Neutralization Potential Research Articles

Exploring B-cell epitope conservation and antigenicity shift in current COVID-19 variants: Analyzing spike-antibody interactions for therapeutic uses

SARS-CoV-2, responsible for the global COVID-19 pandemic, has undergone significant genetic changes, leading to various variants impacting transmissibility, severity, and vaccine efficacy. The methodology involved evaluating SARS-CoV-2 variants designated by WHO as Variants of Interest (VOIs) and Variants Under Monitoring (VUMs). Several noteworthy mutations including G446S, K417N, T478K, E484A, N501Y, and Y505H exhibit a strong pattern of convergent evolution across all these variants, particularly at antigenic sites within the spike protein. Conformational epitopes mapping and antigenicity shift analyses implicated epitope changes which were compared for therapeutic purposes. VUMs BA.2.86 and XBB.2.3 show significant antigenicity changes and epitope dynamics, correlating with high root mean square deviation values and epitope expansions or contractions. Nonsynonymous mutations are predominant in all variants, suggesting functional changes affecting transmissibility and immune evasion. VOIs XBB.1.5, BA.2.86, and CH.1.1 show high solvent-accessible surface area and radius of gyration, indicating structural expansion and increased epitope availability. In contrast, stable VOI EG.5.1 displays minimal structural changes and moderate epitope expansions. We evaluated two classes of antibodies for their effectiveness in neutralizing SARS-CoV-2 variants. Antibodies CC12.1 and P4A1 from Class I, alongside CV07-250, P5A-2G9, and MW05 from Class II, display strong binding across multiple variants, indicating broad neutralizing capabilities. Specifically, P4A1 shows the highest affinity for EG.5 and EG.5.1, while MW05 exhibits the strongest binding to XBB.1.5, CH.1.1, and XBB.2.3, highlighting their potent neutralization potential. This study aims to elucidate epitope variations in evolving SARS-CoV-2 strains, offering critical insights for developing targeted interventions against current challenges posed by the virus.

Evaluation of Pollution Linked to Open-Air Storage of Black Shale by the Company Frontier S.A in Sakania in the South-East of the DR. Congo

The black shale from the company “Frontier S.A” in Sakania is impregnated with sulphide minerals such as pyrite which is an iron sulphide (FeS2) and chalcopyrite which is a double sulphide of copper and iron (Cu FeS2). Due to its storage in the open air, these sulphides are particularly oxidized. In addition, this black shale presents a certain physical and chemical instability which can be the basis of the degradation of the nearby surrounding environments (watercourses, soils, groundwater, etc.). It results from our chemical characterization tests that this black shale contains 0.05% Cu, 0.007% Co, 1.3% Fe, 0.007% Ni, 0.001% As; 0.0012% Pb; 0.0021 Cd; 1.75% of S.The mineralogical analysis reveals that the sample contains the main minerals: sulphides, in the form of chalcopyrite and pyrite; oxidized, in the form of quartz; carbonates, in the form of dolomite and calcite, and graphitic material (C). For the determination of the character of acid mine drainage, the static tests for predicting the AMD on the one hand, gave values for the net neutralization potential (NNP) and the ratio between the neutralization and acidification potentials (RPN). respectively 37.5 and 41.39, that is to say values classifying the black shale of Frontier as not generating ADM. And on the other hand, during the kinetic tests using the principle of testing periodic leaching of the sample over a long period, the percolates obtained made it possible to monitor the pH (between 6.2 to 7.07), the redox potential (between -39.8 to 92mV), the electrical conductivity (between 640 to 672μS/Cm), as well as the concentration rate of metals (low mobilization). This made it possible to conclude that the AMD did not exist on the site.

Comparison of the Neutralization Power of Sotrovimab Against SARS-CoV-2 Variants: Development of a Rapid Computational Method.

