High Neutralizing Capacity Research Articles

Rapid discovery of monoclonal antibodies by microfluidics-enabled FACS of single pathogen-specific antibody-secreting cells.

Monoclonal antibodies are increasingly used to prevent and treat viral infections and are pivotal in pandemic response efforts. Antibody-secreting cells (ASCs; plasma cells and plasmablasts) are an excellent source of high-affinity antibodies with therapeutic potential. Current methods to study antigen-specific ASCs either have low throughput, require expensive and labor-intensive screening or are technically demanding and therefore not widely accessible. Here we present a straightforward technology for the rapid discovery of monoclonal antibodies from ASCs. Our approach combines microfluidic encapsulation of single cells into an antibody capture hydrogel with antigen bait sorting by conventional flow cytometry. With our technology, we screened millions of mouse and human ASCs and obtained monoclonal antibodies against severe acute respiratory syndrome coronavirus 2 with high affinity (<1 pM) and neutralizing capacity (<100 ng ml-1) in 2 weeks with a high hit rate (>85% of characterized antibodies bound the target). By facilitating access to the underexplored ASC compartment, the approach enables efficient antibody discovery and immunological studies into the generation of protective antibodies.

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.

Improvement of immune dysregulation in individuals with long COVID at 24-months following SARS-CoV-2 infection

This study investigates the humoral and cellular immune responses and health-related quality of life measures in individuals with mild to moderate long COVID (LC) compared to age and gender matched recovered COVID-19 controls (MC) over 24 months. LC participants show elevated nucleocapsid IgG levels at 3 months, and higher neutralizing capacity up to 8 months post-infection. Increased spike-specific and nucleocapsid-specific CD4+ T cells, PD-1, and TIM-3 expression on CD4+ and CD8+ T cells were observed at 3 and 8 months, but these differences do not persist at 24 months. Some LC participants had detectable IFN-γ and IFN-β, that was attributed to reinfection and antigen re-exposure. Single-cell RNA sequencing at the 24 month timepoint shows similar immune cell proportions and reconstitution of naïve T and B cell subsets in LC and MC. No significant differences in exhaustion scores or antigen-specific T cell clones are observed. These findings suggest resolution of immune activation in LC and return to comparable immune responses between LC and MC over time. Improvement in self-reported health-related quality of life at 24 months was also evident in the majority of LC (62%). PTX3, CRP levels and platelet count are associated with improvements in health-related quality of life.

Investigação e desenvolvimento de imunoensaios comparativos para produção de imunoglobulinas contra veneno da cobra (Bungarus sindanus) em aves

ABSTRACT: Present study aimed for detection, purification, quantification of Sind Krait (Bungarus sindanus) antivenom from chicken eggs and to determine extracted antivenom efficacy in mice. Hens’ three groups were immunized by sub-lethal doses of Sind Krait venom with adjuvant paraffin oil+lecithin. Booster doses were injected subcutaneously on pectorals muscles at multiple sites after every two weeks upto eight weeks. Antibodies-IgY produced against Sind Krait venom was purified form eggs’ yolk by precipitation method with PEG-6000. Purified antivenom-IgY protein contents were quantified by Nanodrop-photometer, purity accessed by SDS-PAGE, specificity checked by Ochterloneys method and titer estimated by indirect ELISA. Antivenom efficacy was assessed in albino mice. Purified antivnom-IgY exhibited single protein band 180-190 kDa on SDS-PAGE under non-reduced condition and two-bands 63 - 65 kDa and 22 - 25 kDa correspondingly under-reduced condition. Immunodiffusion exhibited sharp precipitation lines of immune-complex (venom and extracted-IgY). In all groups (G1, G2 and G3) antivenom level sharply increase from 3rd to 4th week and maintained thereafter. G2 and G3 presented high titer upto 1:2048 dilutions, while G1 showed upto 1:1024 dilutions, as tested by indirect ELISA. In neutralization assay ED50 dose of G2 and G3 obtained antivenom was 400.23 µg/mice for more than twofold LD50 dose of venom and 100% protection was at 508.84 µg/mice that completely neutralized highly lethal dose of venom. But G1 ED50 was 405.66 µg/mice and provides 100% protection at 554.21 µg/mice. Extracted antivenom, against Sind Krait venom were highly pure, and with high neutralization capacity were produced successfully from eggs yolk first time in Pakistan.

