Orf in India: Opportunities and challenges
Orf in India: Opportunities and challenges
G. Venkatesan* and Amit Kumar
ABSTRACT
Orf virus is the most studied poxvirus next to Vaccinia virus that has been used as vaccine candidate for small pox infection in humans. This virus causes contagious form of disease, mainly but not limited to sheep and goats, which lead to high economic impact in developing countries including India. The causative agent, Orf virus (ORFV) belong to the genus Parapoxvirus (PPV) of the family poxviridae produces a typical papillomatous, cauliflower like external growth around mouth regions and rarely the lesions are found in other parts of the body and internal organs. Another characteristic feature of ORFV including other PPVs is the ability to re-infect the same host and conferring short term immunity in contrast to other pox viruses and also produce localized skin lesions in humans who are in contact with infected animals and their products. Unique and specific virulence genes located at termini of ORFV genome with their encoded products are attributed to host immune evasion, short-term immunity both in natural infection post-vaccination in target species and repeated host susceptibility. However, these genes are variable among ORFV isolates/strains as they are not located in central part of genome and some of them are either virus specific namely Viral interferon resistant (VIR) and GM-CSF/IL2 inhibition factor (GIF) genes and or host specific namely vascular endothelial growth factor (VEGF-E) and viral IL-10 genes. ORFV can cause high morbidity in adults along with considerable mortality in young suckling animals and showing an expanding host range even to marine species make this contagious virus, an important animal pathogen globally. Being zoonotic and endemic in most parts of the developing world, it is necessary to prevent and control the infection using latest molecular diagnostics and effective vaccine along with anti-viral therapeutics. This short commentary deals with current knowledge and opportunities on ORFV and future challenges as control perspectives in India.
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