IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume 12, Issue 3 Ser. II (March 2019), PP 48-57 www.iosrjournals.org DOI: 10.9790/2380-1203024857 www.iosrjournals.org 48 | Page Serological and Histopathological Studies on Infectious Bronchitis in Non Vaccinated Layers and Broiler Chickens in Al- Jabel El- Khdar in Libya Nawara M. Eissa 1 , Ajlal A. Alzergy* 2 , Azza El- Sawah 3 , Mahmood Ezzat 4 and Fauzia Elgnay 5 1 Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine Omar Al Mukhtar University, Al Bayda Libya. 2 *Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Omar Al Mukhtar University, Al Bayda Libya. 3 Department of Poultry Diseases, Faculty of Veterinary Medicine Omar Al Mukhtar University, Al Bayda Libya. 4 Department of Microbiology, Faculty of Veterinary Medicine Omar Al Mukhtar University, Al Bayda Libya 5 Central Veterinary laboratory at Technical Center of Animal Health and Animal Breeder Corresponding Author: Nawara M. Eissa Abstract: This study was aimed to characterize the sero-prevalence and histopathological lesions on infectious bronchitis (IB) in non vaccinated layers and broiler chickens in Al Jabel El-Khdar - Libya using Agar Gel Immunodiffusion (AGID) and ELISA test. A total of 150 serum samples were collected from non vaccinated layers and broiler chickens for serological IB investigation. IB antibodies were detected in serum samples using AGID test and ELISA test. All tested farms were ELISA positive for IB antibodies, the percent of positivity were 42% and 75% in samples from broiler and layer chicken respectively. Severe clinical signs and gross lesions in infected chickens included drop in egg production , decline of egg quantity and quality , as well as loss of body weight and mortality reached 30% among flock of layers chicken with a total population of 40200 birds in a large poultry farms at Al-weseta region in Al Jabel El-Khdar - Libya were recorded . Also, respiratory manifestation in broiler birds of 21 day old with mortality rate 30% and loss of body weight in broiler chicken farm with a total population of 6000 birds were observed. Post mortem examination of illness birds and freshly dead birds revealed sever renal congestion, shorting and narrowing of oviduct, congestion in trachea, airs aculitis, caseous plugs in trachea and two bronchi and peritonitis. Tissue samples (lung, trachea , spleen , ovary, oviduct, kidney, liver, cerebellum and spinal cord) were collected and processed for histological studies by light microscopy. Examination of histological sections of trachea, lung, kidney ovary, oviduct, kidney, liver, cerebellum and spinal cord of non vaccinated naturally infectious bronchitis virus (IBV) infected chicken revealed many and sever histopathological alterations in all tested tissue which were more pronounced in oviduct and kidney. Key Words: Serology , histopathology , infectious bronchitis virus , non vaccinated laying and broiler chicken and Agar Gel Immunodiffusion and ELISA test --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 04-03-2019 Date of acceptance: 20-03-2019 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Infectious bronchitis is an acute, highly contagious, and primarily respiratory infection in chickens, occurring at all ages. Infectious bronchitis virus (IBV) is present in most poultry producing areas [1]. Infectious bronchitis virus has a great economic effect on the layer industry, because it affects egg production. Besides respiratory lesions, early exposure to IBV causes extensive damage to a wide range of epithelial surfaces in various parts of the body [2] . Infectious bronchitis (IB) is one of the major economically important poultry diseases distributed worldwide. It is caused by infectious bronchitis virus (IBV) and affects both galliform and nongalliform birds. Infectious bronchitis (IB) is an acute, highly contagious, and primarily respiratory infection in chickens, occurring at all ages. Its economic impact includes decreased egg production and poor egg quality in layers, stunted growth, poor carcass weight, and mortality in broiler chickens [3]. IBV is caused by a corona virus, of the family Corona viridae with over twenty five known genotypes worldwide [4]. It is a single stranded RNA, envelope virus IBV is present in most poultry producing areas [1]. The disease was first identified in North Dakota, USA, when Schalk and Hawn reported a new respiratory disease in young chickens [5]. Since then, IBV has been recognized widely, especially in countries with large commercial poultry populations. IBV has a wide geographical distribution and it wasfound in regions of Africa, Asia, Australia, Europe, and the