Cocktail Vaccine Research Articles

Safety and Efficacy of the East Coast Fever Muguga Cocktail Vaccine: A Systematic Review

Immunisation of livestock with high quality vaccines is considered an essential approach to controlling many animal diseases. The only currently available commercial vaccine to protect cattle from East Coast fever (ECF), a tick-borne disease caused by Theileria parva, is an unconventional “infection and treatment method” (ITM) involving administration of a combination of live T. parva isolates, referred to as the “Muguga cocktail”, and simultaneous treatment with long-acting oxytetracycline. Veterinary vaccine research and development typically involves studies designed to demonstrate vaccine quality, safety, and efficacy; however, as there were no such purpose-designed registration studies conducted for the Muguga cocktail, evidence for safety and efficacy is solely based on that which is available in the clinical literature. An extensive systematic review was conducted to analyse the evidence available in the literature in order to establish the safety and efficacy of the Muguga cocktail vaccine. A combination of meta-analyses and narrative summaries was conducted. A total of 61 studies met the criteria to be included in the systematic review. The majority of studies demonstrated or reported in favour of the vaccine with regards to safety and efficacy of the Muguga cocktail vaccine. Proximity to buffalo often resulted in reduced vaccine efficacy, and reports of shed and transmission of vaccine components affected the overall interpretation of safety. Better understanding of control options for this devastating livestock disease is important for policymakers and livestock keepers, enabling them to make informed decisions with regards to the health of their animals and their livelihoods.

Molecular docking and pharmacokinetic studies of phytocompounds from Nigerian Medicinal Plants as promising inhibitory agents against SARS-CoV-2 methyltransferase (nsp16)

BackgroundSince the index case was reported in China, COVID-19 has led to the death of at least 4 million people globally. Although there are some vaccine cocktails in circulation, the emergence of more virulent variants of SARS-CoV-2 may make the eradication of COVID-19 more difficult. Nsp16 is an S-adenosyl-L-Methionine-dependent methyltransferase that plays an important role in SARS-CoV-2 viral RNA cap formation—a crucial process that confers viral stability and prevents virus detection by cell innate immunity mechanisms. This unique property makes nsp16 a promising molecular target for COVID-19 drug design. Thus, this study aimed to identify potent phytocompounds that can effectively inhibit SARS-CoV-2 nsp16. We performed in silico pharmacokinetic screening and molecular docking studies using 100 phytocompounds—isolated from fourteen Nigerian plants—as ligands and nsp16 (PDB: 6YZ1) as the target. ResultsWe found that only 59 phytocompounds passed the drug-likeness analysis test. However, after the docking analysis, only six phytocompounds (oxopowelline, andrographolide, deacetylbowdensine, 11, 12-dimethyl sageone, sageone, and quercetin) isolated from four Nigerian plants (Crinum jagus, Andrographis paniculata, Sage plants (Salvia officinalis L.), and Anacardium occidentale) showed good binding affinity with nsp16 at its active site with docking score ranging from − 7.9 to − 8.4 kcal/mol. ConclusionsOur findings suggest that the six phytocompounds could serve as therapeutic agents to prevent viral survival and replication in cells. However, further studies on the in vitro and in vivo inhibitory activities of these 6 hit phytocompounds against SARS-CoV-2 nsp16 are needed to confirm their efficacy and dose.

Screening HLA-A-restricted T cell epitopes of SARS-CoV-2 and the induction of CD8+ T cell responses in HLA-A transgenic mice

