Theses and Dissertations


Issuing Body

Mississippi State University


Ramachandran, Reshma

Committee Member

Zhang, Li

Committee Member

Adhikari, Pratima

Date of Degree


Document Type

Graduate Thesis - Open Access



Degree Name

Master of Science (M.S.)


College of Agriculture and Life Sciences


Department of Poultry Science


Avian pathogenic Escherichia coli (APEC) is a bacterium that is responsible for colibacillosis in birds. However, information about broiler breeder APEC isolates is limited, but the data is critical due to the transfer of this bacteria down the production pyramid to progenies resulting in high mortality. Therefore, we evaluated the phenotypic virulence characteristics of 28 isolates using embryo lethality and day-old chick challenge assays. Also, the in vitro adhesion and invasion potential of selected nine isolates were identified. Results showed more than 1/3rd of the isolates were highly virulent and the virulence increased as the number of virulence-associated genes increased. High adhesion and invasion rates were observed among the isolates. Overall, the study helped us to evaluate the virulence characteristics of APEC from broiler breeders. However, future studies based on whole genome approach would help to identify the specific targets which can be used to develop effective interventions.