Abstract
The Takavirus, a variant of Newcastle disease virus (NDV), was found to agglutinate chicken erythrocytes unstably at room temperature. Two clones were obtained from the plaques formed in the chick embryo fibroblasts (CEF): one showed an constant hemagglutinating (HA) reaction only at 4°C (L+R-); while the other showed no significant reversion in an HA reaction both at 4°C and room temperature (L+R+). There was no difference in the structural polypeptides and serological identity among two clones of Takavirus and two strains of NDV. The hemolytic activity of the Takaviruses (L+R-, L+R+ and parent) was similar to that of NDV-Sato strain, but much lower than that of NDV-Bl strain. The elution of L+R- from the chicken erythrocytes occurred more rapidly at room temperature. The amount of the eluted virus was greater than that obtained from L+R+ or NDVs. The reaction did not occur when fresh viruses were added to the erythrocytes which had eluted the viruses.
