Overlaid Lateral Flow Immunoassay for the Simultaneous Detection of Two Variant-Specific SARS-CoV-2 Neutralizing Antibodies.

COVID-19 vaccines have been provided to the general public to build immunity since the 2019 coronavirus pandemic. Once vaccinated, SARS-CoV-2 neutralizing antibodies (NAbs-COVID-19) are needed for excellent protection against COVID-19. However, monitoring NAbs-COVID-19 is complicated and requires hospital visits. Moreover, the resulting NAbs-COVID-19 are effective against different strains of COVID-19 depending on the type of vaccine received. Here, an overlaid lateral flow immunoassay (O-LFIA) was developed for the simultaneous detection of two NAbs-COVID-19 against different virus strains, Delta and Omicron. The O-LFIA was visualized with two T-lines with a single device using competition between the free antigen and the antigen-binding antibody. Angiotensin-converting enzyme 2 (ACE2) immobilized on the T-line binds to the antigen remaining after antibody binding. Under the optimum conditions, the proposed device exhibited 50% inhibition concentrations (IC50 values) of 45.1 and 53.6 ng/mL for the Delta and Omicron variants, respectively. Additionally, the proposed platform was applied to real-world samples of animal and human serum, and the developed immunoassay provided results that were in good agreement with those obtained with the standard method. In conclusion, this developed O-LFIA can be used as an alternative method to detect NAbs-COVID-19 and can be enabled for future advancements toward commercialization.

Heterologous prime-boost immunization induces protection against dengue virus infection in cynomolgus macaques.

IMPORTANCE: Currently licensed dengue vaccines do not induce long-term protection in children without previous exposure to dengue viruses in nature. These vaccines are based on selected attenuated strains of the four dengue serotypes and employed in combination for two or three consecutive doses. In our search for a better dengue vaccine candidate, live attenuated strains were followed by non-infectious virus-like particles or the plasmids that generate these particles upon injection into the body. This heterologous prime-boost immunization induced elevated levels of virus-specific antibodies and helped to prevent dengue virus infection in a high proportion of vaccinated macaques. In macaques that remained susceptible to dengue virus, distinct mechanisms were found to account for the immunization failures, providing a better understanding of vaccine actions. Additional studies in humans in the future may help to establish whether this combination approach represents a more effective means of preventing dengue by vaccination.

Performance evaluation of a novel platelet count parameter, hybrid platelet count, on the BC-780 automated hematology analyzer.

OBJECTIVES: Automated hematology analysis is expected to improve the performance of platelet counting. We evaluated the performance of a new platelet counting, hybrid (PLT-H) and also impedance (PLT-I) and optical (PLT-O) on the BC-780 automated hematology analyzer compared to the international reference method (IRM) in blood samples with thrombocytopenic and platelet interference. METHODS: The basic platelet count performance of the BC-780 automated hematology analyzer was evaluated according to the requirements of the Clinical Laboratory and Standards Institute (CLSI) Document H26-A2. Additionally, the thrombocytopenic (low PLT count) blood samples and the platelet interference blood samples including fragmented red blood cells (RBCs), microcytes or small RBCs, and giant platelets were determined with the BC-780 hematology analyzer compared to the IRM. RESULTS: Blank counting and the carry-over contamination rate of platelet count using the BC-780 both met the manufacturers' claim. For both 123 thrombocytopenic and 232 platelet interference blood samples (72 fragmented RBCs, 91 microcytes and 51 giant platelets), all three platelet counting methods exhibited high comparability with the IRM (the lowest correlation (r)=0.916). Interestingly, the comparability of PLT-H (r=0.928-0.986) with the IRM was better than that of PLT-I (r=0.916-0.979). CONCLUSIONS: The performance of PLT-H in the BC-780 met the manufacturer's specifications. PLT-H exhibits better reproducibility than did PLT-I, correlates well with the PLT-O for thrombocytopenic samples and demonstrates good anti-interference ability. PLT-H counting is therefore recommended as a zero-cost alternative platelet counting method for platelet interference samples in clinical settings.

Performance evaluation of alternate ESR measurement method using BC-780 automated hematology analyzer: a comparison study with the Westergren reference method.

