Recovery of infectious human immunodeficiency virus from cells treated with 1% paraformaldehyde

Fixation and preservation of cells with 1% paraformaldehyde is a common practice in laboratories performing flow cytometric analysis of cells from persons infected with human immunodeficiency virus (HIV). Previous studies indicated that 1% paraformaldehyde effectively inactivates cell-free HIV. In this study, we tested the inactivation capacity of 1% paraformaldehyde on a cell line chronically infected with HIV and human peripheral blood lymphocytes acutely infected with the virus. We found a significant decrease in the infectious titer of the cells after treatment with 1% paraformaldehyde. However, we did not find total inactivation of the specimens treated for up to 18 h.