Interestingly, recombinant viruses in which rMd5 meq had been replaced with the meq gene from CVI988 (rMd5-CVI-Meq) caused MD nerve lesions in 7% of inoculated chickens, whereas in previous studies using an RB1B backbone, expression of CVI-Meq resulted in total abrogation of pathogenesis [26]. This evidence concerns the gene RMND5A and Menkes disease.