OBJECTIVES: Implementation of alternate erythrocyte sedimentation rate (ESR) measurement method is increasing worldwide due to its various advantages. In this study, we aim to evaluate the analytical performance of the BC-780 automated hematology analyzer in measurement of ESR value. METHODS: Analyzer performance including precision study, carryover, sample stability and potential interferences are examined. Samples with ESR values spanning the whole analytical ESR range are included for method comparison study. Samples with different hematocrit (Hct) and mean corpuscular volume (MCV) values are also analyzed and compared with the results obtained from the Westergren reference method. RESULTS: Precisions and carryover results are consistent with the manufacturers' claim. ESR values do not change significantly in the samples stored at 2-8 °C for 24 h (h) or at room temperature (RT) for 8 h, but significantly decreased (p<0.001) when stored at RT for 24 h. Significant increase in ESR value is documented in samples that are hemolyzed (hemoglobin concentration ranged from 1.28-6.01 g/L) (p=0.010) or lipemic (triglyceride above 4.75 mmol/L) (p=0.001). Method comparison study yields a proportional difference with a regression equation=3.08+ 0.98x. Bland-Altman analysis shows a mean absolute bias of 3.12 mm. The obtained absolute mean biases are below 5 mm in all analytical categories except for the group where MCV>100 fL. CONCLUSIONS: Most tested parameters met the manufacturer's specifications and were comparable to the reference method. Despite the presence of positive bias, it falls within acceptable criteria. Extensive validation against potential interferences such as hemolysis/lipemia is still necessary in future.

Mpox global health emergency: Insights into the virus, immune responses, and advancements in vaccines PART II: Insights into the advancements in vaccines.

Mpox is currently a global health emergency. This review (Part II) aims to provide insights into Mpox vaccines and their advancements, offering easily digestible information for healthcare workers and researchers. Current Mpox vaccines are all live-attenuated, previously approved for smallpox, and are classified into non-replicating (Modified Vaccinia Ankara-Bavarian Nordic or MVA-BN) and replicating vaccines (Lister clone16m8 KM Biologic or LC16m8KMB and Acambis2000 or ACAM2000). Replicating vaccines offer long-lasting immunity but are contraindicated for immunocompromised individuals and those with extensive dermatitis. Replicating vaccines are administered as a single dose via epicutaneous scarification, while the non-replicating vaccine is given as two subcutaneous doses. Regulatory approvals in various countries are based on animal challenge studies, with limited effectiveness data available. Only LC16m8 is approved for children in Japan, while the others are approved for individuals aged 18 and older. Clinical trials are currently investigating the efficacy and safety of MVA-BN, particularly in children and for post-exposure prophylaxis (PEP). Novel Mpox vaccines that provide cross-protection against orthopoxviruses are needed, with DNA, subunit, and mRNA platforms under development. MPXV-neutralizing antibody-inducing target antigens for vaccine development include the outer envelope antigens of extracellular enveloped virus (EEV): A35R and B6R, and the inner membrane antigens of intracellular mature virus (IMV): M1R, A29L, H3L, and E8L. Two mRNA vaccines are currently in early clinical stages. Importantly, the COVID-19 pandemic underscored the importance of addressing vaccine disparities and improving global access. Transformative approaches are being explored to overcome this challenge and to enhance access in low- and middle-income countries.

Mpox global health emergency: Insights into the virus, immune responses, and advancements in vaccines PART I: Insights into the virus and immune responses.

Mpox, the zoonotic disease caused by Monkeypox virus (MPXV), is currently a global health emergency. This review (Part I) aims to provide insights into the virus life cycle, epidemiology, host immune responses, and immune evasion mechanisms. Mpox symptoms is similar to smallpox but with lower mortality rates and lower transmissibility. In the past, the virus has been endemic in Central (Clade I) and West (Clade II) African countries. The first outbreak in outside Africa is reported in the United States in 2003. A multi-country outbreak across all continents occurred in 2022, predominantly driven by Clade II. Recently, the emergence of Clade Ib with sustained person-to-person transmission characteristic in the 2023-2024 outbreaks has raised significant public health concerns. Its apparent capacity for rapid spread and potential for causing severe disease highlight the need for enhanced surveillance, especially in regions not traditionally affected by Mpox. Immune responses induced by MPXV infection in humans and animal models provide the insights into the key step in which the host immune response recognizes and responds to the infection. The sophisticated immune evasion strategy by MPXV at both innate and adaptive arms also emerges that are useful for vaccine-based control measures. Taken together, understanding MPXV life cycle, epidemiology and immune response will facilitate better control, limit viral spread, and provide important insights for vaccine development.

