Abstract
Background: Ovine pulmonary adenocarcinoma (OPA), caused by Jaagsiekte sheep retrovirus (JSRV), is a contagious neoplastic disease of sheep characterized by chronic respiratory signs and induce the transformation of secretory epithelial cells of the distal respiratory tract.
Aims: This research aims to perform a clinical, epidemiological and molecular studies with evaluation of some predisposing factors at the herd level of OPA infection in sheep in Al-Qadisiyah province, Iraq.
Methods: a first step of the study was undertaken to evaluate the clinical cases of JSRV in naturally infected sheep and correlation with observing respiratory signs, 75 sheep with chronic respiratory signs were examined clinical, molecular and sequences analysis, second step was the epidemiological parte was performed on 195 random-selected animals from 30 flocks, prevalence rate based PCR, and sex, age, and size of flocks was assessed. as well as macro-microscopic features of the neoplastic lung. Deep nasal swabs and nasal secretion were taken from all animals were collected. RNA extraction and RT-PCR were done.
Results: The result showed that 12 (16%) samples were positive to OPA, based on env gene-specific primers. Nucleotides sequences of partial 545 bp of the env gene were shown (0.07-0.12) varied from global strains of NCBI database. The second part of a study conducted with 195 (in different ages and sex) samples were selected randomly. The prevalence rate of OPA was 21 /195(10.76 %) with PCR, the epidemiological factors analysis showed, there was no effect of all sex, herd size on prevalence rates (P≥ 0.01), despite the age of the animal being significantly affected and (2-4) years more susceptible (P≥ 0.01). A gross examination and microscopic were discussed and confirmed an OPA infection.
Conclusions: The current study provides useful data about clinical and epidemiological features of JSRV that circulating in sheep of Iraq, and concludes that epidemiological studies and disease control may require multi-diagnostic assays.

Key words: Adenocarcinoma, OPA, ovine, pulmonary, Iraq.