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 vaccines
Sujets)
Animaux , Embryon de poulet , Poulets/virologie , Virus de la maladie de Newcastle/pathogénicité , Maladies de la volaille/prévention et contrôle , Vaccins atténués/usage thérapeutique , Vaccins antiviraux/usage thérapeutique , Techniques de culture cellulaire , Cellules cultivées , Poulets/immunologie , Virus de la maladie de Newcastle/classification , Virus de la maladie de Newcastle/croissance et développement , Culture de cellules primaires , Maladies de la volaille/immunologie , Maladies de la volaille/virologie , Vaccination , Vaccins atténués/effets indésirables , Vaccins atténués/immunologie , Vaccins antiviraux/effets indésirables , Vaccins antiviraux/immunologieRésumé
Raw white rice has not been considered a good carrierfor oral vaccination, probably because of its antiviralactivity. Methods are required to overcome antiviralactivity in raw white rice. This study was carried out todetermine the effects of various treatments of raw whiterice on the survival of strain I-2 of Newcastle diseasevirus. These included cooking and baking the rice ormixing the rice with vegetable oil prior to coating withvaccine virus. The vaccine-coated rice was then stored for30min and 24h, followed by quantitative recovery of thevirus. Thirty min after mixing, uncooked, cooked, andbaked rice, and rice mixed with vegetable oil showed titersof 10(6.2), 10(7.2), 10(6.6), and 10(7.0) EID50/0.1ml, respectively.After storage for 24h at 22-25oC, the titers dropped to10(5.0), 10(6.5), 10(5.0), and 10(6.0) EID50/0.1ml for uncooked,cooked, baked, and oiled rice, respectively.