INFECŢLIA CU VIRUSUL BOLII LUI MAREK AFECTEAZĂ IMUNITATEA CELULARĂ NESPECIFICĂ Ş1 SPECIFICĂ.

Marek's disease provides excellent opportunities for the study of a herpesvirus-induced tumour both experimentally and under natural conditions in the field. The mechanism of protection against this disease is mainly through an antiviral cell mediated immune response. Over the last decades, Marek's disease viruses have been evolving greater oncogenicity, some of which are not adequately controlled by the vaccines that are currently available (Biggs, 1997; 2001). The experiment aimed to monitor during a naturally occuring episode of Marek's disease, the changes in phagocytosis and blast transformation capacity of 65 weeks old Rosso hens (n=20) under field conditions. The influence of certain vegetal extracts on these two functions was observed in order to evaluate their restoring potential. Heparinized blood samples were taken on a farm where the disease appeared spontaneously. The birds in the experimental group were selected based on the changes of the iris and pupilla, characteristic to the eye affection during the disease as well as their progressive weight loss, worsening of general condition and abdominal distension. Total leukocytes, with a dominance of lymphoblasts and myeloid cells, varried from 35,000 to 66.000/mm3 . The birds were subjected to blod sampling twice, 11 days apart. Heparinized blood was used to perfom the in vitro carbon particle inclusion and blast transformation tests. Spontaneous phagocytosis and blast transformation were recorded and afterwards the effects of Calendula officinalis, Symphitum officinale, Echinaceea angustifolia and E. purpureea was monitored by the same techniques. The phagocytosis was diminished at the begining of the experiment and increased as a compensatory mechanism towrds the end of the experiment. The spontaneous blast transformation capacity was slightly increased at the first sampling in infected birds, when compared to that of healthy birds of the same category, but it degraded to day 11 as a consequence of the progressive disease. While during the first phases of the infection, the active principles from Echinaceea stimulated the phagocytosis, as the disease evolved, the stimulating effects became weaker. E. purpureea extract increased the in vitro growt of leukocytes from Marek's disease virus infected birds when compared to controls. Nevertheless, by day 11 none of the extracts acted stimnulating, pleeding for the lack of responsiveness of the lymphocytes to restoring treatments. [ABSTRACT FROM AUTHOR]