Important Zoonoses in Animals: Parapoxviruses: Extraordinary “Ball of Wool” Particle Shape—Masters of Local Infection and Immune Escape

Abstract

Parapoxviruses (PPV) represent a separate genus within the subfamiliy Chordopoxvirinae of the family Poxviridae. Species members of the genus Parapoxvirus (PPV) within the family Poxviridae cause contagious pustular dermatitis in small ruminants (prototype Orf virus, ORFV) and mostly mild localized inflammation in cattle (bovine papular stomatitis virus, BPSV and pseudocowpox virus, PCPV) and red deer in New Zealand (Parapoxvirus of red deer, PVNZ). All PPVs show a widespread and worldwide occurrence and are known to be zoonotic, leading to circumscribed skin lesions in humans, historically known as milker's nodules. Human PPV isolates are often ill defined concerning their allocation to an animal origin. PPV cause local infections and are specialized to counteract skin and mucous membrane defense mechanisms after virus entry into damaged skin by micro-lesions or wounds. Sophisticated escape mechanisms mediated by virulence genes of PPV have been elucidated in recent times. Whole genome sequencing (WGS) of various PPV species genomes allows more detailed and comparative determination of virus peculiarities. After PPV transmission to man, molecular conservation of the animal's virus genome can indicate the origin of the virus. Due to their high stability in the environment and local persistence in the host PPV have established as a worldwide problem in livestock especially in small ruminants. With regard to diagnostic differentiation after manifestation in human patients as well as for reliable differentiation from notifiable diseases in livestock PPV still pose a challenge for clinicians and microbiologists.