A clade of picornaviruses recently discovered in New York State is globally distributed and is found in association with community outbreaks of ARI and severe LRTIs of infants. These viruses contribute both to a substantial proportion of previously undiagnosed respiratory illness and to diagnosed, but nontyped cases of HRV infection. Similar viruses were recently characterized also in Queensland, Australia (11); California, USA (12); Hong Kong Special Administrative Region, People's Republic of China (13) ; and Germany (16) . Our fi ndings indicate the need for further investigation into this third (HRV-C) group of rhinoviruses with emphasis on epidemiology, pathogenesis, and strategies to prevent and ameliorate disease caused by HRV infection. Cost effective strategies for completing the Interactome Comprehensive protein interaction mapping projects are underway for many model species and humans. A key step in these projects is estimating the time, cost, and personnel required for obtaining an accurate and complete map. Here, we model the cost of interaction map completion across a spectrum of experimental designs. We show that current efforts may require up to 20 independent tests covering each protein pair to approach completion. We explore designs for reducing this cost substantially, including prioritization of protein pairs, probability thresholding, and interaction prediction. The best designs lower cost by four-fold overall and >100-fold in early stages of mapping. We demonstrate the best strategy in an ongoing project in Drosophila, in which we map 450 high-confidence interactions using 47 microtiter plates, versus thousands of plates expected using current designs. This study provides a framework for assessing the feasibility of interaction mapping projects and for future efforts to increase their efficiency. Mapping a complete gene or protein network evokes similar challenges and considerations as mapping a complete genome sequence. In the case of the human and model genome projects, large-scale sequencing efforts were accompanied by a series of feasibility studies27,28 which used mathematical formulations and pilot projects to explore strategies for genome assembly and the work required for each. In the case of interaction networks, similar feasibility studies are just beginning29-31. Some of the questions to be addressed are: What is the cost of completing an interactome map and what is the best strategy for minimizing that cost? Given practical cost constraints, how can the quality and coverage of interaction data be maximized? How many independent assay types are needed? How should direct pairwise tests for interaction be combined with pooled screening? What is the effect of the test sensitivity on the final cost? How should interaction predictions be incorporated, and what is their effect on the mapping cost? Which specific improvements to experimental and computational methods are likely to have the largest effect?