The rapid evolution of SARS-CoV-2 imposed a huge challenge on disease control. Immune evasion caused by genetic variations of the SARS-CoV-2 spike protein's immunogenic epitopes affects the efficiency of monoclonal antibody-based therapy of COVID-19. Therefore, a rapid method is needed to evaluate the efficacy of the available monoclonal antibodies against the new emerging variants or potential novel variants. The aim of this study is to develop a rapid computational method to evaluate the neutralization power of anti-SARS-CoV-2 monoclonal antibodies against new SARS-CoV-2 variants and other potential new mutations. The amino acid sequence of the extracellular domain of the spike proteins of the severe acute respiratory syndrome coronavirus (GenBank accession number YP_009825051.1) and SARS-CoV-2 (GenBank accession number YP_009724390.1) were used to create computational 3D models for the native spike proteins. Specific mutations were introduced to the curated sequence to generate the different variant spike models. The neutralization potential of sotrovimab (S309) against these variants was evaluated based on its molecular interactions and Gibbs free energy in comparison to a reference model after molecular replacement of the reference receptor-binding domain with the variant's receptor-binding domain. Our results show a loss in the binding affinity of the neutralizing antibody S309 with both SARS-CoV and SARS-CoV-2. The binding affinity of S309 was greater to the Alpha, Beta, Gamma, and Kappa variants than to the original Wuhan strain of SARS-CoV-2. However, S309 showed a substantially decreased binding affinity to the Delta and Omicron variants. Based on the mutational profile of Omicron subvariants, our data describe the effect of the G339H and G339D mutations and their role in escaping antibody neutralization, which is in line with published clinical reports. This method is rapid, applicable, and of interest to adapt the use of therapeutic antibodies to the treatment of emerging variants. It could be applied to antibody-based treatment of other viral infections.

The radiological hazard and potential for generating acid mine drainage from a coal tailings dam.

The aim of this study was to analyze the radiological hazards and the potential for generating acid mine drainage from the fine coal waste commonly stored in tailings dams. The magnetic susceptibility, natural gamma radioactivity, and net neutralization potential of the tailings are characterized. The results show that the fine coal waste has a uranium equivalent concentration (eU) of 46-48Bqkg-1, which is 37.14% higher than the world average, and 39-47Bqkg-1 equivalent concentration of thorium (eTh), which is 56.66% higher than the world average. Also, the absorbed gamma radiation dose rate is higher than the world average. Acid-base balance tests indicate that the net neutralization potential ranged from 0.38 to 2.44. The physical properties indicate a possible radiological risk, while the chemical properties show that generating and non-generating acid drainage can coexist in the fine dam tailings.

IgG neutralization potential of COVISHIELD™ vaccinated individual’s sera after booster vaccination: Longitudinal and prospective cohort study

The novel SARS-CoV-2 (COVID-19) has caused widespread human turmoil by posing challenges concerning infection prevention, disease diagnosis, and treatment. Several approved vaccines including Sinovac (CoronaVac), COVISHIELD™ (Oxford/AstraZeneca formulation), Janssen (Johnson & Johnson), Sputnik V (Gamaleya), Covaxin (Bharat Biotech), Pfizer (BNT162b2), and others are being used to combat COVID-19. It is crucial to evaluate the kinetics of SARS-CoV-2 antibodies to predict the possibility of reinfection and the longevity of vaccination protection. There is a lack of data on longitudinal humoral antibody dynamics following two and three doses of the SARS-CoV-2 vaccination ChAdOx1-nCOV (COVISHIELDTM) in Indians. Thus, concerns about the efficacy of current vaccines have been raised by a sharp rise in coronavirus disease 2019 (Covid-19) cases caused by sub-variants of SARS-CoV-2 (Severe acute respiratory syndrome corona virus 2) in communities that have received massive vaccinations. The relative immunogenicity and safety of various COVID-19 immunizations administered as a third (booster) dose are not well known. We examined the reactogenicity and immunogenicity of the COVID-19 vaccine as a third dose after two doses of COVISHIELDTM to produce data to optimize the selection of booster vaccinations. After three doses of the COVID-19 vaccine, we evaluated the sera of COVISHIELDTM vaccine recipients for their ability to neutralize the virus. Primary immunization with two doses of COVISHIELDTM vaccine recipients provided significant protection against symptomatic disease caused by the SARS-CoV-2 variants. A COVISHIELDTM vaccine booster vaccine recipient substantially increased protection. The immunization findings showed a significant difference (p ≥ 0.001) between the COVID-19 naive vaccine (n = 438) and the sera of COVID-19-positive recovered subjects (n = 371) who received three doses of COVISHIELDTM. Our findings reveal that anti-RBD antibodies persist over time, which may reduce the probability of reinfection. A three-dose vaccination (n = 53) increases defense against variations by noticeably increasing cross-neutralizing antibody titers. Particularly against variants with antibody escape mutations.

