Plasmodium juxtanucleare (Apicomplexa: Plasmodiidae) Versiani & Gomes 1941 e Vírus da Anemia Infecciosa das Galinhas (CAV) Yuasa 1979: modelo de estudo da interação parasito-hospedeiro

Abstract

Plasmodium juxtanucleare, one of the two species that cause malaria in chickens, can be found in different countries around the world including Brazil. The aim of this study was to evaluate the effect of infection caused by P. juxtanucleare in specific pathogen free (SPF) chicks previously immunosuppressed with chicken anemia virus (CAV). To establish this model two distinct experimental strategies were addressed: (i) assessment of hematological, pathological and biological parameters; (ii) immunological evaluation of cellular response of infected birds. For this, we defined four groups: P. juxtanucleare Group: chicks exclusively infected by P. juxtanucleare; CAV Group: chicks exclusively infected with CAV; co-infected Group: co-infected chicks with P. juxtanucleare and CAV; control Group: uninfected chicks. The parasitemia caused by P. juxtanucleare was low for all infected avian (P. juxtanucleareand co-infected groups), although significantly higher values were detected in co-infected chicks. Anemia was observedin all infected groups. However, co-infected chicks showed lowest values ofhematocrit. Mortality was more pronounced in co-infected group, however the pathologic lesions were mild when compared to serious injury observed in P. juxtanucleare and CAV groups. The results indicate that pathogenic effects can be boosted during the infection caused for these two microorganisms. Significant reduction in the number of leukocytes and lymphocytes (p<0.05) was observed in CAV and co-infected groups. P. juxtanucleare group showed an increase in total leukocytes and lymphocytes and a decrease in heterophils. Furthermore, it was demonstrated increased in co-stimulated and activated T cells in this group. The chicks of CAV and co-infected groups showed a significant decrease of co-stimulated T cell cytotoxic and decrease of T helper cell co-activated and co-stimulated. The CAVgroup, differently from of co-infected group showed reduction of T helper cells and reduction of activated T helper cell; and differences in B cell number. These data indicate an immunomodulatory effect dependent on T and B cells in co-infection P. juxtanucleare-CAV and this effect is different of exclusive CAV or P. juxtanucleare infections.