Rv. Srinivas et al., CALMODULIN ANTAGONISTS INHIBIT HUMAN IMMUNODEFICIENCY VIRUS-INDUCED CELL-FUSION BUT NOT VIRUS-REPLICATION, AIDS research and human retroviruses, 10(11), 1994, pp. 1489-1496
We have reported that amphipathic helical segments in the cytoplasmic
domain of the HIV-1 envelope glycoproteins bind to calmodulin (CaM) wi
th high affinity, and inhibit calmodulin-regulated proteins. To invest
igate the possible role of calmodulin activity in HIV-1 replication, w
e investigated the anti-HIV activity of various CaM antagonists-triflu
operazine and naphthalenesulfonamide W13 or W7-in HeLa T4 cells, PBMCs
, and various T lymphocytic cell lines. The different CaM antagonists
were found to inhibit the proliferation of the different cell types to
varying extent. Also, the CaM antagonists were found to exert a great
er antiproliferative effect on H9/HIV-1(IIIB), as compared to uninfect
ed H9 cells, suggesting a deficit of CaM function in HIV-infected cell
s. The CaM antagonists inhibited virus-induced cell fusion in HeLa T4
cells infected with a recombinant vaccinia virus expressing HIV-1 enve
lope proteins at threshold concentrations that do not inhibit cell pro
liferation. The fusion-inhibitory effects of the CaM antagonists were
also observed in cocultures of HIV-infected (H9/HIV-1(IIIB)) and uninf
ected H9 cells. Under these conditions, the synthesis and surface expr
ession of the viral glycoproteins were not affected, although the kine
tics of processing of HIV envelope precursor was delayed. Virus produc
tion from both HIV-infected peripheral blood mononuclear cell (PBMC) a
nd MT-2 cell cultures was inhibited by CaM antagonists at concentratio
ns that were inhibitory to cell proliferation. Surprisingly, threshold
concentrations of CaM antagonists that do not inhibit cell proliferat
ion were found to enhance virus production from HIV-infected MT-2 cell
s, but not PBMCs. These results suggest that intracellular CaM may reg
ulate the extent of virus replication and cytopathology in HIV-infecte
d cells.