Transcriptonic Analysis of Micrurus corallinus (coral snake) venon glands and identification of antigenic candidates to an alternative anti-servm

Author(s)

Luciana Iwanaga Leão

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2008-09-12

Examining board members

Inácio de Loiola Meirelles Junqueira de Azevedo; Eduardo Gorab; Mirian Akemi Furuie Hayashi

• Advisor: Inácio de Loiola Meirelles Junqueira de Azevedo

Abstract

Micrurus corallinus(coral snake) is a tropical forest snake belonging to the Elapidae Family, and is very common in Brazil. From the cDNA library of its venom glands, 1.438 Expressed Sequences Tags (ESTs) were generated and grouped into 611 clusters. This database contains the most expressed genes in the M. corallinus venom glands. The transcripts related to toxins represent approximately 46% of the total genes in this database. The toxin compound consists of: three finger toxins (24%), phospholipases A2 (PLA2s) (16%), type-C lectins (5%), among others. This database allowed not only the identification of possible toxins, but also the identification of cellular transcripts, most of which seems to be involved in physiological functions of venom gland cells. The majority of these molecules are involved in gene and protein expression, revealing the high level of specialization of the tissue for toxin synthesis. The analysis of the M. corallinus venom gland transcriptome allowed the identification of some antigenic candidates for an alternative antielapidic antiserum. Five antigenic candidates were selected after analysing the transcriptome: Atg1 (Homolog group 8), Atg2 (Homolog group 7/3/1), Atg3 (Other neurotoxins 1), Atg5 (A2-type phospholipase). These five antigenic groups were used for DNA immunization. Then they were first cloned in pGEM-T and, after, in pSecTag2A, which is an expression vector in mammal cells. The cloning was tested in COS-type cells (transient transfection), without signs of expression. To analyze the immunological response, recombinant proteins were produced in E. coli and used for ELISA coating to react with the primary serum deriving from the DNA immunization. The results showed that the serum from the immunized animals was able to recognize the recombinant antigens, indicating that the DNA immunization in mice could be a feasible alternative regarding the traditional immunization with crude snake venom, which is costly and heavily dependent on the availability of the venom. Regardless the need for additional tests, this is a promising result, because the antibody production can be achieved by intramuscular immunization, a more effective method when aiming for downstream production. (AU)