Molecular studies have revealed significant amounts of human immunodeficiency virus type 1 (HIV-1) provirus DNA in saliva of HIV-infected persons. However, cellular localization has not been determined. In situ polymerase chain reaction (IS-PCR) was done on saliva-associated cells for localization of HIV-1 provirus DNA. Results indicate its presence in the nuclei of saliva-associated epithelial cells in 29 (83%) of 35 HIV-1-seropositive subjects. In 24 (83%) of the 29 IS-PCR-positive samples, 0.1%-4.0% of the mucosal epithelial cells exhibited nuclear localization of HIV-1 DNA. In addition, HIV-1 provirus DNA was detected in monocytes or lymphocytes of all salivary samples from the 35 subjects. The localization of HIV-1 provirus DNA indicates that epithelial cells are another cell type infected by HIV-1 in vivo. These findings suggest epithelial cells in other body sites might also be infected with HIV-1.

Our results suggest that epithelial cells can be productively infected by HIV. Epithelial cells in buccal mucosa may acquire HIV in the basal layers through contact with submucosal HIV-positive lymphocytes and/or Langerhans' cells. HIV infection may also spread by inter-epithelial cell contact. As HIV infected cells mature they travel to more superficial layers and are shed into the oral cavity.

Cocultivation of Acanthamoeba casteUlanii and Acanthamoeba polyphaga with live Pseudomonas aeruginosa and with broth filtrates of P. aeruginosa proved equally lethal to the Acanthamoeba spp. The P. aeruginosainduced amebicidal activity is apparently toxin mediated and has two operative modes: it can function through binding ofP. aeruginosa to the ameba membrane and in the presence of one or more P. aeruginosa exoproducts.

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We encountered a patient with Acanthamoeba keratitis whose contact lens care solution contained numerous trophozoites and cysts admixed with Xanthomonas maltophilia organisms, many of which were adherent to the trophozoite surface and internalized within endocytic vacuoles. Because of this finding, we investigated the role of bacterial cocontaminants in contact lens care systems as substrates for the growth of Acanthamoeba spp. Individual cocultivation of Acanthamoeba castellanii and A. polyphaga with X. maltophilia, Flavobacterium breve, and Pseudomonas paucimobilis showed better enhancement (1.5x) of ameba growth after 96 h than that obtained in the presence of Staphylococcus aureus, S. epidermidis, and Escherichia coli, the standard cocultivation species used for isolation of amebae from clinical specimens. Our data suggest that contamination of contact lens care systems with Acanthamoeba spp. and a bacterial species capable of supporting amebic growth may be the first step in the pathogenesis of ameba-induced keratitis by the provision of large inocula of amebae.