Heterogeneity within Strains of Newcastle Disease Virus: Key to Survival

Virulence of six heterogeneous-origin Newcastle disease virus isolates before and after sequential passages in domestic chickens

“…This was proven by the increased overt clinical disease, lesions, and mortality observed during the intracloacal test with the passaged virus. The selection of a more virulent clone among a ''quasispecies'' population of viral genomes (Hanson, 1988;Kissi, 1988;King, 1993, Morimoto et al, 1998, typical of RNA viruses (Cann, 1997), is a possible mechanism to explain the virulence increase observed with the Dove isolate after passage in chickens.…”

Clone Purification, Characterization and Standardization of LaSota Strain for Developing a Live Vaccine against Newcastle Disease Virus

“…Based on the morphological properties of the plaques, subpopulations from the ND strain were defined. The heterogenicity of the plaques and the presence of large plaques have been associated with pathogenic indices (10,22). Each selected plaque derived from one single virus particle was verified for pathogenicity.…”

“…Lentogenic strains such as the Hitchner B1 and LaSota are widely used as live vaccines against ND (9). The vaccines are mixtures of sub-populations which differ significantly from each other in immunogenicity and pathogenicity (10,11). These sub-populations may differ in plaque morphology which correlates with virus virulence.…”

Sequence Analysis of the Hemagglutinin-Neuraminidase Gene of Newcastle Disease Virus from Punjab Pakistan

“…The Newcastle disease virus (NDV) is enveloped, negative sense ssRNA, and has non-segmented genome of length 15156 bases (Millar and Emmerson, 1988). Based on pathogenicity, three classes of NDV namely lentogenic (apathogenic), mesogenic (intermediate), and velogenic (highly pathogenic) are recognized (Hanson, 1988). However, based on the hypervariable region of the fusion gene, the NDV can be divided into two main classes, I and II.…”