Since severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific T cells have been found to play essential roles in host immune protection and pathology in patients with coronavirus disease 2019 (COVID-19), this study focused on the functional validation of T cell epitopes and the development of vaccines that induce specific T cell responses. A total of 120 CD8+ T cell epitopes from the E, M, N, S, and RdRp proteins were functionally validated. Among these, 110, 15, 6, 14, and 12 epitopes were highly homologous with SARS-CoV, OC43, NL63, HKU1, and 229E, respectively; in addition, four epitopes from the S protein displayed one amino acid that was distinct from the current SARS-CoV-2 variants. Then, 31 epitopes restricted by the HLA-A2 molecule were used to generate peptide cocktail vaccines in combination with Poly(I:C), R848 or poly (lactic-co-glycolic acid) nanoparticles, and these vaccines elicited robust and specific CD8+ T cell responses in HLA-A2/DR1 transgenic mice as well as wild-type mice. In contrast to previous research, this study established a modified DC-peptide-PBL cell coculture system using healthy donor PBMCs to validate the in silico predicted epitopes, provided an epitope library restricted by nine of the most prevalent HLA-A allotypes covering broad Asian populations, and identified the HLA-A restrictions of these validated epitopes using competitive peptide binding experiments with HMy2.CIR cell lines expressing the indicated HLA-A allotype, which initially confirmed the in vivo feasibility of 9- or 10-mer peptide cocktail vaccines against SARS-CoV-2. These data will facilitate the design and development of vaccines that induce antiviral CD8+ T cell responses in COVID-19 patients.

A Review of Australian Tick Vaccine Research.

Tick vaccine research in Australia has demonstrated leadership worldwide through the development of the first anti-tick vaccine in the 1990s. Australia’s Commonwealth Scientific and Industrial Research Organisation’s (CSIRO) research led to the development of vaccines and/or precursors of vaccines (such as crude extracts) for both the cattle tick and the paralysis tick. CSIRO commercialised the Bm86 vaccine in the early 1990s for Rhipicephalus australis; however, issues with dosing and lack of global conservation led to the market closure of Tick-GARD in Australia. New research programs arose both locally and globally. The Australian paralysis tick Ixodes holocyclus has perplexed research veterinarians since the 1920s; however, not until the 2000s did biotechnology exist to elucidate the neurotoxin—holocyclotoxin family of toxins leading to a proof of concept vaccine cocktail. This review revisits these discoveries and describes tributes to deceased tick vaccine protagonists in Australia, including Sir Clunies Ross, Dr Bernard Stone and Dr David Kemp.

Simultaneous Immunization with Multiple Diverse Immunogens Alters Development of Antigen-Specific Antibody-Mediated Immunity.

Vaccination remains one of the most successful medical interventions in history, significantly decreasing morbidity and mortality associated with, or even eradicating, numerous infectious diseases. Although traditional immunization strategies have recently proven insufficient in the face of many highly mutable and emerging pathogens, modern strategies aim to rationally engineer a single antigen or cocktail of antigens to generate a focused, protective immune response. However, the effect of cocktail vaccination (simultaneous immunization with multiple immunogens) on the antibody response to each individual antigen within the combination, remains largely unstudied. To investigate whether immunization with a cocktail of diverse antigens would result in decreased antibody titer against each unique antigen in the cocktail compared to immunization with each antigen alone, we immunized mice with surface proteins from uropathogenic Escherichia coli, Mycobacterium tuberculosis, and Neisseria meningitides, and monitored the development of antigen-specific IgG antibody responses. We found that antigen-specific endpoint antibody titers were comparable across immunization groups by study conclusion (day 70). Further, we discovered that although cocktail-immunized mice initially elicited more robust antibody responses, the rate of titer development decreases significantly over time compared to single antigen-immunized mice. Investigating the basic properties that govern the development of antigen-specific antibody responses will help inform the design of future combination immunization regimens.

Definition and Characterization of a Peptide Warehouse for the Patient-Individualized Peptide Vaccination Study (iVAC-L-CLL01) after First Line Therapy of CLL

