The p40 subunit of interleukin (IL)-12 promotes stabilization and export of the p35 subunit: implications for improved IL-12 cytokine production.

IL-12 is a 70-kDa heterodimeric cytokine composed of the p35 and p40 subunits. To maximize cytokine production from plasmid DNA, molecular steps controlling IL-12p70 biosynthesis at the posttranscriptional and posttranslational levels were investigated. We show that the combination of RNA/codon-optimized gene sequences and fine-tuning of the relative expression levels of the two subunits within a cell resulted in increased production of the IL-12p70 heterodimer. We found that the p40 subunit plays a critical role in enhancing the stability, intracellular trafficking, and export of the p35 subunit. This posttranslational regulation mediated by the p40 subunit is conserved in mammals. Based on these findings, dual gene expression vectors were generated, producing an optimal ratio of the two subunits, resulting in a ~1 log increase in human, rhesus, and murine IL-12p70 production compared with vectors expressing the wild type sequences. Such optimized DNA plasmids also produced significantly higher levels of systemic bioactive IL-12 upon in vivo DNA delivery in mice compared with plasmids expressing the wild type sequences. A single therapeutic injection of an optimized murine IL-12 DNA plasmid showed significantly more potent control of tumor development in the B16 melanoma cancer model in mice. Therefore, the improved IL-12p70 DNA vectors have promising potential for in vivo use as molecular vaccine adjuvants and in cancer immunotherapy.

DNA vaccination by intradermal electroporation induces long-lasting immune responses in rhesus macaques.

BACKGROUND: A desirable HIV vaccine should induce protective long-lasting humoral and cellular immune responses. METHODS: Macaques were immunized by env DNA, selected from a panel of recently transmitted SIVmac251 Env using intradermal electroporation as vaccine delivery method and magnitude, breadth and longevity of humoral and cellular immune responses. RESULTS: The macaques developed high, long-lasting humoral immune responses with neutralizing capacity against homologous and heterologous Env. The avidity of the antibody responses was also preserved over 1-year follow-up. Analysis of cellular immune responses demonstrated induction of Env-specific memory T cells harboring granzyme B, albeit their overall levels were low. Similar to the humoral responses, the cellular immunity was persistent over the ~1-year follow-up. CONCLUSION: These data show that vaccination by this intradermal DNA delivery regimen is able to induce potent and durable immune responses in macaques.

Phase III Pivotal comparative clinical trial of intranasal (iNCOVACC) and intramuscular COVID 19 vaccine (Covaxin®).

One of the most preferable characteristics for a COVID-19 vaccine candidate is the ability to reduce transmission and infection of SARS-CoV-2, in addition to disease prevention. Unlike intramuscular vaccines, intranasal COVID-19 vaccines may offer this by generating mucosal immunity. In this open-label, randomised, multicentre, phase 3 clinical trial (CTRI/2022/02/40065; ClinicalTrials.gov: NCT05522335), healthy adults were randomised to receive two doses, 28 days apart, of either intranasal adenoviral vectored SARS-CoV-2 vaccine (BBV154) or licensed intramuscular vaccine, Covaxin®. Between April 16 and June 4, 2022, we enrolled 3160 subjects of whom, 2971 received 2 doses of BBV154 and 161 received Covaxin. On Day 42, 14 days after the second dose, BBV154 induced significant serum neutralization antibody titers against the ancestral (Wuhan) virus, which met the pre-defined superiority criterion for BBV154 over Covaxin®. Further, both vaccines showed cross protection against Omicron BA.5 variant. Salivary IgA titers were found to be higher in BBV154. In addition, extensive evaluation of T cell immunity revealed comparable responses in both cohorts due to prior infection. However, BBV154 showed significantly more ancestral specific IgA-secreting plasmablasts, post vaccination, whereas Covaxin recipients showed significant Omicron specific IgA-secreting plasmablasts only at day 42. Both vaccines were well tolerated. Overall reported solicited reactions were 6.9% and 25.5% and unsolicited reactions were 1.2% and 3.1% in BBV154 and Covaxin® participants respectively.

