Detection and Molecular Characterization of Avian Encephalomyelitis Virus in India: A Preliminary Report

Tremovirus A, previously recognized as Avian encephalomyelitis virus (AEV) is, one of the viruses that have been reported to be associated with nervous and enteric disorders in young birds. In Kerala, there has been an increase in the cases of nervous and enteric diseases in chickens. The detection and characterization of other viruses associated with nervous and enteric viruses in chickens has been established in Kerala. While there have been reports of nervous and enteric diseases in chickens in the region, no previous research had focused on AEV as the causative agent. A total of 50 samples were tested to detect AEV by reverse-transcriptase polymerase chain reaction (RT-PCR) targeting the 5' untranslated region (5'UTR) of AEV. Of the samples tested, one (2%) was found to be positive for the virus. The most immunogenic protein of AEV is VP1 protein forming the major capsid protein. The VP1gene segment of the detected virus isolate was amplified and molecular characterization was done. The phylogenetic analysis of the VP1 gene sequence revealed that the virus was identical to AEV viruses detected in Hungary, China, and Hong Kong (64% similarity). The current isolate showed a nonsynonymous mutation of I184V which was noticed only in Hungary isolate. The results of the study indicate that AEV is rarely present in chickens of Kerala, India, and that its occurrence is very low. Since the virus is capable of inducing nervous signs, mortality, and economic losses, measures are to be taken to control the spread of the virus in chickens in Kerala, India.