Construction Of A Recombinant Chimeric Vesicular Stomatitis Virus Expressing SARS-CoV Spike Protein And Evaluation Its Immunogenicity In Mice And Rhesus Monkeys

Severe acute respiratory syndrome(SARS)is an acute,febrile and fatal infectious disease which caused by severe acute respiratory syndrome coronavirus(SARS-CoV).Although there are no more SARS cases have been reported in China since 2004,SARS is characterized by rapid spread and high mortality rates,so we should pay more attention to this zoonotic disease.In December 2019,COVID-19 epidemic occurred in Hubei province,studies have proved that the virus is a novel coronavirus which highly similar to the SARS-like coronavirus,it can be seen that SARS-CoV still has the potential risk of cross-species transmission,so the development of SARS-CoV reserve vaccine is of great significance for the prevention and control of SARS in China.SARS-CoV belongs to the family Coronaviridae,genus ?-coronavirus.SARS-CoV spike(S)protein is a transmembrane glycoprotein,which mainly responsible for the combination of virus and cell receptor,the induction of virus and cell fusion,and the induction of immune response.In a word,spike protein is the most important immunogenic protein of SARS-CoV.Vesicular stomatitis virus(VSV)belongs to the family Rhabdoviridae,genus Vesiculovirus.VSV has many advantages as recombinant viral vector vaccine carrier.VSV is an RNA virus which genome is not integrated into host cells.VSV also has a fast replication rate and a high titer,a single immunization can produce effective protection.Then the inserted foreign gene in VSV genome is stable and expresses efficiently.Lastly,VSV has low pathogenicity to the general population and has a high safety.In this study,two chimeric recombinant viruses respectively called VSV?G-SARS and VSV?GeGFP-SARS were constructed in which the VSV glycoprotein(G)gene was replaced with the S gene of SARS-CoV.Western blot and CLSM test showed the S protein could express correctly and assemble into the virus capsule.The results of IFA showed the virus was dependent on host cell receptor ACE2 to invaded host cell,indicating that SARS-CoV spike protein was successfully expression in the recombinant virus.The recombinant virus showed the typical shape of bullet virus through electron microscopy.The growth dynamics demonstrated the titer of viruses was lower than that of wtVSV,but still could satisfy the need of immune titer.In the mice safety evaluation,during the observation period all mice were alive and well which proved the virus had good safety in mice.In the evaluation of immune efficacy,the results of neutralization test and ELISA showed virus could stimulate the humoral immunity of mice,then the virus inoculated rhesus monkeys and utilized ELISPOT test to prove rhesus monkeys could produce specific cellular immunity,which showed that the virus had good immunogenicity for mice and rhesus monkeys.Here,we constructed two chimeric recombinant viruses and using the mice and rhesus monkeys to evaluate the immunogenicity of VSV?G-SARS.We prove the recombinant virus has reserves as SARS vaccine potential value,also it is feasible to develop a VSV-vectored vaccine against for SARS-CoV-2.