The present invention provides a compound of the formula ##STR00001## or a pharmaceutically acceptable salt or solvate thereof, wherein the various moieties are as defined in the specification. The present invention also provides pharmaceutical compositions containing the compound of this invention, and methods of treatment using the compound of this invention. The invention also relates to the use of a combination of a compound of this invention and one or more antiviral or other agents useful in the treatment of Human Immunodeficiency Virus (HIV). The invention further relates to the use of a compound of this invention, alone or in combination with another agent, in the treatment of solid organ transplant rejection, graft v. host disease, arthritis, rheumatoid arthritis, inflammatory bowel disease, atopic dermatitis, psoriasis, asthma, allergies or multiple sclerosis.