[1] SAIC Frederick Inc, Pathol & Histotechnol Lab, Frederick Natl Lab Canc Res, Frederick, MD USA
[2] SAIC Frederick Inc, AIDs & Canc Virus Program, Frederick Natl Lab Canc Res, Frederick, MD USA
[3] SAIC Frederick Inc, Lab Anim Sci Program, Frederick Natl Lab Canc Res, Frederick, MD USA
[4] NIID, Mol Microbiol Lab, NIH, Bethesda, MD USA