Generation, transmission and infectiosity of chicken MDV aerosols under experimental conditions

To further investigate the airborne infection mechanism of Marek's disease virus (MDV), a MDV aerosol infection model was established, and the generation, transmission and infectiosity of MDV aerosols were monitored in this study. Two positive/negative pressure isolators, in which SPF chickens were raised, were connected with a closed conduit. Two repetitive trials, Trial 1 (T1) and Trial 2 (T2) were carried out for objective assessment. Air samples were collected using the AGI-30 sampler. Viral DNA in air samples and feather follicle samples were detected using real-time quantitative PCR (QRT-PCR). MDV in air and blood samples was detected by indirect immunofluorescence assay (IFA). In chickens of isolator A (MDV inoculation group), MDV was detected in feather follicles in 100% of the tested chickens at 6 days post inoculation (dpi) in both trials; and MDV was isolated from blood samples at 9-10 dpi. MDV DNA was detected in air samples from isolator A at 12 dpi in T1 and 14 dpi in T2 and concentration of aerosolized MDV DNA was peaked at 3.84 × 10(6)copies/m(3) air at 40 dpi in T1, and 6.17 × 10(5)copies/m(3) air at 38 dpi in T2, respectively. Infectious MDV (cell culture) was isolated from isolator A at 17 in T1 and 19 dpi in T2, respectively. MDV aerosol in Isolator B was almost same as isolator A. Viremia was detected in isolator B at 26-30 dpi. The incidence of viremia in isolator B reached 70% at 3 months post inoculation. These results demonstrated that infected chicken could discharge virus, the MDV could form aerosols and infect neighboring chickens. Understanding the mechanism of generation and infection of MDV aerosols is helpful to prevent and control MD.