Unveiling the Antiviral Properties of Panduratin A through SARS-CoV-2 Infection Modeling in Cardiomyocytes.

Establishing a drug-screening platform is critical for the discovery of potential antiviral agents against SARS-CoV-2. In this study, we developed a platform based on human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to investigate SARS-CoV-2 infectivity, with the aim of evaluating potential antiviral agents for anti-SARS-CoV-2 activity and cardiotoxicity. Cultured myocytes of iPSC-CMs and immortalized human cardiomyocyte cell line (AC-16) were primarily characterized for the expression of cardiac markers and host receptors of SARS-CoV-2. An infectivity model for the wild-type SARS-CoV-2 strain was then established. Infection modeling involved inoculating cells with SARS-CoV-2 at varying multiplicities of infection (MOIs) and then quantifying infection using immunofluorescence and plaque assays. Only iPSC-CMs, not AC16 cells, expressed angiotensin-converting enzyme 2 (ACE-2), and quantitative assays confirmed the dose-dependent infection of iPSC-CMs by SARS-CoV-2, unlike the uninfectable AC16 cells lacking the expression of ACE2. Cytotoxicity was evaluated using MTT assays across a concentration range. An assessment of the plant-derived compound panduratin A (panA) showed cytotoxicity at higher doses (50% cytotoxic concentration (CC50) 10.09 µM) but promising antiviral activity against SARS-CoV-2 (50% inhibition concentration (IC50) 0.8-1.6 µM), suppressing infection at concentrations 10 times lower than its CC50. Plaque assays also showed decreased viral production following panA treatment. Overall, by modeling cardiac-specific infectivity, this iPSC-cardiomyocyte platform enables the reliable quantitative screening of compound cytotoxicity alongside antiviral efficacy. By combining disease pathogenesis and pharmacology, this system can facilitate the evaluation of potential novel therapeutics, such as panA, for drug discovery applications.

DC-SIGN and Galectin-3 individually and collaboratively regulate H5N1 and H7N9 avian influenza A virus infection via interaction with viral envelope hemagglutinin protein.

DC-SIGN and Galectin-3 are two different lectins and have been reported to participate in regulation of several virus infections. WHO has pointed that H5N1 and H7N9 avian influenza viruses (AIVs) play continuous threats to global health. AIV hemagglutinin (HA) protein-a highly glycosylated protein-mediates influenza infection and was proposed to have DC-SIGN and Gal3 interactive domains. This study aims to address the individual and collaborative roles of DC-SIGN and Gal3 toward AIVs infection. Firstly, A549 cells with DC-SIGN expression or Gal3-knockdown, via lentiviral vector-mediated CD209 gene expression or LGALS-3 gene knockdown, respectively were generated. Quantitative reverse transcription PCR (qRT-PCR) results indicated that DC-SIGN expression and Gal3 knockdown in A549 cells significantly promoted and ameliorated HA or NP gene expression, respectively after H5N1 and H7N9-reverse genetics (RG) virus postinfections (P < 0.05). Similar results observed in immunoblotting, indicating that DC-SIGN expression significantly facilitated H5N1-RG and H7N9-RG infections (P < 0.05), whereas Gal3 knockdown significantly reduced both viral infections (P < 0.05). Furthermore, we found that DC-SIGN and Gal3 co-expression significantly enhanced infectivity of both H5N1-RG and H7N9-RG viruses (P < 0.01) and higher regulatory capabilities by DC-SIGN and Gal3 in H5N1-RG than H7N9-RG were noted. The promoting effect mainly relied on exogenous Gal3 and DC-SIGN directly interacting with the HA protein of H5N1 or H7N9 AIVs, subsequently enhancing virus infection. This study sheds light on two different lectins individually and collaboratively regulating H5N1 and H7N9 AIVs infection and suggests that inhibitors against DC-SIGN and Gal3 interacting with HA could be utilized as alternative antiviral strategies.

Facile and Unplugged Surface Plasmon Resonance Biosensor with NIR-Emitting Perovskite Nanocomposites for Fast Detection of SARS-CoV-2.