Immune responses in COVID-19 and potential vaccines: Lessons learned from SARS and MERS epidemic.

As the world is witnessing the epidemic of COVID-19, a disease caused by a novel coronavirus, SARS-CoV-2, emerging genetics and clinical evidences suggest a similar path to those of SARS and MERS. The rapid genomic sequencing and open access data, together with advanced vaccine technology, are expected to give us more knowledge on the pathogen itself, including the host immune response as well as the plan for therapeutic vaccines in the near future. This review aims to provide a comparative view among SARS-CoV, MERS-CoV and the newly epidemic SARS-CoV-2, in the hope to gain a better understanding of the host-pathogen interaction, host immune responses, and the pathogen immune evasion strategies. This predictive view may help in designing an immune intervention or preventive vaccine for COVID-19 in the near future.

Dengue vaccine: Global development update.

The first licensed dengue vaccine, CYD-TDV (Dengvaxia®), has received regulatory approval in a number of countries. However, this vaccine has some limitations. Its efficacy against DENV2 was consistently lower than other serotypes. Protective efficacy also depended on prior dengue sero-status of the vaccinees. Lower efficacy was observed in children with < 9 years old and dengue-na?ve individuals. More importantly, risk of hospitalization and severe dengue was increased in the youngest vaccine recipients (2-5 years) compared to controls. Thus, the quest of a better vaccine candidate continues. There are two live-attenuated vaccine candidates currently testing in phase III trial including DENVax, developed by US CDC and Inviragen (now licensed to Takeda) and TV003/TV005, constructed by US NIAID. In addition, there are several phase I-II as well as preclinical phase studies evaluating vaccines for safety and immunogenicity, this include other live-attenuated platform/strategy, purified-inactivated viruses formulated with adjuvants, DNA vaccine, subunit vaccine, viral vector and also heterologous prime/boost strategies. The major difficulties of dengue vaccine development are included the lack of the best animal model, various immune status of individual especially in endemic areas and clear cut off of protective immunity. Several research and development efforts are ongoing to find a better effective and accessible dengue vaccine for people needed.

Strategies to improve the immunogenicity of prM+E dengue virus type-2 DNA vaccine.

BACKGROUND: An important goal for dengue vaccines is to induce a high and durable level of neutralizing antibody. OBJECTIVE: Three strategies were investigated for improving the immunogenicity of a prM+E dengue serotype 2 (DENV-2) DNA vaccine: 1) expression in two different plasmids; 2) adjustment of dose; and, 3) introduction of the E sequence of Japanese encephalitis virus (JEV) at the carboxy-terminal portion of DENV-2 E. METHOD: Expression cassettes were designed to encode a full-length prM+E sequence of DENV-2 virus employing human-preferred codons (D2prMEopt), or a chimeric prM+E sequence in which the 100-residue carboxy-terminal region of E was derived from JEV (D2prMEJE20opt). pHIS and pCMVkan in the presence and absence of CpG motif, respectively, were used for cassette expression. The immunogenicity was compared in mice. RESULTS: Three injections of full-length-D2prMEopt in pHIS and pCMVkan induced a comparable neutralizing antibody titer at post-week-2-injection and post-week-4-injection. The 100-µg DNA dose induced a numerically but not statistically higher neutralizing antibody titer than the 10-µg dose. The chimeric-D2prMEJE20opt produced higher extracellular prM and E protein levels in transfected Vero cells, but had a tendency to induce a lower neutralizing antibody titer in mice when compared with the full-length-D2prMEopt. To optimize the immunogenicity of D2prMEopt-DNA candidate, both expression plasmids can be used to generate reproducible high neutralizing titer. A higher dose of DNA immunogen may induce a higher neutralizing antibody response. CONCLUSION: The strategy of the C-terminal region chimeric counterpart with JE20 did not improve but may have reduced the induction of neutralizing antibodies.

The immunogenicity of tetravalent dengue DNA vaccine in mice pre-exposed to Japanese encephalitis or Dengue virus antigens.

