Different formulations of inactivated SARS-CoV-2 vaccine candidates in human compatible adjuvants: Potency studies in mice showed different platforms of immune responses

Several inactivated SARS-CoV-2 vaccines were approved for human use but are not highly potent. Here, different formulations of inactivated SARS-CoV-2 virus in Alum, Montanide 51VG and Montanide ISA720VG adjuvants were developed and then immune responses were assessed. SARS-CoV-2 virus was inactivated with formalin and formulated in the adjuvants. BALB/c mice were immunized subcutaneously with 4µg of experimental vaccines on days 0 and 14 and two weeks after the final immunization, IL-4 and IFN-γ cytokines, CTL activity and specific IgG titer and IgG1, IgG2a, IgG2a/IgG1 ratio and also anti-RBD IgG response were assessed. Immunization with SARS-CoV-2-Montanide ISA51VG showed a significant increase in IFN-γ cytokine versus SARS-CoV-2-Alum, SARS-CoV-2-Montanide ISA720VG and control groups (P<0.0033). Cytokine IL-4 response in SARS-CoV-2-Alum group showed a significant increase versus SARS-CoV-2-Montanide ISA51VG, SARS-CoV-2-Montanide ISA720VG and control groups (P<0.0206). In addition, SARS-CoV-2-Montanide ISA51VG vaccine induced the highest IFN-γ/IL-4 cytokine ratio versus other groups (P<0.0004). CTL activity in SARS-CoV-2- Montanide ISA51 VG and SARS-CoV-2-Montanide ISA720 VG groups showed a significant increase versus SARS-CoV-2-Alum and control groups (P<0.0075). Specific IgG titer in SARS-CoV-2- Montanide ISA51 VG and SARS-CoV-2-Montanide ISA720VG showed significant increase versus SARS-CoV-2-Alum and control groups (P<0.0143). Results of specific IgG1and IgG2a level in SARS-COV-2-Alum, SARS-COV-2-Montanide ISA51VG and SARS-COV-2-Montanide ISA720VG vaccine showed a significant increase versus the control group (P<0.0001) but SARS-COV-2-Montanide ISA51VG and SARS-COV-2-Montanide ISA 720VG groups showed highest IgG2a/IgG1 ratio and a significant increase versus SARS-COV-2-Alum group (P<0.0379). Results of anti-RBD IgG response showed that inactivated SARS-COV-2+Alum and SARS-COV-2-Montanide ISA 720VG vaccine groups demonstrated a significant increase versus SARS-COV-2-Montanide ISA51VG group. It seems that the type of vaccine formulation is a critical parameter that effect on immunologic patterns and vaccine potency. Here, results showed that human compatible oil-based adjuvants were more potent than Alum adjuvant in the induction of cellular and humoral immune responses versus SARS-CoV-2 virus.

Antibody immunoglobulin G1 and immunoglobulin G2a responses against some cystic fluid proteins of Cysticercus bovis in Balb/c mice

Background and Aim: Immunoglobulin (Ig) G1 and IgG2a are the surrogate markers respectively for humoral and cellular immune responses of hosts against antigens including cystic fluid proteins of Cysticercus bovis. A study was conducted to investigate the IgG1 and IgG2a responses of Balb/c mice against some individual cystic fluid proteins of C. bovis in an effort to determine the roles of each protein in inducing the humoral and cellular immune responses in host. Materials and Methods: Individual p71, p31, and p14 proteins of C. bovis were purified by separation of the proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and elution of individual proteins from the gel. Six female Balb/c mice were immunized 4 times at 10-day intervals with the crude cystic fluid proteins, and sera were collected for the measurement of IgG1 and IgG2a levels against the individual proteins. Sera samples collected before the first immunization were used as negative antibody control, sera samples collected after the fourth immunization were used as positive antibody control, and crude cystic fluid protein was used as positive antigen control. Results: All immunized mice were immune to p71, p31, p14, and crude cystic fluid proteins of C. bovis. The crude cystic fluid proteins of C. bovis induced a higher IgG2a than IgG1 level following the first and the second immunizations but switched into a higher IgG1 than IgG2a level following the fourth immunization. Protein 71 kDa (p71) induced a higher IgG2a than IgG1 level following the fourth immunization. In contrast, p14 induced a higher IgG1 than IgG2a level following the fourth immunization. Low and balance IgG1 and IgG2a levels against p31 were observed following the first to the fourth immunizations. Conclusion: Using IgG1 and IgG2a levels as the surrogate markers, it appears that cystic fluid antigens of C. bovis induce both humoral and cellular immune responses in Balb/c mice. The p71 appears to be a better inducer of cellular immune response, whereas p14 is a better inducer of humoral immune response of mice.

Effects of Ginseng Treatment on Neutrophil Chemiluminescence and Immunoglobulin G Subclasses in a Rat Model of Chronic Pseudomonas aeruginosa Pneumonia

ABSTRACT Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is almost impossible to eradicate with antibiotic treatment. In the present study, the effects of treatment with the Chinese herbal medicine ginseng on blood polymorphonuclear leukocyte (PMN) chemiluminescence and serum specific antibody responses were studied in a rat model of chronic P. aeruginosapneumonia mimicking CF. An aqueous extract of ginseng was administered by subcutaneous injection at a dosage of 25 mg/kg of body weight/day for 2 weeks. Saline was used as a control. Two weeks after the start of ginseng treatment, significantly increased PMN chemiluminescence (P ≤ 0.001) and a decreased level in serum of immunoglobulin G (IgG) against P. aeruginosa(P < 0.05) were found. Furthermore, a higher IgG2a level (P < 0.04) but lower IgG1 level (P < 0.04) were found in the ginseng-treated infected group than in the control group. In the ginseng-treated group the macroscopic lung pathology was milder (P = 0.0003) and the percent PMNs in the cells collected by bronchoalveolar lavage was lower (P = 0.0006) than in the control group. However, the alveolar macrophage (AM) chemiluminescence values were not significantly different in the two groups infected with P. aeruginosa. The differences between the ginseng-treated noninfected rats and the control group (without P. aeruginosa lung infection) for the PMN chemiluminescence and AM chemiluminescence were not significant. These results suggest that ginseng treatment leads to an activation of PMNs and modulation of the IgG response to P. aeruginosa, enhancing the bacterial clearance and thereby reducing the formation of immune complexes, resulting in a milder lung pathology. The changes in IgG1 and IgG2a subclasses indicate a possible shift from a Th-2-like to a Th-1-like response. These findings indicate that the therapeutic effects of ginseng may be related to activation of a Th-1 type of cellular immunity and down-regulation of humoral immunity.