Virus-specific humoral immune response in Bulgarian COVID-19 patients with varying disease severity.

Our study aimed to analyze virus-specific humoral immune responses in COVID-19 patients with varying disease severity. A total of 109 serum samples from 87 patients, symptomatic for COVID-19 were studied using anti-SARS-CoV-2 immunoassays detecting different classes of immunoglobulins. Clinical samples were divided into 2 groups - collected up to and more than 2 weeks post-onset of symptoms (PoS). In the first group, the highest percentage of positive samples was found for IgA class virus-specific antibodies (78.1%), followed by IgM (71.9%/59.4%) and IgG (56.3%/53.1%). In the second group, samples positive for virus-specific IgA class antibodies were also the most (97.7%) along with those positive for IgG. A total of 72 IgA and/or IgM and/or IgG positive samples were further tested for SARS-CoV-2 neutralizing antibodies (NAbs) - 89.1% and 100% of samples obtained up to and after 2 weeks PoS, respectively were positive. Serological test results were also analyzed depending on the severity of the disease - SARS-CoV-2 positive samples in mild forms of COVID-19 were fewer than in moderate and severe forms but this difference was not statistically significant. SARS-CoV-2 specific antibodies and a high virus neutralization capacity of these antibodies appear early PoS; Immunoglobulins of IgA class are of most significant diagnostic value for detection of SARS-CoV-2 infection; Timing of testing is the most important factor for positivity rate.

A 12-month follow-up of the immune response to SARS-CoV-2 primary vaccination: evidence from a real-world study.

A real-world population-based longitudinal study, aimed at determining the magnitude and duration of immunity induced by different types of vaccines against COVID-19, started in 2021 by enrolling a cohort of 2,497 individuals at time of their first vaccination. The study cohort included both healthy adults aged ≤65 years and elderly subjects aged >65 years with two or more co-morbidities. Here, patterns of anti-SARS-CoV-2 humoral and cell-mediated specific immune response, assessed on 1,182 remaining subjects, at 6 (T6) and 12 months (T12) after the first vaccine dose, are described. At T12 median anti-Spike IgG antibody levels were increased compared to T6. The determinants of increased anti-Spike IgG were the receipt of a third vaccine dose between T6 and T12 and being positive for anti-Nucleocapside IgG at T12, a marker of recent infection, while age had no significant effect. The capacity of T12 sera to neutralize in vitro the ancestral B strain and the Omicron BA.5 variant was assessed in a subgroup of vaccinated subjects. A correlation between anti-S IgG levels and sera neutralizing capacity was identified and higher neutralizing capacity was evident in healthy adults compared to frail elderly subjects and in those who were positive for anti-Nucleocapside IgG at T12. Remarkably, one third of T12 sera from anti-Nucleocapside IgG negative older individuals were unable to neutralize the BA.5 variant strain. Finally, the evaluation of T-cell mediated immunity showed that most analysed subjects, independently from age and comorbidity, displayed Spike-specific responses with a high degree of polyfunctionality, especially in the CD8 compartment. In conclusion, vaccinated subjects had high levels of circulating antibodies against SARS-CoV-2 Spike protein 12 months after the primary vaccination, which increased as compared to T6. The enhancing effect could be attributable to the administration of a third vaccine dose but also to the occurrence of breakthrough infection. Older individuals, especially those who were anti-Nucleocapside IgG negative, displayed an impaired capacity to neutralize the BA.5 variant strain. Spike specific T-cell responses, able to sustain immunity and maintain the ability to fight the infection, were present in most of older and younger subjects assayed at T12.

SARS-CoV-2 antibody response duration and neutralization following natural infection