Immunogenicity and reactogenicity of an inactivated SARS-CoV-2 vaccine (BBV152) in children aged 2-18 years: interim data from an open-label, non-randomised, age de-escalation phase 2/3 study.

BACKGROUND: Despite having milder symptoms than adults, children are still susceptible to and can transmit SARS-CoV-2. Vaccination across all age groups is therefore necessary to curtail the pandemic. Among the available COVID-19 vaccine platforms, an inactivated vaccine platform has the advantage of excellent safety profile across all age groups; hence, we conducted an age de-escalation study to assess the safety, reactogenicity, and immunogenicity of an inactivated COVID-19 vaccine, BBV152 (COVAXIN; Bharat Biotech International, Hyderabad, India), in children aged 2-18 years. METHODS: In this phase 2/3 open-label, non-randomised, multicentre study done in six hospitals in India, healthy children (male or female) aged 2-18 years were eligible for inclusion into the study. Children who had positive SARS-CoV-2 nucleic acid and serology tests at baseline, or any history of previous SARS-CoV-2 infection, or with known immunosuppressive condition were excluded. Children were sequentially enrolled into one of three groups (>12 to ≤18 years [group 1], >6 to 12 years [group 2], or ≥2 to 6 years [group 3]) and administered with adult formulation of BBV152 as two 0·5 mL intramuscular doses on days 0 and 28. Co-primary endpoints were solicited adverse events for 7 days post-vaccination and neutralising antibody titres on day 56, 28 days after the second dose. Immunogenicity endpoints were compared with Biodefense and Emerging Infections, Research Resources Repository (BEI) reference serum samples and from adults who received two doses of BBV152 in the same schedule in a previously reported phase 2 study. The trial is registered with the Clinical Trials Registry, India (CTRI/2021/05/033752) and ClinicalTrials.gov (NCT04918797). FINDINGS: From May 27, 2021, to July 10, 2021, we enrolled 526 children sequentially into groups 1 (n=176), 2 (n=175), and 3 (n=175). Vaccination was well tolerated, with no differences in reactogenicity between the three age groups, and no serious adverse events, deaths, or withdrawals due to an adverse event. Local reactions mainly consisted of mild injection site pain in 46 (26%) of 176 participants in group 1, 61 (35%) of 175 in group 2, and 39 (22%) of 175 in group 3 after dose 1; and 39 (22%) of 176 in group 1, 43 of 175 (25%) in group 2, and 14 of 175 (8%) in group 3 after dose 2; there were no cases of severe pain and few reports of other local reactions. After dose 1, the most frequent solicited systemic adverse event was mild-to-moderate fever, reported in eight (5%) of 176 participants in group 1, 17 (10%) of 175 in group 2, and 22 (13%) of 175 in group 3. No case of severe fever was reported, and rates of all fever were all 4% or less after dose 2. Geometric mean titres (GMTs) of microneutralisation antibodies at day 56 in groups 1 (138·8 [95% CI 111·0-173·6]), 2 (137·4 [99·1-167·5]), and 3 (197·6 [176·4-221·4]) were similar to titres in vaccinated adults (160·1 [135·8-188·8]) and with BEI reference serum samples (103·3 [50·3-202·1]). Similar results were obtained using the plaque reduction neutralisation test (PRNT), in which 166 (95%) of 175 participants in group 1, 165 (98%) of 168 in group 2, and 169 (98%) of 172 in group 3 seroconverted at day 56. The GMT ratio of PRNT titres in children and adults was 1·76 (95% CI 1·32-2·33), indicating a superior response in children compared with adults. INTERPRETATION: BBV152 was well tolerated in children aged 2-18 years, and induced higher neutralising antibody responses than those observed in adults, in whom the efficacy (ie, the prevention or decrease in the severity of COVID-19 infection) has been demonstrated. FUNDING: Bharat Biotech International.

Protective efficacy of COVAXIN® against Delta and Omicron variants in hamster model.

