RESUMO
Envenoming due to Loxosceles spider bites still remains a neglected disease of particular medical concern in the Americas. To date, there is no consensus for the treatment of envenomed patients, yet horse polyclonal antivenoms are usually infused to patients with identified severe medical conditions. It is widely known that venom proteins in the 30-35 kDa range with sphingomyelinase D (SMasesD) activity, reproduce most of the toxic effects observed in loxoscelism. Hence, we believe that monoclonal antibody fragments targeting such toxins might pose an alternative safe and effective treatment. In the present study, starting from the monoclonal antibody LimAb7, previously shown to target SMasesD from the venom of L. intermedia and neutralize its dermonecrotic activity, we designed humanized antibody V-domains, then produced and purified as recombinant single-chain antibody fragments (scFvs). These molecules were characterized in terms of humanness, structural stability, antigen-binding activity, and venom-neutralizing potential. Throughout this process, we identified some blocking points that can impact the Abs antigen-binding activity and neutralizing capacity. In silico analysis of the antigen/antibody amino acid interactions also contributed to a better understanding of the antibody's neutralization mechanism and led to reformatting the humanized antibody fragment which, ultimately, recovered the functional characteristics for efficient in vitro venom neutralization.
Assuntos
Anticorpos Monoclonais , Antivenenos , Anticorpos de Cadeia Única , Venenos de Aranha/imunologia , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/imunologia , Antígenos/imunologia , Antivenenos/administração & dosagem , Antivenenos/imunologia , Eritrócitos/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Humanos , Modelos Moleculares , Testes de Neutralização , Anticorpos de Cadeia Única/administração & dosagem , Anticorpos de Cadeia Única/imunologia , Picada de Aranha/terapia , Venenos de Aranha/efeitos adversos , Aranhas/imunologiaRESUMO
AIM: To develop a monoclonal antibody against dehydroepiandrosterone (DHEA) and miniaturize it, generating a single-chain antibody variable fragment (scFv) against DHEA as an adrenocortical carcinoma (ACC) marker. MATERIAL & METHODS: DHEA conjugated to keyhole limpet hemocyanin was used as an immunogen to obtain anti-DHEA hybridomas. Variable fragments were cloned from hybridoma 5B7 total RNA, and used to detect DHEA in normal adrenal tissue and ACC cells. RESULTS: IgM monoclonal antibody was highly specific, and the recombinant scFv preserved parental antibody characteristics, allowing tissue localization of DHEA. CONCLUSION: Undefined small lesions are challenges for clinicians and impact clinical adrenocortical tumor management. Generating an anti-DHEA scFv facilitates development of imaging tests for early diagnosis of pediatric ACC.
Assuntos
Neoplasias do Córtex Suprarrenal/diagnóstico , Carcinoma Adrenocortical/diagnóstico , Biomarcadores Tumorais/análise , Desidroepiandrosterona/análise , Anticorpos de Cadeia Única/metabolismo , Animais , Biomarcadores Tumorais/metabolismo , Desidroepiandrosterona/metabolismo , Expressão Gênica , Humanos , Camundongos Endogâmicos BALB C , Simulação de Acoplamento Molecular , Conformação Proteica , Engenharia de Proteínas/métodos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Anticorpos de Cadeia Única/genética , Zona Reticular/metabolismoRESUMO
Loxosceles spider bites often lead to serious envenomings and no definite therapy has yet been established. In such a context, it is of interest to consider an antibody-based targeted therapy. We have previously prepared a murine monoclonal IgG (LiMab7) that binds to 32-35kDa components of Loxosceles intermedia venom and neutralizes the dermonecrotic activity of the venom. Here, we re-engineered LiMab7 into a recombinant diabody. The protein was produced in bacteria and then it was functionally characterized. It proved to be efficient at neutralizing sphingomyelinase and hemolytic activities of the crude venom despite the slightly altered binding kinetic constants and the limited stability of the dimeric configuration. This is the first report of a specific recombinant antibody for a next-generation of Loxosceles antivenoms.