Genotipagem da imunoglobulina G, em éguas das raças Campolina e Mangalarga Marchador, na Zona da Mata de Pernambuco

Abstract

The fundamental objectives of immunology are to describe the organization of the immune system and the relationships between its components as well as outline the boundaries(interfaces and intersections) between the immune system and body. As the equine placenta does not allow the passage of immunoglobulin, the newborn foal has low resistance to disease and depends on the ingestion of colostrum in the first hours of life in order to gain this protection. The aim of the present study was to identify genetic differences in immunoglobulin G (IgG) in mares of the Campolina and Mangalarga Marchador breeds for the future determination of differences in IgG production and use this information in animal selection programs. Blood samples were collected from 40 animals (20 of each breed) from properties in the coastal zone of the state of Pernambuco, Brazil. The known fragment of the IGHG4 gene was amplified by polymerase chain reaction (PCR). The product was digested by the endonuclease enzymes AvaI; PmlI, PvuII and TaqI (PCR-RFLP) and the result was evaluated in 1.5% agarose gel. The endonuclease AvaI digested the fragment, leading to the identification of three different alleles: A (232 pb), B (140 + 92 bp) and C (200 + 32 bp). There was a higher frequency of allele A than alleles B and C in all animals studied. Allele B was found at a higher proportion than allele C in the Campolina breed, but at a lesser proportion in the Mangalarga breed. There was a prevalence of the AA genotype in both breeds studied. However, there was a high frequency of heterozygous individuals. The analysis of frequencies revealed that the populations are in Hardy-Weinberg equilibrium. In conclusion, polymorphism in the IGHG4 gene was found in mares of the same breed as well as between the breeds studied (Mangalarga and Campolina). Studies are needed to investigate whether this is related to different capacities of responding to immune stimulation.