The treatment of chronic lymphocytic leukemia (CLL) has substantially advanced over the last decade with chemo/immunotherapy as standard of care achieving overall response rates up to 90%. However, besides allogeneic stem cell transplantation, so far no curative treatment for CLL is available. This is mostly due to the persistence of residual CLL cells after therapy (minimal residual disease, MRD), which cause disease relapse. Thus, novel strategies such as peptide-based immunotherapy aiming to eliminate MRD are needed to achieve lasting disease remission or even cure. With this aim, we implemented a first-in-man multi-centric clinical phase II study (iVAC-L-CLL01, NCT02802943), in which patient-individualized peptide vaccination with or without lenalidomide as systemic immune modulator is applied after first-line therapy of CLL. The peptide vaccine cocktail consists of 10 tumor-associated peptides selected according to the HLA ligandome of the individual patients from a pre-manufactured “peptide warehouse”. This peptide warehouse contains CLL-associated antigens, which are frequently and exclusively presented by HLA molecules on the surface of CLL cells. The peptides have been selected using a direct mass spectrometry based comparative analysis of the HLA ligandome of 30 CLL patients and a normal tissue ligandome database (Kowalewski et al. PNAS, 2015). The warehouse includes 35 HLA class I and 5 HLA class II peptides. The HLA class I peptides are restricted by the 7 most common HLA class I allotypes (A*01, A*02, A*03, A*24, B*07, B*08 and B*44). Prior to clinical application, the immunogenicity of the warehouse peptides was validated using different T-cell assays. We performed IFNg ELISpot assays using PBMC obtained from CLL patients and healthy donors. Peptide-specific memory T-cell responses were detected for 20/35 (57%) HLA class I peptides (A*01, A*02, A*03 and B*08) and 5/5 (100%) HLA class II peptides in samples obtained from CLL patients. Immune responses in healthy donors could not be detected for any of the 40 warehouse peptides, indicating a strictly CLL directed T-cell response. The immunogenicity of the remaining peptides could not be approved by detection of spontaneous memory T-cell responses in CLL patients due to lack of HLA-matched CLL-patient samples. Hence, we implemented artificial APC-based in vitro priming assays using CD8+ T cells of healthy donors proofing the ability of the peptides to prime naïve CD8+ T cells. For all 15 analyzed peptides (HLA A*24, B*07 and B*44), an induction of tetramer positive CD8+ T cell populations with frequencies of 0.1-35.1% could be detected. Therefore, all 40 warehouse peptides could be confirmed as immunogenic T-cell epitopesThe iVAC-L-CLL01 study is recruiting since October 2016. Vaccination of the first included study patient was performed in July 2017. DisclosuresNo relevant conflicts of interest to declare.

Sendai Virus-Vectored Vaccines That Express Envelope Glycoproteins of Respiratory Viruses.

Human respiratory syncytial virus (HRSV), human metapneumovirus (HMPV), and human parainfluenza viruses (HPIVs) are leading causes of respiratory disease in young children, the elderly, and individuals of all ages with immunosuppression. Vaccination strategies against these pneumoviruses and paramyxoviruses are vast in number, yet no licensed vaccines are available. Here, we review development of Sendai virus (SeV), a versatile pediatric vaccine that can (a) serve as a Jennerian vaccine against HPIV1, (b) serve as a recombinant vaccine against HRSV, HPIV2, HPIV3, and HMPV, (c) accommodate foreign genes for viral glycoproteins in multiple intergenic positions, (d) induce durable, mucosal, B-cell, and T-cell immune responses without enhanced immunopathology, (e) protect cotton rats, African green monkeys, and chimpanzees from infection, and (f) be formulated into a vaccine cocktail. Clinical phase I safety trials of SeV have been completed in adults and 3–6-year-old children. Clinical testing of SeVRSV, an HRSV fusion (F) glycoprotein gene recombinant, has also been completed in adults. Positive results from these studies, and collaborative efforts with the National Institutes of Health and the Serum Institute of India assist advanced development of SeV-based vaccines. Prospects are now good for vaccine successes in infants and consequent protection against serious viral disease.

Efficacy finding cohort of a cancer peptide vaccine, TAS0313, in treating recurrent glioblastoma.

