Genetic susceptibility to Marek's disease virus of local chickens in Taiwan.
Marek's disease is a contagious disease in chickens caused by Marek's disease virus (MDV) infection. Invasion of very virulent MDV (vvMDV) was considered to be a major cause of vaccine break, resulting in a large economic loss in the poultry industry. Two strains of the vvMDV (strains LTB-1 and LTS-1) have been reported in Taiwan, causing early mortality and formation of lymphoid tumors in broilers and layers. In this study, we report the susceptibility of local chickens in Taiwan to inoculation with strains LTB-1 and LTS-1 at 1 day of age. Five lines of Taiwanese local chickens (lines B, D, L2, KM, and BG) were used to compare the susceptibility to vvMDV. The chicks were inoculated via intraperitoneal route at 1 day of age. All MDV-inoculated chickens showed atrophy of various lymphoid organs. Protection tests were also conducted in local chickens, using vaccine of herpesvirus of turkey (HVT) at 1 day of age followed by vvMDV challenge at 10 days of age. Among the vaccinated chickens, 0-20.0% showed early mortality, and tumor occurrences in visceral organs and in peripheral nerves were 66.7%-100% and 0-27.2%, respectively. From these results, it could be concluded that local chickens in Taiwan have different susceptibilities to vvMDVs. Furthermore, vaccination with HVT showed no protective effect against Taiwanese vvMDV isolate challenge in this experiment.
Lin
J A
JA
Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Lee
T S
TS
D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000235:genetics / Q000821:virology*; D004198:Disease Susceptibility / Q000662:veterinary; D020022:Genetic Predisposition to Disease; D008381:Herpesvirus 2, Gallid / Q000235:genetics*; D008380:Marek Disease / Q000235:genetics* / Q000473:pathology; D009929:Organ Size; D011201:Poultry Diseases / Q000235:genetics / Q000473:pathology / Q000821:virology*; D013045:Species Specificity; D013154:Spleen / Q000473:pathology; D013624:Taiwan; D013950:Thymus Gland / Q000473:pathology