Inhibition of NL4-3 infection. (a) Effects of HOCl-modified serum albumins (molar ratio 1:1000) on cell growth. HeLa-P4 cells were cultured in the presence of MTT and various concentrations of mHSA, mBSA and mMSA (white symbols, 1, 5, 20 and 50 μg per ml; Black symbols, non-modified serum albumins). Cells were seeded at 104 cells per well in 96-well plates in triplicate. After adding the yellow tetrazolium salt MTT, metabolically active cells produced purple formazan. The amount of formazan was measured at 530 nm and is a correlate for cell viability and proliferation. (b) NL4-3 neutralization by HOCl-modified serum albumins (molar ratio 1:1000). HeLa-P4 cells were infected with 1000 TCID of the HIV-1 laboratory strain NL4-3. Shown are the averages of triplicate wells. Infection was monitored 5 days after infection by a standard p24 antigen ELISA.