Trichinellosis is one of the most widespread parasitic zoonoses in the world.

3 Antioxidant enzymes take part in evasive mechanisms adopted by parasites such as Trichinella spp., to persist a long time in a host. A fruitful relation host- parasite is established when parasite is able to interfere with host immune response: it can modulate effector cells activity and defend itself against reactive oxygen species (ROS) which are produced by these cells.

An experimental model of helminthic infection is that caused by the parasitic nematode Trichinella spp. The 8 known species of this genus diverged into 2 distinct clades: clade encapsulated and clade not encapsulated.

Trichinellosis is one of the most widespread parasitic zoonoses in the world.

After the intestinal phase of Trichinella spp. infection, the larvae penetrate in striated skeletal muscles causing morphological and structural changes in host cell which acquire a new phenotype called nurse cell (NC). Host immunological reaction is characterized by increased numbers of blood eosinophils and IgE antibodies.

This thesis aims to evaluate antioxidant defence during muscle phase of infection by studying the glutathione transferases Omega class enzyme (GSTO).

GSTO lacks any glutathione transferase activity therefore it is endowed with many other functions so relevant in reply to cell stress, i.e. the thioltransferase activity and the dehydroascorbate reductase activity.

Using polyclonal antibodies against rat GSTO we have carried out immunoblot and immunohistochemistry experiments on isolated larvae, on infected muscle and not infected muscle. We have analyzed GSTO’s gene expression by in situ hybridization, using digoxigenin (DIG)-labeled probes for

ABSTRACT

4 specific detection of mouse transcript sequence on infected tissue at different times.

The results obtained show that:

- in Trichinella spp. L

larvae there is no protein recognized by anti-GSTO polyclonal antibody;

- in immunohistochemistry analyses, the nurse cell infected by Trichinella spiralis and Trichinella britovi (both encapsulated species) is heavily stained by

anti-GSTO sera, compared to the surrounding muscle tissue. Immunoblot studies confirmed this data.

- the nurse cell infected by Trichinella pseusospiralis, which is a tipical not encapsulated species, doesn’t show antibody reactivity;

- muscle tissue from mice infected with T. spiralis and treated with anthelmintics hasn’t a similar GSTO up-regulation suggesting an active role of the parasite in this process;

- in situ hybridization shows a gradual increase of GSTO expression level during Trichinella britovi’s infection;

- Trichinella spp. GST sequence hasn’t significant homology with mammalian GST.

This research could open new ways for identification of useful drug target,

employed to control this parasitic disease.