Specific Glycoprotein E (gE) Gene Based Nested Polymerase Chain Reaction Assay for Detection of Marek’s Disease Virus in Chickens

Abstract

Poultry industry is one of the prime agricultural sectors that not only contributes to Global economy but also supports livelihood sustainability of the poultry farmers. However, this sector often faces severe economic losses due to various infectious diseases. Marek’s disease (MD) is one of the common viral diseases of poultry, caused by Marek’s disease virus (MDV). In spite of routine vaccination, events of vaccine failure as well as disease outbreaks are often seen in the field conditions. Several methods including polymerase chain reaction (PCR) based techniques are available for diagnosis of MD. Nested PCR (nPCR) is one of the highly sensitive and specific techniques used for disease diagnosis. Present study reports a highly sensitive glycoprotein E (gE) gene based nPCR for MDV detection. The outer set of primers amplified 567 base pair (bp), while inner set of primers amplified 230 bp of the of the MDV genome. The minimum detection limit was 17.6 picogram of genomic material in clinical sample. It was also shown as highly specific for the detection of field MDV and did not amplify one of the commercial vaccine strains, mostly used for vaccination against MD in chickens i.e., Turkey Herpes virus (HVT) FC 126 strain. It also did not amplify the fowl pox virus (FPV) genome. The applicability of the technique was assessed with the field tissue (liver) samples (n = 22), comprising of eleven (n = 11) samples collected during post-mortem examination of birds suspected of MD and eleven (n = 11) samples from apparently healthy birds collected from commercial retail poultry outlets. It was found positive in eight out of eleven clinical samples in nPCR; while, all samples from healthy birds were tested negative. The developed assay was found highly sensitive and specific. The developed nPCR technique could be used for diagnosis of MD infection caused by the field strains in the vaccinated as well as non-vaccinated poultry flocks.