Towards a safe and efficient SARS-coronavirus vaccine: Mechanism and prevention of genetic instability of a live attenuated virus

Live attenuated (weakened) viral vaccines are considered safe so long as their “reversal” to a virulent (or disease-causing) virus is prevented. A study published on October 29th in PLOS Pathogens reports on how to rationally modify an effective live attenuated SARS vaccine to make it genetically stable. Luis Enjuanes, from the Centro Nacional de Biotecnología in Madrid, Spain, and colleagues had previously introduced a SARS-CoV lacking the envelope (or E) gene as a promising vaccine candidate. The researchers had shown that this vaccine, which they called SARS-CoV-ΔE, was attenuated in different animal models, indicating that the E protein is necessary for the virus’ ability to cause disease. They had also demonstrated that vaccination with SARS-CoV-ΔE fully protected mice against challenge with virulent SARS-CoV that is lethal in unvaccinated mice, suggesting that it is an efficient vaccine. In this study, the researchers addressed the question of stability of the vaccine candidate. To do...