1. Figure 2. Reaction strategy for the synthesis of 6SLN-lipo PGA
Figure 2. Reaction strategy for the synthesis of 6SLN-lipo PGA. Conditions: a, reaction in DMF/MeOH, room temperature (r.t.), 18 h; b, Et₃N/MeOH, r.t., 20 h; and c, DMT-MM, THF/H₂O, r.t., 2 h.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
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2. Figure 1. Chemical structure of 6SLN-lipo PGA
Figure 1. Chemical structure of 6SLN-lipo PGA. 6SLN-lipo PGA has an average mol. wt of 116 520 and is composed of 6SLN conjugated with an eicosanoyl chain via a lysine residue attached to the γ carbon atom of about every 20th glutamic acid residue of a PGA backbone (Dp: 560). Roles of 6SLN, eicosanoyl chain and PGA in antiviral activity are proposed as indicated.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
J Antimicrob Chemother | © The Author Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please

3. Figure 5. Confocal microscopy of synergism of the 6SLN-lipo PGA/NAI combination against influenza A/Fukui/20/2004 (H3N2) virus infection. The viruses were mock treated (top panel), treated with 5 μM 6SLN-lipo PGA (a mixed-type multimeric inhibitor) or 5 μM NAI (a reversible competitive monomeric inhibitor; either zanamivir or oseltamivir carboxylate) (middle panels) or treated with 2.5 μM zanamivir + 2.5 μM oseltamivir carboxylate, 1.3 μM 6SLN-lipo PGA + 1.3 μM zanamivir or 1.3 μM 6SLN-lipo PGA + 1.3 μM oseltamivir carboxylate (bottom panels) for 1 h at 4°C. The inhibitor/virus mixtures were transferred to AX4 cells. Following 255 min of incubation, amplified viral NP proteins were detected with antiviral NP mouse antibody and antimouse Alexa Fluor^® 488 (green). The cellular nuclei were stained with DAPI (blue). This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
J Antimicrob Chemother | © The Author Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please

4. Figure 6. Combined effects of NAIs and those of 6SLN-lipo PGA and NAIs against multiplication of influenza A/Narita/1/2009 (left panels) or A/Fukui/20/2004 (right panels) virus in AX4 cells. Isobolograms of zanamivir/oseltamivir carboxylate (a), zanamivir/6SLN-lipo PGA (b) and oseltamivir carboxylate/6SLN-lipo PGA (c) combinations were generated from mean FIC ± SD of each combination derived from two to four independent experiments shown in Figure S1. The broken diagonal line drawn from the FIC index of 1 represents the theoretical additive effect. Each point of mean FIC ± SD derived from zanamivir/oseltamivir carboxylate combinations distributed around the theoretical additive line indicates no interaction between zanamivir and oseltamivir carboxylate, with mean ΣFIC indices of 0.99 ± 0.28 (for A/Narita/1/2009) and 0.90 ± 0.18 (for A/Fukui/20/2004). Mean FIC ± SD derived from NAI/6SLN-lipo PGA combinations drawn point by point showing concave curves below the diagonal line indicating synergy of zanamivir/6SLN-lipo PGA and oseltamivir carboxylate/6SLN-lipo PGA combinations with mean ΣFIC indices of 0.29 ± 0.07 and 0.34 ± 0.12 for A/Narita/1/2009 and 0.36 ± 0.14 and 0.40 ± 0.12 for A/Fukui/20/2004, respectively.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
J Antimicrob Chemother | © The Author Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please

5. Figure 3. Effects of 6SLN-lipo PGA on receptor-binding activities of influenza pandemic A/H1N1 and seasonal A/H3N2 viruses. (a) Direct binding activities of influenza A/Narita/1/2009 (H1N1) virus and A/Fukui/20/2004 (H3N2) virus to 6SLN-lipo PGA. The percentage of virus binding to 6SLN-lipo PGA was plotted against the 6SLN-lipo PGA concentration (log scale) and the best-fit curve was generated by non-linear regression analysis. Each point is each value of duplicate concentrations. (b) Inhibitory activities of fetuin and 6SLN-lipo PGA as indicated against binding of A/H1N1 virus and A/H3N2 virus to guinea pig erythrocytes.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
J Antimicrob Chemother | © The Author Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please

6. Figure 4. Comparison of the anti-influenza virus activities of compounds targeting HA. Reduction of influenza A/Narita/1/2009 viruses in AX4 cells was visualized as a decrease in the size and number of infectious focus-forming units displayed by coloration (top panel) and graphically illustrated (bottom panel) as a function of the concentration of 6SLN-lipo PGA, fetuin or 6SGP with non-linear regression analysis. Each point is each value of duplicate wells.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
J Antimicrob Chemother | © The Author Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please

7. Figure 7. A proposed cellular mechanism of the action of 6SLN-lipo PGA against human influenza virus infection. (a) Proposed formation of 6SLN-lipo PGA in solution. (b) A simplified hypothetical model of HA and NA dual control of virus attachment to and discharge from receptors in the absence or presence of 6SLN-lipo PGA and/or NAI. (I) In the absence of both 6SLN-lipo PGA (magenta double-solid line with side chains) and NAI (red diamond), HAs mediate virus attachment to sialylated cell membrane receptors, whereas NAs catalyse removal of Sia residues, discharging HAs from their attachment. Balanced HA–NA activities are critical for releasing the virus from a non-endocytosis site for virus binding to an endocytosis site to achieve successful infection. (II) When 6SLN-lipo PGAs are present, they block virus binding to the host cell through potentially cooperative inhibitions of (i) 6SLNs competing with cell membrane receptors for binding to the viral HAs, (ii) acyl chains stabilizing the compound/HA complex via hydrophobic interactions and (iii) PGAs stabilizing the viral membrane sterically from attachment to the negatively charged sialylated host cell membrane. (III) When NAIs are present, they compete with sialylated cell membrane receptors for the active sites of NAs, blocking sialidase activity and consequently preventing discharge of HAs from their binding. (IV) In the presence of both 6SLN-lipo PGAs and NAIs, 6SLN-lipo PGAs arrest the virus and impede virus attachment to the cell membrane receptor and NAIs prevent discharge of HAs from binding to either sialylated cell membrane receptors or 6SLN-lipo PGAs [freezing the virus with its binding molecule(s)], resulting in a greater reduction in virus release and entry than the summation of the effects of the individual inhibitor. This figure appears in colour in the online version of JAC and in black and white in the print version of JAC.
From: 6SLN-lipo PGA specifically catches (coats) human influenza virus and synergizes neuraminidase-targeting drugs for human influenza therapeutic potential
J Antimicrob Chemother. 2015;70(10): doi: /jac/dkv193
J Antimicrob Chemother | © The Author Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please