Molecular diagnosis and adaptation of highly virulent infectious bursal disease virus on chicken embryo fibroblast cell

Abstract

Materials and Methods Infectious bursal disease (IBD) is a highly contagious disease of young chicken caused by infectious bursal disease virus (IBDV), characterized by immunosuppression and mortality generally at 3 to 6 weeks of age [1]. It is economically important to the poultry industry worldwide, due to increased susceptibility to other diseases and negative interference with effective vaccination. IBDV is a double stranded RNA virus with bi-segmented genome and belongs to the genus of family [2]. There are two distinct serotypes of the virus, but only serotype 1 viruses cause disease in poultry and six antigenic types are identified by virus neutralisation test. Although viral antigen has been detected in other organs within the first few hours of infection, the most extensive virus replication takes place primarily in the bursa of fabricius. Activated dividing B lymphocytes that secrete IgM serve as target cells for the virus. Viral infection results in lymphoid depletion of B cells and thedestructionofbursal tissues, leading to an increased susceptibility to other infectious diseases and poor immune response to vaccines. is considered to be the major host protective antigen and contains the major antigenic site responsible for eliciting neutralizing antibodies [3]. induces virus neutralizing antibodies that protect chickens from IBDV [4]. It is responsible for antigenic variation [5], tissue culture adaptation and virulence [6]. Study of virological characterization and molecular diagnosis of IBD will strengthen the antiviral therapy and disease control. IBD virus can infect and grow on various primary cell cultures of avian origin. Commonly used cell lines are chicken embryo fibroblast (CEF), chicken embryo kidney, chicken embryo bursa, vero, baby hamster kidney etc. The virulence of IBDV is lost during the adaptation on CEF cell culture but antigenicity is retained [7]. The present study aims at RT-PCR based detection and adaptation of IBDV field isolates.