HIV-1 infection (EFO_0000180, an Experimental Factor Ontology term) is the type species of lentivirus and the etiologic agent of acquired immunodeficiency syndrome (AIDS). It is characterized by its cytopathic effect and affinity for the T4-lymphocyte. Also known as: HIV-1 seropositive, Human Immunodeficiency Virus 1, Human Immunodeficiency Virus, Type 1.