1. B. L. Levine and C. H. June, Naval Medical Research Institute, Bethesda, MD 20889, USA.
2. J. D. Mosca, R. G. Carroll, L. L. Jagodzinski, K. F. Wagner, D. C. St. Louis, Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD 20850, USA.
3. J. L. Riley, M. T. Vahey, D. S. Burke, Division of Retrovirology, Walter Reed Army Institute for Research, Rockville, MD 20850, USA.
4. D. L. Mayers, Naval Medical Research Institute, Bethesda, MD 20889, USA, and Division of Retrovirology, Walter Reed Army Institute for Research, Rockville, MD 20850, USA.
5. O. S. Weislow, Life Sciences Division, SRA Technologies, Rockville, MD 20850, USA.