Energy self-sufficiency and carbon neutrality potential of Chinese urban wastewater treatment

The implementation of some energy-saving and emission reduction measures can effectively offset the energy consumption and carbon emissions in the wastewater treatment process. Integrated policy-making information on carbon-energy-economy of these technologies is not clear in national wastewater treatment industry. This study investigated energy self-sufficiency, carbon neutralization potential and economic performance of wastewater treatment industry, as well as related synergy effect among the three aspects using the proposed approach. Then the approach was used to investigate energy-saving and carbon emission reduction potential of the three technologies (photovoltaic power (PV), combined heat and power (CHP) and water source heat pump (WSHP)) and technological combinations as well as related economic performance in urban wastewater treatment of Chinese different provinces in 2021. The results showed that (1) The national energy self-sufficiency is 95%; therein, 13 provinces have the potential to achieve or exceed energy self-sufficiency of 100%, and the top 3 provinces are Heilongjiang, Yunnan and Hunan. (2) The national carbon neutral potential is 87%; therein, 9 provinces have the potential to achieve or surpass carbon neutralization of 100%, and the top 3 provinces include Beijing, Hunan and Shaanxi. (3) these technologies or their combinations are potentially economically viable (net economic benefit ratio >1), and the top three provinces are Beijing, Shaanxi, and Inner Mongolia. (4) Generally, there are 13 provinces with synergy effect >1 in the country; the top three provinces are Liaoning, Heilongjiang and Hunan. Finally, targeted policy suggestions are provided for Chinese urban wastewater treatment. The proposed approach can also act as one of decision-making tools for wastewater treatment industry in other countries or areas in the world.

Geochemical characterization of waste rock dump and its potential to predict acid mine drainage

Acid Mine Drainage (AMD) is an environmental phenomenon that is being experienced by mining companies in Ghana. High levels of heavy metals have been reported in mining areas especially in Obuasi over the years; however, as to whether these heavy metals are being released from the mine wastes (waste rocks) is of concern. Therefore, this paper evaluates the potential of the abandoned Anyankyirem waste rock dump located in Obuasi to cause AMD. Twenty rock samples were collected from various locations of the dump site and their elemental and physicochemical compositions were examined. XRD analysis was conducted to assess the mineralogy of the samples. Acid Base Accounting (ABA) test was used to ascertain the AMD potential of the dump. The ABA test comprises calculating the Acid Neutralization Capacity (ANC) and Maximum Potential Acidity (MPA) of the various samples. The MPA and ANC values were used to compute the rock samples' Net Neutralization Potential (NNP). A column leaching test was carried out. Leachates were collected over a period of 20 weeks. From the column leaching experiment, the rate of weathering of calcium carbonate throughout the 20-week leaching experiment was 3.6 %. Leachates from the column test showed a circumneutral pH (7.1–8.0). The sulphate concentrations from the leachates decreased over the entire period from 96.60 to 3.70 mg/L. Iron recorded the highest concentration of 7783.65 mg kg-1 and the lowest of 0.645 mg kg-1 was recorded in Bi. From ABA test and the column leaching test results, Anyankyirem waste rock dump is not acid generating and therefore can serve as buffer for high pyrite waste rocks. However, significant levels of some heavy metals (As, Fe, Zn, Cr, Mn and Se) were recorded in the leachates even though the leachates’ pH were circumneutral. The results suggest that not only acidic conditions can leach out heavy metals.

