ABSTRACT
Pertussis toxin from the gram-negative bacterium Bordetella pertussis is an ADP-ribosylase that modifies Gi proteins in mammalian lymphocytes and inhibits their capacity to traffic from blood into lymphoid tissues. We used this compound to induce lymphocytosis in rhesus macaques and to study its effects on SIV infection. Pertussis toxin injected at 25 micrograms/kg induced a transient lymphocytosis that peaked 3-8 days after administration and caused a rapid, transient decrease in the frequency of infectious cells in blood as judged by in vitro virus isolation assays. Lymphocyte subsets were altered during the lymphocytosis interval and sustained changes in CD8+ T cell levels were noted as long as 53 days after pertussis toxin injection. In situ hybridization studies showed that pertussis toxin altered the distribution of viral RNA in lymph nodes during the interval of lymphocytosis, and caused long-term changes with decreased virus replication in some tissue specimens.
Subject(s)
Lymphocytosis , Pertussis Toxin , Simian Acquired Immunodeficiency Syndrome/immunology , Simian Immunodeficiency Virus/physiology , Virulence Factors, Bordetella/pharmacology , Virus Replication/drug effects , Animals , CD4-Positive T-Lymphocytes/virology , CD8-Positive T-Lymphocytes/immunology , DNA, Viral/blood , Leukocytes, Mononuclear/virology , Lymph Nodes/pathology , Lymph Nodes/virology , Lymphocyte Count , Lymphocyte Subsets , Lymphocytosis/chemically induced , Lymphocytosis/virology , Macaca mulatta , Male , RNA, Viral/analysis , Simian Acquired Immunodeficiency Syndrome/virology , Viral Load , Virus Replication/immunologyABSTRACT
The unintegrated viral DNA found in human immunodeficiency virus type 1 infection includes linear and circular forms. We targeted the circular form containing two copies of the viral long terminal repeat (2-LTR circle) and developed specific assays to detect this molecule in peripheral blood mononuclear cells from HIV-infected patients. In vitro HIV-1 infection of peripheral blood mononuclear cells showed rapid accumulation and rapid decay of 2-LTR circular viral DNA. Examination of 2-LTR circular viral DNA levels provides a view of spreading infection based on a viral DNA form that is structurally distinct and has a known, short half-life in infected cells. In patients not receiving antiviral therapy, the levels of 2-LTR circular viral DNA and total viral DNA were significantly correlated to CD4 cell counts. Similar correlations were not observed in patients receiving zidovudine (AZT), didanosine (ddA), or zalcitabine (ddC).
