Infection of equine monocyte-derived macrophages with an attenuated equine infectious anemia virus (EIAV) strain induces a strong resistance to the infection by a virulent EIAV strain

Abstract

The Chinese attenuated equine infectious anemia virus (EIAV) vaccine has successfully protected millions of equine animals from EIA disease in China. Given that the induction of immune protection results from the interactions between viruses and hosts, a better understanding of the characteristics of vaccine strain infection and host responses would be useful for elucidating the mechanism of the induction of immune protection by the Chinese attenuated EIAV strain. In this study, we demonstrate in equine monocyte-derived macrophages (eMDM) that EIAV FDDV13 , a Chinese attenuated EIAV strain, induced a strong resistance to subsequent infection by a pathogenic strain, EIAV UK3 . Further experiments indicate that the expression of the soluble EIAV receptor sELR1, Toll-like receptor 3 (TLR3) and interferon β (IFNβ) was up-regulated in eMDM infected with EIAV FDDV13 compared with eMDM infected with EIAV UK3 . Stimulating eMDM with poly I:C resulted in similar resistance to EIAV infection as induced by EIAV FDDV13 and was correlated with enhanced TLR3, sELR1 and IFNβ expression. The knock down of TLR3 mRNA significantly impaired poly I:C-stimulated resistance to EIAV, greatly reducing the expression of sELR1 and IFNβ and lowered the level of infection resistance induced by EIAV FDDV13 . These results indicate that the induction of restraining infection by EIAV FDDV13 in macrophages is partially mediated through the up-regulated expression of the soluble viral receptor and IFNβ, and that the TLR3 pathway activation plays an important role in the development of an EIAV-resistant intracellular environment.

Prospects in Innate Immune Responses as Potential Control Strategies against Non-Primate Lentiviruses

“…The knockdown of TLR3 mRNA significantly impaired poly I:C-stimulated resistance to EIAV, greatly reducing the expression of sELR1 and IFN-β, and the level of resistance induced by EIAVFDDV13. These results indicate that resistance is at least partially mediated by the activation of TLR3 pathways [ 88 ].…”

Equine infectious anemia virus in China

“…Furthermore, vaccine-induced TLR3 activation and INF beta production were higher than in the molecular clone strains [ 27 ]. Infection of equine monocyte-derived macrophages with an attenuated equine infectious anemia virus (EIAV) strain induces a strong resistance to infection by a virulent EIAV strain [ 28 ].…”