The Division of Molecular Virology and Immunology, Georgetown University, supports the NIAID intramural and contract-sponsored extramural programs requiring the expertise and equipment of the NIAID special support laboratory at 5640 Fishers Lane, Rockville, Maryland. Additional work will be conducted outside the Rockville facility to support the NIAID intramural studies of the virology of the causative agent of AIDS (i.e., the isolation of virus from clinical specimens, purification and characterization of antigens, modification and development of assays for virus and antibodies to the virus). In addition to AIDS virus, the research efforts center on hepadna viruses, hepatitis delta virus; a hepatitis testing laboratory is provided; an electron microscope facility for collaborative studies on membrane receptors in neutrophil activation leading to chemotaxis and/or degranulation; and, mast cell aberrations in a variety of conditions associated with physiologic or pathologic mastocytosis.