The immunity acquired after natural infection or vaccinations against SARS-CoV-2 tend to wane with time. Here, we compared the protective efficacy of COVAXIN® following two- and three-dose immunizations against the Delta variant and also studied the efficacy of COVAXIN® against Omicron variants in a Syrian hamster model. Despite the comparable neutralizing antibody response against the homologous vaccine strain in both the two-dose and three-dose immunized groups, considerable reduction in the lung disease severity was observed in the 3 dose immunized group after Delta variant challenge. In the challenge study using the Omicron variants, i.e., BA.1.1 and BA.2, lesser virus shedding, lung viral load and lung disease severity were observed in the immunized groups. The present study shows that administration of COVAXIN® booster dose will enhance the vaccine effectiveness against the Delta variant infection and give protection against the BA.1.1 and BA.2 variants.

Persistence of immunity and impact of third dose of inactivated COVID-19 vaccine against emerging variants.

This is a comprehensive report on immunogenicity of COVAXIN® booster dose against ancestral and Variants of Concern (VOCs) up to 12 months. It is well known that neutralizing antibodies induced by COVID-19 vaccines wane within 6 months of vaccination leading to questions on the effectiveness of two-dose vaccination against breakthrough infections. Therefore, we assessed the persistence of immunogenicity up to 6 months after a two or three-dose with BBV152 and the safety of a booster dose in an ongoing phase 2, double-blind, randomized controlled trial (ClinicalTrials.gov: NCT04471519). We report persistence of humoral and cell mediated immunity up to 12 months of vaccination, despite decline in the magnitude of antibody titers. Administration of a third dose of BBV152 increased neutralization titers against both homologous (D614G) and heterologous strains (Alpha, Beta, Delta, Delta Plus and Omicron) with a slight increase in B cell memory responses. Thus, seronversion rate remain high in boosted recipients compared to non-booster, even after 6 months, post third dose against variants. No serious adverse events observed, except pain at the injection site, itching and redness. Hence, these results indicate that a booster dose of BBV152 is safe and necessary to ensure persistent immunity to minimize breakthrough infections of COVID-19, due to newly emerging variants.Trial registration: Registered with the Clinical Trials Registry (India) No. CTRI/2021/04/032942, dated 19/04/2021 and on Clinicaltrials.gov: NCT04471519.

Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152: a double-blind, randomised, phase 1 trial.

BACKGROUND: To mitigate the effects of COVID-19, a vaccine is urgently needed. BBV152 is a whole-virion inactivated SARS-CoV-2 vaccine formulated with a toll-like receptor 7/8 agonist molecule adsorbed to alum (Algel-IMDG) or alum (Algel). METHODS: We did a double-blind, multicentre, randomised, controlled phase 1 trial to assess the safety and immunogenicity of BBV152 at 11 hospitals across India. Healthy adults aged 18-55 years who were deemed healthy by the investigator were eligible. Individuals with positive SARS-CoV-2 nucleic acid and/or serology tests were excluded. Participants were randomly assigned to receive either one of three vaccine formulations (3 µg with Algel-IMDG, 6 µg with Algel-IMDG, or 6 µg with Algel) or an Algel only control vaccine group. Block randomisation was done with a web response platform. Participants and investigators were masked to treatment group allocation. Two intramuscular doses of vaccines were administered on day 0 (the day of randomisation) and day 14. Primary outcomes were solicited local and systemic reactogenicity events at 2 h and 7 days after vaccination and throughout the full study duration, including serious adverse events. Secondary outcome was seroconversion (at least four-fold increase from baseline) based on wild-type virus neutralisation. Cell-mediated responses were evaluated by intracellular staining and ELISpot. The trial is registered at ClinicalTrials.gov (NCT04471519). FINDINGS: Between July 13 and 30, 2020, 827 participants were screened, of whom 375 were enrolled. Among the enrolled participants, 100 each were randomly assigned to the three vaccine groups, and 75 were randomly assigned to the control group (Algel only). After both doses, solicited local and systemic adverse reactions were reported by 17 (17%; 95% CI 10·5-26·1) participants in the 3 µg with Algel-IMDG group, 21 (21%; 13·8-30·5) in the 6 µg with Algel-IMDG group, 14 (14%; 8·1-22·7) in the 6 µg with Algel group, and ten (10%; 6·9-23·6) in the Algel-only group. The most common solicited adverse events were injection site pain (17 [5%] of 375 participants), headache (13 [3%]), fatigue (11 [3%]), fever (nine [2%]), and nausea or vomiting (seven [2%]). All solicited adverse events were mild (43 [69%] of 62) or moderate (19 [31%]) and were more frequent after the first dose. One serious adverse event of viral pneumonitis was reported in the 6 µg with Algel group, unrelated to the vaccine. Seroconversion rates (%) were 87·9, 91·9, and 82·8 in the 3 µg with Algel-IMDG, 6 µg with Algel-IMDG, and 6 µg with Algel groups, respectively. CD4+ and CD8+ T-cell responses were detected in a subset of 16 participants from both Algel-IMDG groups. INTERPRETATION: BBV152 led to tolerable safety outcomes and enhanced immune responses. Both Algel-IMDG formulations were selected for phase 2 immunogenicity trials. Further efficacy trials are warranted. FUNDING: Bharat Biotech International.

Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152: interim results from a double-blind, randomised, multicentre, phase 2 trial, and 3-month follow-up of a double-blind, randomised phase 1 trial.

BACKGROUND: BBV152 is a whole-virion inactivated SARS-CoV-2 vaccine (3 µg or 6 µg) formulated with a toll-like receptor 7/8 agonist molecule (IMDG) adsorbed to alum (Algel). We previously reported findings from a double-blind, multicentre, randomised, controlled phase 1 trial on the safety and immunogenicity of three different formulations of BBV152 (3 µg with Algel-IMDG, 6 µg with Algel-IMDG, or 6 µg with Algel) and one Algel-only control (no antigen), with the first dose administered on day 0 and the second dose on day 14. The 3 µg and 6 µg with Algel-IMDG formulations were selected for this phase 2 study. Herein, we report interim findings of the phase 2 trial on the immunogenicity and safety of BBV152, with the first dose administered on day 0 and the second dose on day 28. METHODS: We did a double-blind, randomised, multicentre, phase 2 clinical trial to evaluate the immunogenicity and safety of BBV152 in healthy adults and adolescents (aged 12-65 years) at nine hospitals in India. Participants with positive SARS-CoV-2 nucleic acid and serology tests were excluded. Participants were randomly assigned (1:1) to receive either 3 µg with Algel-IMDG or 6 µg with Algel-IMDG. Block randomisation was done by use of an interactive web response system. Participants, investigators, study coordinators, study-related personnel, and the sponsor were masked to treatment group allocation. Two intramuscular doses of vaccine were administered on day 0 and day 28. The primary outcome was SARS-CoV-2 wild-type neutralising antibody titres and seroconversion rates (defined as a post-vaccination titre that was at least four-fold higher than the baseline titre) at 4 weeks after the second dose (day 56), measured by use of the plaque-reduction neutralisation test (PRNT50) and the microneutralisation test (MNT50). The primary outcome was assessed in all participants who had received both doses of the vaccine. Cell-mediated responses were a secondary outcome and were assessed by T-helper-1 (Th1)/Th2 profiling at 2 weeks after the second dose (day 42). Safety was assessed in all participants who received at least one dose of the vaccine. In addition, we report immunogenicity results from a follow-up blood draw collected from phase 1 trial participants at 3 months after they received the second dose (day 104). This trial is registered at ClinicalTrials.gov, NCT04471519. FINDINGS: Between Sept 5 and 12, 2020, 921 participants were screened, of whom 380 were enrolled and randomly assigned to the 3 µg with Algel-IMDG group (n=190) or 6 µg with Algel-IMDG group (n=190). Geometric mean titres (GMTs; PRNT50) at day 56 were significantly higher in the 6 µg with Algel-IMDG group (197·0 [95% CI 155·6-249·4]) than the 3 µg with Algel-IMDG group (100·9 [74·1-137·4]; p=0·0041). Seroconversion based on PRNT50 at day 56 was reported in 171 (92·9% [95% CI 88·2-96·2] of 184 participants in the 3 µg with Algel-IMDG group and 174 (98·3% [95·1-99·6]) of 177 participants in the 6 µg with Algel-IMDG group. GMTs (MNT50) at day 56 were 92·5 (95% CI 77·7-110·2) in the 3 µg with Algel-IMDG group and 160·1 (135·8-188·8) in the 6 µg with Algel-IMDG group. Seroconversion based on MNT50 at day 56 was reported in 162 (88·0% [95% CI 82·4-92·3]) of 184 participants in the 3 µg with Algel-IMDG group and 171 (96·6% [92·8-98·8]) of 177 participants in the 6 µg with Algel-IMDG group. The 3 µg with Algel-IMDG and 6 µg with Algel-IMDG formulations elicited T-cell responses that were biased to a Th1 phenotype at day 42. No significant difference in the proportion of participants who had a solicited local or systemic adverse reaction in the 3 µg with Algel-IMDG group (38 [20·0%; 95% CI 14·7-26·5] of 190) and the 6 µg with Algel-IMDG group (40 [21·1%; 15·5-27·5] of 190) was observed on days 0-7 and days 28-35; no serious adverse events were reported in the study. From the phase 1 trial, 3-month post-second-dose GMTs (MNT50) were 39·9 (95% CI 32·0-49·9) in the 3µg with Algel-IMDG group, 69·5 (53·7-89·9) in the 6 µg with Algel-IMDG group, 53·3 (40·1-71·0) in the 6 µg with Algel group, and 20·7 (14·5-29·5) in the Algel alone group. INTERPRETATION: In the phase 1 trial, BBV152 induced high neutralising antibody responses that remained elevated in all participants at 3 months after the second vaccination. In the phase 2 trial, BBV152 showed better reactogenicity and safety outcomes, and enhanced humoral and cell-mediated immune responses compared with the phase 1 trial. The 6 µg with Algel-IMDG formulation has been selected for the phase 3 efficacy trial. FUNDING: Bharat Biotech International. TRANSLATION: For the Hindi translation of the abstract see Supplementary Materials section.

