title: Duration of maternally derived antibodies against Akabane virus in calves: survival analysis.
abstract: To prevent encephalomyelitis caused by Akabane virus, as observed in 2006, vaccination of calves is one of the most effective prophylactic measures. For vaccination of calves, the duration of the maternal antibodies need to be considered because these antibodies are an obstacle to the effectiveness of the vaccine. In order to estimate the age of antibody decay in calves and to find factors influencing the duration of passive immunity, we conducted survival analysis using data from nationwide sentinel surveillance for Akabane disease. The accelerated failure time model based on the presence of interval censored data was used. The best fit model with a log-logistic distribution indicated that the maternal antibodies of beef calves last 1.11 times longer (95% confidence interval [CI]=1.06-1.16) than those of dairy calves. Calves in the western part of Japan and on Kyushu island, Japan, maintained the maternal antibodies 1.17 times (95% CI=1.11-1.23 and 1.10-1.24, respectively) longer than those in the eastern part of Japan. The ages at which beef calves in the eastern part of Japan, western part of Japan and Kyushu loose the antibodies, with 90% probability, were estimated to be 4.1, 4.8 and 4.8 months, respectively, while the ages were 3.7, 4.3 and 4.3 months for dairy calves in the same regions. The duration of maternal immunity to Akabane virus was different for different types of cattle and among different regions. These differences need to be taken into account when a vaccination strategy is adopted for preventing epizootic encephalomyelitis in the future.
authors: Epidemiological Research Team, National Institute of Animal Health, Ibaraki, Japan. tsutsui@affrc.go.jp
authors: Toshiyuki
authors: T
authors: Tsutsui
authors: Takehisa
authors: T
authors: Yamamoto
authors: Yoko
authors: Y
authors: Hayama
authors: Yasuhiro
authors: Y
authors: Akiba
authors: Akiko
authors: A
authors: Nishiguchi
authors: Sota
authors: S
authors: Kobayashi
authors: Makoto
authors: M
authors: Yamakawa
mesh_terms: D000375:Aging; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002044:Bunyaviridae Infections / Q000453:epidemiology / Q000276:immunology / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000276:immunology* / Q000821:virology; D005260:Female; D007112:Immunity, Maternally-Acquired; D007564:Japan / Q000453:epidemiology; D016851:Orthobunyavirus / Q000276:immunology*; D011247:Pregnancy; D016019:Survival Analysis
chemical_list: D000914:Antibodies, Viral