Effect of processed aloe vera gel on immunogenicity in inactivated quadrivalent influenza vaccine and upper respiratory tract infection in healthy adults: A randomized double-blind placebo-controlled trial.

BACKGROUND: Aloe vera is a functional food with various pharmacological functions, including an immune-modulating effect. Until now, A. vera has never been studied as an adjuvant in influenza vaccine, and its effects on upper respiratory tract infection (URI) are unknown. PURPOSE: The objective of our study was to investigate the effect of processed A. vera gel (PAG) on immunogenicity of quadrivalent inactivated influenza vaccine and URI in healthy adults. STUDY DESIGN: A randomized, double-blind, placebo-controlled clinical trial was performed. METHODS: This study was conducted in 100 healthy adults at a single center from September 2017 to May 2018. Subjects were randomly divided into a PAG group (n = 50) and a placebo group (n = 50). The enrolled subjects were instructed to ingest the study drug for 8 weeks. The participants received a single dose of quadrivalent inactivated influenza vaccine after taking the study drug for the first 4 weeks of the study. The primary endpoint was seroprotection rate against at least one viral strain at 4 weeks post-vaccination. Other outcomes were seroprotection rate at 24 weeks post-vaccination, seroconversion rate, geometric mean fold increase (GMFI) at 4 and 24 weeks post-vaccination, seroprotection rate ratio and geometric mean titer ratio (GMTR) at 4 weeks post-vaccination between PAG and placebo groups, and incidence, severity, and duration of URI. RESULTS: The European Committee for proprietary medicinal products (CPMP) evaluation criteria were met at least one in the PAG and placebo groups for all strains. However, there was no significant difference in the seroprotection rate at 4 weeks post-vaccination against all strains in both PAG and placebo groups. Among secondary endpoints, the GMFI at 4 weeks post-vaccination for the A/H3N2 was significantly higher in the PAG than in placebo group. The GMTR as adjuvant effect was 1.382 (95% CI, 1.014-1.1883). Kaplan-Meier curve analysis showed a reduction in incidence of URI (p = 0.035), and a generalized estimating equation model identified a decrease in repeated URI events (odds ratio 0.57; 95% CI, 0.39-0.83; p = 0.003) in the PAG group. CONCLUSIONS: Oral intake of PAG did not show a significant increase in seroprotection rate from an immunogenicity perspective. However, it reduced the number of URI episodes. A well-designed further study is needed on the effect of PAG's antibody response against A/H3N2 in the future.

Impact of Adjuvants on the Immunogenicity and Efficacy of Split-Virion H7N9 Vaccine in Ferrets.

BACKGROUND: An effective vaccine is urgently needed against the H7N9 avian influenza virus. We evaluated the immunogenicity and protective efficacy of a split-virion H7N9 vaccine with or without the oil-in-water adjuvants in ferrets. METHODS: Ferrets were vaccinated with 2 doses of unadjuvanted, MF59 or AS03-adjuvanted A/Shanghai/2/2013 (H7N9) vaccine, and the induction of antibodies to hemagglutinin (HA) or neuraminidase proteins was evaluated. Ferrets were then challenged with wild-type H7N9 virus to assess the vaccine's protective efficacy. The vaccine composition and integrity was also evaluated in vitro. RESULTS: Adjuvanted vaccines stimulated robust serum antibody titers against HA and neuraminidase compared with the unadjuvanted vaccines. Although there was a difference in adjuvanticity between AS03 and MF59 at a lower dose (3.75 µg of HA), both adjuvants induced comparable antibody responses after 2 doses of 15 µg. On challenge, ferrets that received adjuvanted vaccines showed lower viral burden than the control or unadjuvanted vaccine group. In vitro examinations revealed that the vaccine contained visible split-virus particles and retained the native conformation of HA recognizable by polyclonal and monoclonal antibodies. CONCLUSIONS: The adjuvanted H7N9 vaccines demonstrated superior immunogenicity and protective efficacy against H7N9 infection in ferrets and hold potential as a vaccination regimen.

Influenza virus variation in susceptibility to inactivation by pomegranate polyphenols is determined by envelope glycoproteins.

Pomegranates have high levels of polyphenols (PPs) and may be a rich source of compounds with antiviral activity. We evaluated the direct anti-influenza activity of three commercially available pomegranate extracts: pomegranate juice (PJ), a concentrated liquid extract (POMxl), and a 93% PP powder extract (POMxp). The acidity of PJ and POMxl solutions contributed to rapid anti-influenza activity, but this was not a factor with POMxp. Studies using POMxp showed that 5min treatment at room temperature with 800µg/ml PPs resulted in at least a 3log reduction in the titers of influenza viruses PR8 (H1N1), X31 (H3N2), and a reassortant H5N1 virus derived from a human isolate. However, the antiviral activity was less against a coronavirus and reassortant H5N1 influenza viruses derived from avian isolates. The loss of influenza infectivity was frequently accompanied by loss of hemagglutinating activity. PP treatment decreased Ab binding to viral surface molecules, suggesting some coating of particles, but this did not always correlate with loss of infectivity. Electron microscopic analysis indicated that viral inactivation by PPs was primarily a consequence of virion structural damage. Our findings demonstrate that the direct anti-influenza activity of pomegranate PPs is substantially modulated by small changes in envelope glycoproteins.

Role of specific hemagglutinin amino acids in the immunogenicity and protection of H5N1 influenza virus vaccines.

If H5N1 influenza viruses become transmissible among humans, vaccination will offer the most effective option to limit their spread. Two human vaccine candidates recently generated by reverse genetics are based on antigenically different hemagglutinin (HA) glycoproteins derived from the A/HK/213/03 (H5N1) and A/Vietnam/1203/04 (H5N1) viruses. Their HA1 amino acid sequences differ at 10 positions, one of which (N154) introduces a potential glycosylation site in A/Vietnam/1203/04 (H5N1). To assess the impact of five amino acids in the putative antigenic sites on immunogenicity and immune protection, we generated a series of whole-virus vaccines that differed only in one or two HA amino acids. Sera from ferrets vaccinated with these inactivated preparations had high virus neutralization titers, but their hemagglutination inhibition (HI) titers were usually low. Interestingly, a recombinant virus in which the HA amino acid S223 (characteristic of 2004 viruses) was converted to N223 (as in A/HK/213/03) resulted in higher HI titers. This observation indicates that specific HA residues, such as N223, increase the sensitivity of the HI assay by altering receptor specificity and/or antibody-antigen binding. Ferrets vaccinated with mutant vaccine viruses were protected against lethal challenge with wild-type A/Vietnam/1203/04 virus. Our results suggest that inclusion of the N223 residue in the HA glycoproteins of diagnostic reference viruses may facilitate the evaluation of vaccine efficacy in humans.