Prevalence of MDV in Iraq and sequence variation in the MDV EcoRI-Q (meq) gene

Abstract

A survey was conducted in six provinces southern Iraq to determine the prevalence of MDVl and sequence the meq gene for phylogenetic analysis and molecular pathotyping as per Renz et al. (2012). A total of 113 samples were collected from unvaccinated flocks; 55 dust samples and 30 spleens from broiler farms plus 28 spleens from local layer chickens. DNA was extracted using commercial kits for detection and quantification of MDV-1 by real-time PCR (qPCR) assay. Out of 113 samples, 41 samples (36.3%) were positive for MDV-1. Of these 12 were spleens from broiler chickens (40% positive), 23 were dust samples (42% positive) and 6 were from spleens of local breed layers (21% positive). The incidence of positive samples ranged from 10% Nasriya to 40% in Samawa and Emorah. Primers were designed to amplify the meq gene of positive samples and to date sequencing and alignment of 5 samples is complete. This has revealed encoding of a shorter Meq protein (298 amino acids; aa) than the 339 aa product encoded by the reference MDV, Md5 and other international samples, and also recent Australian MDVs (398 aa). The number of 4-proline repeats in the Meq product was 2 in each case, suggestive of a w+ pathotype (Renz et al., 2012). Results of further analysis and phylogenetic relationships will be presented.