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Sargassum fusiforme fraction is a potent and specific inhibitor of HIV-1 fusion and reverse transcriptase.

Paskaleva EE, Lin X, Duus K, McSharry JJ, Veille JC, Thornber C, Liu Y, Lee DY, Canki M - Virol. J. (2008)

Bottom Line: That represents 230-fold enhancement of antiretroviral potency as compared to the whole extract.We conclude that the SP4-2 fraction contains at least two distinct and biologically active molecules, one that inhibits HIV-1 fusion by interacting with CD4 receptor, and another that directly inhibits HIV-1 RT.We propose that S. fusiforme is a lead candidate for anti-HIV-1 drug development.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Immunology and Microbial Disease, Albany Medical College, Albany, NY, USA. paskale@mail.amc.edu

ABSTRACT
Sargassum fusiforme (Harvey) Setchell has been shown to be a highly effective inhibitor of HIV-1 infection. To identify its mechanism of action, we performed bioactivity-guided fractionation on Sargassum fusiforme mixture. Here, we report isolation of a bioactive fraction SP4-2 (S. fusiforme), which at 8 mug/ml inhibited HIV-1 infection by 86.9%, with IC50 value of 3.7 mug. That represents 230-fold enhancement of antiretroviral potency as compared to the whole extract. Inhibition was mediated against both CXCR4 (X4) and CCR5 (R5) tropic HIV-1. Specifically, 10 mug/ml SP4-2 blocked HIV-1 fusion and entry by 53%. This effect was reversed by interaction of SP4-2 with sCD4, suggesting that S. fusiforme inhibits HIV-1 infection by blocking CD4 receptor, which also explained observed inhibition of both X4 and R5-tropic HIV-1. SP4-2 also inhibited HIV-1 replication after virus entry, by directly inhibiting HIV-1 reverse transcriptase (RT) in a dose dependent manner by up to 79%. We conclude that the SP4-2 fraction contains at least two distinct and biologically active molecules, one that inhibits HIV-1 fusion by interacting with CD4 receptor, and another that directly inhibits HIV-1 RT. We propose that S. fusiforme is a lead candidate for anti-HIV-1 drug development.

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Inhibition of X4 and R5-tropic HIV-1. GHOST X4/R5 and GFP expressing cells were plate at 1 × 105/well in 12-well plates and incubated at 37°C in CO2 atmosphere with increasing concentrations of SP4-2, as indicated, then infected with either X4-tropic NL4-3 (panel A, a-d) or with R5-tropic 81A (panel B, e-h), at 0.3 moi, in replicates (n = 4). 48 h after infection cells were quantified by FACS, and % infected cells is shown on each panel. Uninfected and untreated control (mock) is superimposed over each graph in dotted line. Representative of 4 experiments.
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Figure 2: Inhibition of X4 and R5-tropic HIV-1. GHOST X4/R5 and GFP expressing cells were plate at 1 × 105/well in 12-well plates and incubated at 37°C in CO2 atmosphere with increasing concentrations of SP4-2, as indicated, then infected with either X4-tropic NL4-3 (panel A, a-d) or with R5-tropic 81A (panel B, e-h), at 0.3 moi, in replicates (n = 4). 48 h after infection cells were quantified by FACS, and % infected cells is shown on each panel. Uninfected and untreated control (mock) is superimposed over each graph in dotted line. Representative of 4 experiments.

Mentions: Next, we examined the cells coreceptor specificity and tested SP4-2 fraction for ability to inhibit both X4 and R5-tropic HIV-1 (Fig. 2). GHOST cells expressing both X4 and R5 coreceptors were treated with increasing concentrations of SP4-2, and infected with X4-tropic NL4-3 (A) or with R5-tropic 81A (B), and FACS analyzed 48 h after infection. Treatment with SP4-2 resulted in a dose dependent decrease in number of infected cells by either virus. X4-tropic virus (A) infected 15.7% cells without treatment (a), which decreased to 13.5% (b), 7.6% (c), and 0.7% (d) infected cells after treatment with 1, 6, and 12 μg/ml SP4-2, respectively. Inhibition of infection was calculated to be 14%, 51%, and 95%, respectively. For R5-tropic infection, we observed a mean of 21% infected cells (e), which decreased to 19.9% (f), 17.5% (g), and 11.7% (h) infected cells after treatment with 1, 6, and 12 μg/ml SP4-2, respectively. Inhibition of infection was calculated to be 6%, 17%, and 45%, respectively. However, when we increased SP4-2 treatment to 14, 16, 20, and 24 μg/ml, R5 inhibition of infection increased proportionally to 65%, 70%, 78%, and 88%, respectively (not shown). Based on these results, we conclude that treatment with SP4-2 inhibits both X4 and R5-tropic HIV-1 infection in a dose dependent manner, confirming our previous results with whole S. fusiforme extract, which inhibited both X4 and primary R5-tropic HIV-1.