Immunogenicity and Neutralization Potential of Recombinant Chimeric Protein Comprising the Catalytic Region of Gp63 of Leishmania and LTB against Leishmania donovani

Aim: To study the inhibition potential of antibody against a recombinant chimera comprising of the catalytic epitope of gp63 of Leishmania donovani and B subunit of heat-labile enterotoxin (LTB) in the functional activity of L. donovani. Background: Visceral leishmaniasis, caused by the protozoan parasite Leishmania donavani, is a major health problem and causes mortality in tropical regions. Protozoan proteases play a crucial role in the pathogenesis of the disease and in establishing infection by countering the host's innate immune responses, namely complement-mediated lysis and phagocytosis. A surface-bound metalloprotease (gp63) has been reported to be a major virulence factor resulting in the evasion of complement- mediated lysis, cleaving host extracellular and intracellular substrates, resulting in intra- phagolysosomal survival. Method: The epitope corresponding to the catalytic motif of gp63 of Leishmania donovani was fused with the B subunit of heat-labile enterotoxin, which is known to be immunogenic. The chimera was cloned to a prokaryotic expression vector and purified using Ni NTA affinity chromatography. Antibodies were generated against the purified fusion protein and analyzed for its ability to bind to the gp63 catalytic motif peptide by ELISA. The effect of fusion protein antibody on the functional activity of gp63 was evaluated by assessing the effect of purified IgGs on the protease activity and complement-mediated lysis of L. donovani promastigotes in vitro. Results: The present study reports that a recombinant chimera of the catalytic epitope of gp63 and B subunit of heat-labile enterotoxin (LTB) of E. coli, a potent adjuvant of humoral response can mount significant immune response towards the catalytic epitope. ELISA and Western blot analysis showed that the anti-fusion protein antiserum could recognize the native gp63. Also, it significantly inhibited the protease activity of promastigotes and subsequently increased complement-mediated lysis of the promastigotes in vitro. Conclusion: It could be concluded that the hybrid protein containing catalytic motif L. donovani gp63 protein and carrier protein (LTB) could elicit antibodies that could neutralise the functional activity of gp63 and thus could be a potential candidate for subunit leishmaniasis vaccine.

SARS-CoV-2 BA.4/5 infection triggers more cross-reactive FcγRIIIa signaling and neutralization than BA.1, in the context of hybrid immunity.

The continued evolution of SARS-CoV-2 has resulted in a number of variants of concern. Of these, the Omicron sublineage is the most immune evasive. Within Omicron, the BA.4/5 sublineage drove the fifth wave of infection in South Africa prior to becoming the dominant variant globally. As a result this spike sequence was approved as part of a bivalent vaccine booster, and rolled out worldwide. We aimed to understand the cross-reactivity of neutralizing and Fc mediated cytotoxic functions elicited by BA.4/5 infection following infection or breakthrough infection. We find that, in contrast to BA.1 which triggered fairly strain-specific antibodies, BA.4/5 triggered antibodies that are highly cross-reactive for neutralization and antibody-dependent cellular cytotoxicity potential. Despite this cross-reactivity, these antibodies are compromised against highly resistant variants such as XBB.1.5 and BQ.1. This suggests that next-generation vaccines will require XBB sublineage immunogens in order to protect against these evasive variants.

Serological immune biomarker for disease severity in dengue-infectedpediatric hospitalized patients.

