Orf Virus: A New Class of Immunotherapy Drugs

Abstract

Orf is one of the most widespread viral diseases worldwide, usually benign and self-limiting, and mainly affects not only sheep and goats, but also various other ruminants and mammals. The causative agent, orf virus (ORFV) is a member of the genus parapoxvirus, owing to its zoonotic importance and ability to crossinfect other species sporadically. ORFV encodes virulence and immunomodulatory factors that interfere with host inflammatory effect and antiviral immune mechanisms and induces a transient and complex cytokine response, initially represented by Th1-related cytokines followed by Th2-related cytokines. The ORFV has evolved several mechanisms to survive in the presence of the immune system, resulting in repeated infections. Currently, ORFV has been developed as vaccines in veterinary field. The unique host immune escape ability obtained by ORFV has made it one of the important candidates for prevention and treatment of various diseases (including chronic viral diseases, tumor, and liver fibrosis).

A Review on Human Orf: A Neglected Viral Zoonosis

“…The inhibition of a Th1 response happens indirectly through abating the function of antigenpresenting macrophages and dendritic cells. 32 In addition, IL-10 has co-stimulatory functions on T lymphocytes associated with Th2 responses, mast cells and B cells. The molecular mass of IL-10 homologue protein is 21.7 kDa (185 amino acids sequence) making the ORFV IL-10s slightly larger than their mammalian counterparts which is ~18.6 kDa.…”

“…The amino acid sequence identity of the virus IL-10 with human IL-10 is known to be 67% in the C-terminal two thirds of the polypeptide, although the relatedness at the nucleotide level is less apparent. Curiously, the N-terminal region of the IL-10 like contains little similarity to that of mammalian IL-10 23,32 and this may help to deduce that the viral IL-10 polypeptide is larger than the mammalian counterpart.…”

“…Data from Wang and Luo. 32 molecules that recruit and activate immune cells at sites of inflammation and infection. 39 CBP has been described in ORFV and is thought to interact with the chemokine families with strong affinity and results in anti-inflammatory process.…”

“…The other genes indicated are studied as vital for poxviruses and are extremely conserved. Data from Wang and Luo 32.…”

Construction and characterization of a contagious ecthyma virus double-gene deletion strain and evaluation of its potential as a live-attenuated vaccine in goat

“…It was reported that ORFV112 deletion resulted in the attenuation of ORFV NZ2 (18). GIF is expressed in the late stage of infection and is the only known viral or cellular protein that has the dual activity of inhibiting host GM-CSF and IL-2 (14,19). The function of GIF, similar to CBP, is reported to inhibit the trafficking of monocytes into the skin to preventing inflammatory response (19).…”