Sargassum fusiforme fraction is a potent and specific inhibitor of HIV-1 fusion and reverse transcriptase.

Paskaleva EE, Lin X, Duus K, McSharry JJ, Veille JC, Thornber C, Liu Y, Lee DY, Canki M - Virol. J. (2008)

Inhibition of X4 and R5-tropic HIV-1. GHOST X4/R5 and GFP expressing cells were plate at 1 × 105/well in 12-well plates and incubated at 37°C in CO2 atmosphere with increasing concentrations of SP4-2, as indicated, then infected with either X4-tropic NL4-3 (panel A, a-d) or with R5-tropic 81A (panel B, e-h), at 0.3 moi, in replicates (n = 4). 48 h after infection cells were quantified by FACS, and % infected cells is shown on each panel. Uninfected and untreated control (mock) is superimposed over each graph in dotted line. Representative of 4 experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2267448&req=5

Figure 2: Inhibition of X4 and R5-tropic HIV-1. GHOST X4/R5 and GFP expressing cells were plate at 1 × 105/well in 12-well plates and incubated at 37°C in CO2 atmosphere with increasing concentrations of SP4-2, as indicated, then infected with either X4-tropic NL4-3 (panel A, a-d) or with R5-tropic 81A (panel B, e-h), at 0.3 moi, in replicates (n = 4). 48 h after infection cells were quantified by FACS, and % infected cells is shown on each panel. Uninfected and untreated control (mock) is superimposed over each graph in dotted line. Representative of 4 experiments.
Mentions: Next, we examined the cells coreceptor specificity and tested SP4-2 fraction for ability to inhibit both X4 and R5-tropic HIV-1 (Fig. 2). GHOST cells expressing both X4 and R5 coreceptors were treated with increasing concentrations of SP4-2, and infected with X4-tropic NL4-3 (A) or with R5-tropic 81A (B), and FACS analyzed 48 h after infection. Treatment with SP4-2 resulted in a dose dependent decrease in number of infected cells by either virus. X4-tropic virus (A) infected 15.7% cells without treatment (a), which decreased to 13.5% (b), 7.6% (c), and 0.7% (d) infected cells after treatment with 1, 6, and 12 μg/ml SP4-2, respectively. Inhibition of infection was calculated to be 14%, 51%, and 95%, respectively. For R5-tropic infection, we observed a mean of 21% infected cells (e), which decreased to 19.9% (f), 17.5% (g), and 11.7% (h) infected cells after treatment with 1, 6, and 12 μg/ml SP4-2, respectively. Inhibition of infection was calculated to be 6%, 17%, and 45%, respectively. However, when we increased SP4-2 treatment to 14, 16, 20, and 24 μg/ml, R5 inhibition of infection increased proportionally to 65%, 70%, 78%, and 88%, respectively (not shown). Based on these results, we conclude that treatment with SP4-2 inhibits both X4 and R5-tropic HIV-1 infection in a dose dependent manner, confirming our previous results with whole S. fusiforme extract, which inhibited both X4 and primary R5-tropic HIV-1.

Bottom Line: That represents 230-fold enhancement of antiretroviral potency as compared to the whole extract.We conclude that the SP4-2 fraction contains at least two distinct and biologically active molecules, one that inhibits HIV-1 fusion by interacting with CD4 receptor, and another that directly inhibits HIV-1 RT.We propose that S. fusiforme is a lead candidate for anti-HIV-1 drug development.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Immunology and Microbial Disease, Albany Medical College, Albany, NY, USA. paskale@mail.amc.edu

ABSTRACT
Sargassum fusiforme (Harvey) Setchell has been shown to be a highly effective inhibitor of HIV-1 infection. To identify its mechanism of action, we performed bioactivity-guided fractionation on Sargassum fusiforme mixture. Here, we report isolation of a bioactive fraction SP4-2 (S. fusiforme), which at 8 mug/ml inhibited HIV-1 infection by 86.9%, with IC50 value of 3.7 mug. That represents 230-fold enhancement of antiretroviral potency as compared to the whole extract. Inhibition was mediated against both CXCR4 (X4) and CCR5 (R5) tropic HIV-1. Specifically, 10 mug/ml SP4-2 blocked HIV-1 fusion and entry by 53%. This effect was reversed by interaction of SP4-2 with sCD4, suggesting that S. fusiforme inhibits HIV-1 infection by blocking CD4 receptor, which also explained observed inhibition of both X4 and R5-tropic HIV-1. SP4-2 also inhibited HIV-1 replication after virus entry, by directly inhibiting HIV-1 reverse transcriptase (RT) in a dose dependent manner by up to 79%. We conclude that the SP4-2 fraction contains at least two distinct and biologically active molecules, one that inhibits HIV-1 fusion by interacting with CD4 receptor, and another that directly inhibits HIV-1 RT. We propose that S. fusiforme is a lead candidate for anti-HIV-1 drug development.

Show MeSH
Related in: MedlinePlus