Barbara J. Potts

Replication of HIV-1 in primary monocyte cultures

A subpopulation of human monocytes began to express surface CD4 during its in vitro cultivation in the presence of recombinant M-CSF and became susceptible to infection with an isolate of HIV-1 [AD-87(M)], originally recovered from a seropositive individual by cocultivation with primary monocytes. Approximately 10% of the adherent cells synthesized CD4; a similar fraction was infectable with AD-87(M) and produced high levels of progeny particles. An interesting feature of the HIV-1 infection of primary monocytes was the detection of gp 160/120 inside but not on the surface of virus-producing cells. The implication of these results on HIV infection in vivo will be discussed.

Peroxidase-labeled primary antibody method for detection of pestivirus contamination in cell cultures

Contaminating bovine viral diarrhea (BVD) virus in cell cultures and in fetal bovine serum (FBS) is a well recognized problem. This study describes a direct peroxidase (DP) labeled primary antibody method for detection of pestivirus antigens in cell culture that is simple and reliable. Using this method, most bovine and porcine cell cultures, a cat lung, four mosquito and two monkey cell cultures were found contaminated with BVD virus. The rodent and human cell cultures tested were negative by this method for BVD virus.

Replication of HIV-1 and HIV-2 in human bone marrow cultures

The bone marrow is a target organ for the human immunodeficiency virus (HIV), but the mechanisms by which suppression of hematopoiesis occurs during the course of HIV infection are not well understood. To study this issue, the effect of several different HIV-1 isolates (monotrophic and lymphotrophic) and one HIV-2 isolate on in vitro colony formation by BFU-E and CFU-GM from normal human marrow were examined. The monotrophic strain AD-87 (M) failed to replicate in marrow cultures as documented by RT, and colony formation by BFU-E and CFU-GM was unaffected by this virus. A derivative of this isolate AD-87 (M-P), which was replicated in peripheral blood lymphocytes (PBL), however, replicated well and markedly inhibited colony formation by BFU-E and CFU-GM. Two additional PBL isolates replicated less efficiently; neither inhibited CFU-GM but one consistently inhibited BFU-E colony formation. Inhibition of colony formation by the HIV-1 isolates was a late event, presumably a secondary lysis of cells, since up to 7 days after inoculation colony numbers were normal but diminished markedly by 10 days, and since only up to 10% of the cells of the monocyte lineage contained detectable virus by in situ, EM, and IFA studies. In contrast, the HIV-2 isolate was so lytic that by 4 days after inoculation the majority of the marrow cells were destroyed.

Multiple neural cell types are infected in vitro by border disease virus.

Border disease (BD) of sheep results from a congenitally acquired non-arbotogavirus infection which causes a highly selective central nervous system (CNS) pathological lesion consisting of diffuse decreased myelination without inflammation or neuronal destruction. Thus, a selective disruption of oligodendroglial function appears to occur. In order to investigate the in vitro cell tropism of BD virus, primary cultures derived from fetal and adult ovine CNS and peripheral nervous system were inoculated with BD virus. Infected cell types were determined by dual immunofluorescent labeling for viral and cell type specific antigens. Infection of all the major cell types represented in these cultures, including oligodendrocytes, astrocytes, fibroblasts, dorsal root ganglion neurons and Schwann cells was found. Oligodendrocytes were only infected earlier and appeared to remain infected longer than astrocytes and fibroblasts. Infectious virus was produced by all cultures and continued to be produced even after the disappearance of nearly all immunocytochemically detectable viral antigen within cells. These studies suggest that the selective dysfunction of the oligodendrocyte in BD is not based on a selective viral tropism.