Protein Vaccine Induces a Durable, More Broadly Neutralizing Antibody Response in Macaques than Natural Infection with SARS-CoV-2 P.1

FDA-approved and Emergency Use Authorized (EUA) vaccines using new mRNA and viral-vector technology are highly effective in preventing moderate to severe disease, however, information on their long-term efficacy and protective breadth against SARS-CoV-2 Variants of Concern (VOCs) is currently scarce. Here we describe the durability and broad-spectrum VOC immunity of a prefusion-stabilized spike (S) protein adjuvanted with liquid or lyophilized CoVaccine HTTM in cynomolgus macaques. This recombinant subunit vaccine is highly immunogenic and induces robust spike-specific and broadly neutralizing antibody responses effective against circulating VOCs (B.1.351 [Beta], P.1 [Gamma], B.1.617 [Delta]) for at least 3 months after the final boost. Protective efficacy and post-exposure immunity were evaluated using a heterologous P.1 challenge nearly 3 months after the last immunization. Our results indicate that while immunization with both high and low S doses shorten and reduce viral loads in the upper and lower respiratory tract, a higher antigen dose is required to provide durable protection against disease as vaccine immunity wanes. Histologically, P.1 infection causes similar COVID-19-like lung pathology as seen with early pandemic isolates. Post-challenge IgG concentrations were restored to peak immunity levels and vaccine-matched and cross-variant neutralizing antibodies were significantly elevated in immunized macaques indicating an efficient anamnestic response. Only low levels of P.1-specific neutralizing antibodies with limited breadth were observed in control (non-vaccinated but challenged) macaques suggesting that natural infection may not prevent reinfection by other VOCs. Overall, these results demonstrate that a properly dosed and adjuvanted recombinant subunit vaccine can provide long-lasting and protective immunity against circulating VOCs.

Assessment of the acid phosphatase CP01850 from Corynebacterium pseudotuberculosis in DNA and subunit vaccine formulations against caseous lymphadenitis

ABSTRACT The target cp1002_RS01850 from Corynebacterium pseudotuberculosis was used to construct a DNA and recombinant subunit vaccine against caseous lymphadenitis. Recombinant protein rCP01850 was expressed in Escherichia coli using pAE vector, and DNA vaccine was engineered with pTARGET vector. BALB/c mice were divided in five groups containing eight animals each, inoculated with: pTARGET/cp01850 as DNA vaccine (G1); rCP01850 plus Al (OH)3 as recombinant subunit vaccine (G2); pTARGET/cp01850 and a boost with rCP01850 plus Al (OH)3 (G3); pTARGET (G4); or Al (OH)3 (G5). Mice were inoculated and blood samples were collected on days 0, 21, and 42 for the analysis of total IgG, IgG1 and IgG2a by ELISA. In each group, five animals were challenged with Mic-6 C. pseudotuberculosis strain, and three were used for cytokine quantification by qPCR. Although no group has been protected by vaccines against lethal challenge, G2 showed an increase in the survival rate after challenge. Significantly higher levels of IL-4, IL-12, IFN-γ, total IgG, IgG1 and IgG2a were also detected for G2, evidencing a mixed Th1/Th2 immunological profile. In conclusion, despite no protection level provided by different vaccinal strategies using cp1002_RS01850 from C. pseudotuberculosis, G2 developed a Th1/Th2 immune response with an increase in survival rate.

Efficacy, effectiveness, and safety of herpes zoster vaccines in adults aged 50 and older: systematic review and network meta-analysis

ObjectiveTo compare the efficacy, effectiveness, and safety of the herpes zoster live attenuated vaccine with the herpes zoster adjuvant recombinant subunit vaccine or placebo for adults aged 50 and older.DesignSystematic review with bayesian meta-analysis and network meta-analysis.Data sourcesMedline, Embase, and Cochrane Library (inception to January 2017), grey literature, and reference lists of included studies.Eligibility criteria for study selectionExperimental, quasi-experimental, and observational studies that compared the live attenuated vaccine with the adjuvant recombinant subunit vaccine, placebo, or no vaccine in adults aged 50 and older. Relevant outcomes were incidence of herpes zoster (primary outcome), herpes zoster ophthalmicus, post-herpetic neuralgia, quality of life, adverse events, and death.Results27 studies (22 randomised controlled trials) including 2 044 504 patients, along with 18 companion reports, were included after screening 2037 titles and abstracts, followed by 175 full text articles. Network meta-analysis of five randomised controlled trials found no statistically significant differences between the live attenuated vaccine and placebo for incidence of laboratory confirmed herpes zoster. The adjuvant recombinant subunit vaccine, however, was statistically superior to both the live attenuated vaccine (vaccine efficacy 85%, 95% credible interval 31% to 98%) and placebo (94%, 79% to 98%). Network meta-analysis of 11 randomised controlled trials showed the adjuvant recombinant subunit vaccine to be associated with statistically more adverse events at injection sites than the live attenuated vaccine (relative risk 1.79, 95% credible interval 1.05 to 2.34; risk difference 30%, 95% credible interval 2% to 51%) and placebo (5.63, 3.57 to 7.29 and 53%, 30% to 73%, respectively). Network meta-analysis of nine randomised controlled trials showed the adjuvant recombinant subunit vaccine to be associated with statistically more systemic adverse events than placebo (2.28, 1.45 to 3.65 and 20%, 6% to 40%, respectively).ConclusionsUsing the adjuvant recombinant subunit vaccine might prevent more cases of herpes zoster than using the live attenuated vaccine, but the adjuvant recombinant subunit vaccine also carries a greater risk of adverse events at injection sites.Protocol registrationProspero CRD42017056389.