Detecção de ácidos nucléicos (DNA) de Neospora caninum em tecidos de gerbils (Meriones unguiculatus) submetidos à infecção aguda e crônica

Abstract

The neosporosis is a disease of great economic importance, is distributed worldwide and is considered today one of the major causes of abortion and neonatal deaths in cattle. The pathogenesis of Neospora caninum infection is not fully understood and some issues in this regard are important in determining the most efficient measures of control and prophylaxis of a flock. The exclusive use of animals in these studies are expensive and time consuming so, some species of animals, such as, the rodents, can be used to make it possible. The gerbils (Meriones unguiculatus) mimic infection in cattle and are considered highly sensitive to replication of the protozoan. This study evaluated the responses of these animal models, at different moments of infection, especially in the amount and severity of acute and chronic/persistent infections by N. caninum. In addition, the research sheds light the tissues preferred location/replication the protozoan in these rodent at different conditions depending on disease progresses. The results are presented in two articles. In chapter one, the aim was to characterize the acute infection by the protozoan for to determine the major tissue sites of replication in experimental models of M. unguiculatus. Thus we have demonstrated that, initially the protozoan made a replication, but there is a distribution in virtually all tissues of the host. In addition, we observed that without an effective action of the immune system to combat agent, the infection progresses to death of animals with characteristic signs rapidity detected between 3 and 5 days after initiation of infection. The second chapter, sought to establish in rodents (M. unguiculatus) chronically infected, which places the N. caninum prefers to develops chronic evolutive form bradyzoites that are characteristic of a phase of persistent disease, especially in regions of the CNS. Furthermore, we note that the dose inoculated interfere significantly in the induction of acute and chronic infection and this is reflected in the amount of detection of nucleic acids in different tissues, above all in the CNS. In this context, it was observed that the emergence of clinical signs was milder without the induction of severe and lethal infections in most chronically infected animals. Thus, through this study we can conclude that highly sensitive techniques are necessary to detect nucleic acids from N. caninum, especially in the CNS tissues in animals chronically infected.