Teratogenicity of Australian Simbu serogroup and some other Bunyaviridae viruses: the embryonated chicken egg as a model.

The use of embryonated chicken eggs as a model for assessing the teratogenic potential of animal viruses was investigated with 12 members of the Bunyaviridae family. Infection of 4-day-old embryonated chicken eggs via the yolk sac with 10 of the viruses resulted in deaths or congenital deformities that were similar to those observed in Akabane virus infections of fetal ruminants and included arthrogryposis, scoliosis, mandible defects, and retarded development. Statistical analysis showed that the viruses fell into three main groupings, namely, those that caused both death and deformities (Akabane, Aino, Tinaroo, and Belmont viruses), those that mainly caused death (Peaton, Thimiri, and Facey's Paddock viruses), and those that required very high doses to cause either death or deformities (Douglas and CSIR0296 viruses). In addition, two viruses (Kowanyama and Mapputta viruses) caused neither death nor deformities. A difference in the pathogenic potential between two Akabane isolates (B8935 and CSIR016) in the embryonated chicken egg model was found to correlate with differences previously observed in experimentally infected sheep; Akabane CSIR016 was the more pathogenic. It is concluded that the embryonated chicken egg model should also be of value in assessing the teratogenic potential of other Bunyaviridae and attenuated vaccine viruses, although it does not assess the ability of the virus to cross the placenta.