BackgroundThe role of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) neutralizing antibody response from natural infection and vaccination, and the potential determinants of this response are poorly understood. Characterizing this antibody response and the factors associated with neutralization can help inform future prevention efforts and improve clinical outcomes in those infected. ObjectivesThe goals of this study were to prospectively evaluate SARS-CoV-2 antibody levels and the neutralizing antibody responses among naturally infected adults and to determine demographic and behavioral factors independently associated with these responses. MethodsSerum was collected from seropositive individuals at baseline, four-weeks, and three-months following their first study visit to be evaluated for antibody levels. Detection of neutralizing antibodies was performed at baseline. Participant demographic and behavioral information was collected via web questionnaire prior to their first visit. ResultsAt baseline, higher antibody levels were associated with better neutralization capacity, with 83% of participants having detectable neutralizing antibodies. We found an age-dependent effect on antibody level and neutralization capacity with participants over 65 years having significantly higher levels. Ethnicity, heart disease, autoimmune disease, and COVID symptoms were associated with higher antibody levels, but not with increased neutralization capacity. Work environment during the pandemic correlated with increased neutralization capacity, while kidney or liver disease and traveling out of state after February 2020 correlated with decreased neutralization capacity, however neither correlated with antibody levels. ConclusionsOur data show that natural infection by SARS-CoV-2 can induce a humoral response reflected by high antibody levels and neutralization capacity.

Convergent antibody responses are associated with broad neutralization of hepatitis C virus.

Early development of broadly neutralizing antibodies (bNAbs) targeting the hepatitis C virus (HCV) envelope glycoprotein E2 is associated with spontaneous clearance of infection, so induction of bNAbs is a major goal of HCV vaccine development. However, the molecular antibody features important for broad neutralization are not known. To identify B cell repertoire features associated with broad neutralization, we performed RNA sequencing of the B cell receptors (BCRs) of HCV E2-reactive B cells of HCV-infected individuals with either high or low plasma neutralizing breadth. We then produced a monoclonal antibody (mAb) expressed by pairing the most abundant heavy and light chains from public clonotypes identified among clearance, high neutralization subjects. We found distinctive BCR features associated with broad neutralization of HCV, including long heavy chain complementarity determining region 3 (CDRH3) regions, specific VH gene usage, increased frequencies of somatic hypermutation, and particular VH gene mutations. Most intriguing, we identified many E2-reactive public BCR clonotypes (heavy and light chain clones with the same V and J-genes and identical CDR3 sequences) present only in subjects who produced highly neutralizing plasma. The majority of these public clonotypes were shared by two subjects who cleared infection. A mAb expressing the most abundant public heavy and light chains from these clearance, high neutralization subjects had features enriched in high neutralization clonotypes, such as increased somatic hypermutation frequency and usage of IGHV1-69, and was cross-neutralizing. Together, these results demonstrate distinct BCR repertoires associated with high plasma neutralizing capacity. Further characterization of the molecular features and function of these antibodies can inform HCV vaccine development.

Impact of Mining and Ore Processing on Soil, Drainage and Vegetation in the Zambian Copperbelt Mining Districts: A Review

The regional environmental–geochemical surveying of the long-term impacts of mining and ore processing on a large part of the Zambian Copperbelt mining district was carried out by the Czech Research Group with cooperation of the Geology Department, University of Zambia, and the Geological Survey of Zambia in the period 2002–2018. This included the characterization of various sources of contamination, the extent of contamination of soils and crops, and the degree of contamination of river water and sediments. Solid speciation studies of potentially harmful chemical elements (PHEs), plant and human bioaccessibility studies, and a range of mineralogical techniques were used to assess the pathways of PHE cycling in terrestrial and aqueous systems and their impacts on human health. Ores of the Zambian Copperbelt mining district are mined for Cu and Co, but a number of other trace elements (Pb, As, Cd, Hg, Pb, Zn) gradually accumulated in soils and stream sediments. It was concluded that the most important problems related to ore mining and processing are the contamination of soil and crops due to dust fall out from tailing facilities and emissions from smelters. Moreover, leakages of solutions from tailing dams, insufficient technological control of their stability and breakdowns on pipelines transporting slurry from treatment plants to tailing impoundments cause contamination of water courses and deposition of metal(loids) in stream sediments. However, the contamination of the Kafue River water is relatively limited due to its high neutralization capacity. In contrast, in some Kafue River tributaries, especially those close to big mining centers, the concentrations of dissolved Cu and Co are high (up to 14,752 μg/L and 1917 μg/L) and exceed Zambian effluent limits. We also recommend measures that could contribute to minimizing the impact of ore mining and processing on the environment and the health of the local population.