2038 Background: TAS0313 is a cancer vaccine cocktail comprising three long peptides with a total of 12 cytotoxic T lymphocyte (CTL) epitope peptides. These peptides were derived from eight cancer-associated antigens (EGFR, KUA, LCK, MRP3, PTHRP, SART2, SART3, and WHSC2) that are overexpressed in various cancer types including glioblastoma (GBM). We performed a single-arm, multicenter efficacy confirmatory cohort study as part of the TAS0313 Phase I/II study in patients with recurrent GBM. Methods: The enrolled patients with histologically or cytologically confirmed grade IV GBM (including gliosarcoma, giant cell glioblastoma, and epithelioid glioblastoma) had at least one of the following HLA types: HLA-A*02:01, -A*02:06, -A*02:07, -A*11:01, -A*24:02, -A*31:01, or -A*33:03. Eligible patients were those who received standard radiotherapy and temozolomide, had a confirmed first or second recurrence, or progression with measurable disease outcomes with good performance status (Karnofsky Performance Status score > 70). TAS0313 (27mg) was subcutaneously administered on days 1, 8, and 15 of cycles 1 and 2 and day 1 of cycle 3 or later in 21-day cycles until disease progression or unacceptable toxicity occurred. Tumor response was evaluated using The Response Assessment in Neuro-Oncology criteria. The antigen-specific CTL and immunoglobulin G (IgG) were analyzed by ELISPOT assay and Luminex assay, respectively, before and after treatment. The primary objective was to evaluate the efficacy of TAS0313. Secondary and exploratory methods were used to evaluate the safety and immune response of TAS0313. Results: As of 10th September 2020, 10 patients have been treated with TAS0313 (eight with GBM and two with gliosarcoma). The median age of participants was 56.5 [range, 33–69 years], and methylation status of the MGMT promoter was methylated in four patients, unmethylated in four, and unknown in two. The best overall response was partial response 1/10 (10.0%) and stable disease 4/10 (40.0%). One case showed 69.1% tumor shrinkage. The treatment of two patients was ongoing for over 7 months. The 6-month progression-free survival (PFS) rate was 25.0%, and the median PFS was 2.3 months. The most common adverse drug reactions (ADRs) were grade 1–2 injection site reactions and pyrexia. There were no grade 4 or 5 ADRs. In some patients, TAS0313 treatment was confirmed to increase CTL and IgG levels compared with pre-treatment samples. Conclusions: TAS0313 showed promising efficacy with expected immune responses and favorable safety and tolerability in patients with recurrent GBM. Further investigation of TAS0313 is warranted to validate our findings. Clinical trial information: JapicCTI-183824.

Phase I/II study to evaluate the efficacy of TAS0313, a cancer peptide vaccine, combined with pembrolizumab for locally advanced or metastatic urothelial carcinoma.

4522 Background: TAS0313 is a cancer vaccine cocktail comprising three long peptides with a total of 12 cytotoxic T lymphocyte epitope peptides. We performed a multicenter phase I/II study including patient (pts) with urothelial carcinoma (UC) treated using TAS0313 combined with pembrolizumab. Methods: The enrolled pts with a histologically or cytologically confirmed diagnosis of urothelial carcinoma had at least one of the following HLA types: HLA-A*02:01, -A*02:06, -A*02:07, -A*11:01, -A*24:02, -A*31:01, or -A*33:03. For cohort C1, eligible pts were those who received platinum-based chemotherapy and were naïve to immune checkpoint inhibitors (ICI). For cohort C2, eligible pts were those who progressed onto treatment with pembrolizumab. TAS0313 (9 mg) was subcutaneously administered on days 1, 8, and 15 of cycles 1 and 2 and day 1 of cycle 3 or later in 21-day cycles, while pembrolizumab (200 mg) was intravenously administered on day 1 of cycle 1 or later in 21-day cycles until disease progression or unacceptable toxicity occurred. Tumor response was evaluated using the RECIST v1.1 criteria. The TAS0313 target antigen-specific immunoglobulin G (IgG) was analyzed before and after treatment. The primary objective was to evaluate efficacy, while the secondary objective was to evaluate the safety and tolerability of the combination therapy. Results: As of 10th September 2020, 46 pts with a median age of 71.0 and 65.5 years, in cohort C1 (n = 36) and cohort C2 (n = 10), respectively, have been treated with the combination therapy. For cohorts C1 and C2, the median follow-up duration was 6.47 and 6.95 months, while the median treatment duration was 4.86 and 2.56 months, respectively. In cohort C1, the overall response rate and disease control rate (DCR) were 33.3% (16.7% complete response, 16.7% partial response) and 66.7% (33.3% stable disease), respectively. The median progression-free survival was 5.0 months, median overall survival (OS) was not yet reached, and 1-year OS rate was 74.3%. The best overall response in cohort C2 was stable disease in 5/10 pts, resulting in a DCR of 50.0%. Increase in IgG level was detected after treatment in both the cohorts. The most common adverse drug reactions (ADRs) of TAS0313 and/or pembrolizumab were grade 1–2 injection site reactions and pyrexia. There were no grade 3–5 ADRs with an incidence of ≥10%. Conclusions: This study confirmed the tolerability, safety, and immune response of TAS0313 combined with pembrolizumab in cohorts C1 and C2. We observed promising efficacy in pts with ICI-naïve UC in cohort C1; however, in pts with pembrolizumab-refractory UC in cohort C2, limited efficacy was seen. Therefore, a large-scale randomized study is needed to clarify the benefits of TAS0313 combined with ICI in ICI-naïve pts. Clinical trial information: 183824.

