scholarly journals Generation of Highly Efficient Equine-Derived Antibodies for Post-Exposure Treatment of Ricin Intoxications by Vaccination with Monomerized Ricin

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 466 ◽  
Author(s):  
Reut Falach ◽  
Anita Sapoznikov ◽  
Ron Alcalay ◽  
Moshe Aftalion ◽  
Sharon Ehrlich ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Ricinus Communis ◽  
Lethal Dose ◽  
Clinical Signs ◽  
Neutralizing Antibody ◽  
Exposure Treatment ◽  
Safety Issues ◽  
Post Exposure ◽  
A Cell ◽  
High Level

Ricin, a highly lethal toxin derived from the seeds of Ricinus communis (castor beans) is considered a potential biological threat agent due to its high availability, ease of production, and to the lack of any approved medical countermeasure against ricin exposures. To date, the use of neutralizing antibodies is the most promising post-exposure treatment for ricin intoxication. The aim of this work was to generate anti-ricin antitoxin that confers high level post-exposure protection against ricin challenge. Due to safety issues regarding the usage of ricin holotoxin as an antigen, we generated an inactivated toxin that would reduce health risks for both the immunizer and the immunized animal. To this end, a monomerized ricin antigen was constructed by reducing highly purified ricin to its monomeric constituents. Preliminary immunizing experiments in rabbits indicated that this monomerized antigen is as effective as the native toxin in terms of neutralizing antibody elicitation and protection of mice against lethal ricin challenges. Characterization of the monomerized antigen demonstrated that the irreversibly detached A and B subunits retain catalytic and lectin activity, respectively, implying that the monomerization process did not significantly affect their overall structure. Toxicity studies revealed that the monomerized ricin displayed a 250-fold decreased activity in a cell culture-based functionality test, while clinical signs were undetectable in mice injected with this antigen. Immunization of a horse with the monomerized toxin was highly effective in elicitation of high titers of neutralizing antibodies. Due to the increased potential of IgG-derived adverse events, anti-ricin F(ab’)2 antitoxin was produced. The F(ab’)2-based antitoxin conferred high protection to intranasally ricin-intoxicated mice; ~60% and ~34% survival, when administered 24 and 48 h post exposure to a lethal dose, respectively. In line with the enhanced protection, anti-inflammatory and anti-edematous effects were measured in the antitoxin treated mice, in comparison to mice that were intoxicated but not treated. Accordingly, this anti-ricin preparation is an excellent candidate for post exposure treatment of ricin intoxications.

scholarly journals Experimental rabies infection in haematophagous bats Desmodus rotundus

2005 ◽  
Vol 133 (3) ◽  
pp. 523-527 ◽  
Author(s):  
M. F. ALMEIDA ◽  
L. F. A. MARTORELLI ◽  
C. C. AIRES ◽  
P. C. SALLUM ◽  
E. L. DURIGON ◽  
...  
Keyword(s):  
Antibody Response ◽  
Rabies Virus ◽  
Neutralizing Antibodies ◽  
Fluorescent Antibody ◽  
Lethal Dose ◽  
Clinical Signs ◽  
Neutralizing Antibody ◽  
Pectoral Muscle ◽  
Desmodus Rotundus ◽  
Virus Dose

In order to determine the susceptibility and serum neutralizing antibody response of Desmodus rotundus to rabies virus, bats were inoculated with a virus isolated from a naturally infected haematophagous bat. Bats were divided into four groups of 10 animals each. Dilutions of rabies virus containing 100, 1000, 10000 and 100000 MICLD50 (lethal dose 50% for mice inoculated by the intracerebral route) were administrated in the pectoral muscle. The presence of rabies virus was detected in brain and salivary glands by fluorescent antibody, mouse inoculation and RT–PCR. The observed mortality for each virus dose was 0, 20, 20 and 60% respectively. Serum neutralizing antibodies were tested for by the rapid fluorescent focus inhibition test, and antibody titres greater than 0·5 IU/ml were found in 53% of bats 30 days after virus inoculation. Resistance to infection was seen in bats that developed low or no detectable antibody response as well as in bats with high titres. Among the 10 bats that died of rabies, eight showed signs of paralytic rabies and two bats showed no clinical signs.

