Abstract
Newcastle disease virus (NDV) threatens global poultry production, with genotype VII the most prevalent strain in China. However, little information is available regarding viral multiplication and pathogenicity based inoculation route. The objectives of this study were to sequence NDV VII isolates and to analyze their biological characteristics in detail. A total of 86 oral and cloacal swabs were collected from Shaanxi and Gansu provinces in northwest China. Identification of genotype VII NDV based on the M gene was performed by qPCR. Viral multiplication and pathogenicity were assessed as a function of route of infection. We observed increased morbidity and mortality using intravenous injection, whereas intranasal, intraocular, and cloacal infections resulted in slower progression and milder clinical disease, with viral proliferation obvious in different tissues. These results provide an important basis for the clinical control and prevention of NDV epidemics in poultry.