Molecular characterization and population genetics of Theileria parva in Burundi's unvaccinated cattle: Towards the introduction of East Coast fever vaccine.

Theileria parva (T. parva) is a protozoan parasite that causes East Coast fever (ECF). The disease is endemic in Burundi and is a major constraint to livestock development. In this study, the parasite prevalence in cattle in six regions namely; Northern, Southern, Eastern, Western, Central and North Eastern was estimated. Furthermore, the sequence diversity of p67, Tp1 and Tp2 genes was assessed coupled with the population genetic structure of T. parva using five satellite markers. The prevalence of ECF was 30% (332/1109) on microscopy, 60% (860/1431) on ELISA and 79% (158/200) on p104 gene PCR. Phylogenetic analysis of p67 gene revealed that only allele 1 was present in the field samples. Furthermore, phylogenetic analysis of Tp1 and Tp2 showed that the majority of samples clustered with Muguga, Kiambu and Serengeti and shared similar epitopes. On the other hand, genetic analysis revealed that field samples shared only two alleles with Muguga Cocktail. The populations from the different regions indicated low genetic differentiation (FST = 0.047) coupled with linkage disequilibrium and non-panmixia. A low to moderate genetic differentiation (FST = 0.065) was also observed between samples and Muguga cocktail. In conclusion, the data presented revealed the presence of a parasite population that shared similar epitopes with Muguga Cocktail and was moderately genetically differentiated from it. Thus, use of Muguga Cocktail vaccine in Burundi is likely to confer protection against T. parva in field challenge trials.

Harnessing Natural Mosaics: Antibody-Instructed, Multi-Envelope HIV-1 Vaccine Design.

The year 2021 marks the 40th anniversary since physicians recognized symptoms of the acquired immunodeficiency syndrome (AIDS), a disease that has since caused more than 30 million deaths worldwide. Despite the passing of four decades, there remains no licensed vaccine for the human immunodeficiency virus type 1 (HIV-1), the etiologic agent of AIDS. Despite the development of outstanding anti-retroviral drugs, there are currently more than one-half million deaths each year due to AIDS. Here, we revisit a conventional vaccine strategy used for protection against variable pathogens like HIV-1, which combines an array of diverse surface antigens. The strategy uses antibody recognition patterns to categorize viruses and their surface antigens into groups. Then a leader is assigned for each group and group leaders are formulated into vaccine cocktails. The group leaders are ‘natural mosaics’, because they share one or more epitope(s) with each of the other group members. We encourage the application of this conventional approach to HIV-1 vaccine design. We suggest that the partnering of an antibody-instructed envelope cocktail with new vaccine vectors will yield a successful vaccine in the HIV-1 field.

Effect of epitope variant co-delivery on the depth of CD8 T cell responses induced by HIV-1 conserved mosaic vaccines

To stop the HIV-1 pandemic, vaccines must induce responses capable of controlling vast HIV-1 variants circulating in the population as well as those evolved in each individual following transmission. Numerous strategies have been proposed, of which the most promising include focusing responses on the vulnerable sites of HIV-1 displaying the least entropy among global isolates and using algorithms that maximize vaccine match to circulating HIV-1 variants by vaccine cocktails of optimized complementing sequences. In this study, we investigated CD8 T cell responses induced by a bi-valent mosaic of highly conserved HIVconsvX regions delivered by a combination of simian adenovirus ChAdOx1 and poxvirus MVA. We compared partially and fully mono- and bi-valent prime-boost regimens and their ability to elicit T cells recognizing natural epitope variants using an interferon-γ enzyme-linked immunospot (ELISPOT) assay. We used 11 well-defined CD8 T cell epitopes in two mouse haplotypes and, for each epitope, assessed recognition of the two vaccine forms together with the other most frequent epitope variants in the HIV-1 database. We conclude that for the magnitude and depth of epitope recognition, CD8 T cell responses benefitted in most comparisons from the combined bi-valent mosaic and envisage the main advantage of the bi-valent vaccine during its deployment to diverse populations.

