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Newcastle disease virus (NDV) is the causative agent of a highly contagious disease in avian species. All strains of NDV belong to avian paramyxovirus serotype-1. The disease is endemic in different parts of the world and vaccination is the only way to protect birds from NDV infection. The virus non-structural phosphoprotein (P) is the second most abundant protein and a major modulator of viral replication. Although P protein shows lesser evolutionary divergence among NDV isolates, it is known to be highly divergent among different avian paramyxovirus serotypes. In the present study, a recombinant P protein based single serum dilution ELISA was developed which showed better sensitivity, specificity and accuracy as compared to conventional methods for NDV detection. The recombinant P protein based ELISA could be an alternative to existing diagnostics against NDV infection in chickens. [ABSTRACT FROM AUTHOR]

Abstract: The avian paramyxoviruses (APMVs) belong to the genus Avulavirus of family Paramyxoviridae. The APMVs are classified into nine serotypes on the basis of hemagglutination inhibition (HI) and neuraminidase inhibition (NI) assays, although some serologic cross-reaction exists. Newcastle disease virus (NDV), which constitutes serotype 1 (APMV-1), is an important pathogen of poultry, but the pathogenic potential of the other APMV serotypes is poorly understood. Although antibodies to APMV -2 to -9 are prevalent in chickens, the effect of prior exposure to these serotypes on susceptibility to NDV infection and disease was not known. In the present study, chickens were immunized with APMV-2 to -9 by the oculo-nasal route and later were challenged by the same route with a highly virulent strain of NDV. Among APMV-2 to -9, only APMV-3 induced serum antibodies that cross-reacted significantly with NDV and had significant NDV-neutralizing activity in vitro. In mock-immunized chickens, challenge NDV replicated throughout the respiratory tract as well as in the brain, spleen, and enteric tract. In contrast, in APMV-3-immunized chickens, challenge NDV replication was restricted to the upper respiratory tract and trachea. Some of the other APMVs also induced partial restriction of challenge NDV replication: for example, challenge NDV was not detected in the brains of APMV-9-immunized chickens, and shedding from the respiratory tract was reduced in chickens immunized with APMV-8 and -9. All of the chickens immunized with APMV-3 survived the NDV challenge; with APMV-2, -7, -8, and -9 the percentage survival was 30%, 20%, 20%, and 52.5%, respectively; whereas none of the chickens immunized with APMV-4, -5, or -6 survived. These results show that prior infection of chickens with APMV-3 induced substantial protection against NDV challenge, whereas prior infection with APMV-2, -7, -8, and -9 can alter subsequent NDV infection. The induction of NDV-neutralizing antibodies was a marker for efficient protection, but partial protection also was observed in their absence. [Copyright &y& Elsevier]

Abstract: Avian paramyxoviruses (APMVs) belong to the genus Avulavirus in the family Paramyxoviridae and include at least nine serotypes, APMV-1 to -9, as well as two additional provisional serotypes. Newcastle disease virus (NDV), which comprises APMV-1, is the most extensively studied APMV because it is an important poultry pathogen. A moderate level of antigenic and genetic diversity is recognized for APMV-1 isolates, but our knowledge of the antigenic and genetic diversity of the other APMV serotypes is limited. APMV-4 is frequently isolated from waterfowl around the world. To date complete genome sequences of APMV-4 are available for only strains, which were isolated from ducks in Hong Kong, Korea and Belgium over a period of 37 years. We have carried out genome sequencing from the nucleocapsid (N) gene-end signal to the polymerase (L) gene-start signal of five APMV-4 strains recently isolated from Italy. Each of the eight APMV-4 strains has the same F protein cleavage site, DIQPR↓F. They also share a high level of nucleotide and amino acid sequence identity: for example, the F and HN glycoproteins have greater than 97% sequence identity between the various strains. Thus, comparison of these eight strains of APMV-4 did not provide evidence of substantial diversity, in contrast to similar studies with APMV-2, -3, and -6, in which the F and HN glycoproteins exhibited up to 20–30% amino acid sequence variation within a subgroup. Reciprocal cross-HI assay using post infection chicken sera also failed to detect significant antigenic variation among the available APMV-4 strains. [Copyright &y& Elsevier]