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First Author:  Shipo Wu 

Journal/preprint name: Nature Communication 

Tags: Vaccine; Ad5; in vivo; Immune response 

Summary 

  • Wu S et al, evaluate the protective efficacy of the mucosal vaccination route, in addition to the normal intramuscular vaccination route. Demonstrating that a single mucosal inoculation of Ad5-nCoV can protect the upper and lower respiratory tracts against SARS-CoV-2. For what they study the induction of antibodies, T-cell responses in wild type BALB/c mice (mouse-adapted model) and ferrets. 

Research Highlights 

  1.  Ad5-nCoV induce humoral and cellular immune responses at week 2 p.i 

  1. Complete protection for the upper and lower respiratory tracts against SARS-CoV-2 infection can be achieved using a single mucosal inoculation of Ad5-nCoV in mice. 

Impact for COVID-19 research:  

  • Although this Ad5-nCov vaccine is already in clinical trials, it shows the benefits of intranasal infection in comparison to intramuscular vaccination route. Highlighting the importance of the vaccination route that should be considered in human clinical trials for the development of vaccines. 

Methodologies: 

  • Study TypeIn vivo Mouse and Ferret model 

  • Important cell lines/viral models used: Virus used is a mouse-adapted SARS-CoV-2/HRB26/human/2020/CHN (HRB26M, GISAID access no. EPI_ISL_459910) which was generated by passaging the human patient isolate in 4-6 week old female mice for 14 passages. Ad5-nCoV consist in a deficient replicative adenovirus which contains a codon optimized version of the full spike protein gene of SARS-CoV-2 based on the Wuhan-Hu-1 strain.  

  • Key Techniques: intramuscular and intranasal vaccination of mice and ferrets with Ad5-nCov-2. Neutralization assay of sera from mice; ELIspot, cellular immune responses in ferrets; cytokine staining of spleen. 

Limitations: 

  • In this study they used a mouse-adapted SARS-CoV-2 (MASC) which is not the Wuhan strain. Although it’s able to infect mouse the mutation MASC contains affect to the RBD section of the spike protein. 

  • The number of animals used is low. Whilst the n=10 per group as there are different conditions the groups are reduced (from 3-4 mice see Fig.2) 

  • As mention by the authors, intranasal vaccination and some virus (such as adenovirus) can cause asthma. There is no data about this might have occurred.