Annual Meeting 2014

March 23-27
Phoenix, AZ

Visit with IIVS study directors at booth #1029 during the ToxExpo of this year's SOT meeting. IIVS Study Directors will be presenting several posters on recent work. Please contact us to set up a meeting time to discuss your testing needs and/or the new assays available at IIVS.


Struggling to comply with 1223/2009? Contact us to learn what in vitro methods can be used in safety dossiers.
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BASF has received the 32nd Research Prize in Berlin, Germany for the promotion of work aimed at reducing and replacing animal experimentation. The BASF research team, Experimental Toxicology and Ecology received this honor for developing strategies for testing the local toxicity of chemicals without animal experimentation. IIVS, a collaborator on several of the projects, congratulates BASF scientists on this achievement. 

EURL ECVAM Releases DPRA Recommendations   

EURL ECVAM has fully endorsed the ECVAM Scientific Advisory Committee's (ESAC) opinion on the validation study of the Direct Peptide Reactivity Assay (DPRA). The ESAC opinion states that  information from peptide reactivity assays, such as the DPRA, is relevant for the assessment of the skin sensitization potential of chemicals.  The DPRA is transferable to suitably equipped laboratories that are proficient in HPLC analysis, and both the within and between laboratory repeatability was quite high (87% and 75% respectively). Although full review of the assay's predictive capacity was outside the scope of this review, its accuracy of distinguishing between sensitizers and non-sensitizers is 82%. To read EURL ECVAMs' full recommendation, click here.  

The EPA has launched a new web tool to improve access to chemical specific information developed by the EPA and data submitted under TSCA. Utilizing flexible search tools, ChemView gives access to EPA assessments, hazard characterizations and information on ingredients. In the months ahead, the EPA will be adding additional chemicals, functionality and links. When fully populated, the portal will contain data for thousands of chemicals. The EPA has incorporated stakeholder input into the design, and welcomes feedback on the
current version of the site.

ASCCT Banner

American Society for Cellular and

Computational Toxicology



ASCCT held its second annual meeting in October on the campus of NIH in Bethesda, Maryland. The program featured plenary lectures by Don Ingber, Wyss Institute; "Human Organs on Chips as Replacements for Animal Testing" and Tom Knudsen, US Environmental Protection Agency; "Virtual Embryological Systems: Challenges for Predictive Toxicology". The poster session and selected member presentations and panel discussion provided another forum for information exchange and networking. ASCCT has some exciting webinars planned for the upcoming year. For more information about the society or to renew your membership for 2014, please follow the link to the website below.