The antigenic evolution of influenza A (H3N2) virus was quantified and visualized from its introduction into humans in 1968 to 2003. Although there was remarkable correspondence between antigenic and genetic evolution, significant differences were observed: Antigenic evolution was more punctuated than genetic evolution, and genetic change sometimes had a disproportionately large antigenic effect. The method readily allows monitoring of antigenic differences among vaccine and circulating strains and thus estimation of the effects of vaccination. Further, this approach offers a route to predicting the relative success of emerging strains, which could be achieved by quantifying the combined effects of population level immune escape and viral fitness on strain evolution.

https://science.sciencemag.org/content/sci/305/5682/371.full.pdf

Mapping the Antigenic and Genetic Evolution of Influenza Virus

Newcastle disease (ND), caused by avian paramyxovirus serotype 1 (APMV-1) viruses, is included in List A of the Office International des Epizooties. Historically, ND has been a devastating disease of poultry, and in many countries the disease remains one of the major problems affecting existing or developing poultry industries. Even in countries where ND may be considered to be controlled, an economic burden is still associated with vaccination and/or maintaining strict biosecurity measures. The variable nature of Newcastle disease virus strains in terms of virulence for poultry and the different susceptibilities of the different species of birds mean that for control and trade purposes, ND requires careful definition. Confirmatory diagnosis of ND requires the isolation and characterisation of the virus involved. Assessments of virulence conventionally require in vivo testing. However, in vitro genetic characterisation of viruses is being used increasingly now that the molecular basis of pathogenicity is more fully understood. Control of ND is by prevention of introduction and spread, good biosecurity practices and/or vaccination. Newcastle disease viruses may infect humans, usually causing transient conjunctivitis, but human-to-human spread has never been reported. Eight other serotypes of avian paramyxoviruses are recognised, namely: APMV-2 to APMV-9. Most of these serotypes appear to be present in natural reservoirs of specific feral avian species, although other host species are usually susceptible. Only APMV-2 and APMV-3 viruses have made a significant disease and economic impact on poultry production. Both types of viruses cause respiratory disease and egg production losses which may be severe when exacerbated by other infections or environmental stresses. No reports exist of natural infections of chickens with APMV-3 viruses.

Newcastle disease and other avian paramyxoviruses.

Third genome size category of avian paramyxovirus serotype 1 (Newcastle disease virus) and evolutionary implications

Newcastle disease: Evolution of genotypes and the related diagnostic challenges

Substantial variation in the virulence of Newcastle disease virus (NDV) isolates means that the detection of NDV or evidence of infection is insufficient for an adequate diagnosis, as control measures for avirulent viruses are very different to those for virulent viruses. Diagnosis therefore requires further characterization, at least as to whether an isolate is virulent or avirulent. Conventional detection and differentiation of ND viruses is perceived as slow, laborious and requiring an undesirable use of in vivo techniques. In addition, further characterization is needed to give greater information on origin and spread. This review concentrates on the application of monoclonal antibody and molecular biological approaches. Panels of monoclonal antibodies were a major advance for the characterization of NDV isolates, although confirmation of virulence for poultry still required in vivo testing. As molecular-based techniques become easier and more reliable, they are likely to supersede the use of monoclonal antibodies, especially for characterizing viruses for epidemiological purposes. The attraction of molecular-based techniques is that they may be able to cover all three aspects of Newcastle disease diagnosis (detection of virus, characterization, including inference of virulence, and epidemiology) quickly, accurately and definitively in a single test. A number of approaches based on the reverse transcriptase polymerase chain reaction have been developed, with subsequent analysis of the product by restriction enzyme analysis, probe hybridization and nucleotide sequencing. Although extensive variation among NDVs still poses technical problems, the real and potential advantages of a molecular biological approach to Newcastle disease diagnosis appear to be overwhelming.

https://www.tandfonline.com/doi/pdf/10.1080/03079450120044515

Detection and differentiation of Newcastle disease virus (avian paramyxovirus type 1).

Summary Newcastle disease (ND) virus (APMV‐1) isolates submitted to the International Reference Laboratory for ND were characterised antigenically by their ability to cause binding of mouse monoclonal antibodies (mAbs) to cell cultures infected with the isolate. Since the availability of the mAbs 1526 viruses have been examined using a panel of nine mAbs and 818 with an extended panel of 26 mAbs. Using the nine mAb panel a total of 14 different patterns was seen and viruses grouped by the same pattern showed relationships with each other which were either biological, temporal or geographical or more than one of these. There was a marked tendency of viruses placed in the same group to show similar virulence for chickens. Extension of the panel to 26 mAbs produced 39 distinct patterns, although some of these were seen with only a single virus. Again, viruses inducing similar binding patterns shared similar properties and some binding patterns were specific for viruses causing discrete epizootics. Cluster an...

J. E. Smith

Papers

Antigenic diversity and similarities detected in avian paramyxovirus type 1 (Newcastle disease virus) isolates using monoclonal antibodies.