BACKGROUND: Asian countries are an endemic area for both dengue (DENV) and Japanese encephalitis viruses (JEV). While JEV vaccines have been used extensively in this region, DENV vaccines remains under development. Whether preexisting naturally acquired or vaccination-induced immunity against JEV may affect the immune response to dengue vaccine candidate is unclear. In this study we used mice previously immunized with JEV vaccines to evaluate the impact on dengue-specific neutralizing antibody responses to a tetravalent dengue DNA vaccine candidate (TDNA). METHODS: A tetravalent cocktail of plasmids encoding pre-membrane and envelope proteins from each dengue serotype was administered into mice which had been previously primed with inactivated or live-attenuated JEV vaccines, or dengue serotype2 virus (DENV-2). Neutralizing antibody response was measured employing a plaque reduction neutralization test at two weeks after the priming and at four weeks after the second dose of the dengue tetravalent plasmids. RESULTS: Inactivated or live-attenuated JEV vaccines, or DENV-2 induced low levels of neutralizing antibodies against the homologous viruses (JE and dengue virus, respectively). DENV-2 injection induced also low levels of cross-reactive antibodies against DENV-1, -3 and -4. JEV vaccines have no effect on the dengue-specific neutralizing antibody responses to the subsequent TDNA immunization. Pre-exposure to DENV-2 infection increased DENV-2 specific response neutralizing antibody to two doses of TDNA plasmids by six folds, but did not affect antibody response to other serotypes. CONCLUSIONS: Priming with JEV vaccines did not impact on dengue virus-specific neutralizing antibody response to a dengue TDNA vaccine candidate in mice.

Immunogenicity of a recombinant plant-produced respiratory syncytial virus F subunit vaccine in mice.

Respiratory syncytial virus (RSV) is a highly infectious respiratory virus that causes serious illness, particularly in young children, elderly people, and those with immunocompromised individuals. RSV infection is the leading cause of infant hospitalization and can lead to serious complications such as pneumonia and bronchiolitis. Currently, there is an RSV vaccine approved exclusively for the elderly population, but no approved vaccine specifically designed for infants or any other age groups. Therefore, it is crucial to continue the development of an RSV vaccine specifically tailored for these populations. In this study, the immunogenicity of the two plant-produced RSV-F Fc fusion proteins (Native construct and structural stabilized construct) were examined to assess them as potential vaccine candidates for RSV. The RSV-F Fc fusion proteins were transiently expressed in Nicotiana benthamiana and purified using protein A affinity column chromatography. The recombinant RSV-F Fc fusion protein was recognized by the monoclonal antibody Motavizumab specific against RSV-F protein. Moreover, the immunogenicity of the two purified RSV-F Fc proteins were evaluated in mice by formulating with different adjuvants. According to our results, the plant-produced RSV-F Fc fusion protein is immunogenic in mice. These preliminary findings, demonstrate the immunogenicity of plant-based RSV-F Fc fusion protein, however, further preclinical studies such as antigen dose and adjuvant optimization, safety, toxicity, and challenge studies in animal models are necessary in order to prove the vaccine efficacy.

Phase II prefusion non-stabilised Covid-19 mRNA vaccine randomised study.

ChulaCov19 mRNA vaccine demonstrated promising phase 1 results. Healthy adults aged 18-59 years were double-blind randomised 4:1 to receive two intramuscular doses of ChulaCov19 50 µg or placebo. Primary endpoints were safety and microneutralization antibody against-wild-type (Micro-VNT50) at day 50. One hundred fifty adults with median (IQR) age 37 (30-46) years were randomised. ChulaCov19 was well tolerated, and most adverse events were mild to moderate and temporary. Geometric mean titres (GMT) of neutralizing titre against wild-type for ChulaCov19 on day 50 were 1367 IU/mL. T-cell IFN-γ-ELISpot showed the highest responses at one week (Day29) after dose 2 then gradually declined. ChulaCov19 50 µg is well tolerated and elicited high neutralizing antibodies and strong T-cell responses in healthy adults.Trial registration number: ClinicalTrials.gov Identifier NCT04566276, 28/09/2020.

High-Sensitivity Troponins and Subclinical Coronary Atherosclerosis Evaluated by Coronary Calcium Score Among Older Asians Living With Well-Controlled Human Immunodeficiency Virus.

