HTCC: Broad Range Inhibitor of Coronavirus Entry

<div><p>To date, six human coronaviruses have been known, all of which are associated with respiratory infections in humans. With the exception of the highly pathogenic SARS and MERS coronaviruses, human coronaviruses (HCoV-NL63, HCoV-OC43, HCoV-229E, and HCoV-HKU1) circulate worldwide and typically cause the common cold. In most cases, infection with these viruses does not lead to severe disease, although acute infections in infants, the elderly, and immunocompromised patients may progress to severe disease requiring hospitalization. Importantly, no drugs against human coronaviruses exist, and only supportive therapy is available. Previously, we proposed the cationically modified chitosan, N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC), and its hydrophobically-modified derivative (HM-HTCC) as potent inhibitors of the coronavirus HCoV-NL63. Here, we show that HTCC inhibits interaction of a virus with its receptor and thus blocks the entry. Further, we demonstrate that HTCC polymers with different degrees of substitution act as effective inhibitors of all low-pathogenic human coronaviruses.</p></div

Primers and probes used for a quantitative RT-PCR.

<p>Primers and probes used for a quantitative RT-PCR.</p

HTCC-63 blocks HCoV-NL63 binding to the ACE protein.

<p>LLC-Mk2 cells were incubated with gradient-purified HCoV-NL63 in the presence of control PBS (Virus) or HTCC-63 at 200 μg/ml (Virus+HTCC) or mock. HCoV-NL63 interaction with the ACE2 protein was analyzed with confocal microscopy. Each image represents maximum projection of axial planes. Virus interaction with the ACE2 was marked with white arrows.</p

HTCC-63 inhibits HCoV-NL63, HCoV-OC43, and HCoV-HKU1 replication in human airway epithelium (HAE) cultures.

<p><b>(A)</b> HAE cultures were exposed to HCoV-NL63, HCoV-OC43, HCoV-229E, or HCoV-HKU1 in the presence of HTCC-63 (200 μg/ml) or control PBS. To analyze virus replication kinetics, each day post infection, 100 μl of 1× PBS was applied to the apical surface of HAE cultures and collected after 10 min of incubation at 32°C. Replication of viruses was evaluated using quantitative RT-PCR. The data are presented as Log Removal Value (LRV) compared to the untreated sample. The assay was performed in triplicate, and average values with standard errors are presented. * <i>P</i> < 0.05; ns = not significant.</p

HTCC-63 does not affect HCoV-NL63 attachment to target cells.

<p>LLC-Mk2 cells were incubated with gradient-purified HCoV-NL63 or mock in the presence of control PBS <b>(A)</b> or HTCC-63 at 200 μg/ml <b>(B)</b> for 2 h at 4°C. Analysis of HCoV-NL63 adherence was conducted with flow cytometry using specific antibodies. The data shown are representative of at least three independent experiments, each performed in duplicate.</p

Anticoagulant Properties of Poly(sodium 2‑(acrylamido)-2-methylpropanesulfonate)-Based Di- and Triblock Polymers

Di- and triblock copolymers with low dispersity of molecular weight were synthesized using radical addition–fragmentation chain transfer polymerization. The copolymers contained anionic poly­(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS) block as an anticoagulant component. The block added to lower the toxicity was either poly­(ethylene glycol) (PEG) or poly­(2-(methacryloyloxy)­ethyl phosphorylcholine) (PMPC). The polymers prolonged clotting times both in vitro and in vivo. The influence of the polymer architecture and composition on the efficacy of anticoagulation and safety parameters was evaluated. The polymer with the optimal safety/efficacy profile was PEG47-<i>b</i>-PAMPS108, i.e., a block copolymer with the degrees of polymerization of PEG and PAMPS blocks equal to 47 and 108, respectively. The anticoagulant action of copolymers is probably mediated by antithrombin, but it differs from that of unfractionated heparin. PEG47-<i>b</i>-PAMPS108 also inhibited platelet aggregation in vitro and increased the prostacyclin production but had no antiplatelet properties in vivo. PEG47-<i>b</i>-PAMPS108 anticoagulant activity can be efficiently reversed with a copolymer of PEG and poly­((3-(methacryloylamino)­propyl)­trimethylammonium chloride) (PMAPTAC) (PEG41-<i>b</i>-PMAPTAC53, HBC), which may be attributed to the formation of polyelectrolyte complexes with PEG shells without anticoagulant properties