Chagas' disease: TCRBV9 over-representation and sequence oligoclonality in the fine specificity of T lymphocytes in target tissues of damage

Using the same mouse strain and two Trypanosoma cruzi sub-populations (CA-I and RA) it is possible to induce pathology in different target tissues: skeletal muscle (CA-I) or sciatic nerve and spinal cord (RA). On the other hand, T cells are directly involved in tissue injury in a strain-dependent way, resembling the abnormalities of chronic Chagas' disease. In the present work, we examined the TCRBV repertoire and the CDR3 sequence polymorphism of T cells infiltrating spinal cord, sciatic nerve and skeletal muscle in chronically infected mice. The TCRBV9 segment was systematically over-represented in the target tissues for each T. cruzi strain: sciatic nerve and spinal cord in RA and skeletal muscle in CA-I-infected mice. The analysis of CDR3 sequence polymorphism in the same tissues showed a high proportion of identical TCRBV9 clones in RA-infected mice: 66.6% of the TCRBV9 clones found in sciatic nerve and spinal cord expressed one out of four major CDR3 rearrangements. Sequence identity was shared among clones from sciatic nerve and spinal cord, tissues that are also damaged by passive transfer of CD8 + TL. Those observations are consistent with an antigen driven T-cell expansion sequestered at the inflammation site and demonstrate -- for the first time -- the presence of an oligoclonal repertoire in the antigen recognition site of over-represented T cells in nervous system tissues in chronic Chagas' disease.

[Clinical neosporosis in the dog: a review]

Neospora caninum is an intracellular protozoan parasite that was first recognized in dogs in 1988. N. caninum may cause neuromuscular disease in dogs. Later, it was discovered that N. caninum has a wide host range and is an important cause of abortion in cattle. In this article, the literature on N. caninum in the dog is reviewed, with emphasis on clinical signs, pathology, diagnosis, treatment, and prognosis.

[Trypanosoma cruzi pathology. Strain dependent?]

There is agreement today about the role that the characteristics of the population of Trypanosoma cruzi play in the pathogenesis of the different clinical forms of Chagas disease. In our laboratory, we have studied the outcome of the infection of mice with two populations with polar biological behaviour: RA and CA-I. We have demonstrated that the neuromuscular damage is, in part, mediated by different T cell subsets. We have also observed that the T cell phenotype responsible for the pathology and the targetted tissues depend on the parasite population. Although we found no differences regarding the reactivity of IgG to native nerve structures in sera from mice infected with either strain, it is presumed that the humoral response would play an additional role in the development of strain-dependent neuromuscular pathology since passive transfer of sera from mice infected with RA triggered alterations of the nerve action potential whereas sera from CA-I-infected mice did not. We have also detected a reduction in the fertility of female mice infected with CA-I/K98, whereas females infected with RA showed no difference in comparison with uninfected controls. However, congenital transmission was only observed in mice infected with RA. The differences observed in fertility, in newborn survival, and in the number of fetal resorptions in mice infected with the myotropic strain could be attributed to the uterine inflammatory response, since no estrous alterations were observed between infected and control groups.

Generalized encephalitozoonosis in a Jersey wooly rabbit

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[Chronic trichinosis and neuromuscular diseases. Morphologic and pathogenetic aspects]

Muscle biopsies were carried out on five patients affected by a chronic neuromuscular disorder, mostly in the form of a spinal muscle atrophy. All patients had suffered from acute trichinellosis many years before, the interval between acute parasitic infection and the appearance of the slowly progressive neuromuscular syndrome being of 21, 13, 35, 26 and 16 years respectively. In biopsy specimens, morphological and enzyme-histochemical changes typical of a progressive neurogenic muscular atrophy were present; in addition, encapsulated but still living, enzyme-positive parasites and signs of focal myositis were detected. The possible pathogenetic correlations between the "chronic" trichinellosis and the "degenerative" neuromuscular disorder are discussed.