Persistent infection of normal mice with human immunodeficiency virus

In this article, we report the establishment of persistent HIV type 1 infection of normal Swiss mice after a single intraperitoneal injection with high-producing HIV-infected U937 cells. Anti-HIV antibodies were found more than 500 days after the original injection, and p24 antigenemia was detected in approximately 50% of the mice. By polymerase chain reaction (PCR) techniques, HIV-specific gag and env sequences were detected in DNA samples from peripheral blood mononuclear cells (PBMC) and peritoneal cells of seropositive mice 300 to 500 days after inoculation with HIV-infected cells. These DNA samples did not contain human DNA sequences, as determined by PCR analysis using primers and the probe for the HLA-DQ alpha gene. Low levels of p24 and detectable human reverse transcriptase activity were found in cultures of PBMC and peritoneal macrophages. Cocultivation of PBMC, peritoneal cells, and spleen cells with human uninfected U937 or CEM (a T lymphoma cell line) cells resulted in HIV infection of the target cells, as determined by PCR analysis and/or p24 assays. The intravenous injection of untreated Swiss mice with the PBMC from PCR-positive mice resulted in the development of an increasing antibody response to HIV in the recipient animals. Together these results indicate that cells from seropositive Swiss mice were persistently infected with HIV and were capable of producing infectious virus. The development of persistent HIV infection in an immunocompetent mouse may represent the starting point for further studies aimed at defining the host mechanisms involved in the restriction of virus replication, defining the pathogenesis of HIV infection, and testing antiviral compounds and vaccines.