Epidemiological Molecular Study of Combined Severe Immune Deficiency in Arabian Horses in Tunisia

Abstract

Background: Severe Combined Immuno Deficiency (SCID) is a heritable deficiency transmitted through autosomal recessive gene, carried on by purebred Arabian and crossbred horses. A deletion of five base pairs at the gene encoding the catalytic subunit of the Protein Kinase DNA-dependent (DNA-PKcs) is responsible for this disease and SCID-affected animals always die in the first six months of life. Considering this problem, it is important to perform a molecular epidemiological study to estimate the frequency of the SCID allele in Arabian purebred horses in Tunisia.Methods: The DNA of the peripheral blood lymphocytes of 164 purebred Arabian horses belonging to the Sidi Thabet stud was extracted by the spin-column method, in order to verify the quality of the DNAs used, the samples were dosed by a spectrophotometer. The amplification of the DNA was carried out by two specific primers in a Polymerase Chain Reaction (PCR) to flank the deletion zone of the DNA sample by adding to each PCR sample a marker or a standard of size knowing that the fragment we wanted to amplify is composed of 163 base pairs. Then, the PCR products were sequenced using an automatic sequencer. Result: By analyzing the electropherograms results, we noted the absence of the SCID deletion in the studied group of Arab purebreds. Hence, it is essential to carry out molecular screening of the SCID deletion in other sites in order to determine its prevalence in the country’s purebred Arabian horse population.