Th1 skewed immune response of whole virion inactivated SARS CoV 2 vaccine and its safety evaluation.

We report the development and evaluation of safety and immunogenicity of a whole virion inactivated (WVI) SARS-CoV-2 vaccine (BBV152), adjuvanted with aluminum hydroxide gel (Algel), or TLR7/8 agonist chemisorbed Algel. We used a well-characterized SARS-CoV-2 strain and an established Vero cell platform to produce large-scale GMP-grade highly purified inactivated antigen. Product development and manufacturing process were carried out in a BSL-3 facility. Immunogenicity and safety were determined at two antigen concentrations (3µg and 6µg), with two different adjuvants, in mice, rats, and rabbits. Our results show that BBV152 vaccine formulations generated significantly high antigen-binding and neutralizing antibody titers (NAb), at both concentrations, in all three species with excellent safety profiles. The inactivated vaccine formulation contains TLR7/8 agonist adjuvant-induced Th1-biased antibody responses with elevated IgG2a/IgG1 ratio and increased levels of SARS-CoV-2-specific IFN-γ+ CD4+ T lymphocyte response. Our results support further development for phase I/II clinical trials in humans.

HIV-1 p24(gag) derived conserved element DNA vaccine increases the breadth of immune response in mice.

Viral diversity is considered a major impediment to the development of an effective HIV-1 vaccine. Despite this diversity, certain protein segments are nearly invariant across the known HIV-1 Group M sequences. We developed immunogens based on the highly conserved elements from the p24(gag) region according to two principles: the immunogen must (i) include strictly conserved elements of the virus that cannot mutate readily, and (ii) exclude both HIV regions capable of mutating without limiting virus viability, and also immunodominant epitopes located in variable regions. We engineered two HIV-1 p24(gag) DNA immunogens that express 7 highly Conserved Elements (CE) of 12-24 amino acids in length and differ by only 1 amino acid in each CE ('toggle site'), together covering >99% of the HIV-1 Group M sequences. Altering intracellular trafficking of the immunogens changed protein localization, stability, and also the nature of elicited immune responses. Immunization of C57BL/6 mice with p55(gag) DNA induced poor, CD4(+) mediated cellular responses, to only 2 of the 7 CE; in contrast, vaccination with p24CE DNA induced cross-clade reactive, robust T cell responses to 4 of the 7 CE. The responses were multifunctional and composed of both CD4(+) and CD8(+) T cells with mature cytotoxic phenotype. These findings provide a method to increase immune response to universally conserved Gag epitopes, using the p24CE immunogen. p24CE DNA vaccination induced humoral immune responses similar in magnitude to those induced by p55(gag), which recognize the virus encoded p24(gag) protein. The inclusion of DNA immunogens composed of conserved elements is a promising vaccine strategy to induce broader immunity by CD4(+) and CD8(+) T cells to additional regions of Gag compared to vaccination with p55(gag) DNA, achieving maximal cross-clade reactive cellular and humoral responses.

