Complete protection against severe acute respiratory syndrome coronavirus-mediated lethal respiratory disease in aged mice by immunization with a mouse-adapted virus lacking E protein

J Virol. 2013 Jun;87(12):6551-9. doi: 10.1128/JVI.00087-13. Epub 2013 Apr 10.

Abstract

Zoonotic coronaviruses, including the one that caused severe acute respiratory syndrome (SARS), cause significant morbidity and mortality in humans. No specific therapy for any human coronavirus is available, making vaccine development critical for protection against these viruses. We previously showed that recombinant SARS coronavirus (SARS-CoV) (Urbani strain based) lacking envelope (E) protein expression (rU-ΔE) provided good but not perfect protection in young mice against challenge with virulent mouse-adapted SARS-CoV (MA15). To improve vaccine efficacy, we developed a second set of E-deleted vaccine candidates on an MA15 background (rMA15-ΔE). rMA15-ΔE is safe, causing no disease in 6-week-, 12-month-, or 18-month-old BALB/c mice. Immunization with this virus completely protected mice of three ages from lethal disease and effected more-rapid virus clearance. Compared to rU-ΔE, rMA15-ΔE immunization resulted in significantly greater neutralizing antibody and SARS-CoV-specific CD4 and CD8 T cell responses. After challenge, inflammatory cell infiltration, edema, and lung destruction were decreased in the lungs of rMA15-ΔE-immunized mice compared to those in rU-ΔE-immunized 12-month-old mice. Collectively, these results show that immunization with a species-adapted attenuated coronavirus lacking E protein expression is safe and provides optimal immunogenicity and long-term protection against challenge with lethal virus. This approach will be generally useful for development of vaccines protective against human coronaviruses as well as against coronaviruses that cause disease in domestic and companion animals.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Neutralizing / blood
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / blood
  • Antibodies, Viral / immunology
  • CD4-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / immunology
  • Disease Models, Animal
  • Gene Deletion
  • Humans
  • Immunization
  • Lung / pathology
  • Lung / virology
  • Mice
  • Mice, Inbred BALB C
  • SARS Virus / genetics*
  • SARS Virus / immunology*
  • SARS Virus / pathogenicity
  • Severe Acute Respiratory Syndrome / immunology*
  • Severe Acute Respiratory Syndrome / mortality
  • Severe Acute Respiratory Syndrome / prevention & control*
  • Severe Acute Respiratory Syndrome / virology
  • Survival Analysis
  • Vaccination
  • Viral Envelope Proteins / genetics*
  • Viral Load
  • Viral Vaccines / administration & dosage*
  • Viral Vaccines / adverse effects
  • Viral Vaccines / genetics
  • Viral Vaccines / immunology

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • E protein, SARS coronavirus
  • Viral Envelope Proteins
  • Viral Vaccines