Background: Elevated levels of high-sensitivity cardiac troponin (hs-cTn) are suggestive of myocardial cell injury and coronary artery disease. We explored the association between hs-cTn and subclinical arteriosclerosis using coronary artery calcification (CAC) scoring among 337 virally suppressed patients with human immunodeficiency virus (HIV) who were ≥50 years old and without evidence of known coronary artery disease. Methods: Noncontrast cardiac computed tomography and blood sampling for hs-cTn, both subunit I (hs-cTnI) and subunit T (hs-cTnT), were performed. The relationship between CAC (Agatston score) and serum hs-cTn levels was analyzed using Spearman correlation and logistic regression models. Results: The patients, of whom 62% were male, had a median age of 54 years and had been on antiretroviral therapy for a median of 16 years; the CAC score was >0 in 50% of patients and ≥100 in 16%. Both hs-cTn concentrations were positively correlated with the Agatston score, with correlation coefficients of 0.28 and 0.27 (P < .001) for hs-cTnI and hs-cTnT, respectively. hs-cTnI and hs-cTnT concentrations of ≥4 and ≥5.3 pg/mL, respectively, provided the best performance for discriminating patients with Agatston scores ≥100, with a sensitivity and specificity of 76% and 60%, respectively, for hs-cTnI and 70% and 50% for hs-cTnT. In multivariable logistic regression analysis, each log unit increase in hs-cTnI level was independently associated with increased odds of having an Agatston score ≥100 (odds ratio, 2.83 [95% confidence interval, 1.69-4.75]; P <.001). Although not an independent predictor, hs-cTnT was also associated with an increased odds of having an Agatston score ≥100 (odds ratio, 1.58 [95% confidence interval, .92-2.73]; P = .10). Conclusions: Among Asians aged ≥50 years with well-controlled HIV infection and without established cardiovascular disease, 50% had subclinical arteriosclerosis. Increasing hs-cTnI and hs-cTnT concentrations were associated with an increased risk of severe subclinical arteriosclerosis, and hs-cTn may be a potential biomarker to detect severe subclinical arteriosclerosis.

Blockade-of-Binding Activities toward Envelope-Associated, Type-Specific Epitopes as a Correlative Marker for Dengue Virus-Neutralizing Antibody.

Humans infected with dengue virus (DENV) acquire long-term protection against the infecting serotype, whereas cross-protection against other serotypes is short-lived. Long-term protection induced by low levels of type-specific neutralizing antibodies can be assessed using the virus-neutralizing antibody test. However, this test is laborious and time-consuming. In this study, a blockade-of-binding enzyme-linked immunoassay was developed to assess antibody activity by using a set of neutralizing anti-E monoclonal antibodies and blood samples from dengue virus-infected or -immunized macaques. Diluted blood samples were incubated with plate-bound dengue virus particles before the addition of an enzyme-conjugated antibody specific to the epitope of interest. Based on blocking reference curves constructed using autologous purified antibodies, sample blocking activity was determined as the relative concentration of unconjugated antibody that resulted in the same percent signal reduction. In separate DENV-1-, -2-, -3-, and -4-related sets of samples, moderate to strong correlations of the blocking activity with neutralizing antibody titers were found with the four type-specific antibodies 1F4, 3H5, 8A1, and 5H2, respectively. Significant correlations were observed for single samples taken 1 month after infection as well as samples drawn before and at various time points after infection/immunization. Similar testing using a cross-reactive EDE-1 antibody revealed a moderate correlation between the blocking activity and the neutralizing antibody titer only for the DENV-2-related set. The potential usefulness of the blockade-of-binding activity as a correlative marker of neutralizing antibodies against dengue viruses needs to be validated in humans. IMPORTANCE This study describes a blockade-of-binding assay for the determination of antibodies that recognize a selected set of serotype-specific or group-reactive epitopes in the envelope of dengue virus. By employing blood samples collected from dengue virus-infected or -immunized macaques, moderate to strong correlations of the epitope-blocking activities with the virus-neutralizing antibody titers were observed with serotype-specific blocking activities for each of the four dengue serotypes. This simple, rapid, and less laborious method should be useful for the evaluation of antibody responses to dengue virus infection and may serve as, or be a component of, an in vitro correlate of protection against dengue in the future.

Immunogenicity and protective efficacy of SARS-CoV-2 mRNA vaccine encoding secreted non-stabilized spike in female mice.