Clinical manifestation of dengue disease ranges from asymptomatic, febrile fever without warning sign (DOS) to serious outcome dengue with warning sign (DWS) and severe disease (SD) leading to shock syndrome and death. The role of antibody response in natural dengue infection is complex and not completely understood. Here, we aimed to assess serological marker for disease severity. Antibody response of dengue-confirmed pediatric patients with acute secondary infection were evaluated against infecting virus, immature virus, and recombinant envelop protein. Immature virus antibody titers were significantly higher in DWS as compared to DOS (p = 0.0006). However, antibody titers against recombinant envelop protein were higher in DOS as compared to DWS, and antibody avidity was significantly higher against infecting virus in DOS. Serum samples of DOS patients displayed higher in vitro neutralization potential in plaque assay as compared to DWS, whereas DWS serum samples showed higher antibody-dependent enhancement in the in vitro enhancement assays. Thus, antibodies targeting immature virus can predict disease severity and could be used in early forecast of disease outcome using anenzyme-linked immunoassay assaysystem which is less laborious and cheaper than plaque assay system for correlates of protection and could help optimize medical care and resources.

ACE2-Decorated Virus-Like Particles Effectively Block SARS-CoV-2 Infection.

Over the past three years, extensive research has been dedicated to understanding and combating COVID-19. Targeting the interaction between the SARS-CoV-2 Spike protein and the ACE2 receptor has emerged as a promising therapeutic strategy against SARS-CoV-2. This study aimed to develop ACE2-coated virus-like particles (ACE2-VLPs), which can be utilized to prevent viral entry into host cells and efficiently neutralize the virus. Virus-like particles were generated through the utilization of a packaging plasmid in conjunction with a plasmid containing the ACE2 envelope sequence. Subsequently, ACE2-VLPs and ACE2-EVs were purified via ultracentrifugation. The quantification of VLPs was validated through multiple methods, including Nanosight 3000, TEM imaging, and Western blot analysis. Various packaging systems were explored to optimize the ACE2-VLP configuration for enhanced neutralization capabilities. The evaluation of neutralization effectiveness was conducted using pseudoviruses bearing different spike protein variants. Furthermore, the study assessed the neutralization potential against the Omicron BA.1 variant in Vero E6 cells. ACE2-VLPs showed a high neutralization capacity even at low doses and demonstrated superior efficacy in in vitro pseudoviral assays compared to extracellular vesicles carrying ACE2. ACE2-VLPs remained stable under various environmental temperatures and effectively blocked all tested variants of concern in vitro. Notably, they exhibited significant neutralization against Omicron BA.1 variant in Vero E6 cells. Given their superior efficacy compared to extracellular vesicles and proven success against live virus, ACE2-VLPs stand out as crucial candidates for treating SARS-CoV-2 infections. This novel therapeutic approach of coating VLPs with receptor particles provides a proof-of-concept for designing effective neutralization strategies for other viral diseases in the future.

Development of chicken egg yolk antibodies (IgY) against venom of cobra (Naja naja) and krait (Bungarus caeruleus) and a study on its neutralization potential

The Big Four snakes are the leading causes of snakebite mortality in India. Among them, The Indian spectacled cobra (Naja naja) and common krait (Bungarus caeruleus) contribute about one-third of the deaths. The conventional anti-snake venoms (ASV) produced from equine serum are found to be expensive, with a high frequency of clinical side effects, low specificity, and production drawbacks. The current study, therefore, attempted to develop chicken egg yolk immunoglobulins (IgY) as antivenoms against the venoms of cobra and krait venoms. The major pathophysiological properties of the venoms and the efficacy of monovalent ASV IgY were evaluated. The titer of anti-cobra and anti-krait IgY was found to be 1:64000 on the 145th day post-immunization. The results showed that venoms (lethal doses (LD50): cobra:0.375 mg/kg, krait:0.0375 mg/kg of mice) had hemolytic, pro-coagulant, inflammatory, hemorrhagic, and edematic activities that were effectively neutralized by ASV-IgY. 1 mL of monovalent ASV IgY was able to neutralize 0.22 mg of cobra venom and 0.028 mg of krait venom whereas 1 mL of commercial polyvalent antivenom was able to neutralize 0.28 mg of cobra venom and 0.035 mg of krait venom. The study results suggest that using chicken IgY as an monovalent antivenom could effectively treat snakebites.