The emergence of the coronavirus disease 2019 (COVID-19) pandemic prompted researchers to develop portable biosensing platforms, anticipating to detect the analyte in a label-free, direct, and simple manner, for deploying on site to prevent the spread of the infectious disease. Herein, we developed a facile wavelength-based SPR sensor built with the aid of a 3D printing technology and synthesized air-stable NIR-emitting perovskite nanocomposites as the light source. The simple synthesis processes for the perovskite quantum dots enabled low-cost and large-area production and good emission stability. The integration of the two technologies enabled the proposed SPR sensor to exhibit the characteristics of lightweight, compactness, and being without a plug, just fitting the requirements of on-site detection. Experimentally, the detection limit of the proposed NIR SPR biosensor for refractive index change reached the 10-6 RIU level, comparable with that of state-of-the-art portable SPR sensors. In addition, the bio-applicability of the platform was validated by incorporating a homemade high-affinity polyclonal antibody toward the SARS-CoV-2 spike protein. The results demonstrated that the proposed system was capable of discriminating between clinical swab samples collected from COVID-19 patients and healthy subjects because the used polyclonal antibody exhibited high specificity against SARS-CoV-2. Most importantly, the whole measurement process not only took less than 15 min but also needed no complex procedures or multiple reagents. We believe that the findings disclosed in this work can open an avenue in the field of on-site detection for highly pathogenic viruses.

A real-world prospective cohort study of immunogenicity and reactogenicity of ChAdOx1-S[recombinant] among patients with immune-mediated dermatological diseases.

BACKGROUND: Immunogenicity and reactogenicity of COVID-19 vaccines have been established in various groups of immunosuppressed patients; however, studies involving patients with immune-mediated dermatological diseases (IMDDs) are scarce. OBJECTIVES: To investigate the influence of IMDDs on the development of SARS-CoV-2-specific immunity and side-effects following ChAdOx1-S[recombinant] vaccination. METHODS: This prospective cohort study included 127 patients with IMDDs and 97 participants without immune-mediated diseases who received ChAdOx1-S[recombinant]. SARS-CoV-2-specific immunity and side-effect profiles were assessed at 1 month postvaccination and compared between groups. Immunological (primary) outcomes were the percentages of participants who tested positive for neutralizing antibodies [seroconversion rate (SR)] and those who developed T-cell-mediated immunity demonstrated by an interferon-γ-releasing assay (IGRA) [positive IGRA rate (+IGRA)]. Reactogenicity-related (secondary) outcomes were the unsolicited adverse reactions and worsening of IMDD activity reflected by the uptitration of immunosuppressants during and within 1 month of vaccination. RESULTS: Overall, the SR for the IMDD group was similar to that of participants without immune-mediated conditions (75·6 vs. 84·5, P = 0·101), whereas + IGRA was lower (72·4 vs. 88·7, P = 0·003). Reactogenicity was similar between groups. No severe adverse reaction was reported. By stratifying the participants in the IMDD group according to individual disease, the immunogenicity of the vaccine was lowest in patients with autoimmune bullous diseases (AIBD) (SR 64·5%, +IGRA 62·9%) and highest in patients with psoriasis (SR 87·7%, +IGRA 80·7%). The reverse trend was found for vaccine-related reactions. Immunosuppressants were uptitrated in 15·8% of cases; 75% of these were patients with AIBD. CONCLUSIONS: Among participants with IMDDs, ChAdOx1-S[recombinant] showed good immunogenicity among patients with psoriasis, but demonstrated lower levels of immunogenicity for patients with AIBD. Some patients, especially patients with AIBD, should be closely monitored as they may require treatment escalation within 1 month postvaccination.

Receptor binding domain proteins of SARS-CoV-2 variants produced in Nicotiana benthamiana elicit neutralizing antibodies against variants of concern.

