Validity including conductivity and specificity of Avian Encephalomyelitis (AE) virusinfectivity titration of combined AE-Fowl Pox (FP) vaccine in 5-7 day-old embryonated chicken eggs (ECEs) has been faced almost with nonspecific embryos mortality due to FP virus infectivity. The present study was performed to establish whether or not the treatment of such vaccine with chloroform to eliminate the pathogenicity of FP virus before titration guarantees a validated accurate AE virus titer. The study goal was achieved throughout statistical analyzed titration data of AE virus infectivity of three commercial
batches of AE vaccine and seven commercial batches of combined AE-FP vaccine in chicken embryos before and after treatment with chloroform. The results obtained from titration tests showed that treatment of AE vaccine batches with chloroform had no significant effect on its infectivity titers comparing with those titers which exhibited by the vaccine batches before treatment, and demonstrated that treatment of combined AE-FP vaccine batches with chloroform significantly affected the conductivity and specificity of AE virus infectivity titration. The present study proved the validity of using chloroform for treatment of combined AE-FP vaccine before AE virus titration, and using of distilled water for reconstitution of AE-FP vaccines instead of normal saline solution before dilutions made for titration