scholarly journals Virus-Neutralizing Monoclonal Antibody Expressed in Milk of Transgenic Mice Provides Full Protection against Virus-Induced Encephalitis

2001 ◽  
Vol 75 (6) ◽  
pp. 2803-2809 ◽  
Author(s):  
Andreas F. Kolb ◽  
Lecia Pewe ◽  
John Webster ◽  
Stanley Perlman ◽  
C. Bruce A. Whitelaw ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Neutralizing Antibodies ◽  
Defense Mechanism ◽  
Viral Infections ◽  
Hepatitis Virus ◽  
Recombinant Antibody ◽  
Lethal Dose ◽  
Neutralizing Antibody ◽  
Murine Hepatitis Virus

ABSTRACT Neutralizing antibodies represent a major host defense mechanism against viral infections. In mammals, passive immunity is provided by neutralizing antibodies passed to the offspring via the placenta or the milk as immunoglobulin G and secreted immunoglobulin A. With the long-term goal of producing virus-resistant livestock, we have generated mice carrying transgenes that encode the light and heavy chains of an antibody that is able to neutralize the neurotropic JHM strain of murine hepatitis virus (MHV-JHM). MHV-JHM causes acute encephalitis and acute and chronic demyelination in susceptible strains of mice and rats. Transgene expression was targeted to the lactating mammary gland by using the ovine β-lactoglobulin promoter. Milk from these transgenic mice contained up to 0.7 mg of recombinant antibody/ml. In vitro analysis of milk derived from different transgenic lines revealed a linear correlation between antibody expression and virus-neutralizing activity, indicating that the recombinant antibody is the major determinant of MHV-JHM neutralization in murine milk. Offspring of transgenic and control mice were challenged with a lethal dose of MHV-JHM. Litters suckling nontransgenic dams succumbed to fatal encephalitis, whereas litters suckling transgenic dams were fully protected against challenge, irrespective of whether they were transgenic. This demonstrates that a single neutralizing antibody expressed in the milk of transgenic mice is sufficient to completely protect suckling offspring against MHV-JHM-induced encephalitis.

scholarly journals Thermostable ricin vaccine protects rhesus macaques against aerosolized ricin: Epitope-specific neutralizing antibodies correlate with protection

2015 ◽  
Vol 112 (12) ◽  
pp. 3782-3787 ◽  
Author(s):  
Chad J. Roy ◽  
Robert N. Brey ◽  
Nicholas J. Mantis ◽  
Kelly Mapes ◽  
Iliodora V. Pop ◽  
...  
Keyword(s):  
Castor Oil ◽  
Mammalian Cells ◽  
Neutralizing Antibodies ◽  
Rhesus Macaques ◽  
Lethal Dose ◽  
Lung Damage ◽  
Ricin Toxin ◽  
A Cell ◽  
A Chain ◽  
Antibody Competition

Ricin toxin (RT) is the second most lethal toxin known; it has been designated by the CDC as a select agent. RT is made by the castor bean plant; an estimated 50,000 tons of RT are produced annually as a by-product of castor oil. RT has two subunits, a ribotoxic A chain (RTA) and galactose-binding B chain (RTB). RT binds to all mammalian cells and once internalized, a single RTA catalytically inactivates all of the ribosomes in a cell. Administered as an aerosol, RT causes rapid lung damage and fibrosis followed by death. There are no Food and Drug Administration-approved vaccines and treatments are only effective in the first few hours after exposure. We have developed a recombinant RTA vaccine that has two mutations V76M/Y80A (RiVax). The protein is expressed in Escherichia coli and is nontoxic and immunogenic in mice, rabbits, and humans. When vaccinated mice are challenged with injected, aerosolized, or orally administered (gavaged) RT, they are completely protected. We have now developed a thermostable, aluminum-adjuvant–containing formulation of RiVax and tested it in rhesus macaques. After three injections, the animals developed antibodies that completely protected them from a lethal dose of aerosolized RT. These antibodies neutralized RT and competed to varying degrees with a panel of neutralizing and nonneutralizing mouse monoclonal antibodies known to recognize specific epitopes on native RTA. The resulting antibody competition profile could represent an immunologic signature of protection. Importantly, the same signature was observed using sera from RiVax-immunized humans.

