Preclinical Services for HIV Therapeutics: The purpose of these Indefinite Delivery/Indefinite Quantity contracts is to provide the extramural scientific community with research materials and preclinical product development support for candidate products that emerge from investigator-initiated research studies or from collaborations with private sector or academic partners. The scope of work encompasses activities that range from basic research and initial product discovery to activities required for clinical trials and/or product licensure. These services may also be used to support product discovery and development leading to Investigational New Drug Application (IND), Investigational Device Exemption (IDE), and/or New Drug Application (NDA) filings with the Food and Drug Administration (FDA). NIAID Division of AIDS will primarily use these contracts to fill critical development and resource gaps more rapidly and efficiently and advance promising products into clinical testing. The purpose of this task order is to conduct assay development to establish a phenotypic assay for assessing Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) targeted activator of cell kill (TACK) activity and to subsequently test known NNRTIs for this activity.