RESUMO
Previous evidence for the presence of chicken anemia virus (CAV) in the gonads of immune specific-pathogen-free chickens raised the question whether this occurs also in commercial breeders. The presence of CAV was investigated by nested PCR in the gonads and spleens of hens from two 55- and 59-week-old, CAV-vaccinated (flocks 2 and 3), and two 48- and 31-week-old non-vaccinated broiler breeder flocks (flocks 1 and 4). In addition, lymphoid tissues of 20-day-old embryos from these hens were also investigated for the presence of CAV. CAV was detected in the gonads and of 5/6 and 11/22 of the vaccinated hens and in some hens also in the spleen alone. Embryos from 7/8 and 5/18 of these hens were positive. In the non-vaccinated flocks, CAV was detected in the gonads of 11/34 and 10/10 hens in flocks 1 and 4, respectively. In addition, 11 birds in flock 1 had positive spleens. CAV DNA was detected in 3/11 and 2/10 of their embryos. CAV-positive gonads and embryos were detected in samples from hens with moderate as well as high VN antibody titers. Vaccinated chickens positive for CAV in the gonads and in their embryos had VN titers ranging from >1:512 to <1:2048. In non-vaccinated chickens, the VN titers of CAV positive chickens ranged from 1:128 to 1:4096. These results demonstrate that CAV genome can remain present in the gonads of hens in commercial broiler breeder flocks even in the presence of high neutralizing antibody titers that have been associated with protection against CAV vertical transmission. It also suggests that transmission to the progeny may occur irrespectively of the level of the humoral immune response in the hens.
Assuntos
Embrião de Galinha/virologia , Vírus da Anemia da Galinha/isolamento & purificação , Galinhas , Infecções por Circoviridae/veterinária , Gônadas/virologia , Transmissão Vertical de Doenças Infecciosas/veterinária , Doenças das Aves Domésticas/virologia , Animais , Anticorpos Antivirais/sangue , Vírus da Anemia da Galinha/genética , Infecções por Circoviridae/transmissão , Infecções por Circoviridae/virologia , DNA Viral/química , DNA Viral/genética , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Masculino , Testes de Neutralização/veterinária , Reação em Cadeia da Polimerase/veterinária , Doenças das Aves Domésticas/transmissão , Baço/virologiaRESUMO
Focal spinal cord lesions have been present in all previously reported cases of MRI appearances in myelopathy complicating vitamin B12 deficiency. We describe two further cases showing mild atrophy only and review the salient features of the previous 11 publications. MRI findings reflect quite closely the known pathological changes in this condition.