Influence of adjuvant type and route of administration on the immunogenicity of Leishmania-derived tick-borne encephalitis virus-like particles – A recombinant vaccine candidate

Tick-borne encephalitis virus (TBEV) is a tick-borne flavivirus that induces severe central nervous system disorders. It has recently raised concerns due to an expanding geographical range and increasing infection rates. Existing vaccines, though effective, face low coverage rates in numerous TBEV endemic regions. Our previous work demonstrated the immunogenicity and full protection afforded by a TBEV vaccine based on virus-like particles (VLPs) produced in Leishmania tarentolae cells in immunization studies in a mouse model. In the present study, we explored the impact of adjuvants (AddaS03™, Alhydrogel®+MPLA) and administration routes (subcutaneous, intramuscular) on the immune response. Adjuvanted groups exhibited significantly enhanced antibody responses, higher avidity, and more balanced Th1/Th2 response. IFN-γ responses depended on the adjuvant type, while antibody levels were influenced by both adjuvant and administration routes. The combination of Leishmania-derived TBEV VLPs with Alhydrogel® and MPLA via intramuscular administration emerged as a highly promising prophylactic vaccine candidate, eliciting a robust, balanced immune response with substantial neutralization potential.

A dual-targeting approach using a human bispecific antibody against the receptor-binding domain of the Middle East Respiratory Syndrome Coronavirus

The emergence of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) has posed a significant global health concern due to its severe respiratory illness and high fatality rate. Currently, despite the potential for resurgence, there are no specific treatments for MERS-CoV, and only supportive care is available. Our study aimed to address this therapeutic gap by developing a potent neutralizing bispecific antibody (bsAb) against MERS-CoV. Initially, we isolated four human monoclonal antibodies (mAbs) that specifically target the MERS-CoV receptor-binding domain (RBD) using phage display technology and an established human antibody library. Among these four selected mAbs, our intensive in vitro functional analyses showed that the MERS-CoV RBD-specific mAb K111.3 exhibited the most potent neutralizing activity against MERS-CoV pseudoviral infection and the molecular interaction between MERS-CoV RBD and human dipeptidyl peptidase 4. Consequently, we engineered a novel bsAb, K207.C, by utilizing K111.3 as the IgG base and fusing it with the single-chain variable fragment of its non-competing pair, K111.1. This engineered bsAb showed significantly enhanced neutralization potential against MERS-CoV compared to its parental mAb. These findings suggest that K207.C may serve as a potential candidate for effective MERS-CoV neutralization, further highlighting the promise of the bsAb dual-targeting approach in MERS-CoV neutralization.

Genetic targeting of the mouse immunoglobulin locus to permit the expression of heavy-chain only antibodies against viral antigens

Abstract Conventional antibodies are composed of two identical sets of heavy and light chains, forming a dimer. The CH1 domain of the antibody heavy chain is essential for the pairing of heavy and light chains. However, certain animals, such as camels and sharks, evolved to produce heavy-chain-only antibodies (HCAbs) by losing this crucial CH1 domain in some of their antibody heavy chain constant regions. These HCAbs boast unique physicochemical properties that confer significant advantages: their smaller size allows for improved access to target antigens, increased hydrophilicity, enhanced tissue penetration, and greater structural stability compared to standard antibodies. Our research has successfully established a mouse model that intrinsically produces HCAbs from the mouse's own immunoglobulin heavy chain locus. Our findings demonstrate that heavy-chain-only B cell receptors, once introduced, facilitate normal B cell development, promote germinal center formation, and enhance plasma cell differentiation relative to B cells producing conventional antibodies. These genetically modified mice were vaccinated with viral antigens, resulting in the production of HCAbs that specifically target the SARS-CoV-2 spike protein and the HIV-1 Env trimer. Through single-cell sequencing, we have identified unique nucleotide sequences of clonotypes; the HCAbs are being synthesized to assess their viral neutralization potential and antigen-binding affinity to highlight the efficacy of our model.

