Caracterización molecular y bioquímica del efecto asociado a patología infecciosa severa compatible con deficiencia de Properdina (CFP) en un paciente con Meningitis Meningocócica recurrente

Agudo Riba, Ana Mei (2019). Caracterización molecular y bioquímica del efecto asociado a patología infecciosa severa compatible con deficiencia de Properdina (CFP) en un paciente con Meningitis Meningocócica recurrente. Proyecto Fin de Carrera / Trabajo Fin de Grado, E.T.S. de Ingeniería Agronómica, Alimentaria y de Biosistemas (UPM), Madrid.

Description

Title: Caracterización molecular y bioquímica del efecto asociado a patología infecciosa severa compatible con deficiencia de Properdina (CFP) en un paciente con Meningitis Meningocócica recurrente
Author/s:
  • Agudo Riba, Ana Mei
Contributor/s:
  • Torres Lacruz, Miguel Ángel
  • López Lera, Alberto
  • Corvillo Rodríguez, Fernando
Item Type: Final Project
Degree: Grado en Biotecnología
Date: June 2019
Subjects:
Faculty: E.T.S. de Ingeniería Agronómica, Alimentaria y de Biosistemas (UPM)
Department: Biotecnología - Biología Vegetal
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

Properdin (P) is a positive regulator of the alternative pathway of the complement system (immune system). It is codified by the complement factor properdin (CFP) recessive gene, located at the X chromosome. The deficiency of this protein leads to an increased susceptibility to bacterial infections caused by Neisseria, among other genera. In this study, a clinical case of a Spanish 17 – years old boy who suffered from meningitis and meningococcal sepsis at the age of 16 is reported. A deficiency in the immune system of this patient was suspected after the meningococcal episodes already mentioned. Therefore, the aim of this study was the determination of the immune component altered in the patient. Moreover, the underlying molecular cause of this alteration was also analysed. For the first purpose, two immunochemical methods were applied: nephelometry and Enzyme-Linked Immunosorbent Assay (ELISA). Plasmatic proteins C3 and C4 (complement system proteins), and immunoglobulins G (IgG), A (IgA) and M (IgM), were determined by nephelometry. P and factor B (FB), both complement system proteins as well, were quantified by ELISA. Further characterization of the molecular defect included western blot and colorimetric functional assays such as the so–called Total Haemolytic Complement 50% (CH50) assay and Alternative Pathway 50% (AP50) assay. For the second purpose, a genetic screening by PCR and Sanger sequencing was performed. Biochemical studies revealed normal levels of immunoglobulins (Igs) and complement proteins C3 and C4. The functional assays showed normal CH50 levels but reduced AP50 levels. The ELISA assay showed normal levels of FB but undetectable P. The western blot assay confirmed the absence of P in the patient’s serum. Based on the results obtained in these different molecular diagnostic approaches and on the information found in literature, it was concluded that the protein affected was P. Sequencing and genetic analyses allowed the detection of a novel CFP missense mutation in exon 8. This mutation (position p.337; change p.C337R) leads to the replacement of a cysteine (Cys) residue by arginine (Arg). After a bioinformatic analysis, the Cys replaced was found to interact with a Cys located in p.376 through a disulfide bond. The loss of this bond is proposed to involve severe structural and, thus, functional consequences in the final protein. Since the number of P deficiency cases described so far is very low, this new case and the mutation discovered represent an important contribution both to P deficiency´s clinical and genetic background. Besides, the mutation described will help building up a family study with the identification of affected family members that will receive Genetic Counselling and who may be protected by vaccination.

More information

Item ID: 56887
DC Identifier: http://oa.upm.es/56887/
OAI Identifier: oai:oa.upm.es:56887
Deposited by: Biblioteca ETSI Agrónomos
Deposited on: 15 Oct 2019 10:49
Last Modified: 15 Oct 2019 10:50
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