Characterization of two in vivo challenge models to measure functional activity of monoclonal antibodies to Plasmodium falciparum circumsporozoite protein

2020 ◽  
Author(s):  
Rama Raghunandan ◽  
Bryan T Mayer ◽  
Yevel Flores-Garcia ◽  
Monica W Gerber ◽  
Raphael Gottardo ◽  
...  

Abstract Background New strategies are needed to reduce the incidence of malaria, and promising approaches include the development of vaccines and monoclonal antibodies (mAbs) that target the circumsporozoite protein (CSP). To select the best candidates and speed development, it is essential to standardize preclinical assays to measure the potency of such interventions in animal models. Methods Two assay configurations were studied using transgenic Plasmodium berghei expressing Plasmodium falciparum full-length circumsporozoite protein. The assays measured 1) reduction in parasite infection of the liver (liver burden) following an intravenous (i.v) administration of sporozoites and 2) protection from parasitaemia following mosquito bite challenge. Two human CSP mAbs, AB311 and AB317, were compared for their ability to inhibit infection. Multiple independent experiments were conducted to define assay variability and resultant impact on the ability to discriminate differences in mAb functional activity. Results Overall, the assays produced highly consistent results in that all individual experiments showed greater functional activity for AB317 compared to AB311 as calculated by the dose required for 50% inhibition (ID50) as well as the serum concentration required for 50% inhibition (IC50). The data were then used to model experimental designs with adequate statistical power to rigorously screen, compare, and rank order novel anti-CSP mAbs. Conclusion The results indicate that in vivo assays described here can provide reliable information for comparing the functional activity of mAbs. The results also provide guidance regarding selection of the appropriate experimental design, dose selection, and group sizes.

2020 ◽  
Author(s):  
Rama Raghunandan ◽  
Bryan T Mayer ◽  
Yevel Flores-Garcia ◽  
Monica W Gerber ◽  
Raphael Gottardo ◽  
...  

Abstract Background. New strategies are needed to reduce the incidence of malaria, and promising approaches include the development of vaccines and monoclonal antibodies (mAbs) that target the circumsporozoite protein (CSP). To select the best candidates and speed development, it is essential to standardize preclinical assays to measure the potency of such interventions in animal models. Method. Two assay configurations were studied using transgenic P. berghei expressing P. falciparum full-length circumsporozoite protein. The assays measured 1) reduction in parasite infection of the liver (liver burden) following an intravenous (i.v) administration of sporozoites and 2) protection from parasitemia following mosquito bite challenge. Two human CSP mAbs, AB311 and AB317, were compared for their ability to inhibit infection. Multiple independent experiments were conducted to define assay variability and resultant impact on the ability to discriminate differences in mAb functional activity.Results. Overall, the assays produced highly consistent results in that all individual experiments showed greater functional activity for AB317 compared to AB311 as calculated by the dose required for 50 % inhibition (ID50) as well as the serum concentration required for 50% inhibition (IC50). The data were then used to model experimental designs with adequate statistical power to rigorously screen, compare, and rank order novel anti-CSP mAbs. Conclusion. Our results indicate that in vivo assays described here can provide reliable information for comparing the functional activity of mAbs. Our results also provide guidance regarding selection of the appropriate experimental design, dose selection, and group sizes.


2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Rama Raghunandan ◽  
Bryan T. Mayer ◽  
Yevel Flores-Garcia ◽  
Monica W. Gerber ◽  
Raphael Gottardo ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Merricka C. Livingstone ◽  
Alexis A. Bitzer ◽  
Alish Giri ◽  
Kun Luo ◽  
Rajeshwer S. Sankhala ◽  
...  