The constantly emerging severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) variants of concerns (VOCs) with mutations in the receptor-binding domain (RBD) spread rapidly and has become a severe public health problem worldwide. Effective vaccines and optimized booster vaccination strategies are thus highly required. Here, the gene encoding six different RBD (Alpha, Beta, Gamma, Kappa, Delta, and Epsilon variants) along with the Fc fragment of human IgG1 (RBD-Fc) was cloned into plant expression vector and produced in Nicotiana benthamiana by transient expression. Further, the immunogenicity of plant-produced variant RBD-Fc fusion proteins were tested in cynomolgus monkeys. Each group of cynomolgus monkeys was immunized three times intramuscularly with variant RBD-Fc vaccines at Day 0, 21, 42, and neutralizing antibody responses were evaluated against ancestral (Wuhan), Alpha, Beta, Gamma, and Delta variants. The results showed that three doses of the RBD-Fc vaccine significantly enhanced the immune response against all tested SARS-CoV-2 variants. In particular, the vaccines based on Delta and Epsilon mutant RBD elicit broadly neutralizing antibodies against ancestral (Wuhan), Alpha, and Delta SARS-CoV-2 variants whereas Beta and Gamma RBD-Fc vaccines elicit neutralizing antibodies against their respective SARS-CoV-2 strains. The Delta and Epsilon RBD-Fc based vaccines displayed cross-reactive immunogenicity and might be applied as a booster vaccine to induce broadly neutralizing antibodies. These proof-of-concept results will be helpful for the development of plant-derived RBD-Fc-based vaccines against SARS-CoV-2 and its variants.

Virus MIP-composites for SARS-CoV-2 detection in the aquatic environment.

SARS-CoV-2 is the virus responsible for causing the global COVID-19 pandemic. Identifying the presence of this virus in the environment could potentially improve the effectiveness of disease control measures. Environmental SARS-CoV-2 monitoring may become increasingly demanded in areas where the available testing methods are ineffective. In this study, we present an electrochemical polymer composites biosensor for measuring SARS-CoV-2 whole-virus particles in the environment. The sensitized layer was prepared from molecularly imprinted polymer (MIP) composites of inactivated SARS-CoV-2. Testing demonstrated increased sensor signaling with SARS-CoV-2 specifically, while lower responses were observed to the negative controls, H5N1 influenza A virus and non-imprinted polymers (NIPs). This sensor detected SARS-CoV-2 at concentrations as low as 0.1 fM in buffer and samples prepared from reservoir water with a 3 log-scale linearity.

Colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) as a visual diagnostic platform for the detection of the emerging coronavirus SARS-CoV-2.

COVID-19, caused by the infection of SARS-CoV-2, has emerged as a rapidly spreading infection. The disease has now reached the level of a global pandemic and as a result a more rapid and simple detection method is imperative to curb the spread of the virus. We aimed to develop a visual diagnostic platform for SARS-CoV-2 based on colorimetric RT-LAMP with levels of sensitivity and specificity comparable to that of commercial qRT-PCR assays. In this work, the primers were designed to target a conserved region of the RNA-dependent RNA polymerase gene (RdRp). The assay was characterized for its sensitivity and specificity, and validated with clinical specimens collected in Thailand. The developed colorimetric RT-LAMP assay could amplify the target gene and enabled visual interpretation in 60 min at 65 °C. No cross-reactivity with six other common human respiratory viruses (influenza A virus subtypes H1 and H3, influenza B virus, respiratory syncytial virus types A and B, and human metapneumovirus) and five other human coronaviruses (MERS-CoV, HKU-1, OC43, 229E and NL63) was observed. The limit of detection was 25 copies per reaction when evaluated with contrived specimens. However, the detection rate at this concentration fell to 95.8% when the incubation time was reduced from 60 to 30 min. The diagnostic performance of the developed RT-LAMP assay was evaluated in 2120 clinical specimens and compared with the commercial qRT-PCR. The results revealed high sensitivity and specificity of 95.74% and 99.95%, respectively. The overall accuracy of the RT-LAMP assay was determined to be 99.86%. In summary, our results indicate that the developed colorimetric RT-LAMP provides a simple, sensitive and reliable approach for the detection of SARS-CoV-2 in clinical samples, implying its beneficial use as a diagnostic platform for COVID-19 screening.

Anti-SARS-CoV-2 Activity of Andrographis paniculata Extract and Its Major Component Andrographolide in Human Lung Epithelial Cells and Cytotoxicity Evaluation in Major Organ Cell Representatives.

