In vitro and in vivo characteristics of the recombinant viruses.

aMDT (mean death time), average number of hours required to kill the inoculated eggs.bAccording to the criteria set by OIE for evaluating the pathogenesis in chickens, the viruses with an IVPI value greater than 1.2 are defined as highly pathogenic avian influenza virus (HPAIV), or are defined as low pathogenic avian influenza virus (LPAIV).cNumber of birds that died/number of birds inoculated.dThe mean virus titer was expressed as the log10 PFU/ml±standard deviation. “-”, virus was not recovered from the cloacal swabs in inoculated chickens on day 3 p.i.