TNF and infection: However, as the infection progressed (20 dpi), a stronger Th1-based proinflammatory Th1-based response were observed in animals infected by the high-virulence isolate, that was stronger for some cytokines as IL-8 and TNF-α in placentomes from animals carrying non-viable fetuses (5).The placenta plays a key role in the pathogenesis of neosporosis: on the one hand, it acts as a physical and immunological barrier against infection, but on the other hand, it is able to trigger abortion through immune-mediated mechanisms (1).