The coronaviruses disease 2019 (COVID-19) caused by a novel coronavirus (SARS-CoV-2) has become a major health problem, affecting more than 50 million people with over one million deaths globally. Effective antivirals are still lacking. Here, we optimized a high-content imaging platform and the plaque assay for viral output study using the legitimate model of human lung epithelial cells, Calu-3, to determine the anti-SARS-CoV-2 activity of Andrographis paniculata extract and its major component, andrographolide. SARS-CoV-2 at 25TCID50 was able to reach the maximal infectivity of 95% in Calu-3 cells. Postinfection treatment of A. paniculata and andrographolide in SARS-CoV-2-infected Calu-3 cells significantly inhibited the production of infectious virions with an IC50 of 0.036 µg/mL and 0.034 µM, respectively, as determined by the plaque assay. The cytotoxicity profile developed over the cell line representatives of major organs, including liver (HepG2 and imHC), kidney (HK-2), intestine (Caco-2), lung (Calu-3), and brain (SH-SY5Y), showed a CC50 of >100 µg/mL for A. paniculata extract and 13.2-81.5 µM for andrographolide, respectively, corresponding to a selectivity index of over 380. In conclusion, this study provided experimental evidence in favor of A. paniculata and andrographolide for further development as a monotherapy or in combination with other effective drugs against SARS-CoV-2 infection.

Identification of Important N-Linked Glycosylation Sites in the Hemagglutinin Protein and Their Functional Impact on DC-SIGN Mediated Avian Influenza H5N1 Infection.

DC-SIGN, a C-type lectin mainly expressed in dendritic cells (DCs), has been reported to mediate several viral infections. We previously reported that DC-SIGN mediated H5N1 influenza A virus (AIVs) infection, however, the important DC-SIGN interaction with N-glycosylation sites remain unknown. This study aims to identify the optimal DC-SIGN interacting N-glycosylation sites in HA proteins of H5N1-AIVs. Results from NetNGlyc program analyzed the H5 hemagglutinin sequences of isolates during 2004-2020, revealing that seven and two conserved N-glycosylation sites were detected in HA1 and HA2 domain, respectively. A lentivirus pseudotyped A/Vietnam/1203/04 H5N1 envelope (H5N1-PVs) was generated which displayed an abundance of HA5 proteins on the virions via immuno-electron microscope observation. Further, H5N1-PVs or reverse-genetics (H5N1-RG) strains carrying a serial N-glycosylated mutation was generated by site-directed mutagenesis assay. Human recombinant DC-SIGN (rDC-SIGN) coated ELISA showed that H5N1-PVs bound to DC-SIGN, however, mutation on the N27Q, N39Q, and N181Q significantly reduced this binding (p < 0.05). Infectivity and capture assay demonstrated that N27Q and N39Q mutations significantly ameliorated DC-SIGN mediated H5N1 infection. Furthermore, combined mutations (N27Q&N39Q) significantly waned the interaction on either H5N1-PVs or -RG infection in cis and in trans (p < 0.01). This study concludes that N27 and N39 are two essential N-glycosylation contributing to DC-SIGN mediating H5N1 infection.

The activation of B cells enhances DC-SIGN expression and promotes susceptibility of B cells to HPAI H5N1 infection.

The interplay between highly pathogenic avian influenza (HPAI) H5N1 virus and immune cells has been extensively studied for years, as host immune components are thought to play significant roles in promoting the systemic spread of the virus and responsible for cytokine storm. Previous studies suggested that the interaction of B cells and monocytes could promote HPAI H5N1 infection by enhancing avian influenza virus receptor expression. In this study, we further investigate the relationship between the HPAI H5N1 virus, activated B cells, and DC-SIGN expression. DC-SIGN has been described as an important factor for mediating various types of viral infection. Here, we first demonstrate that HPAI H5N1 infection could induce an activation of B cells, which was associated with DC-SIGN expression. Using CD40L and recombinant IL-4 for B cell stimulation, we determined that DC-SIGN expressed on activated B cells was able to enhance its susceptibility to HPAI H5N1 infection. Our findings uncover the interplay between this H5N1 virus and B cells and provide important information in understanding how the virus overcomes our immune system, contributing to its unusual immunopathogenesis.

The presence of monocytes enhances the susceptibility of B cells to highly pathogenic avian influenza (HPAI) H5N1 virus possibly through the increased expression of α2,3 SA receptor.

