Design and Construction of a Synthetic Nanobody Library: Testing Its Potential with a Single Selection Round Strategy.

Nanobodies (Nbs) are single domain antibody fragments derived from heavy-chain antibodies found in members of the Camelidae family. They have become a relevant class of biomolecules for many different applications because of several important advantages such as their small size, high solubility and stability, and low production costs. On the other hand, synthetic Nb libraries are emerging as an attractive alternative to animal immunization for the selection of antigen-specific Nbs. Here, we present the design and construction of a new synthetic nanobody library using the phage display technology, following a structure-based approach in which the three hypervariable loops were subjected to position-specific randomization schemes. The constructed library has a clonal diversity of 108 and an amino acid variability that matches the codon distribution set by design at each randomized position. We have explored the capabilities of the new library by selecting nanobodies specific for three antigens: vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF) and the glycoprotein complex (GnGc) of Andes virus. To test the potential of the library to yield a variety of antigen-specific Nbs, we introduced a biopanning strategy consisting of a single selection round using stringent conditions. Using this approach, we obtained several binders for each of the target antigens. The constructed library represents a promising nanobody source for different applications.

Selecting Nanobodies Specific for the Epidermal Growth Factor from a Synthetic Nanobody Library.

The epidermal growth factor (EGF) is one of the most critical ligands of the EGF receptor (EGFR), a well-known oncogene frequently overexpressed in cancerous cells and an important therapeutic target in cancer. The EGF is the target of a therapeutic vaccine aimed at inducing an anti-EGF antibody response to sequester this molecule from serum. However, strikingly, very few investigations have focused on EGF immunotargeting. Since the use of nanobodies (Nbs) for EGF neutralization may be an effective therapeutic strategy in several types of cancer, in this study, we decided to generate anti-EGF Nbs from a recently constructed, phage-displaying synthetic nanobody library. To our knowledge, this is the first attempt to obtain anti-EGF Nbs from a synthetic library. By applying a selection strategy that uses four different sequential elution steps along with three rounds of selection, we obtained four different EGF-specific Nb clones, and also tested their binding capabilities as recombinant proteins. The obtained results are very encouraging and demonstrate the feasibility of selecting nanobodies against small antigens, such as the EGF, from synthetic libraries.

Obtención de un diagnosticador rápido de cólera, basado en partículas de látex acopladas a un anticuerpo monoclonal contra lipopolisacárido de Vibrio cholerae O1 / Obtaining of a rapid diagnostic test for Cholera, based on latex particles coupled with a monoclonal antibody against Vibrio cholerae O1 lipopolysaccharide

El cólera es una enfermedad infecto-contagiosa intestinal aguda, causada por la ingestión de alimentos o agua contaminada con los serotipos O1 y O139 de la bacteria Vibrio cholerae. Se caracteriza por diarrea secretora abundante que llevan rápidamente a la deshidratación. Sin tratamiento adecuado produce la muerte en horas, por lo que el diagnostico precoz es muy importante sobre todo porque al inicio es difícil diferenciarla de otras enfermedades diarreicas agudas. La prueba diagnóstico de oro es el coprocultivo; sin embargo, no garantiza una detección rápida de la enfermedad. Recientemente se desarrollaron ensayos rápidos, se basan en tiras reactivas y aglutinación con partículas de látex, muy efectivos, pero difíciles de adquirir por sus altos precios. El objetivo de este trabajo fue obtener un diagnosticador rápido basado en partículas de látex acopladas a un anticuerpo monoclonal (AcM) contra el lipopolisacárido de V. cholerae O1, el cual se obtuvo en el Instituto Finlay. Se usaron partículas de látex de 0,8 µm en una suspensión al 10 por ciento a las que se acopló durante 2 h a 37°C el AcM a 0,25 mg/mL. Se evaluó la sensibilidad, especificidad y el desempeño en 84 muestras de heces de pacientes con diagnóstico presuntivo de cólera. El diagnosticador que se obtuvo no evidenció reactividad cruzada frente a cepas no-O1, ni contra otros enteropatógenos. El diagnosticador látex presentó valores de sensibilidad, especificidad y eficacia de 97,87; 97,29 y 97,6 por ciento respectivamente, muy similares al diagnosticador comercial CTK-Biotech. El diagnosticador látex que se obtuvo se puede utilizar en el diagnóstico rápido de la enfermedad(AU)

Cholera is an acute contagious intestinal disease caused by ingestion of food or water contaminated with O1 and O139 serotypes of the bacterium Vibrio cholerae . Cholera is characterized by abundant secretory diarrhea leading to dehydration. Death occurs within hours without treatment, so early diagnosis is very important, especially at the beginning of the disease, because it is difficult to differentiate from other acute diarrheal diseases. The diagnostic golden test is the stool culture; however, it does not guarantee a rapid detection of the disease. Rapid tests have been recently developed; they are based on test strips and agglutination with latex particles, which are very effective, but difficult to acquire for their high prices. The objective of this research was to obtain a quick assay based on latex particles coupled with a monoclonal antibody (mAb) against V. cholerae O1 lipopolysaccharide obtained in Finlay Institute. Latex particles of 0.8 µm were used in a 10 percent suspension, and they were coupled to the mAb (0.25 mg/ml) for 2 hours at 37°C. The sensitivity, specificity and performance were evaluated in 84 stool samples from patients with presumptive diagnosis of cholera. The diagnostic test obtained showed no cross-reactivity against no-O1 strains and other enteropathogens. Latex diagnostic test showed values of sensitivity, specificity and efficacy of 97.87; 97.29 and 97.6 percent respectively, very similar to the commercial diagnostic test CTK-Biotech. The latex reagent obtained can be used in the rapid diagnosis of the disease(AU)

Obtención de un anticuerpo monoclonal murino que reconoce al polisacárido capsular Vi de Salmonella Typhi / Generation of a murine monoclonal antibody to capsular polysaccharide Vi from Salmonella Typhi

La tecnología clásica del hibridoma permitió el desarrollo de anticuerpos monoclonales (AcM) contra una inmensa variedad de antígenos, los cuales tienen diversas aplicaciones en el campo de la investigación básica, diagnóstico, inmunoterapia y en los procesos industriales de vacunas. En este trabajo se generaron hibridomas productores de AcM específicos contra el polisacárido capsular Vi de Salmonella Typhi, para lo cual se realizó la inmunización intraperitoneal de ratones BALB/c con 10 Ág de polisacárido capsular Vi conjugado a Toxoide Diftérico y la subsiguiente fusión entre los linfocitos aislados del bazo y células de mieloma SP2/O. Se seleccionó y caracterizó un AcM que se denominó 4G3E11. El isotipo del AcM resultó IgG1. Se demostró que AcM 4G3E11 reconoce diferentes valores de concentración del polisacárido en muestras de vacunas vax-TyVi®, mediante un ELISA tipo sándwich. El AcM obtenido como parte de este estudio permitirá la identificación y cuantificación del polisacárido Vi en vacunas anti-tifoídicas(AU)

The conventional hybridoma technology has enabled the development of monoclonal antibodies (Mabs) against many antigens. Mabs have several applications in the field of basic research, diagnosis, immunotherapy and vaccine manufacturing processes. Mabs-producing hybridomas against the capsular polysaccharide from