Severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection

Abstract

Before the emergence of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) in 2003, only 12 other animal or human coronaviruses were known. The discovery of this virus was soon followed by the discovery of the civet and bat SARS-CoV and the human coronaviruses NL63 and HKU1. Surveillance of coronaviruses in many animal species has increased the number on the list of coronaviruses to at least 36. The explosive nature of the first SARS epidemic, the high mortality, its transient reemergence a year later, and economic disruptions led to a rush on research of the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the virus and the disease. This research resulted in over 4,000 publications, only some of the most representative works of which could be reviewed in this article. The marked increase in the understanding of the virus and the disease within such a short time has allowed the development of diagnostic tests, animal models, antivirals, vaccines, and epidemiological and infection control measures, which could prove to be useful in randomized control trials if SARS should return. The findings that horseshoe bats are the natural reservoir for SARS-CoV-like virus and that civets are the amplification host highlight the importance of wildlife and biosecurity in farms and wet markets, which can serve as the source and amplification centers for emerging infections.

Figures

FIG. 1.

Phylogenetic tree of 28 coronaviruses with complete protein sequences of helicase. Their accession numbers are shown in parentheses. Italic type indicates the complete genome accession numbers since helicase protein sequence accession numbers of these coronaviruses are not available. The helicase of another eight coronaviruses of spotted hyena, cheetah, ferret, puffinosis, rat, pigeon, goose, and duck are not included because no complete protein sequence is available. The classification of Asian leopard cat coronavirus is undefined. The tree was constructed by the neighbor-joining method using clustalX 1.83. The scale bar indicates the estimated number of substitutions per 50 nucleotides. (Data are from references , , , , , and .)

FIG. 2.

Genome arrangement of SARS-CoV. Gray boxes indicate 3CL protease (3CLpro), polymerase (pol), spike (S), envelope (E), membrane (M), and nucleocapsid (N) genes.