scholarly journals Fast and long-lasting immune response to S-trimer COVID-19 vaccine adjuvanted by PIKA

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Yuan Liu ◽  
Lianpan Dai ◽  
Xiaoli Feng ◽  
Ran Gao ◽  
Nan Zhang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Candidate ◽  
Neutralizing Antibody ◽  
Protein Vaccine ◽  
Humoral Immune ◽  
Humoral Immune Responses ◽  
The Face ◽  
Potential Vaccine ◽  
High Level

AbstractIn the face of the emerging variants of SARS-CoV-2, there is an urgent need to develop a vaccine that can induce fast, effective, long-lasting and broad protective immunity against SARS-CoV-2. Here, we developed a trimeric SARS-CoV-2 S protein vaccine candidate adjuvanted by PIKA, which can induce robust cellular and humoral immune responses. The results showed a high level of neutralizing antibodies induced by the vaccine was maintained for at least 400 days. In the study of non-human primates, PIKA adjuvanted S-trimer induced high SARS-CoV-2 neutralization titers and protected from virus replication in the lung following SARS-CoV-2 challenge. In addition, the long-term neutralizing antibody response induced by S-trimer vaccine adjuvanted by PIKA could neutralize multiple SARS-CoV-2 variants and there is no obvious different among the SARS- CoV-2 variants of interest or concern, including B.1.351, B.1.1.7, P.1, B.1.617.1 and B.1.617.2 variants. These data support the utility of S-trimer protein adjuvanted by PIKA as a potential vaccine candidate against SARS-CoV-2 infection.

scholarly journals The feasibility of convalescent plasma therapy in severe COVID- 19 patients: a pilot study

2020 ◽  
Author(s):  
Kai Duan ◽  
Bende Liu ◽  
Cesheng Li ◽  
Huajun Zhang ◽  
Ting Yu ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Clinical Symptoms ◽  
Antiviral Agents ◽  
Neutralizing Antibody ◽  
Optimal Dose ◽  
Plasma Therapy ◽  
Reactive Protein ◽  
Antibody Titers ◽  
Novel Coronavirus ◽  
High Level

AbstractCurrently, there are no approved specific antiviral agents for 2019 novel coronavirus disease (COVID-19). In this study, ten severe patients confirmed by real-time viral RNA test were enrolled prospectively. One dose of 200 mL convalescent plasma (CP) derived from recently recovered donors with the neutralizing antibody titers above 1:640 was transfused to the patients as an addition to maximal supportive care and antiviral agents. The primary endpoint was the safety of CP transfusion. The second endpoints were the improvement of clinical symptoms and laboratory parameters within 3 days after CP transfusion. The median time from onset of illness to CP transfusion was 16.5 days. After CP transfusion, the level of neutralizing antibody increased rapidly up to 1:640 in five cases, while that of the other four cases maintained at a high level (1:640). The clinical symptoms were significantly improved along with increase of oxyhemoglobin saturation within 3 days. Several parameters tended to improve as compared to pre-transfusion, including increased lymphocyte counts (0.65×109/L vs. 0.76×109/L) and decreased C-reactive protein (55.98 mg/L vs. 18.13 mg/L). Radiological examinations showed varying degrees of absorption of lung lesionswithin 7 days. The viral load was undetectable after transfusion in seven patients who had previous viremia. No severe adverse effects were observed. This study showed CP therapy was welltolerated and could potentially improve the clinical outcomes through neutralizing viremia in severe COVID-19 cases. The optimal dose and time point, as well as the clinical benefit of CP therapy, needs further investigation in larger well-controlled trials.Significance StatementCOVID-19 is currently a big threat to global health. However, no specific antiviral agents are available for its treatment. In this work, we explored the feasibility of convalescent plasma (CP) transfusion to rescue severe patients. The results from 10 severe adult cases showed that one dose (200 mL) of CP was welltolerated and could significantly increase or maintain the neutralizing antibodies at a high level, leading to disappearance of viremia in 7 days. Meanwhile, clinical symptoms and paraclinical criteria rapidly improved within 3 days. Radiological examination showed varying degrees of absorption of lung lesions within 7 days. These results indicate that CP can serve as a promising rescue option for severe COVID-19 while the randomized trial is warranted.