AbstractPlasmodium falciparum malaria contributes to a significant global disease burden. Circumsporozoite protein (CSP), the most abundant sporozoite stage antigen, is a prime vaccine candidate. Inhibitory monoclonal antibodies (mAbs) against CSP map to either a short junctional sequence or the central (NPNA)n repeat region. We compared in vitro and in vivo activities of six CSP-specific mAbs derived from human recipients of a recombinant CSP vaccine RTS,S/AS01 (mAbs 317 and 311); an irradiated whole sporozoite vaccine PfSPZ (mAbs CIS43 and MGG4); or individuals exposed to malaria (mAbs 580 and 663). RTS,S mAb 317 that specifically binds the (NPNA)n epitope, had the highest affinity and it elicited the best sterile protection in mice. The most potent inhibitor of sporozoite invasion in vitro was mAb CIS43 which shows dual-specific binding to the junctional sequence and (NPNA)n. In vivo mouse protection was associated with the mAb reactivity to the NANPx6 peptide, the in vitro inhibition of sporozoite invasion activity, and kinetic parameters measured using intact mAbs or their Fab fragments. Buried surface area between mAb and its target epitope was also associated with in vivo protection. Association and disconnects between in vitro and in vivo readouts has important implications for the design and down-selection of the next generation of CSP based interventions.


2021 ◽  
Vol 17 (11) ◽  
pp. e1010042
Author(s):  
Yevel Flores-Garcia ◽  
Lawrence T. Wang ◽  
Minah Park ◽  
Beejan Asady ◽  
Azza H. Idris ◽  
...  

Rare and potent monoclonal antibodies (mAbs) against the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) on infective sporozoites (SPZ) preferentially bind the PfCSP junctional tetrapeptide NPDP or NVDP minor repeats while cross-reacting with NANP major repeats in vitro. The extent to which each of these epitopes is required for protection in vivo is unknown. Here, we assessed whether junction-, minor repeat- and major repeat-preferring human mAbs (CIS43, L9 and 317 respectively) bound and protected against in vivo challenge with transgenic P. berghei (Pb) SPZ expressing either PfCSP with the junction and minor repeats knocked out (KO), or PbCSP with the junction and minor repeats knocked in (KI). In vivo protection studies showed that the junction and minor repeats are necessary and sufficient for CIS43 and L9 to neutralize KO and KI SPZ, respectively. In contrast, 317 required major repeats for in vivo protection. These data establish that human mAbs can prevent malaria infection by targeting three different protective epitopes (NPDP, NVDP, NANP) in the PfCSP repeat region. This report will inform vaccine development and the use of mAbs to passively prevent malaria.


2021 ◽  
Vol 17 (12) ◽  
pp. e1010133
Author(s):  
Lawrence T. Wang ◽  
Lais S. Pereira ◽  
Patience K. Kiyuka ◽  
Arne Schön ◽  
Neville K. Kisalu ◽  
...  

Combinations of monoclonal antibodies (mAbs) against different epitopes on the same antigen synergistically neutralize many viruses. However, there are limited studies assessing whether combining human mAbs against distinct regions of the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) enhances in vivo protection against malaria compared to each mAb alone or whether passive transfer of PfCSP mAbs would improve protection following vaccination against PfCSP. Here, we isolated a panel of human mAbs against the subdominant C-terminal domain of PfCSP (C-CSP) from a volunteer immunized with radiation-attenuated Pf sporozoites. These C-CSP-specific mAbs had limited binding to sporozoites in vitro that was increased by combination with neutralizing human “repeat” mAbs against the NPDP/NVDP/NANP tetrapeptides in the central repeat region of PfCSP. Nevertheless, passive transfer of repeat- and C-CSP-specific mAb combinations did not provide enhanced protection against in vivo sporozoite challenge compared to repeat mAbs alone. Furthermore, combining potent repeat-specific mAbs (CIS43, L9, and 317) that respectively target the three tetrapeptides (NPDP/NVDP/NANP) did not provide additional protection against in vivo sporozoite challenge. However, administration of either CIS43, L9, or 317 (but not C-CSP-specific mAbs) to mice that had been immunized with R21, a PfCSP-based virus-like particle vaccine that induces polyclonal antibodies against the repeat region and C-CSP, provided enhanced protection against sporozoite challenge when compared to vaccine or mAbs alone. Collectively, this study shows that while combining mAbs against the repeat and C-terminal regions of PfCSP provide no additional protection in vivo, repeat mAbs do provide increased protection when combined with vaccine-induced polyclonal antibodies. These data should inform the implementation of PfCSP human mAbs alone or following vaccination to prevent malaria infection.


Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4221
Author(s):  
Aage Kristian Olsen Alstrup ◽  
Svend Borup Jensen ◽  
Ole Lerberg Nielsen ◽  
Lars Jødal ◽  
Pia Afzelius

The development of new and better radioactive tracers capable of detecting and characterizing osteomyelitis is an ongoing process, mainly because available tracers lack selectivity towards osteomyelitis. An integrated part of developing new tracers is the performance of in vivo tests using appropriate animal models. The available animal models for osteomyelitis are also far from ideal. Therefore, developing improved animal osteomyelitis models is as important as developing new radioactive tracers. We recently published a review on radioactive tracers. In this review, we only present and discuss osteomyelitis models. Three ethical aspects (3R) are essential when exposing experimental animals to infections. Thus, we should perform experiments in vitro rather than in vivo (Replacement), use as few animals as possible (Reduction), and impose as little pain on the animal as possible (Refinement). The gain for humans should by far exceed the disadvantages for the individual experimental animal. To this end, the translational value of animal experiments is crucial. We therefore need a robust and well-characterized animal model to evaluate new osteomyelitis tracers to be sure that unpredicted variation in the animal model does not lead to a misinterpretation of the tracer behavior. In this review, we focus on how the development of radioactive tracers relies heavily on the selection of a reliable animal model, and we base the discussions on our own experience with a porcine model.


2014 ◽  
Vol 21 (4) ◽  
pp. 587-593 ◽  
Author(s):  
Martha J. Brown ◽  
Hanna Seitz ◽  
Victoria Towne ◽  
Martin Müller ◽  
Adam C. Finnefrock

ABSTRACTHuman papillomavirus (HPV) is the etiological agent for all cervical cancers, a significant number of other anogenital cancers, and a growing number of head and neck cancers. Two licensed vaccines offer protection against the most prevalent oncogenic types, 16 and 18, responsible for approximately 70% of cervical cancer cases worldwide and one of these also offers protection against types 6 and 11, responsible for 90% of genital warts. The vaccines are comprised of recombinantly expressed major capsid proteins that self-assemble into virus-like particles (VLPs) and prevent infection by eliciting neutralizing antibodies. Adding the other frequently identified oncogenic types 31, 33, 45, 52, and 58 to a vaccine would increase the coverage against HPV-induced cancers to approximately 90%. We describe the generation and characterization of panels of monoclonal antibodies to these five additional oncogenic HPV types, and the selection of antibody pairs that were high affinity and type specific and recognized conformation-dependent neutralizing epitopes. Such characteristics make these antibodies useful tools for monitoring the production and potency of a prototype vaccine as well as monitoring vaccine-induced immune responses in the clinic.


Hybridoma ◽  
2000 ◽  
Vol 19 (5) ◽  
pp. 363-367 ◽  
Author(s):  
Steve Holmes ◽  
Julie A. Abrahamson ◽  
Niam Al-Mahdi ◽  
Sherin S. Abdel-Meguid ◽  
Yen Sen Ho

2001 ◽  
Vol 97 (1) ◽  
pp. 45-49 ◽  
Author(s):  
W Roeffen ◽  
K Teelen ◽  
J van As ◽  
M vd Vegte-Bolmer ◽  
W Eling ◽  
...  

1987 ◽  
Vol 2 (3) ◽  
pp. 143-150 ◽  
Author(s):  
Federico Genzano ◽  
Ada Funaro ◽  
Massimo Alessio ◽  
Lucia B. De Monte ◽  
Graziella Bellone ◽  
...  

Murine monoclonal antibodies (MoAbs) have found widespread applications in the characterization of the molecular and functional features of lymphocyte differentiation antigens. The present paper summarizes the results of our work dealing with the production and selection of a murine MoAb recognizing a molecule expressed during the whole differentiative life of T lymphocytes. The MoAb CB01 resulted to be specific for an apparently unique epitope of the T-cell specific membrane glycoprotein T1-CD5.


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