A high frequency of Gallid herpesvirus-2 co-infection with Reticuloendotheliosis virusis associated with high tumor rates in Chinese chicken farms

Publication date: October 2019Source: Veterinary Microbiology, Volume 237Author(s): Yanping Zhang, Zhenghao Yu, Xingge Lan, Feng Zhang, Qi Wang, Kai Li, Qing Pan, Yulong Gao, Xiaole Qi, Hong-yu Cui, Yongqiang Wang, Li Gao, Xiaomei Wang, Changjun LiuAbstractThe prevalence of Marek’s disease (MD) caused by Gallid herpesvirus-2 (GaHV-2) has been increasing in chickens in China despite universal vaccination. Among the possible reasons for this trend, of Reticuloendotheliosis virus (REV) contamination in vaccines could lead to co-infection and reduce the vaccine efficacy. Here, we report the epidemiological findings of our continuous surveillance of MD, and an examination of the effects of REV and/or GaHV-2 co-infection. A total of 1230 samples were collected between 2011 and 2015 from 305 flocks covering many of the chicken-raising regions of China. Among these, 606 samples were determined to be GaHV-2-positive, 13.0% of which were found to be co-infected with REV from 18.8% of the flocks. One GaHV-2 strain (HS/1412), a REV strain (HS/1412R), and a GaHV-2 and REV-co-infected strain (HS/1412 GR) were isolated from different chickens of a GaHV-2 and REV co-infected flock. Pathogenicity tests showed that HS/1412 and HS/1412 GR caused disease in all chickens and that HS/1412R induced morbidity in 84.6% of the infected chickens. HS/1412 GR induced 100% mortality and 76.9% tumor formation, which were significantly higher frequencies than those observed with strain HS/1412 (38.5...
Source: Veterinary Microbiology - Category: Veterinary Research Source Type: research