Thermostable Ebola virus vaccine formulations lyophilized in the presence of aluminum hydroxide

Abstract

No United States Food and Drug Administration-licensed vaccines protective against Ebola virus (EBOV) infections are currently available. EBOV vaccine candidates currently in development, as well as most currently licensed vaccines in general, require transport and storage under a continuous cold chain in order to prevent potential decreases in product efficacy. Cold chain requirements are particularly difficult to maintain in developing countries. To improve thermostability and reduce costly cold chain requirements, a subunit protein vaccine against EBOV was formulated as a glassy solid using lyophilization. Formulations of the key antigen, Ebola glycoprotein (EBOV-GP), adjuvanted with microparticulate aluminum hydroxide were prepared in liquid and lyophilized forms, and the vaccines were incubated at 40°C for 12 weeks. Aggregation and degradation of EBOV-GP were observed in liquid formulations during the 12week incubation period, whereas changes were minimal in lyophilized formulations. Antibody responses against EBOV-GP following three intramuscular immunizations in BALB/c mice were used to determine vaccine immunogenicity. EBOV-GP formulations were equally immunogenic in liquid and lyophilized forms. After lyophilization and reconstitution, adjuvanted vaccine formulations produced anti-EBOV-GP IgG antibody responses in mice similar to those generated against corresponding adjuvanted liquid vaccine formulations. More importantly, antibody responses in mice injected with reconstituted lyophilized vaccine formulations that had been incubated at 40°C for 12 weeks prior to injection indicated that vaccine immunogenicity was fully retained after high-temperature storage, showing promise for future vaccine development efforts.

Recombinant Protein Filovirus Vaccines Protect Cynomolgus Macaques From Ebola, Sudan, and Marburg Viruses

“…Recombinant protein vaccines offer safer, thermostable alternatives to virally vectored vaccines (24,25). In prior publications, we showed that lyophilized component antigens and adjuvant as well as lyophilized complete vaccine formulations were highly stable at 40°C for 12 weeks, maintaining immunogenicity after extended periods at elevated temperatures (7,11). Such thermostability offers a distinct advantage with regard to rapid distribution and stockpiling of vaccines in tropical regions where filovirus outbreaks have historically occurred.…”

“…Our group has developed vaccines comprised of adjuvanted recombinant glycoproteins from EBOV, SUDV and MARV that have demonstrated immunogenicity and protective efficacy in mice (9) and guinea pigs (10). In addition, these vaccine formulations have been successfully thermostabilized by lyophilization, resulting in retention of full immunogenicity after several weeks at high temperatures (11). Here we demonstrate immunogenicity and protective efficacy of recombinant protein filovirus vaccines in cynomolgus macaques, the animal model deemed most predictive of vaccine protection in humans.…”

Recombinant protein subunit SARS-CoV-2 vaccines formulated with CoVaccine HT adjuvant induce broad, Th1 biased, humoral and cellular immune responses in mice

“…It has been used for influenza virus and malaria vaccines and shown to enhance humoral and cellular protective immunity, in particular antibody response [44][45][46][47][48]. In addition, we have successfully utilized CoVaccine HT™ in our previous recombinant subunit EBOV, ZIKV and preliminary SARS-CoV-2 vaccine studies and have shown this adjuvant to elicit robust antibody responses [8][9][10]29]. Use of CoVaccine HT™ with SdTM and SdTM2P yielded significantly enhanced total IgG and neutralizing antibody responses after both the first and second dose as compared to protein alone which reached similar IgG concentrations after two doses as a single dose of the adjuvanted formulations.…”

“…Immunization with recombinant ZIKV E protein induced potent neutralizing titers in mice [9] and non-human primates [8] and protection against viremia after viral challenge. Similarly, immunization with recombinant subunit formulations consisting of the EBOV glycoprotein and matrix proteins VP40 and VP24 was able to induce potent antibody titers and protection in both mouse [10] and guinea pig models [11]. More recently, we have demonstrated that these recombinant subunits, in combination with CoVaccine HT™, can be formulated as a glassy solid using lyophilization.…”

Who is running faster, the virus or the vaccine?

“…Deviations from the required storage conditions may render vaccines unusable, potentially putting users at greater risks of contracting illnesses (Kartoglu and Milstien 2014 ). Important lessons come from the mass vaccination of polio (Billah et al 2017 ), Ebola (Chisholm et al 2019 ; Davis et al 2020 ) and influenza (Dubrovina et al 2018 ). For instance, manufacturers firstly need to test the effectiveness of vaccines in the widest possible temperature ranges (Zipursky et al 2011 ), and make their data accessible to allow enough time of preparation for the upcoming logistics.…”