Severe acute respiratory syndrome (SARS) - Emerging treatments

Nitric oxide and nitric oxide donors

These compounds, which inhibit the SARS-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 by affecting viral RNA production and palmitoylation of the S protein.[61][62]

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.[63]

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.[64]

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.[65][66][67]

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.[68][69]

Glycopeptide antibiotics

Various semi-synthetic derivatives of glycopeptide antibiotics have shown inhibitory activity against SARS-CoV. One high throughput screening study of US Food and Drug Administration (FDA)-approved drugs identified teicoplanin, a glycopeptide antibiotic, as able to block the entry of SARS envelope pseudotyped viruses.[70] No clinical trials or documentation of efficacy in humans have been reported.[71]

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]