Serum Dehydroepiandrosterone sulfate (DHEA-S) level and its potential impact on immune responses and symptom severity after Oxford-AstraZeneca COVID-19 vaccination

BackgroundDehydroepiandrosterone sulfate (DHEA-S) has been associated with an immunomodulatory function. This study aims to explore the relationship between serum levels of DHEA-S and the immune responses triggered by the Oxford–AstraZeneca COVID-19 vaccine in individuals candidate for vaccination. MethodsSerum levels of DHEA-S, cytokine release, antibody production and virus neutralization potential were assessed in 50 male and 50 female subjects before and 2 weeks after vaccination with Oxford–AstraZeneca COVID-19 vaccine. ResultsLevel of DHEA-S before and 2 weeks after first and second dose of vaccination was not different significantly. Levels of Interleukin (IL)-2 and Interferon (IFN)-γ were significantly higher in the supernatant of peripheral blood mononuclear cells (PBMCs) obtained from subjects 2 weeks after both first and second dose of vaccination compared to before vaccination. Serum levels of IgM 2 weeks after first dose of vaccination was significantly higher compared to before first dose of vaccination. However, serum levels of IgG 2 weeks after first and second dose of vaccination were significantly higher compared to before first and second dose of vaccination. The 50 % focus reduction neutralization test (FRNT50) titer was significantly higher 2 weeks after both first and second dose of vaccination compared to before vaccination. Levels of DHEA-S did not have significant correlation with levels of IL-2, IFN-γ, IgM and IgG, and FRNT50 before and after first and second dose of vaccination. Vaccination did not result in intense unwanted clinical presentations. ConclusionDHEA-S is not involved in the quality of protective immune response during Oxford-AstraZeneca COVID-19 vaccination.

Differential Immune Response Patterns Induced by Anionic and Cationic Lipid Adjuvants in Intranasal Anti-Influenza Immunization.

Currently, vaccine development against different respiratory diseases is at its peak. It is of utmost importance to find suitajble adjuvants that can increase the potency of the vaccine candidates. This study aimed to determine the systemic and splenic immune mechanisms in mice models induced by anionic and cationic lipid adjuvants in the presence of the vaccine-candidate influenza antigen hemagglutinin (HA). In the presence of the HA antigen, the cationic adjuvant (N3) increased conventional dendritic cell 1 (cDC1) abundance with enhanced MHCI and CD80-CD86 costimulatory marker expression, and significantly higher CD8T and Th17 populations with enhanced interferon-gamma (IFNγ) expression in CD8T and CD4T populations. Conversely, the anionic adjuvant (L3) increased the cDC2 population percentage with significantly higher MHCII and DEC205 expression, along with an increase in the CD4T and regulatory T cell populations. The L3-treated group also exhibited higher percentages of activated B and plasma cell populations with significantly higher antigen-specific IgG and IgA titer and virus neutralization potential. While the anionic adjuvant induced significantly higher humoral responses than the cationic adjuvant, the latter influenced a significantly higher Th1/Th17 response. For customized vaccine development, it is beneficial to have alternative adjuvants that can generate differential immune responses with the same vaccine candidate antigen. This study will aid the selection of adjuvants based on their charges to improve specific immune response arms in the future development of vaccine formulation.

Potent HPIV3-neutralizing IGHV5-51 Antibodies Identified from Multiple Individuals Show L Chain and CDRH3 Promiscuity.

Human parainfluenza virus 3 (HPIV3) is a widespread pathogen causing severe and lethal respiratory illness in at-risk populations. Effective countermeasures are in various stages of development; however, licensed therapeutic and prophylactic options are not available. The fusion glycoprotein (HPIV3 F), responsible for facilitating viral entry into host cells, is a major target of neutralizing Abs that inhibit infection. Although several neutralizing Abs against a small number of HPIV3 F epitopes have been identified to date, relatively little is known about the Ab response to HPIV3 compared with other pathogens, such as influenza virus and SARS-CoV-2. In this study, we aimed to characterize a set of HPIV3-specific Abs identified in multiple individuals for genetic signatures, epitope specificity, neutralization potential, and publicness. We identified 12 potently neutralizing Abs targeting three nonoverlapping epitopes on HPIV3 F. Among these, six Abs identified from two different individuals used Ig heavy variable gene IGHV 5-51, with five of the six Abs targeting the same epitope. However, despite the use of the same H chain variable (VH) gene, these Abs used multiple different L chain variable genes (VL) and diverse H chain CDR 3 (CDRH3) sequences. Together, these results provide further information about the genetic and functional characteristics of HPIV3-neutralizing Abs and suggest the existence of a reproducible VH-dependent Ab response associated with VL and CDRH3 promiscuity. Understanding sites of HPIV3 F vulnerability and the genetic and molecular characteristics of Abs targeting these sites will help guide efforts for effective vaccine and therapeutic development.

