A severe acute respiratory syndrome coronavirus that lacks the E gene is attenuated in vitro and in vivo

J Virol. 2007 Feb;81(4):1701-13. doi: 10.1128/JVI.01467-06. Epub 2006 Nov 15.

Abstract

A deletion mutant of severe acute respiratory syndrome coronavirus (SARS-CoV) has been engineered by deleting the structural E gene in an infectious cDNA clone that was constructed as a bacterial artificial chromosome (BAC). The recombinant virus lacking the E gene (rSARS-CoV-DeltaE) was rescued in Vero E6 cells. The recovered deletion mutant grew in Vero E6, Huh-7, and CaCo-2 cells to titers 20-, 200-, and 200-fold lower than the recombinant wild-type virus, respectively, indicating that although the E protein has an effect on growth, it is not essential for virus replication. No differences in virion stability under a wide range of pH and temperature were detected between the deletion mutant and recombinant wild-type viruses. Although both viruses showed the same morphology by electron microscopy, the process of morphogenesis seemed to be less efficient with the defective virus than with the recombinant wild-type one. The rSARS-CoV-DeltaE virus replicated to titers 100- to 1,000-fold lower than the recombinant wild-type virus in the upper and lower respiratory tract of hamsters, and the lower viral load was accompanied by less inflammation in the lungs of hamsters infected with rSARS-CoV-DeltaE virus than with the recombinant wild-type virus. Therefore, the SARS-CoV that lacks the E gene is attenuated in hamsters, might be a safer research tool, and may be a good candidate for the development of a live attenuated SARS-CoV vaccine.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caco-2 Cells
  • Chlorocebus aethiops
  • Cricetinae
  • Gene Deletion
  • Humans
  • Respiratory System / virology
  • Severe Acute Respiratory Syndrome / virology*
  • Severe acute respiratory syndrome-related coronavirus / physiology*
  • Vero Cells
  • Viral Structural Proteins / genetics*
  • Virus Replication

Substances

  • Viral Structural Proteins