The highly pathogenic avian influenza (HPAI) H5N1 virus causes severe systemic infection in avian and mammalian species, including humans by first targeting immune cells. This subsequently renders the innate and adaptive immune responses less active, thus allowing dissemination of the virus to systemic organs. To gain insight into the pathogenesis of H5N1, this study aims to determine the susceptibility of human PBMCs to the H5N1 virus and explore the factors which influence this susceptibility. We found that PBMCs were a target of H5N1 infection, and that monocytes and B cells were populations which were clearly the most susceptible. Analysis of PBMC subpopulations showed that isolated monocytes and monocytes residing in whole PBMCs had comparable percentages of infection (28.97 ± 5.54% vs 22.23 ± 5.14%). In contrast, isolated B cells were infected to a much lower degree than B cells residing in a mixture of whole PBMCs (0.88 ± 0.34% vs 34.87 ± 4.63%). Different susceptibility levels of B cells for these tested conditions spurred us to explore the B cell-H5N1 interaction mechanisms. Here, we first demonstrated that monocytes play a crucial role in the enhancement of B cell susceptibility to H5N1 infection. Although the actual mechanism by which this enhancement occurs remains in question, α2,3-linked sialic acid (SA), known for influenza virus receptors, could be a responsible factor for the greater susceptibility of B cells, as it was highly expressed on the surface of B cells upon H5N1 infection of B cell/monocyte co-cultures. Our findings reveal some of the factors involved with the permissiveness of human immune cells to H5N1 virus and provide a better understanding of the tropism of H5N1 in immune cells.

Infection kinetics, syncytia formation, and inflammatory biomarkers as predictive indicators for the pathogenicity of SARS-CoV-2 Variants of Concern in Calu-3 cells.

The ongoing COVID-19 pandemic has led to the emergence of new SARS-CoV-2 variants as a result of continued host-virus interaction and viral genome mutations. These variants have been associated with varying levels of transmissibility and disease severity. We investigated the phenotypic profiles of six SARS-CoV-2 variants (WT, D614G, Alpha, Beta, Delta, and Omicron) in Calu-3 cells, a human lung epithelial cell line. In our model demonstrated that all variants, except for Omicron, had higher efficiency in virus entry compared to the wild-type. The Delta variant had the greatest phenotypic advantage in terms of early infection kinetics and marked syncytia formation, which could facilitate cell-to-cell spreading, while the Omicron variant displayed slower replication and fewer syncytia formation. We also identified the Delta variant as the strongest inducer of inflammatory biomarkers, including pro-inflammatory cytokines/chemokines (IP-10/CXCL10, TNF-α, and IL-6), anti-inflammatory cytokine (IL-1RA), and growth factors (FGF-2 and VEGF-A), while these inflammatory mediators were not significantly elevated with Omicron infection. These findings are consistent with the observations that there was a generally more pronounced inflammatory response and angiogenesis activity within the lungs of COVID-19 patients as well as more severe symptoms and higher mortality rate during the Delta wave, as compared to less severe symptoms and lower mortality observed during the current Omicron wave in Thailand. Our findings suggest that early infectivity kinetics, enhanced syncytia formation, and specific inflammatory mediator production may serve as predictive indicators for the virulence potential of future SARS-CoV-2 variants.

Neutralizing activity of anti-respiratory syncytial virus monoclonal antibody produced in Nicotiana benthamiana.

Respiratory syncytial virus (RSV) is a highly contagious virus that affects the lungs and respiratory passages of many vulnerable people. It is a leading cause of lower respiratory tract infections and clinical complications, particularly among infants and elderly. It can develop into serious complications such as pneumonia and bronchiolitis. The development of RSV vaccine or immunoprophylaxis remains highly active and a global health priority. Currently, GSK's Arexvy™ vaccine is approved for the prevention of lower respiratory tract disease in older adults (>60 years). Palivizumab and currently nirsevimab are the approved monoclonal antibodies (mAbs) for RSV prevention in high-risk patients. Many studies are ongoing to develop additional therapeutic antibodies for preventing RSV infections among newborns and other susceptible groups. Recently, additional antibodies have been discovered and shown greater potential for development as therapeutic alternatives to palivizumab and nirsevimab. Plant expression platforms have proven successful in producing recombinant proteins, including antibodies, offering a potential cost-effective alternative to mammalian expression platforms. Hence in this study, an attempt was made to use a plant expression platform to produce two anti-RSV fusion (F) mAbs 5C4 and CR9501. The heavy-chain and light-chain sequences of both these antibodies were transiently expressed in Nicotiana benthamiana plants using a geminiviral vector and then purified using single-step protein A affinity column chromatography. Both these plant-produced mAbs showed specific binding to the RSV fusion protein and demonstrate effective viral neutralization activity in vitro. These preliminary findings suggest that plant-produced anti-RSV mAbs are able to neutralize RSV in vitro.