Soil fertilisation with 137Cs-contaminated and uncontaminated wood ash as a countermeasure to reduce 137Cs uptake by forest plants

The purpose of present study was to find out whether wood ash with a high pH value and neutralizing capacity reduces 137Cs uptake by forest plants many years after the radionuclide fallout. The effects of one-time point fertilisation with 137Cs-contaminated and uncontaminated wood ash alone or in combination with KCl on 137Cs transfer from soil to young leaves and green shoots of various dwarf shrubs and tree species were examined in a long-term fertilisation experiment (2012–2021) conducted in Bazar mixed forest, around 70 km from Chernobyl nuclear power plant. The results indicated minor effects of soil fertilisation, although there were differences between 137Cs uptake by species and years. Soil amendment with 137Cs-contaminated wood ash generally did not affect 137Cs uptake by young shoots and leaves of plants over the growing season in the first year and only slightly decreased Tag for 137Cs in the following years. The effect of a single application of 137Cs-uncontaminated wood ash on reducing 137Cs uptake by plants was generally negligible. Application of 137Cs-contaminated wood ash in combination with KCl reduced plant 137Cs uptake by about 45%, however, such reduction was only significant in some years for bilberry berries, young leaves and green shoots of lingonberry and alder buckthorn. Thus application of wood ash to 137Cs-contaminated forest soil many years after radionuclide fallout generally does not reduce 137Cs uptake by forest vegetation in a mixed forest ecosystem and this countermeasure should be applied with caution.

Discovery and optimization of a broadly-neutralizing human monoclonal antibody against long-chain α-neurotoxins from snakes

Snakebite envenoming continues to claim many lives across the globe, necessitating the development of improved therapies. To this end, broadly-neutralizing human monoclonal antibodies may possess advantages over current plasma-derived antivenoms by offering superior safety and high neutralization capacity. Here, we report the establishment of a pipeline based on phage display technology for the discovery and optimization of high affinity broadly-neutralizing human monoclonal antibodies. This approach yielded a recombinant human antibody with superior broadly-neutralizing capacities in vitro and in vivo against different long-chain α-neurotoxins from elapid snakes. This antibody prevents lethality induced by Naja kaouthia whole venom at an unprecedented low molar ratio of one antibody per toxin and prolongs the survival of mice injected with Dendroaspis polylepis or Ophiophagus hannah whole venoms.

Safety and Effectiveness of SA58 Nasal Spray Against COVID-19 Infection in Medical Personnel: An Open-Label, Blank-Controlled Study - Hohhot City, Inner Mongolia Autonomous Region, China, 2022.

The active ingredient of the SA58 Nasal Spray is a broad-spectrum neutralizing antibody with a high neutralizing capacity against different Omicron sub-variants in vitro studies. This study demonstrated the safety and effectiveness of SA58 Nasal Spray against coronavirus disease 2019 (COVID-19) infection in medical personnel for the first time. This study provides an effective approach for the public to reduce their risk of COVID-19 infection. The findings of this research have the potential to significantly reduce the risk of infection and limit human-to-human transmission in the event of a COVID-19 outbreak.

Suppressing transmembrane-pressure rise by pulse dosing of submicron super-fine powdered activated carbon: Effects of filtration flux, coagulant types, and coagulant-dose timing during precoating

Submicron-sized powdered activated carbon (SSPAC, diameter 200 nm) dosed in a pulse after coagulation pretreatment has recently been found to effectively mitigate membrane fouling and thus to suppress the rise of transmembrane pressure (TMP) in the microfiltration process because SSPAC has a higher capacity to adsorb membrane foulants, such as natural organic matter, than conventional PAC and a precoat layer formed by SSPAC on the membrane surface retards membrane fouling. This study investigated the effects of the filtration flux during precoating, the timing of coagulant dosing, and the types of coagulants on the suppression of TMP rise by pulse-dosed SSPAC. The TMP rise was insensitive to the filtration flux during precoating. However, the efficacy of the SSPAC was sensitive to the use of the coagulant polyaluminum-chloride (PACl). Unlike pulse dosing of SSPAC, pulse dosing of coagulant led to excessive aggregation and settling of SSPAC and insufficient formation of a precoating layer. The best filterability was achieved when the coagulant was dosed continuously in the entire operation period. It is also effective to use treated water for feeding during the preparation stage. For sulfated PACl, high basicity (70 %), with its high charge neutralization capacity, was preferred to medium basicity (50 %). Meanwhile, the TMP rise was more effectively suppressed by non-sulfated PACl with a low-to-medium basicity (20–40 %) than zero or high basicity (70 %). This behavior was explained by the fact that, as the basicity increases, hydrolysis of the coagulants is lessened, but the charge neutralization effect becomes stronger.