Neutralizing antibody responses to SARS-CoV-2 Omicron variants: Post six months following two-dose & three-dose vaccination of ChAdOx1 nCoV-19 or BBV152.

The Omicron sub-lineages are known to have higher infectivity, immune escape and lower virulence. During December 2022 - January 2023 and March - April 2023, India witnessed increased SARS-CoV-2 infections, mostly due to newer Omicron sub-lineages. With this unprecedented rise in cases, we assessed the neutralization potential of individuals vaccinated with ChAdOx1 nCoV (Covishield) and BBV152 (Covaxin) against emerging Omicron sub-lineages. Neutralizing antibody responses were measured in the sera collected from individuals six months post-two doses (n=88) of Covishield (n=44) or Covaxin (n=44) and post-three doses (n=102) of Covishield (n=46) or Covaxin (n=56) booster dose against prototype B.1 strain, lineages of Omicron; XBB.1, BQ.1, BA.5.2 and BF.7. The sera of individuals collected six months after the two-dose and the three-dose demonstrated neutralizing activity against all variants. The neutralizing antibody (NAbs) level was highest against the prototype B.1 strain, followed by BA5.2 (5-6 fold lower), BF.7 (11-12 fold lower), BQ.1 (12 fold lower) and XBB.1 (18-22 fold lower). Persistence of NAb responses was comparable in individuals with two- and three-dose groups post six months of vaccination. Among the Omicron sub-variants, XBB.1 showed marked neutralization escape, thus pointing towards an eventual immune escape, which may cause more infections. Further, the correlation of study data with complete clinical profile of the participants along with observations for cell-mediated immunity may provide a clear picture for the sustained protection due to three-dose vaccination as well as hybrid immunity against the newer variants.

WITHDRAWN: Successful use of haemato-polyvalent anti-venom cross-neutralisation in the clinical management of Rhabdophis subminiatus (Rhabdophis keelback) envenomation

BackgroundAs the landscape becomes more urbanized, snakebites have increasingly become uncommon presentations to the emergency departments in Singapore, while snakebites causing significant envenomation are even rarer. Case reportIn this case report, we discuss a 55-year-old man who had significant envenomation from a Rhabdophis keelback (Rhabdophis subminiatus) and who was successfully treated with haemato-toxic polyvalent antivenom (HPAV). He initially presented with pain, swelling and bleeding over his wound. Due to a deterioration in his coagulation profile, he was given two doses of HPAV which is typically reserved for viperid snakes instead. Following administration of the anti-venom, the patient’s coagulation profile improved and the local soft tissue effects of the venom resolved. He did not manifest any adverse effects and was discharged uneventfully about 72 hours after the snakebite.The cross-neutralization potential of HPAV for Rhabdophis Colubrid venom in this case study suggests that there may be a possible common underlying chemical structure and pathophysiology among the venom proteins of various snake species. Given that Rhabdophis-specific antivenom is unavailable in most countries, this cross-neutralization strategy deserves further consideration and evaluation in similar circumstances. Why should an emergency physician be aware of this?The patient was successfully treated using HPAV with resolution of envenomation and discharged uneventfully. The possible cross neutralization potential of HPAV for Rhabdophis (colubrid) venom in our case may suggest a possible common underlying structure and pathophysiology of venom proteins amongst different snake species.