Table 1.

Comparative antiviral efficacy and virucidal activity of PNA_TAR in presence of different peptides

PNATAR–peptide conjugate	Antiviral efficacy			Virucidal activity
	IC50 (nM)	m	r	IC50 (nM)	m	r
PNATAR–penetratin	800	2.8	0.93	28	0.69	0.98
PNATAR–tat-peptide	720	2.6	0.87	37	0.94	0.43
PNATAR–transportan-27	400	1.4	0.98	66	0.69	0.92
PNATAR–transportan-21	1000	0.6	0.99	34	0.46	0.79
PNATAR–transportan-22	1100	1.78	0.98	72	0.86	0.86

For carrying out antiviral efficacy experiments CEM cells were infected with VSV-G pseudotyped S1 strain of HIV-1 and then grown in the presence of increasing concentrations of PNA_TAR–MTD peptides. Cells were harvested, lysed and assayed for luciferase expression 48 h post infection. The effects of PNA_TAR–MTD peptide concentrations on the luciferase expression were analyzed using the Calcusyn software (Biosoft) based on Median-effect equation of Chou (34,35). The IC₅₀ values determined from the ratio of the log of luciferase expression in treated cells (fa) and untreated cells (fu) as a function of log concentration of PNA_TAR–MTD peptide. Sigmoidicity (m) of the dose–effect curve is derived from slope of median-effect plot and values of 1, >1, <1 indicate hyperbolic, sigmoidal, and negative sigmoidal shapes, respectively. Linear correlation coefficient of the median-effect plot is represented by r and a value of 1 indicates perfect conformity.

For carrying out virucidal activity experiments PNA_TAR conjugated with different peptides at varying concentrations (25, 50, 100, 250 and 500 nM) were incubated at 37°C with HIV-1 virions for 2 h. The virion particles were spun down by ultracentrifugation and then the virions were used for infection of CEM cells for 48 h at 37°C in a 5% CO₂ incubator. The cells were harvested, lysed and assayed for luciferase activity. The median dose effect was calculated using Calcusyn software program (Biosoft). Penetratin displays the greatest virucidal efficacy among this group of MTD peptides.