Establishment of an mRNA vaccine platform in low- and middle-income countries (LMICs) is important to enhance vaccine accessibility and ensure future pandemic preparedness. Here, we describe the preclinical studies of "ChulaCov19", a SARS-CoV-2 mRNA encoding prefusion-unstabilized ectodomain spike protein encapsulated in lipid nanoparticles (LNP). In female BALB/c mice, ChulaCov19 at 0.2, 1, 10, and 30 µg elicits robust neutralizing antibody (NAb) and T cell responses in a dose-dependent relationship. The geometric mean titers (GMTs) of NAb against wild-type (WT, Wuhan-Hu1) virus are 1,280, 11,762, 54,047, and 62,084, respectively. Higher doses induce better cross-NAb against Delta (B.1.617.2) and Omicron (BA.1 and BA.4/5) variants. This elicited immunogenicity is significantly higher than those induced by homologous CoronaVac or AZD1222 vaccination. In a heterologous prime-boost study, ChulaCov19 booster dose generates a 7-fold increase of NAb against Wuhan-Hu1 WT virus and also significantly increases NAb response against Omicron (BA.1 and BA.4/5) when compared to homologous CoronaVac or AZD1222 vaccination. Challenge studies show that ChulaCov19 protects human-ACE-2-expressing female mice from COVID-19 symptoms, prevents viremia and significantly reduces tissue viral load. Moreover, anamnestic NAb response is undetectable in challenge animals. ChulaCov19 is therefore a promising mRNA vaccine candidate either as a primary or boost vaccination and has entered clinical development.

Erythrocyte sedimentation rate measurements using MIX-RATE® X20 and VISION A automated analyzers: Method validation and comparison study.

BACKGROUND: The Westergren method for erythrocyte sedimentation rate (ESR) measurement has a few drawbacks such as being a time-consuming process, poses a risk of biohazard exposure and requires high sample volume. Recent alternative methods and analyzers were developed to overcome those limitations. In this study, we validated two automated ESR analyzers, MIX-RATE® X20 and VISION A, and assessed their analytical performance against the Westergren method. METHODS: The analyzers were validated for inter-run and intra-run precision. Hemolysis interference and sensitivity to fibrinogen were also analysed. Analytical performance was performed using 177 patient samples spanning low (<40 mm/h), medium (40-80 mm/h), and high (>80 mm/h) ESR ranges. Method agreement and bias against the Westergren method were calculated. RESULTS: The highest intra-run imprecision was seen in the low ESR range for both analyzers. They showed very high agreement with the Westergren method assessed by Spearmen rank correlation coefficient analysis, r = 1.000, p < .0001 for both analyzers. Bland-Altman analysis yielded overall insignificant mean biases for all comparisons. However, systematic positive and negative bias were observed at medium and high ESR levels analysed by MIX-RATE® X20 while negative bias was evidenced in the high ESR level measured by VISION A. CONCLUSIONS: Overall, results from both automated ESR analyzers showed comparable analytical performance with the Westergren method especially for low ESR levels. However, both positive and negative systematic bias were documented in the high levels. Thus, for clinical use, it must be assessed whether these biases could affect the cut-off for significant clinical values.

Feasibility of plant-expression system for production of recombinant anti-human IgE: An alternative production platform for therapeutic monoclonal antibodies.

Omalizumab, the anti-immunoglobulin IgE antibody is the only approved and available monoclonal antibody as an auxiliary medicament for the severe respiratory allergic reactions. It forms small size immune complexes by binding to free IgE, thereby inhibiting the interaction of IgE with its receptors. Additionally, the anti-IgE can also differently shape the airflow by impeding the stimulation of IgE receptors present on structural cells in the respiratory tract. The present study aimed to use plants as an expression system for anti-human IgE antibody production, using Nicotiana benthamiana as hosts. Recombinant Agrobacterium tumefaciens containing heavy chain (HC) and light chain (LC) domains of anti-human IgE were co-transformed in N. benthamiana. The assembling of the antibody and its expression was detected by SDS-PAGE and Western blot analysis. The functional ability of the anti-IgE antibody was determined via its binding capacity with target IgE by ELISA and the inhibition of basophil activation. The anti-human IgE mAb generated in plants was shown to be effective in binding to its target IgE and inhibit the IgE-crosslink in RS-ATL8 reporter cells. Although, antibody yield and purification process have to be further optimized, this study demonstrates the use of plant expression system as a promising platform for the production of Omalizumab which showed a comparable in vitro function to that of commercial Omalizumab (Xolair) in the inhibition of basophil activation.

Plant-Produced S1 Subunit Protein of SARS-CoV-2 Elicits Immunogenic Responses in Mice.

