“…\ml for EAV. The infection of macrophages and cell lines is highly cytocidal (Burki, 1965 ;Tauraso et al, 1968 ;Pol et al, 1991). The cytopathic effect of EAV, SHFV and PRRSV in cell lines is characterized by rounding of the cells and detachment from the culture plate surface, which allows the titration of these viruses by endpoint dilution or plaque assays (Hyllseth, 1969 ;van Berlo et al, 1980 ;Gravell et al, 1986 b ;Benfield et al, 1992 ;Kim et al, 1993 ;van Nieuwstadt et al, 1996).…”