Neuropathogenic Capacity of Lentogenic, Mesogenic, and Velogenic Newcastle Disease Virus Strains in Day-Old Chickens

Abstract

Strains of Newcastle disease virus (NDV) have different abilities to elicit neurologic signs. To determine the capacity of different NDV strains to replicate and cause lesions in the brain, independently of their peripheral replication, 1-day-old chickens were inoculated in the subdural space with 7 NDV strains of different virulence (4 velogenic, 2 mesogenic, 1 lentogenic). Velogenic strains induced severe necrotizing and heterophilic ventriculitis and meningitis, as well as edema of the neuroparenchyma, and replicated extensively in the nervous tissue by day 2 postinfection, as demonstrated by immunohistochemistry, when all infected birds died. Clinical signs, microscopic lesions, and viral replication were delayed (days 3 and 4 postinfection) with mesogenic strains. Velogenic and mesogenic NDV strains replicated mainly in neurons, and immunolabeling was first detected in surface-oriented areas (periventricular and submeningeal), possibly as a reflection of the inoculation route. The lentogenic NDV strain did not cause death of infected birds; replication was confined to the epithelium of the ependyma and choroid plexuses; and lesions consisted of lymphoid aggregates limited to the choroid plexuses. Results show that extensive NDV replication in the brain is typical of velogenic and mesogenic, but not lentogenic, NDV strains. In addition, this study suggests that differences in the rate of NDV replication in nervous tissue, not differences in neurotropism, differentiate velogenic from mesogenic NDV strains. This study indicates that intracerebral inoculation might be used as an effective method to study the mechanisms of NDV neuropathogenesis.

Natural Infections With Pigeon Paramyxovirus Serotype 1: Pathologic Changes in Eurasian Collared-Doves (Streptopelia decaocto) and Rock Pigeons (Columba livia) in the United States

“…As previously described in infections with certain velogenic and mesogenic strains of NDV in chickens, we observed moderate to severe lymphoid depletion with virus-induced lymphocytolysis in PALS (thymus-derived naïve T lymphocytes) and PELS (bursa-derived naïve B lymphocytes) of the spleen and in the follicular medulla and to lesser extent cortex of the bursa of Fabricius. 24,29 Occasionally, depleted PALS and PELS were replaced by mild to extensive deposits of protein-rich exudates resembling fibrin. 6,31,32 Since lymphocytolysis was only reliably confirmed in few cases, we preferred to avoid the term "necrotizing splenitis or bursitis," which has been used for similar findings by other authors.…”

Transcriptome Analysis in Spleen Reveals Differential Regulation of Response to Newcastle Disease Virus in Two Chicken Lines

“…The outcome of NDV infection depends on both the virulence of the NDV strain and the ability of chickens to resist to the virus. NDV strains can be classified from least to most virulent into lentogenic, mesogenic, and velogenic strains 4 . The severity of infection with the same NDV strain also varies between avian species and chicken breeds due to genetic variation 3 .…”

Complete Genome Sequencing, Molecular Epidemiological, and Pathogenicity Analysis of Pigeon Paramyxoviruses Type 1 Isolated in Guangxi, China during 2012–2018

“…Indeed, it has been reported that only several point mutations are sufficient to increase the pathogenicity of PPMV-1 in chickens [35,40]. Adaptation to chickens after serial passages with increased frequency of clinical signs, mortality, and the level of neuro-invasiveness has been demonstrated [41,42]. Pigeons are reported to also get infected with viruses from other NDV genotypes, including viruses that are pathogenic for chickens.…”