Isolation And Molecular Identification of Infectious Laryngotracheitis Virus from active outbreak in Poultry: the Case of Mekelle Town and Lafto Wereda of Addis Ababa

Abstract

Infectious laryngotracheitis (ILT) is a highly contagious upper respiratory tract disease caused by the Gallid herpesvirus 1 in chickens. In Ethiopia, there have been few scientific reports and molecular isolations of the virus regarding the status of ILT. Therefore this study aimed to isolate and identify the virus from outbreak areas using molecular techniques. Specimens were collected from chickens managed under intensive production systems that were suspected of having Infectious Laryngotracheitis (ILT) disease. A total of eighty-seven samples were collected, comprising 24 tissue samples and 63 tracheal swab samples from Mekele and Lafto Wereda in Addis Ababa, which were then pooled together. The Infectious Laryngotracheitis Virus was screened and isolated using a conventional polymerase chain reaction with a set of primers specifically designed to amplify a fragment of the ICP4 gene. The PCR products of the isolated DNA were analyzed through agarose gel electrophoresis. Consequently, one pooled sample from Mekele and three pooled samples from Lafto Wereda tested positive for ILTV among the eleven pooled samples from both study areas. The isolated virus was propagated via chorioallantoic membrane (CAM) inoculation in 9–11-day-old embryonated chicken eggs, as well as in chicken embryonic fibroblast (CEF), Vero, and DF-1 cell lines. Cytopathic effects (CPE) were observed following the inoculation of the virus in different cell types. Generally, in the study areas, the disease that posed a respiratory challenge and caused the outbreak in the chickens was the Infectious Laryngotracheitis Virus. To combat this challenge, all poultry farm owners in the study areas and the whole country should be aware of control measures for the disease.