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.

The impact of N-glycans on the immune response of plant-produced SARS-CoV-2 RBD-Fc proteins.

Plant-based manufacturing has the advantage of post-translational modifications. While plant-specific N-glycans have been associated with allergic reactions, their effect on the specific immune response upon vaccination is not yet understood. In this study, we produced an RBD-Fc subunit vaccine in both wildtype (WT) and glycoengineered (∆XF) Nicotiana benthamiana plants. The N-glycan analysis: RBD-Fc carrying the ER retention peptide mainly displayed high mannose. When produced in WT RBD-Fc displayed complex-type (GnGnXF) N-glycans. In contrast, ∆XF plants produced RBD-Fc with humanized complex N-glycans that lack potentially immunogenic xylose and core fucose residues (GnGn). The three recombinant RBD-Fc glycovariants were tested. Immunization with any of the RBD-Fc proteins resulted in a similar titer of anti-RBD antibodies in mice. Likewise, antisera from subunit RBD-Fc vaccines also demonstrated comparable neutralization against SARS-CoV-2. Thus, we conclude that N-glycan modifications of the RBD-Fc protein have no impact on their capacity to activate immune responses and induce neutralizing antibody production.

Heterologous Ad26.COV2.S booster after primary BBIBP-CorV vaccination against SARS-CoV-2 infection: 1-year follow-up of a phase 1/2 open-label trial.

BACKGROUND: Inactivated whole-virus vaccination elicits immune responses to both SARS-CoV-2 nucleocapsid (N) and spike (S) proteins, like natural infections. A heterologous Ad26.COV2.S booster given at two different intervals after primary BBIBP-CorV vaccination was safe and immunogenic at days 28 and 84, with higher immune responses observed after the longer pre-boost interval. We describe booster-specific and hybrid immune responses over 1 year. METHODS: This open-label phase 1/2 study was conducted in healthy Thai adults aged ≥ 18 years who had completed primary BBIBP-CorV primary vaccination between 90-240 (Arm A1; n = 361) or 45-75 days (Arm A2; n = 104) before enrolment. All received an Ad26.COV2.S booster. We measured anti-S and anti-N IgG antibodies by Elecsys®, neutralizing antibodies by SARS-CoV-2 pseudovirus neutralization assay, and T-cell responses by quantitative interferon (IFN)-γ release assay. Immune responses were evaluated in the baseline-seronegative population (pre-booster anti-N < 1.4 U/mL; n = 241) that included the booster-effect subgroup (anti-N < 1.4 U/mL at each visit) and the hybrid-immunity subgroup (anti-N ≥ 1.4 U/mL and/or SARS-CoV-2 infection, irrespective of receiving non-study COVID-19 boosters). RESULTS: In Arm A1 of the booster-effect subgroup, anti-S GMCs were 131-fold higher than baseline at day 336; neutralizing responses against ancestral SARS-CoV-2 were 5-fold higher than baseline at day 168; 4-fold against Omicron BA.2 at day 84. IFN-γ remained approximately 4-fold higher than baseline at days 168 and 336 in 18-59-year-olds. Booster-specific responses trended lower in Arm A2. In the hybrid-immunity subgroup at day 336, anti-S GMCs in A1 were 517-fold higher than baseline; neutralizing responses against ancestral SARS-CoV-2 and Omicron BA.2 were 28- and 31-fold higher, respectively, and IFN-γ was approximately 14-fold higher in 18-59-year-olds at day 336. Durable immune responses trended lower in ≥ 60-year-olds. CONCLUSION: A heterologous Ad26.COV2.S booster after primary BBIBP-CorV vaccination induced booster-specific immune responses detectable up to 1 year that were higher in participants with hybrid immunity. CLINICAL TRIALS REGISTRATION: NCT05109559.