Neutralizing SARS-CoV-2 Antibodies in Commercial Immunoglobulin Products Give Patients with X-Linked Agammaglobulinemia Limited Passive Immunity to the Omicron Variant

Immunodeficient individuals often rely on donor-derived immunoglobulin (Ig) replacement therapy (IGRT) to prevent infections. The passive immunity obtained by IGRT is limited and reflects the state of immunity in the plasma donor population at the time of donation. The objective of the current study was to describe how the potential of passive immunity to SARS-CoV-2 in commercial off-the-shelf Ig products used for IGRT has evolved during the pandemic. Samples were collected from all consecutive Ig batches (n = 60) from three Ig producers used at the Immunodeficiency Unit at Karolinska University Hospital from the start of the SARS-CoV-2 pandemic until January 2022. SARS-CoV-2 antibody concentrations and neutralizing capacity were assessed in all samples. In vivo relevance was assessed by sampling patients with XLA (n = 4), lacking endogenous immunoglobulin synthesis and on continuous Ig substitution, for plasma SARS-CoV-2 antibody concentration. SARS-CoV-2 antibody concentrations in commercial Ig products increased over time but remained inconsistently present. Moreover, Ig batches with high neutralizing capacity towards the Wuhan-strain of SARS-CoV-2 had 32-fold lower activity against the Omicron variant. Despite increasing SARS-CoV-2 antibody concentrations in commercial Ig products, four XLA patients on IGRT had relatively low plasma concentrations of SARS-CoV-2 antibodies with no potential to neutralize the Omicron variant in vitro. In line with this observation, three out the four XLA patients had symptomatic COVID-19 during the Omicron wave. In conclusion, 2 years into the pandemic the amounts of antibodies to SARS-CoV-2 vary considerably among commercial Ig batches obtained from three commercial producers. Importantly, in batches with high concentrations of antibodies directed against the original virus strain, protective passive immunity to the Omicron variant appears to be insufficient.

Emerging SARS-CoV-2 Variants and Subvariants: Challenges and Opportunities in the Context of COVID-19 Pandemic.

The COVID-19 pandemic has become the most devastating pandemic of the 21st century since its appearance in December 2019. Like other RNA viruses, continuous mutation is common for coronavirus to create several variants and subvariants. The main reason behind this mutation and evolvement of SARS-CoV-2 was its structural spike (S) glycoprotein. Coronavirus has become a threat to global public health due to its high mutation capability and antibody neutralizing capacity. According to the World Health Organization (WHO), there are 5 major variants of concern (VOC) are Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529). Recently, different Omicron subvariants have gained worldwide dominance, such as BA.1, BA.2, BA.3, BA.4, and BA.5. However, there is a discernible drop in this symptomatic sickness globally due to the success of numerous monoclonal antibodies and vaccinations. Here we also discussed the currently dominant Omicron subvariants and the effectiveness of antiviral agents and vaccines. Based on the available data and our knowledge, we can suggest that the global healthcare organizations can decide on the declaration of the end of the pandemic phase of COVID-19 soon; however, the covid-19 will continue.

Long-term trajectories of SARS-CoV-2 neutralizing antibodies and predictive value of first dose vaccination-induced IgG-antibodies in hemodialysis patients