IL-12 DNA as molecular vaccine adjuvant increases the cytotoxic T cell responses and breadth of humoral immune responses in SIV DNA vaccinated macaques.

Intramuscular injection of macaques with an IL-12 expression plasmid (0.1 or 0.4 mg DNA/animal) optimized for high level of expression and delivered using in vivo electroporation, resulted in the detection of systemic IL-12 cytokine in the plasma. Peak levels obtained by day 4-5 post injection were paralleled by a rapid increase of IFN-γ, indicating bioactivity of the IL-12 cytokine. Both plasma IL-12 and IFN-γ levels were reduced to basal levels by day 14, indicating a short presence of elevated levels of the bioactive IL-12. The effect of IL-12 as adjuvant together with an SIVmac239 DNA vaccine was further examined comparing two groups of rhesus macaques vaccinated in the presence or absence of IL-12 DNA. The IL-12 DNA-adjuvanted group developed significantly higher SIV-specific cellular immune responses, including IFN-γ (+) Granzyme B (+) T cells, demonstrating increased levels of vaccine-induced T cells with cytotoxic potential, and this difference persisted for 6 mo after the last vaccination. Coinjection of IL-12 DNA led to increases in Gag-specific CD4 (+) and CD4 (+) CD8 (+) double-positive memory T cell subsets, whereas the Env-specific increases were mainly mediated by the CD8 (+) and CD4 (+) CD8 (+) double-positive memory T cell subsets. The IL-12 DNA-adjuvanted vaccine group developed higher binding antibody titers to Gag and mac251 Env, and showed higher and more durable neutralizing antibodies to heterologous SIVsmE660. Therefore, co-delivery of IL-12 DNA with the SIV DNA vaccine enhanced the magnitude and breadth of immune responses in immunized rhesus macaques, and supports the inclusion of IL-12 DNA as vaccine adjuvant.

Comparison of immune responses generated by optimized DNA vaccination against SIV antigens in mice and macaques.

Optimized DNA vectors were constructed comprising the proteome of SIV including the structural, enzymatic, regulatory, and accessory proteins. In addition to native antigens as produced by the virus, fusion proteins and modified antigens with altered secretion, cellular localization and stability characteristics were generated. The DNA vectors were tested for expression upon transfection in human cells. In addition, the vectors were tested either alone or in combinations in mice and macaques, which provided an opportunity to compare immune responses in two animal models. DNA only immunization using intramuscular injection in the absence or presence of in vivo electroporation did not alter the phenotype of the induced T cell responses in mice. Although several fusion proteins induced immune responses to all the components of a polyprotein, we noted fusion proteins that abrogated immune response to some of the components. Since the expression levels of such fusion proteins were not affected, these data suggest that the immune recognition of certain components was altered by the fusion. Testing different DNA vectors in mice and macaques revealed that a combination of DNAs producing different forms of the same antigen generated more balanced immune responses, a desirable feature for an optimal AIDS vaccine.