Over the last two decades, AIDS reporting has formed the core of public health surveillance for HIV-related disease in the United States. More recently, all states have implemented some form of HIV reporting as well. However, the need for surveillance data on HIV incidence and atypical and antiretroviral (ARV) resistant strains has become increasingly apparent with advances in prevention, increased awareness of the international characteristics of the epidemic, and changes in the clinical course of the disease due to combination ARV therapy. Current laboratory experience would indicate that use of diagnostic sera for more expanded surveillance is feasible. An alternative to HIV confirmatory testing with sera or oral fluid that will potentially allow expanded surveillance is that of confirmatory HIV testing using dried blood spots (DBS). DBS can be prepared by individuals with minimal technical training who use a disposable lancet to create a pinpoint wound in the finger from which a few drops of blood can be absorbed onto specially prepared filter paper. The purpose of this application is to develop laboratory expertise and acquire field experience in using DBS for atypical and ARV resistant HIV strain surveillance in newly diagnosed persons. The specific aims of this application include: 1) Validate methodology for DBS atypical/ ARV resistant strain testing through paired comparison of sera and DBS; 2) Determine the feasibility and resources required to obtain DBS versus sera in clinical settings; 3) Determine the feasibility and resources required for commercial laboratories to prepare DBS from blood drawn for clinically indicated diagnostic or prognostic tests; 4) Monitor the prevalence of atypical/ARV resistant strains; and 5) Compare atypical/ARV resistant strain prevalence in sites using DBS for this surveillance versus those using sera.