Résumé
Abstract This study was designed with the goal of adding as much information as possible about the role of pigeons (Columba livia) and chickens (Gallus gallus) in Newcastle disease virus epidemiology. These species were submitted to direct experimental infection with Newcastle disease virus to evaluate interspecies transmission and virus-host relationships. The results obtained in four experimental models were analyzed by hemagglutination inhibition and reverse transcriptase polymerase chain reaction for detection of virus shedding. These techniques revealed that both avian species, when previously immunized with a low pathogenic Newcastle disease virus strain (LaSota), developed high antibody titers that significantly reduced virus shedding after infection with a highly pathogenic Newcastle disease virus strain (São Joao do Meriti) and that, in chickens, prevent clinical signs. Infected pigeons shed the pathogenic strain, which was not detected in sentinel chickens or control birds. When the presence of Newcastle disease virus was analyzed in tissue samples by RT-PCR, in both species, the virus was most frequently found in the spleen. The vaccination regimen can prevent clinical disease in chickens and reduce viral shedding by chickens or pigeons. Biosecurity measures associated with vaccination programs are crucial to maintain a virulent Newcastle disease virus-free status in industrial poultry in Brazil.
Sujets)
Animaux , Maladie de Newcastle/anatomopathologie , Maladie de Newcastle/virologie , Virus de la maladie de Newcastle/croissance et développement , Structures anatomiques de l'animal/virologie , Anticorps antiviraux/sang , Brésil , Poulets , Columbidae , Modèles animaux de maladie humaine , Transmission de maladie infectieuse , Tests d'inhibition de l'hémagglutination , Interactions hôte-pathogène , Maladie de Newcastle/immunologie , Maladie de Newcastle/transmission , Virus de la maladie de Newcastle/immunologie , RT-PCR , Excrétion viraleRésumé
Newcastle disease viruses (NDVs) cause systemic diseases in chickens with high mortality. However, little is known about persistence of NDVs in contaminated tissues from infected birds. In this study, we examined viral replication in the feather pulp of chickens inoculated with viscerotropic velogenic NDV (vvNDV) genotype VII. Reverse transcription real-time PCR and immunohistochemistry were used to investigate viral persistence in the samples. vvNDV was detected in the oropharynx and cloaca and viral antigens were detected in the feathers, suggesting that feathers act as sources of viral transmission.