The virus genome encodes a polycistronic mRNA from which three viral proteins are translated [3,4]: ORF1 encodes VP1, the only capsid protein; ORF2 encodes VP2, a scaffold protein which allows the proper folding of VP1 [5,6]; and ORF3 encodes VP3, which is known as an apoptin that induces apoptosis of thymocytes after in vivo infection and apoptosis of transformed avian cell lines after in vitro infection [7,8]. Here, ASZ1 is linked to infection.