THE INFLUENCE OF CELL-CULTURE AND STORAGE-CONDITIONS ON HIV-1 INFECTIVITY AND FUSOGENIC ACTIVITY

We have previously demonstrated that acidic medium inhibits the replic ation of HIV-1. The present study was designed to examine the effects of other growth conditions and infection of fibroblasts by coculture w ith HIV infected lymphoid cells. Several lymphoblastoid cell lines nor mally grown in RPMI-1640 were grown in Eagle's MEM. These cells suppor ted virus replication to higher titres than did RPMI-1640. Peak viral titres were achieved within 24-48 h after newly infected or chronicall y infected cells were placed in fresh medium. When virus was stored in liquid medium either frozen or at higher temperatures, virus titres w ere retained for several months while frozen but decreased upon storag e at 4-degrees-C or higher. If cells were passaged after trypsinizatio n in Ca++-depleted medium, then a decreased susceptibility of cells fo r HIV-1 by 2 log10 at 24 h post infection was observed. Infectivity of cell-free and cell-associated HIV-1 was measured using syncytium form ation, reverse transcriptase activity and p24 antigen. No fusion betwe en HIV-1 infected CD4+ lymphoblasts and CD4-fibroblasts was observed b ut