First‐in‐human study of the cancer peptide vaccine TAS0313 in patients with advanced solid tumors

TAS0313, a novel cancer vaccine cocktail, was developed to overcome the disadvantages of previously developed short and long peptide vaccines; it comprises several long peptides targeting multiple cancer antigens. We evaluated TAS0313 monotherapy in Japanese patients with advanced solid tumors for which no other therapies were available. In the dose‐finding cohort, patients received TAS0313 (9 or 27 mg) on days 1, 8, and 15 of cycles 1 and 2, and then on day 1 of each subsequent 21‐day cycle. The primary objective was the evaluation of safety and tolerability. Secondary objectives were evaluation of efficacy, tumor responses, and immune activation (CTL, IgG, and tumor‐infiltrating lymphocyte [TIL] levels). The full analysis set contained 10 patients in the 9‐mg group and seven in the 27‐mg group. No dose‐limiting toxicities were reported in cycle 1. All adverse drug reactions (ADRs) were grade 1 or 2; the most common ADRs were injection site‐related events. The best response was stable disease in four of 17 patients. The median progression‐free survival (PFS) duration was 2.2 (95% confidence interval, 1.0‐2.3) months overall; patients with baseline low lymphocyte counts (≤750/μL) had shorter PFS. Compared with baseline, TILs were increased in five patients. Although CTLs, IgG, and TILs were induced, no correlative pattern with clinical outcomes was observed. The safety, tolerability, and induction of immune responses in patients with advanced solid tumors receiving TAS0313 were confirmed. Further evaluation of TAS0313’s efficacy as monotherapy or in combination with pembrolizumab is underway. The study is registered at www.clinicaltrials.jp (JapicCTI‐183824).

Phase I Studies of Peptide Vaccine Cocktails Derived from GPC3, WDRPUH and NEIL3 for Advanced Hepatocellular Carcinoma

Aim: Two peptide cocktail vaccines using glypican-3, WD-repeat-containing protein up-regulated in hepatocellular carcinoma (HCC) and nei endonuclease VIII-like three epitopes were evaluated in advanced HCC in two Phase I studies. Patients & methods: Study 1 evaluated dose-limiting toxicities (DLTs) of peptides 1-3 (HLA-A24-restricted) and study 2 evaluated DLTs of peptides 1-6 (HLA-A24 or A02-restricted). Results: Overall, 18 and 14 patients were enrolled in studies 1 and 2, respectively. No DLTs were observed up to 7.1 mg of the vaccine cocktail. No complete response/partial response was observed. Stable disease was reported in nine and five patients with a disease control rate of 52.9%and 35.7% in studies 1 and 2, respectively. Conclusion: Both vaccines showed good tolerability and potential usefulness against HCC. Clinical trial registration: JapicCTI-121933; JapicCTI-142477.

Protective effect of a DNA vaccine cocktail encoding ROP13 and GRA14 with Alum nano-adjuvant against Toxoplasma gondii infection in mice.

Toxoplasma gondii is an obligate intracellular protozoan parasite that can cause serious public health problems. The development of a safe and effective vaccine against T. gondii is urgently needed to prevent and control the spread of toxoplasmosis. The aim of this study was to evaluate the immune responses induced by a pcGRA14 + pcROP13 vaccine cocktail in BALB/c mice. All groups were immunized intramuscularly three times at two-week intervals. The production of anti-Toxoplasma gondii lysate antigen (TLA) antibodies, lymphocyte proliferation, serum levels of IFN-γ and IL-4 cytokines and the survival time were monitored after vaccination and challenged with the virulent RH strain of T. gondii. The results showed that immunization with the pcGRA14 + pcROP13 DNA vaccine significantly increased the production of specific IgG antibodies and cytokines against toxoplasmosis. Interestingly, high levels of IgG2a and IFN-γ were found in animals vaccinated with DNA vaccine cocktail. Furthermore, immunized mice challenged with the RH strain of T. gondii showed prolonged survival time when compared to control groups (P <0.05). The present study demonstrates the potential of a DNA cocktail vaccine expressing pcGRA14 and pcROP13 in developing specific immune responses and providing effective protection against T. gondii infection.

