Purified coronavirus spike protein nanoparticles induce coronavirus neutralizing antibodies in mice

Abstract

Development of vaccination strategies for emerging pathogens are particularly challenging because of the sudden nature of the emergence of these viruses and the long process needed for traditional vaccine development. Therefore, there is a need for development of a rapid method of vaccine development that can respond to emerging pathogens in a short time frame. The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and Middle East respiratory syndrome (MERS-CoV) in late 2012 demonstrate the importance of coronaviruses as emerging pathogens. The spike glycoproteins of coronaviruses reside on the surface of the virion and are responsible for virus entry. The spike glycoprotein is the major immunodominant antigen of coronaviruses and has proven to be an excellent target for vaccine designs that seek to block coronavirus entry and promote antibody targeting of infected cells. Vaccination strategies for coronaviruses have involved live attenuated virus, recombinant viruses, non-replicative virus-like particles expressing coronavirus proteins or DNA plasmids expressing coronavirus genes. None of these strategies has progressed to an approved human coronavirus vaccine in the ten years since SARS-CoV emerged. Here we describe a novel method for generating MERS-CoV and SARS-CoV full-length spike nanoparticles, which in combination with adjuvants are able to produce high titer antibodies in mice.

Human polyclonal immunoglobulin G from transchromosomic bovines inhibits MERS-CoV in vivo

“…2, A 50 assesses cell infection using fluorescence, and the TCID 50 assay assesses cell viability by cytopathic effect endpoint quantification. Neutralizing antibodies were found in the V2 to V5 serum of vaccinated Tc bovines.…”

“…A secondary antibody goat anti-rabbit IgG (heavy and light chain) conjugated to Alexa Fluor 594 (A-11037, Thermo Fisher Scientific) detected the primary antibody and was visualized on Operetta High Content Imager (PerkinElmer). The dilution at which 50% inhibition of relative fluorescence intensity was observed was reported as the FRNA 50 . See Supplementary Materials and Methods for more details.…”

“…The TCID 50 assay was performed as previously described (50). See Supplementary Materials and Methods for more details.…”

An opportunistic Pathogen Afforded Ample Opportunities: Middle East Respiratory Syndrome Coronavirus

“…[87,88] The spike protein and RBD elicit neutralizing antibody responses and have been employed as the payload for a number of platforms [84,89,90] including DNA vaccines, [91], modified vaccinia virus Ankara [92,93], measles virus, [93][94][95][96] human-[25, 97] and chimpanzee-adenovirus-based vectors. [95] There are also Venezuelan equine encephalitis replicons expressing nucleocapsid, [97] nanoparticles, [98] and structural and non-structural deletion mutants of MERS-CoV. [99] Vaccination of camels is likely to be the most rapid, least expensive and best intervention for preventing rare spillovers which then become amplified by humans in healthcare settings.…”

Outbreak Control Policies for Middle East Respiratory Syndrome (MERS): The Present and the Future

“…A large-scale epidemic threatening a potential pandemic? Although a MERS vaccine candidate was successfully tested in mice in 2014, it is still awaiting clinical trials [34]. In order to prevent drastic consequences like that of Ebola, we need to avert delays.…”