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.

MxA expression induced by α-defensin in healthy human periodontal tissue.

Although periodontal tissue is continually challenged by microbial plaque, it is generally maintained in a healthy state. To understand the basis for this, we investigated innate antiviral immunity in human periodontal tissue. The expression of mRNA encoding different antiviral proteins, myxovirus resistance A (MxA), protein kinase R (PKR), oligoadenylate synthetase (OAS), and secretory leukocyte protease inhibitor (SLPI) were detected in both healthy tissue and that with periodontitis. Immunostaining data consistently showed higher MxA protein expression in the epithelial layer of healthy gingiva as compared with tissue with periodontitis. Human MxA is thought to be induced by type I and III interferons (IFNs) but neither cytokine type was detected in healthy periodontal tissues. Treatment in vitro of primary human gingival epithelial cells (HGECs) with α-defensins, but not with the antimicrobial peptides ß-defensins or LL-37, led to MxA protein expression. α-defensin was also detected in healthy periodontal tissue. In addition, MxA in α-defensin-treated HGECs was associated with protection against avian influenza H5N1 infection and silencing of the MxA gene using MxA-targeted-siRNA abolished this antiviral activity. To our knowledge, this is the first study to uncover a novel pathway of human MxA induction, which is initiated by an endogenous antimicrobial peptide, namely α-defensin. This pathway may play an important role in the first line of antiviral defense in periodontal tissue.

Self-assembled glucosamine monolayers as biomimetic receptors for detecting WGA lectin and influenza virus with a quartz crystal microbalance.

N-Acetylglucosamine (GlcNAc) is a natural ligand that interacts with the binding sites of wheat germ agglutinin (WGA) lectin. For immobilization, GlcNAc was linked to p-nitrophenol, and the nitro group was reduced and then bound to cysteine via two-step synthesis. Scanning tunneling microscopy studies revealed proper immobilization of the ligand on the gold surface of a quartz crystal microbalance (QCM) via the cysteine S-H bond as well as binding between GlcNAc and WGA. QCM measurements revealed that maximum sensitivity towards WGA can only be achieved when co-immobilizing one part ligand and 5,000 parts cysteine for steric reasons, because it allows binding of a protein monolayer on the surface. Langmuir-type treatment of the binding isotherm suggests two different binding ranges for WGA and the GlcNAc monolayer, because at concentrations of WGA below 1 µm the Gibbs energy for the binding process is one third higher than that at concentrations above this value. The same systems can be transferred to first proof-of-concept measurements with different strains of influenza A virus (H5N3, H5N1, H1N3) because GlcNAc is part of the oligosaccharide ligand responsible for the first binding step. Thus, it constitutes both a suitable tool for rapid analysis and the basis for future theoretical calculations of ligand-virus interactions.

Immunogenicity and efficacy of recombinant subunit SARS-CoV-2 vaccine candidate in the Syrian hamster model.

SARS-CoV-2 causes devastating impact on the human population and has become a major public health concern. The frequent emergence of SARS-CoV-2 variants of concern urges the development of safe and efficacious vaccine against SARS-CoV-2 variants. We developed a candidate vaccine Baiya SARS-CoV-2 Vax 1, based on SARS-CoV-2 receptor-binding domain (RBD) by fusing with the Fc region of human IgG. The RBD-Fc fusion was produced in Nicotiana benthamiana. Previously, we reported that this plant-produced vaccine is effective in inducing immune response in both mice and non-human primates. Here, the efficacy of our vaccine candidate was tested in Syrian hamster challenge model. Hamsters immunized with two intramuscular doses of Baiya SARS-CoV-2 Vax 1 induced neutralizing antibodies against SARS-CoV-2 and protected from SARS-CoV-2 challenge with reduced viral load in the lungs. These preliminary results demonstrate the ability of plant-produced subunit vaccine Baiya SARS-CoV-2 Vax 1 to provide protection against SARS-CoV-2 infection in hamsters.