Personalized gel-droplet monocyte vaccines for cancer immunotherapy.

Among the numerous forms of cancer immunotherapy, cancer vaccines have attracted increasing attention because of their ability to elicit sustained antitumor immune responses and durable tumor regression. Here, a personalized gel-droplet monocyte vaccine (GEMA) derived from host blood was reported. A streamlined microfluidic vaccine production platform was designed to combine the separation of monocytes from host blood and the encapsulation of monocytes in an alginate gel droplet, which simplified the handling of the blood product and permitted the rapid preparation of vaccines. In addition, the application of alginate gel encapsulation not only improved the efficiency of antigen uptake by monocytes, but it also promoted the production of antigen-specific CD8+ T cells in the spleen, resulting in an intense cytotoxic T lymphocyte (CTL) response. Moreover, depending on the disease profile of a specific patient, different adjuvant- and antigen-loaded monocytes could be simultaneously encapsulated in gel droplets to prepare a cocktail vaccine based on patient needs. In this study, anti-PD-1 antibodies were encapsulated in gel droplets as a model adjuvant to obtain a cocktail vaccine, and this demonstrated enhanced antitumor efficacy in a 4T1 breast tumor model. In summary, this study provided a unique vaccine production strategy and an efficient combination therapy approach, holding great promise for the development of personalized cancer vaccines.

Re-reading ACT, BCG, and Low COVID-19 in Africa.

October 11, 2020, marks the seventh month since the World Health Organization (WHO) officially declared COVID-19 a pandemic. Unlike other coronavirus diseases, there is a geographically disproportionate distribution of the incidence of COVID-19 cases around the world. We observed a significantly high COVID-19 cases and deaths in countries and territories with no or very small number of malaria cases or no or low national TB cases in 2018. We speculate that the high incidence of COVID-19 cases and deaths in countries less affected by malaria is partly due to overexposure to malaria which led to the regular use of the artemisinin anti-malaria drugs as well as the regular use of bacillus Calmette-Guérin (BCG) vaccine for TB prevention. The vaccine produced an almost life-long immunity to TB and meningitis to its recipients. We are thus calling for a COVID-19 containment and clinical management protocol that will incorporate the use of the anti-malaria ACT drug cocktail and BCG vaccine on compassionate ground.

Sequence diversity of cytotoxic T cell antigens and satellite marker analysis of Theileria parva informs the immunization against East Coast fever in Rwanda

BackgroundEast Coast fever (ECF) caused by Theileria parva is endemic in Rwanda. In this study, the antigenic and genetic diversity of T. parva coupled with immunization and field challenge were undertaken to provide evidence for the introduction of ECF immunization in Rwanda.MethodsBlood collected from cattle in the field was screened for T. parva using ELISA and PCR targeting the p104 gene. Tp1 and Tp2 gene sequences were generated from field samples and from Gikongoro and Nyakizu isolates. Furthermore, multilocus genotype data was generated using 5 satellite markers and an immunization challenge trial under field conditions using Muguga cocktail vaccine undertaken.ResultsOut of 120 samples, 44 and 20 were positive on ELISA and PCR, respectively. Antigenic diversity of the Tp1 and Tp2 gene sequences revealed an abundance of Muguga, Kiambu and Serengeti epitopes in the samples. A further three clusters were observed on both Tp1 and Tp2 phylogenetic trees; two clusters comprising of field samples and vaccine isolates and the third cluster comprising exclusively of Rwanda samples. Both antigens exhibited purifying selection with no positive selection sites. In addition, satellite marker analysis revealed that field samples possessed both shared alleles with Muguga cocktail on all loci and also a higher proportion of unique alleles. The Muguga cocktail (Muguga, Kiambu and Serengeti) genotype compared to other vaccine isolates, was the most represented in the field samples. Further low genetic sub-structuring (FST = 0.037) coupled with linkage disequilibrium between Muguga cocktail and the field samples was observed. Using the above data to guide a field immunization challenge trial comprising 41 immunized and 40 control animals resulted in 85% seroconversion in the immunized animals and an efficacy of vaccination of 81.7%, implying high protection against ECF.ConclusionsAntigenic and genetic diversity analysis of T. parva facilitated the use of Muguga cocktail vaccine in field conditions. A protection level of 81.7% was achieved, demonstrating the importance of combining molecular tools with field trials to establish the suitability of implementation of immunization campaigns. Based on the information in this study, Muguga cocktail immunization in Rwanda has a potential to produce desirable results.

