
<ArticleTitle>Analysis of cellular factors influencing the replication of human immunodeficiency virus type I in human macrophages derived from blood of different healthy donors.</ArticleTitle>
<AbstractText>We analyzed parameters influencing HIV-1 infectibility of cells of the monocyte/macrophage lineage (MO/MAC) isolated from different healthy donors. The proportion of in vitro-infected cells and replication kinetics in different donor MAC ranged from 0.03 to 99% p24 antigen-positive MAC and from undetectable RT activity up to 5 x 10(6) cpm/ml/90 min, respectively. As a quantitative measurement for HIV-1 susceptibility of donor MO/MAC, we determined TCID(50) values of defined virus stocks which varied up to 3000-fold depending on the donor MAC used for titration. As host factors which may influence the viral infection we determined the expression of virus receptors <prot>CD4</prot>, <prot>CCR5</prot>, <prot>CXCR4</prot>, and <prot>CCR3</prot> as well as the secretion of the natural ligands of <prot>CCR5</prot>, which altogether showed no correlation with HIV-1 infectibility of the cells. Moreover, other MO-derived secretory factors which might affect viral infection of these cells could be excluded. Furthermore, expression of maturation-related antigens <prot>CD14</prot>, <prot>CD16</prot>, <prot>HLA-DR</prot>, and <prot>MAX.1</prot>/<prot>CPM</prot> was determined. Analysis of the reverse transcription process revealed that restricted HIV-1 infection was reflected by highly reduced or even undetectable full-length HIV-1 DNA formation, although early and intermediate transcripts appeared, suggesting that viral replication is blocked after entry at the level of early reverse transcription.</AbstractText>
