Two-fold power of PPRV
Pathogenicity
PPRV shows a variable pathogenicity, or virulence, but no relationship has been established between viral lineage and level of virulence.
This variability in virulence is likely linked to the susceptibility of the host, which is a function of the host's breed and species. The virus might have varying affinities for the lymphocytes. The most virulent virus strains may be those which have the capacity to multiply rapidly while attenuated strains may have reduced infectivity due to changes in their tissue affinity, resulting in reduced epitheliotropism.
Immunogenicity
The immunogenicity of all PPRV strains is high and independent of their genetic variability. When an animal recovers from a natural infection or is in contact with a virus strain through vaccination, it acquires long term immunity for all of the other strains and can no longer be infected by the disease.
From an immunological perspective, this means that variations in the nucleotide sequences of the F and H proteins do not involve the important antigenic sites.
From an epidemiological perspective, this consequently means that PPR has a cyclical nature. The virus can only maintain itself in a population if susceptible individuals regularly join the population.