scholarly journals The Trend of Neutralizing Antibody Response Against SARS-CoV-2 and the Cytokine/Chemokine Release in Patients with Differing Severities of COVID-19: All Individuals Infected with SARS-CoV-2 Obtained Neutralizing Antibody

2020 ◽  
Author(s):  
Lidya Handayani Tjan ◽  
Tatsuya Nagano ◽  
Koichi Furukawa ◽  
Mitsuhiro Nishimura ◽  
Jun Arii ◽  
...  
Keyword(s):  
Antibody Production ◽  
Neutralizing Antibodies ◽  
Clinical Course ◽  
Antibody Therapy ◽  
Neutralizing Antibody ◽  
Older Individuals ◽  
First Line ◽  
Critical Patients ◽  
High Level ◽  
Different Levels

Background: COVID-19 patients show a wide clinical spectrum ranging from mild respiratory symptoms to severe and fatal disease, and older individuals are known to be affected more severely. Neutralizing antibody for viruses is critical for their elimination, and increased cytokine/chemokine levels are thought to be related to COVID-19 severity. However, the trend of the neutralizing antibody production and cytokine/chemokine levels during the clinical course of COVID-19 patients with differing levels of severity has not been established. Methods: We serially collected 45 blood samples from 12 patients with different levels of COVID-19 severity, and investigated the trend of neutralizing antibody production using authentic SARS-CoV-2 and cytokine/chemokine release in the patients' clinical courses. Results: All 12 individuals infected with SARS-CoV-2 had the neutralizing antibody against it, and the antibodies were induced at approx. 4-10 days after the patients' onsets. The antibodies in the critical and severe cases showed high neutralizing activity in all clinical courses. Most cytokine/chemokine levels were clearly high in the critical patients compared to those with milder symptoms. Conclusion: Neutralizing antibodies against SARS-CoV-2 were induced at a high level in the severe COVID-19 patients, indicating that abundant virus replication occurred. Cytokines/chemokines were expressed more in the critical patients, indicating that high productions of cytokines/chemokines have roles in the disease severity. These results may indicate that plasma or neutralizing antibody therapy could be a first-line treatment for older patients to eliminate the virus, and corticosteroid therapy could be effective to suppress the cytokine storm after the viral genome's disappearance.

scholarly journals Preexposure and Postexposure Prophylaxis of Rabies With Adeno-Associated Virus Expressing Virus-Neutralizing Antibody in Rodent Models

2021 ◽  
Vol 12 ◽  
Author(s):  
Fei Huang ◽  
Meishen Ren ◽  
Jie Pei ◽  
Hong Mei ◽  
Baokun Sui ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Enhanced Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Intrathecal Injection ◽  
Lethal Dose ◽  
Neutralizing Antibody ◽  
Human Rabies ◽  
Postexposure Prophylaxis ◽  
Adeno Associated Virus ◽  
Green Fluorescent

Rabies, a fatal disease in humans and other mammals, is caused by the rabies virus (RABV), and it poses a public health threat in many parts of the world. Once symptoms of rabies appear, the mortality is near 100%. There is currently no effective treatment for rabies. In our study, two human-derived RABV-neutralizing antibodies (RVNA), CR57 and CR4098, were cloned into adeno-associated virus (AAV) vectors, and recombinant AAVs expressing RVNA were evaluated for postexposure prophylaxis after intrathecal injection into RABV-infected rats. At 4days post-infection with a lethal dose of RABV, 60% of the rats that received an intrathecal injection of AAV-CR57 survived, while 100% of the rats inoculated with AAV-enhanced green fluorescent protein (EGFP) succumbed to rabies. Overall, these results demonstrate that AAV-encoding RVNA can be utilized as a potential human rabies postexposure prophylaxis.

scholarly journals Identification of conformational neutralizing epitopes on the capsid protein of canine calicivirus

2001 ◽  
Vol 82 (7) ◽  
pp. 1695-1702 ◽  
Author(s):  
Yuichi Matsuura ◽  
Yukinobu Tohya ◽  
Masami Mochizuki ◽  
Kozo Takase ◽  
Takaaki Sugimura
Keyword(s):  
Amino Acid ◽  
Capsid Protein ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Site Directed Mutagenesis ◽  
Single Amino Acid ◽  
Amino Acid Residues ◽  
Conformational Epitopes ◽  
A Cell ◽  
Neutralizing Epitopes

