Monoclonal Antibodies in Research, Diagnosis and Epizootiology of Newcastle Disease. In: Alexander DJ, editor. Newcastle Disease. Boston: Springer US; 1988. pp. 131-46. [DOI: 10.1007/978-1-4613-1759-3_8]

Newcastle disease virus: is an updated attenuated vaccine needed?

Newcastle disease virus (NDV) is a major cause of infectious mortality and morbidity in poultry worldwide. It is an enveloped virus with two outer-membrane proteins-haemagglutinin-neuraminidase (HN) and fusion protein (F)-that induce neutralizing antibodies. All NDV strains belong to one serotype. Yet, NDV vaccines, derived from genotype II, do not fully prevent infection or shedding of viruses from other genotypes. The aim of this study was to test if an updated vaccine is required. For this purpose, NDVs isolated from infected, albeit heavily vaccinated, flocks were genetically and immunologically characterized. Amino acid differences in F and HN protein sequences were identified between the vaccine strain and each of the isolates, some specifically at the neutralization sites. Whereas all tested isolates showed similar haemagglutination-inhibition (HI) titres, 100-100,000 times higher antibody-to-virus ratios were needed to neutralize viral propagation in embryos by the field isolates versus the vaccine strain. As a result, a model and an equation were developed to explain the phenomenon of escape in one-serotype viruses and to calculate the HI values needed for protection, depending on variation rate at key positions. In conclusion, to confer full protection against NDVs that differ from the vaccine strain at the neutralizing epitopes, very high levels of antibodies should be raised and maintained to compensate for the reduction in the number of effective epitopes; alternatively, an adjusted attenuated vaccine should be developed-a task made possible in the current era of reverse vaccinology.

Newcastle disease virus: macromolecules and opportunities

Over the past two decades, enormous advances have occurred in the structural and biological characterization of Newcastle disease virus (NDV). As a result, not only the complete sequence of the viral genome has been fully determined, but also a clearer understanding of the viral proteins and their respective roles in the life cycle has been achieved. This article reviews the progress in the molecular biology of NDV with emphasis on the new technologies. It also identifies the fundamental problems that need to be addressed and attempts to predict some research opportunities in NDV that can be realized in the near future for the diagnosis, prevention and treatment of disease(s).

Detection of PMV-1 specific antibodies with a monoclonal antibody blocking enzyme-linked immunosorbent assay

A highly reproducible monoclonal antibody (Mab) blocking ELISA (B-ELISA) has been developed and evaluated for the detection of NDV-specific antibodies. The Mab utilised is specific for a conserved PMV-1 serotype-specific epitope, as demonstrated by the indirect immunoperoxidase test. It reacted with all strains representing different serogroups within the PMV-1 serotype, but not with any strain belonging to other PMV serotypes. Sensitivity and specificity of the B-ELISA were compared with the haemagglutina-tion inhibition test (HI). Blocking and HI antibodies were detected in sera of chickens 8 days post-experimental infection. The B-ELISA proved consistently more sensitive than the HI test. In another survey, 62 sera from experimentally vaccinated chickens were tested; 95.2% proved positive by B-ELISA, 85.5% by indirect ELISA and 74% by HI test. When 504 field sera from vaccinated chickens and turkeys were tested, 98% were positive by B-ELISA, and 69% by HI. The specificity was evaluated by testing 1066 samples from NDV-free flocks, all of which proved negative by both methods. Other advantages of the B-ELISA include easy standardization and quality control, and ability to test sera from any species (including exotic or wild birds as well as mammals). The use of low dilution serum or egg-yolk samples makes the test quick and easy to perform and suitable for large-scale screening.

Evaluation of the Newcastle disease virus F and HN proteins in protective immunity by using a recombinant avian paramyxovirus type 3 vector in chickens

Newcastle disease virus (NDV) belongs to serotype 1 of the avian paramyxoviruses (APMV-1) and causes severe disease in chickens. Current live attenuated NDV vaccines are not fully satisfactory. An alternative is to use a viral vector vaccine that infects chickens but does not cause disease. APMV serotype 3 infects a wide variety of avian species but does not cause any apparent disease in chickens. In this study, we constructed a reverse-genetics system for recovery of infectious APMV-3 strain Netherlands from cloned cDNAs. Two recombinant viruses, rAPMV3-F and rAPMV3-HN, were generated expressing the NDV fusion (F) and hemagglutinin-neuraminidase (HN) proteins, respectively, from added genes. These viruses were used to immunize 2-week-old chickens by the oculonasal route in order to evaluate the contribution of each protein to the induction of NDV-specific neutralizing antibodies and protective immunity. Each virus induced high titers of NDV-specific hemagglutination inhibition and serum neutralizing antibodies, but the response to F protein was greater. Protective immunity was evaluated by challenging the immunized birds 21 days later with virulent NDV via the oculonasal, intramuscular, or intravenous route. With oculonasal or intramuscular challenge, all three recombinant viruses (rAPMV3, rAPMV3-F, and rAPMV3-HN) were protective, while all unvaccinated birds succumbed to death. These results indicated that rAPMV3 alone can provide cross-protection against NDV challenge. However, with intravenous challenge, birds immunized with rAPMV3 were not protected, whereas birds immunized with rAPMV3-F alone or in combination with rAPMV3-HN were completely protected, and birds immunized with rAPMV3-HN alone were partially protected. These results indicate that the NDV F and HN proteins are independent neutralization and protective antigens, but the contribution by F is greater. rAMPV3 represents an avirulent vaccine vector that can be used against NDV and other poultry pathogens.

Comparative characteristics of the Israeli Newcastle disease virus field strains by means of a wide panel of monoclonal antibodies against hemagglutinin-neuraminidase glycoprotein

Fourteen mouse monoclonal antibodies (MAB) were tested for their ability to react with 15 reference and 52 local Newcastle disease virus (NDV) strains isolated in Israel during the last decade from feral birds. All the field isolates had no antigenic difference when examined by classic serological tests. However, MAB-mediated analysis revealed wide antigenic heterogeneity amongst the studied viruses. By the pattern of the MAB reactivity, all the isolates could be distributed into 13 groups.