Protective immunity induced by a DNA vaccine cocktail expressing TgSAG1, TgROP2, and the genetic adjuvant HBsAg against Toxoplasma gondii infection

Toxoplasma gondii is an intracellular obligate parasitic protozoon that can infect all warm-blooded animals, causing zoonotic toxoplasmosis. So far, there is no commercial toxoplasmosis vaccine for human use. In the present study, we constructed a DNA vaccine cocktail which includes the surface protein (SAG1) and the rhoptry protein ROP2 denoted as pEGFP-N1-SAG1-ROP2. In order to improve the efficacy, HBsAg was used as a genetic adjuvant to construct pEGFP-N1-HBsAg-SAG1-ROP2. Two eukaryotic plasmids were transiently transfected into HEK293T cells and the expression was examined using fluorescence microscopy and western blotting. We then immunized Kunming mice intramuscularly with the DNA vaccine. After three immunizations, the immune response was evaluated by measuring antibody levels, cytokine production, percentages of CD4+ and CD8+ T lymphocytes, and the survival times of the T. gondii RH strain challenged mice. The results showed that the two DNA vaccines stimulated Th1 responses, and had a higher antibody titer, IL-2, IL-12, and IFN-γ levels, and percentage of CD4+ and CD8+ T lymphocytes than the control group. In addition, mice immunized with the pEGFP-N1-HBsAg-SAG1-ROP2 vaccine showed increased survival times compared with pEGFP-N1-SAG1-ROP2.

COVID-19 Coronavirus Vaccine Design Using Reverse Vaccinology and Machine Learning.

To ultimately combat the emerging COVID-19 pandemic, it is desired to develop an effective and safe vaccine against this highly contagious disease caused by the SARS-CoV-2 coronavirus. Our literature and clinical trial survey showed that the whole virus, as well as the spike (S) protein, nucleocapsid (N) protein, and membrane (M) protein, have been tested for vaccine development against SARS and MERS. However, these vaccine candidates might lack the induction of complete protection and have safety concerns. We then applied the Vaxign and the newly developed machine learning-based Vaxign-ML reverse vaccinology tools to predict COVID-19 vaccine candidates. Our Vaxign analysis found that the SARS-CoV-2 N protein sequence is conserved with SARS-CoV and MERS-CoV but not from the other four human coronaviruses causing mild symptoms. By investigating the entire proteome of SARS-CoV-2, six proteins, including the S protein and five non-structural proteins (nsp3, 3CL-pro, and nsp8-10), were predicted to be adhesins, which are crucial to the viral adhering and host invasion. The S, nsp3, and nsp8 proteins were also predicted by Vaxign-ML to induce high protective antigenicity. Besides the commonly used S protein, the nsp3 protein has not been tested in any coronavirus vaccine studies and was selected for further investigation. The nsp3 was found to be more conserved among SARS-CoV-2, SARS-CoV, and MERS-CoV than among 15 coronaviruses infecting human and other animals. The protein was also predicted to contain promiscuous MHC-I and MHC-II T-cell epitopes, and the predicted linear B-cell epitopes were found to be localized on the surface of the protein. Our predicted vaccine targets have the potential for effective and safe COVID-19 vaccine development. We also propose that an “Sp/Nsp cocktail vaccine” containing a structural protein(s) (Sp) and a non-structural protein(s) (Nsp) would stimulate effective complementary immune responses.