This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The core is for the production and cryopreservation of virus stocks to be used by NIH funded investigators. The core is designed to avoid duplication of effort and cost in the preparation of virus stocks, particularly SIV and SHIV. The viral stocks were quantified by the method TCID50 in the appropriate cell line. Thus, the core prevents the unnecessary duplication of effort and expense among investigators at the TNPRC. The core maintains records on the pedigree of all virus stocks. In 2008, 60 virus stocks were stored in Liquid Nitrogen and 22 in ultra low temperature freezers at the TNPRC. An Excel database with details on each frozen stock was maintained and includes: date frozen, titration date, TCID50, the number of vials of each virus and the exact storage location. In the past year, the core has supplied 74 vials of different viral stocks. Of those stocks, 7 vials were prepared in 2008 as a result of specific investigator requests. In the past year, 1 Rabbitpox virus challenge stock was prepared and stored in Liquid Nitrogen at the TNPRC. Viral isolation and quantification for Rabbitpox was performed on the tissues collected from animals in Groups 2 &3. Quantification was done by plaque assay. This program represents expansion of the core to include other viruses used at the TNPRC. Rabbitpox is part of a biodefense research program headed by Dr. Chad Roy