Ocorrência, co-infecções e diversidade molecular do vírus da doença de Marek em Minas Gerais

Abstract

Marek's disease (MD) is a viral disease that affects poultry (Gallus gallus domesticus), caused by a herpesvirus. It is a disease of global importance and occurrence, since it has a great economic impact on the poultry industry due to the costs of vaccination, mortality, carcass condemnations and decreased egg production. Since the emergence of intensified poultry farming, especially at the beginning of the 20th century, the evolution of Marek's Disease Virus (MDV) has started towards greater pathogenicity. Paradoxically, the creation of vaccines in the early 1970s resulted in selective pressure that increased with the generation of strains of progressively greater pathogenicity, with diversification of pathological conditions. In recent years, the Meq gene has attracted attention as a possible cause of increased oncogenicity, the most important determinant of MDV pathogenicity. The molecular characterization of Brazilian strains of MDV revealed a presence of very virulent strains (vvMDV), both from industrial and subsistence poultry farming. Considering that the infectious agents do not appear in isolation in the organism of the challenged animal, the situation resulting from simultaneous alterations is in itself an extreme challenge for the bird, especially when associated with intensifying stressors, such as stress, overcrowding, social competition, cannibalism , malnutrition, thermal discomfort and appropriate well being, making the immune system of the affected bird unable to suppress an infection