PurposeThe predictive value of antibody titers after the first SARS-CoV-2 vaccination and long-term trajectories of antibody titers in hemodialysis patients are unknown.MethodsSARS-CoV-2 IgG antibodies and their neutralizing effect six weeks after the first and second vaccination were analysed in 30 hemodialysis patients. IgG titers served to classify participants as responders or non-responders and to calculate sensitivity, specificity, and accuracy. Associations between potential risk factors and post-vaccine non-response were analysed by Mann–Whitney-U test and Chi-Squared test. Long-term follow-up analysis (ANOVA) on the evolution of neutralizing IgG-titers was performed in 24 participants 94 and 135 days after the second immunization.ResultsIgG antibodies ≥ 1 AU/L (mean 9 ± 20 AU/L) after the first dose were found in 20 patients (66.7%). After the second dose only two participants (6.7%) remained sero-negative and 16.6% showed neutralizing levels below 30%, whereas 25 patients showed IgG antibodies with the high neutralizing activity of 86 ± 18%. Positive IgG antibodies 6 weeks after the first vaccination predicted vaccination effectiveness after two cycles with a specificity of 100%, sensitivity of 76%, and accuracy of 87%. Even low-dose immunosuppressive therapy increased the relative risk for non-response after the first and second dose 1.9 (95% CI 0.8–4.6) and 4.9 (95% CI 1.0–23.8) times, respectively. Over a period of about 4.5 months IgG titers slowly declined by 51% from baseline or by 0.45 AU/mL per day, respectively.ConclusionTwo cycles of SARS-CoV-2 vaccination-induced high seroconversion rates comparable to the general population. Immunosuppressive medication is a major risk factor for vaccination non-response. Mounted IgG antibodies showed a high neutralizing capacity as evidence of protective effectiveness. IgG antibodies after the first dose may serve to predict later vaccination outcome. Patients on dialysis display a more rapid decline in antibody titers on long-term follow-up compared to healthy controls.

Humoral Responses to Single-Dose BNT162b2 mRNA Vaccination in Dialysis Patients Previously Infected With SARS-CoV-2.

Seroconversion rates following infection and vaccination are lower in dialysis patients compared to healthy controls. There is an urgent need for the characterization of humoral responses and success of a single-dose SARS-CoV-2 vaccination in previously infected dialysis patients. We performed a dual-center cohort study comparing three different groups: 25 unvaccinated hemodialysis patients after PCR-confirmed COVID-19 (Group 1), 43 hemodialysis patients after two-time BNT162b2 vaccination without prior SARS-CoV-2 infection (Group 2), and 13 single-dose vaccinated hemodialysis patients with prior SARS-CoV-2 infection (Group 3). Group 3 consists of seven patients from Group 1 and 6 additional patients with sera only available after single-dose vaccination. Anti-S1 IgG, neutralizing antibodies, and antibodies against various SARS-CoV-2 protein epitopes were measured 3 weeks after the first and 3 weeks after the second vaccination in patients without prior SARS-CoV-2 infection, 6 weeks after the onset of COVID-19 in unvaccinated patients, and 3 weeks after single-dose vaccination in patients with prior SARS-CoV-2 infection, respectively. Unvaccinated patients after COVID-19 showed a significantly higher neutralizing antibody capacity than two-time vaccinated patients without prior COVID-19 [median (IQR) percent inhibition 88.0 (71.5–95.5) vs. 50.7 (26.4–81.0); P = 0.018]. After one single vaccine dose, previously infected individuals generated 15- to 34-fold higher levels of anti-S1 IgG than age- and dialysis vintage-matched unvaccinated patients after infection or two-time vaccinated patients without prior SARS-CoV-2 infection with a median (IQR) index of 274 (151–791) compared to 18 (8–41) and 8 (1–21) (for both P < 0.001). With a median (IQR) percent inhibition of 97.6 (97.2–98.9), the neutralizing capacity of SARS-CoV-2 antibodies was significantly higher in single-dose vaccinated patients with prior SARS-CoV-2 infection compared to other groups (for both P < 0.01). Bead-based analysis showed high antibody reactivity against various SARS-CoV-2 spike protein epitopes after single-dose vaccination in previously infected patients. In conclusion, single-dose vaccination in previously infected dialysis patients induced a strong and broad antibody reactivity against various SARS-CoV-2 spike protein epitopes with high neutralizing capacity.

A novel single-domain antibody multimer that potently neutralizes tetanus neurotoxin

Tetanus antitoxin, produced in animals, has been used for the prevention and treatment of tetanus for more than 100 years. The availability of antitoxins, ethical issues around production, and risks involved in the use of animal derived serum products are a concern. We therefore developed a llama derived single-domain antibody (VHH) multimer to potentially replace the conventional veterinary product. In total, 28 different tetanus neurotoxin (TeNT) binding VHHs were isolated, 14 of which were expressed in yeast for further characterization. Four VHH monomers (T2, T6, T15 and T16) binding TeNT with high affinity (KD < 1 nM), covering different antigenic domains as revealed by epitope binning, and including 3 monomers (T6, T15 and T16) that inhibited TeNT binding to neuron gangliosides, were chosen as building blocks to generate 11 VHH multimers. These multimers contained either 1 or 2 different TeNT binding VHHs fused to 1 VHH binding to either albumin (A12) or immunoglobulin (G13) to extend serum half-life in animals. Multimers consisting of 2 TeNT binding VHHs showed more than a 10-fold increase in affinity (KD of 4–23 pM) when compared to multimers containing only one TeNT binding VHH. The T6 and T16 VHHs showed synergistic in vivo TeNT neutralization and, when incorporated into a single VHH trimer (T6T16A12), they showed a very high TeNT neutralizing capacity (1,510 IU/mg).

