Severe acute respiratory syndrome coronavirus pathogenesis, disease and vaccines: an update

A novel coronavirus has recently been identified as the cause of severe acute respiratory syndrome (SARS-CoV). The ability of this family of positive strand RNA viruses to move between species and cause severe disease in humans, with the potential for pandemic spread, has been confirmed.

An understanding of the disease and its pathogenesis and the genetics of coronavirus infections, as well as strategies to treat or prevent coronavirus infections, are essential. The history of coronavirus vaccines and the occurrence of laboratory-associated SARS-CoV infections underscore the need for stably attenuated strains of SARS-CoV and other coronaviruses.

Rapid progress has been made in understanding the clinical disease of SARS in adults and children. In adults, systemic infection with clinical and biochemical abnormalities, as well as respiratory infection, may be the rule. SARS is much milder in children younger than 12 years old than it is in adolescents and adults. In children age 12 years and younger, symptoms are generally nonspecific and cold-like. Numerous approaches to the development of SARS-CoV vaccines have been undertaken, and there is evidence that antibodies to the spike protein may be protective from replication and pathology in animal models.

The availability of reverse genetic systems has made it possible to engineer and recover coronavirus variants that contain multiple genetically stable mutations that grow well in culture but are attenuated for replication, virulence or both. Such variants will be platforms for the safe growth of SARS-CoV and candidates for live attenuated vaccines.