Antiviral Agents and Vaccines 37

that these wild animal species play a significant role in the epidemiology of SARS outbreaks. The civets sold on Chinese markets are born in the wild and then captured and raised on farms. They could therefore have acquired the virus from a wild animal or from other animals during captivity or even from humans. More research is needed before any firm conclusions can be reached (WHO Update 64, 23 May).

Antiviral Agents and Vaccines

Antiviral Drugs

Efforts are underway at various institutions to assess potential anti- SARS-CoV agents in vitro. According to the data available so far, Ribavirin, a "broad spectrum" agent, which is active against various RNA viruses (Tam) and which has been used extensively in SARS patients (Koren), seems to lack in vitro efficacy. Convalescent plasma and normal human immunoglobulin, not containing specific anti- SARS-CoV antibodies, have also been used in SARS patients (Wong). In addition, interferons may be promising candidate drugs (Cinatl 2003b).

In the light of the widespread utilization of traditional Chinese medicine in SARS patients in the Far East it is interesting that glycyrrhizin, a compound found in liquorice roots, was recently reported to have a good in vitro activity against SARS-CoV (Cinatl 2003a).

Further research includes detailed physico-chemical analysis of SARS-CoV proteins to allow the development of novel compounds based on targeted drug design (Anand; Thiel).

Vaccines

There are currently no commercial veterinary vaccines to prevent respiratory coronavirus infections, except for infectious bronchitis virus infections in chickens. Although an effective vaccine cannot be expected to be available soon, the relative ease with which SARSCoV can be propagated in vitro and the availability of vaccines against animal coronaviruses, such as avian infectious bronchitis virus, transmissible gastroenteritis coronavirus of pigs, and feline infec

Kamps and Hoffmann (eds.)