In vitro Antioxidant potential, Total Phenolic and Flavonoid contents in Justicia gendarussa leaf extracts

Free radicals are triggered in human body by routine metabolic pathways which are highly reactive substance entangled in various physiological functions but excess production may impart with multitude diseases such as cancer, arthritis, inflammation and various neurodegenerative disorders. As a result, previous findings supported that various photochemical constituents present in natural plants exerts prominent role in defense mechanism against rate of excess free radicals’ production. The present study was carried out to investigate phytochemical composition, quantification studies and in vitro antioxidant potential of Justicia gendarussa (JG) various solvent extracts. JG belongs to the family Acanthaceace and used as traditional healers in various ailments. JG plant material was collected, dried, powdered and subjected for soxhlation to prepare ethanolic, ethyl acetate, aqueous and n-hexane extracts. Screening of Active constituents by various qualitative tests, estimation of total phenolic (TPC) and Total flavonoid content (TFC) and in vitro antioxidant potential of plant extracts were performed by DPPH, Lipid peroxidation, Nitric oxide and Superoxide radical scavenging methods. Present investigation reveals that, presence of flavonoids, phenols, amino acids, glycosides, cardiac glycosides, proteins, carbohydrates, alkaloids, steroids, terpenoids and tannins. TPC and TFC of ethanol extract were found to be 9.47 ± 0.0216 mg Gallic acid equivalent (GAE/g) and 97.6 ± 0.0342 mg Rutin equivalent/g (RUE/g). Among all the analyzed extracts ethanolic extract of JG possessed high radical neutralizing capacity and for DPPH (IC50 32µg/ml), Lipid Peroxidation (28 µg/ml), Nitric oxide (30 µg/ml) and superoxide anion radicals (39 µg/ml) respectively and found to be more effective as ascorbic acid (26 µg/ml) which was used as standard. Overall results of the study concluded that JG leaf extracts possess beneficial Phytoconstituents, high phenol and flavonoid contents and potential antioxidant activity, which could be a viable source of natural antioxidants for treating various degenerative disorders.

Comparison of two marketed effervescent fast relief formulations for antacid activity-an in vitro study

Background: Hyper-acidity is excessive formation of acid (pH=1.5-3.5) in the stomach by parietal cells which causes a burning sensation in the chest. The preservation of gastric acid insult is crucial because of the implications of hyperacidity in gastroesophageal reflux disease (GERD), peptic ulcers and duodenal ulcers. Acidity is controlled by use of some over-the-counter (OTC) antacid formulations containing magnesium or aluminum hydroxides.Methods: In the present study, the preliminary antacid test (PAT), the pH acid neutralizing capacity (ANC), acid neutralizing potential (ANP) along with buffering capacity of two well-known quick release formulations (F1 [Digene Ultra Fizz] and F2 [a standard, commercially available product]) were determined. Results: According to US pharmacopeia USP, both the antacid formulations passed the PAT test. PAT results revealed that the pH of the acid-antacid solution was higher in F1 (8.20±0.02) as compared to F2, (6.53±0.01). The ANC results revealed that F1 (46.89±0.6 mEq/dosage) had higher neutralizing capacity as compared to F2(30.12±1.3 mEq/dosage). Higher ANP was observed for F1 (245 mins), and it was 2.7 times that of F2 (90 min). The onset of action for both the antacids was &lt;2 seconds. Additionally, buffering capacity was evidently observed during ANP analysis in the case of F1. Independent T test performed for all the tests revealed that the data obtained was highly significant (p&lt;0.01).Conclusions: F1 showed high antacid and buffering properties when tested in vitro. The present study highlights the need for future research on specific OTC non-prescribed antacid formulations with respect to their price, efficacy and side effects.