Emerging treatments

Fusion inhibitors

Inhibitors of HR1-HR2 complex formation prevent entry of the virus into target cells. Although extensive experimental data are available, no clinical trials or documentation of efficacy in humans have been reported.[57]

Nitric oxide and nitric oxide donors

These compounds, which inhibit the SARS coronavirus (CoV) replication cycle, have been used as salvage therapy in a few SARS patients, and it has been suggested that nitric oxide has a degree of clinical efficacy against the infection.[58]

Neutralising human monoclonal antibodies

These offer passive protection and should ideally be used in the post-infection period. Although a substantial number of experimental studies exist, there is a lack of clinical data to show efficacy of neutralising human monoclonal antibodies in humans.[59]

Chinese herbs

There is weak evidence that Chinese herbs combined with Western medicines may improve symptoms, quality of life, and absorption of pulmonary infiltration, and decrease the corticosteroid dosage for SARS patients. No difference in decreasing mortality was proved with Chinese herbs combined with Western medicines versus Western medicines alone.[60]

Niclosamide

An anthelmintic drug that inhibits SARS-CoV replication. Only in vitro data exist for niclosamide.[61]

Valinomycin

A cyclodepsipeptide insecticide that acts as a potassium ion transporter, inhibiting viral replication. It is perhaps the most potent agent against SARS-CoV in vitro.[62]

Small interfering RNAs (siRNAs)

These act via post-transcriptional regulation of viral mRNA and are a promising intervention, with no adverse effects observed in animal models.[63]

Aurintricarboxylic acid

This compound inhibits SARS-CoV replication inside host cells. No clinical trials or documentation of efficacy in humans have been reported.[64]

RNA interferon inducer (ampligen)

In animal models, this RNA interferon inducer appears to inhibit virus titres in the lungs. No clinical trials or documentation of efficacy in humans have been reported.[65]

Glycopeptide antibiotics

Various semi-synthetic derivatives of glycopeptide antibiotics have shown inhibitory activity against SARS-CoV. No clinical trials or documentation of efficacy in humans have been reported.[66]

Hesperetin

A phenolic compound that inhibits the cleavage activity of 3CLpro. 3CLpro mediates the proteolytic processing of the replicase polypeptides 1a and 1ab into functional proteins required for the existence of the SARS-CoV virus. Only in vitro data exist for hesperetin.[67]

Diterpenoids

Only in vitro data exist of the inhibitory effects of these compounds on SARS-CoV.[62]

Calpain inhibitors

A class of cellular cysteine proteinases that inhibit SARS-CoV replication. There is a lack of clinical data to show efficacy of calpain inhibitors in humans.[68]

Plant lectins

The activity of these compounds against coronaviruses is based on their interference of 2 targets in the viral replication cycle. Only in vitro data exist for plant lectins.[69]

Glycyrrhizin

An active component of licorice root shown to inhibit the replication of SARS-CoV in vitro. There is a lack of clinical data to show efficacy of glycyrrhizin in humans.[70]

Chloroquine

This antimalarial drug appears to be able to negatively influence virus-receptor binding. It is suggested that chloroquine prevents viral spread in cell culture.[71]

Nelfinavir

This compound has been found to have anti-SARS-CoV activity in experimental models. No clinical trials or documentation of efficacy in humans have been reported.

Vaccines

Peripheral memory B-cell responses are undetectable in recovered SARS patients. In contrast, specific T-cell anamnestic responses can be maintained for at least 6 years. These findings have applications in preparation for the possible re-emergence of SARS.[72] Several candidate vaccines are under development, including inactivated virus vaccine, protein-based vaccine (RBD-Fc), recombinant adeno-associated virus vector vaccine (RBD-rAAV), and attenuated virus vaccine. Immunisation against SARS-CoV, although not available for clinical use at present, appears to be possible.[73][74]

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