SARS-CoV-2 is responsible for the ongoing COVID-19 pandemic. The virus spreads rapidly with a high transmission rate among humans, and hence virus management has been challenging owing to finding specific therapies or vaccinations. Hence, an effective, low-cost vaccine is urgently required. In this study, the immunogenicity of the plant-produced S1 subunit protein of SARS-CoV-2 was examined in order to assess it as a potential candidate for SARS-CoV-2. The SARS-CoV-2 S1-Fc fusion protein was transiently produced in Nicotiana benthamiana. Within four days of infiltration, the SARS-CoV-2 S1-Fc protein was expressed in high quantities, and using protein A affinity column chromatography, plant-produced S1-Fc protein was purified from the crude extracts. The characterization of plant-produced S1-Fc protein was analyzed by SDS-PAGE and Western blotting. Immunogenicity of the purified S1-Fc protein formulated with alum induced both RBD specific antibodies and T cell immune responses in mice. These preliminary results indicated that the plant-produced S1 protein is immunogenic in mice.

Translating a Thin-Film Rehydration Method to Microfluidics for the Preparation of a SARS-CoV-2 DNA Vaccine: When Manufacturing Method Matters.

Previous investigations conducted on a liposomal formulation for a SARS-CoV-2 DNA vaccine manufactured using the thin-film layer rehydration method showed promising immunogenicity results in mice. The adaptation of the liposomal formulation to a scalable and reproducible method of manufacture is necessary to continue the investigation of this vaccine candidate. Microfluidics manufacture shows high potential in method translation. The physicochemical characterization of the blank liposomes produced by thin-film layer rehydration or microfluidics were shown to be comparable. However, a difference in lipid nanostructure in the bilayer resulted in a significant difference in the hydration of the thin-film liposomes, ultimately altering their complexation behavior. A study on the complexation of liposomes with the DNA vaccine at various N/P ratios showed different sizes and Zeta-potential values between the two formulations. This difference in the complexation behavior resulted in distinct immunogenicity profiles in mice. The thin-film layer rehydration-manufactured liposomes induced a significantly higher response compared to the microfluidics-manufactured samples. The nanostructural analysis of the two samples revealed the critical importance of understanding the differences between the two formulations that resulted in the different immunogenicity in mice.

Safety and immunogenicity of a prefusion non-stabilized spike protein mRNA COVID-19 vaccine: a phase I trial.

Effective mRNA SARS-CoV-2 vaccines are available but need to be stored in freezers, limiting their use to countries that have appropriate storage capacity. ChulaCov19 is a prefusion non-stabilized SARS-CoV-2 spike-protein-encoding, nucleoside-modified mRNA, lipid nanoparticle encapsulated vaccine that we report to be stable when stored at 2-8 °C for up to 3 months. Here we report safety and immunogenicity data from a phase I open-label, dose escalation, first-in-human trial of the ChulaCov19 vaccine (NCT04566276). Seventy-two eligible volunteers, 36 of whom were aged 18-55 (adults) and 36 aged 56-75 (elderly), were enroled. Two doses of vaccine were administered 21 d apart at 10, 25 or 50 µg per dose (12 per group). The primary outcome was safety and the secondary outcome was immunogenicity. All three dosages of ChulaCov19 were well tolerated and elicited robust dose-dependent and age-dependent B- and T-cell responses. Transient mild/moderate injection site pain, fever, chills, fatigue and headache were more common after the second dose. Four weeks after the second dose, in the adult cohort, MicroVNT-50 geometric mean titre against wild-type SARS-CoV-2 was 848 (95% CI, 483-1,489), 736 (459-1,183) and 1,140 (854-1,522) IU ml-1 at 10, 25 and 50 µg doses, respectively, versus 285 (196-413) IU ml-1 for human convalescent sera. All dose levels elicited 100% seroconversion, with geometric mean titre ratios 4-8-fold higher than for human convalescent sera (P < 0.01), and high IFNγ spot-forming cells per million peripheral blood mononuclear cells. The 50 µg dose induced better cross-neutralization against Alpha, Beta, Gamma and Delta variants than lower doses. ChulaCov19 at 50 µg is well tolerated and elicited higher neutralizing antibodies than human convalescent sera, with strong T-cell responses. These antibodies cross-neutralized four variants of concern. ChulaCov19 has proceeded to phase 2 clinical trials. We conclude that the mRNA vaccine expressing a prefusion non-stabilized spike protein is safe and highly immunogenic.