Two neutralizing monoclonal antibodies (MAbs) against canine calicivirus (CaCV), which has a distinct antigenicity from feline calicivirus (FCV), were obtained. Both MAbs recognized conformational epitopes on the capsid protein of CaCV and were used to identify these epitopes. Neutralization-resistant variants of CaCV were selected in the presence of individual MAbs in a cell culture. Cross-neutralization tests using the variants indicated that the MAbs recognized functionally independent epitopes on the capsid protein. Recombinantly expressed ORF2 products (capsid precursors) of the variants showed no reactivity to the MAbs used for the selection, suggesting that the resistance was induced by a failing in binding of the MAbs to the variant capsid proteins. Several nucleotide changes resulting in amino acid substitutions in the capsid protein were found by sequence analysis. Reactivities of the MAbs to the revertant ORF2 products produced from each variant ORF2 by site-directed mutagenesis identified a single amino acid substitution in each variant capsid protein responsible for the failure of MAb binding. The amino acid residues related to forming the conformational neutralizing epitopes were located in regions equivalent to the 5′ and 3′ hypervariable regions of the FCV capsid protein, where antigenic sites were demonstrated in previous studies. The recombinant ORF2 products expressed in bacteria failed to induce neutralizing antibody, suggesting that neutralizing antibodies were only generated when properly folded capsid protein was used as an antigen. In CaCV, the conformational epitopes may play a more important role in neutralization than do linear epitopes.

POLIOMYELITIS IN FAMILIES ATTACKED BY THE DISEASE

PEDIATRICS ◽  
1948 ◽  
Vol 2 (2) ◽  
pp. 190-199
Author(s):  
HERBERT A. WENNER ◽  
WILLIAM A. TANNER
Keyword(s):  
Antibody Titer ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Poliomyelitis Virus ◽  
Number Of Patients ◽  
High Level

A study has been made concerning the presence, and persistence of neutralizing antibodies to poliomyelitis virus in six individuals. Five individuals had poliomyelitis; the remaining subject was a familial contact. Neutralizing antibodies do appear in the serums of patients convalescent from poliomyelitis. In this study neutralizing antibodies, as a rule, appeared during the first ten days of illness. There is the suggestion that these antibodies appear rapidly, quickly reach their highest level, and that there is little if any fall in titer during the ensuing year. The neutralizing antibody titer may not reach a high level in a considerable number of patients.

scholarly journals Protective Efficacy of the Calicivirus Valency of the Leucofeligen Vaccine against a Virulent Heterologous Challenge in Kittens

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Cynthia Lesbros ◽  
Virginie Martin ◽  
Wojciech Najbar ◽  
Annaele Sanquer ◽  
David Mcgahie ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Efficacy ◽  
Clinical Signs ◽  
Neutralizing Antibody ◽  
Clinical Score ◽  
Immunological Responses ◽  
Heterologous Challenge ◽  
Tetravalent Vaccine ◽  
Clinical Protection ◽  
Unrelated Strain

Feline calicivirus (FCV) is a common feline pathogen with a potential for antigenic diversity. This study aimed to evaluate and characterize the protective efficacy of the FCV-F9 valency of a tetravalent vaccine, Leucofeligen, against challenge with an unrelated strain. Ten 9-week-old kittens were vaccinated while 10 remained as unvaccinated controls. The vaccinated cats received Leucofeligen twice subcutaneously with a 3-week interval. Four weeks after the second vaccination, all cats were challenged with virulent heterologous FCV and followed up for 21 days, monitoring their general condition, clinical signs, and immunological responses. During the vaccination phase, rectal temperatures and body weights were indistinguishable between the two groups. Only vaccinated cats showed FCV-specific seroconversion (both total and neutralizing antibodies). In the first week after challenge, the vaccinated cats had an 82.6% reduction in median clinical score compared to controls. Leucofeligen was thus shown to provide a significant clinical protection to kittens challenged with heterologous virulent FCV. This protection was similar whether the cats had neutralizing antibody or not, indicating a key role for cellular immunity in the overall protection. This also suggests that previously reported seroneutralisation studies may underestimate the level of cross-protection against field strains obtained with this modified live FCV-F9 vaccine.

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