Antiviral and antitumoral effects of recombinant chicken myelomonocytic growth factor in virally induced lymphoma

Abstract

Chicken myelomonocytic growth factor (cMGF) is a 27-kDa glycoprotein that stimulates the growth and activation of cells from the monocyte/macrophage lineage. Recombinant cMGF was produced in a prokaryotic ( Escherichia coli) expression system and purified via a C-terminal His-tag. Treatment of 2-week-old histocompatible B 13/B 13 chickens highly susceptible to Marek's disease (MD) with rcMGF (two daily injections of 50 μg rcMGF per chicken) enhanced background and LPS-inducible systemic NO (NO 3 −+NO 2 −) responses 3 days later. NO has antiviral activity on Marek's disease virus (MDV), a herpesvirus specifically inducing T cell-lymphomas in chickens. When the very virulent strain of MDV RB1-B was inoculated 3 days after treatment with rcMGF, MDV viremia was significantly inhibited and development of visceral tumors was drastically reduced. Combination of rcMGF with partially protective vaccination using a herpesvirus of turkey (HVT) further reduced tumor burden and significantly delayed mortality, but only in very young birds. In conclusion, rcMGF might be worth considering as a stimulator of innate immune response in chickens, such as activation of macrophages and NO production, and thus be beneficial for its antiviral and antitumoral effects in vaccination against MD lymphoma.