Infection with equine infectious anemia virus vaccine strain EIAVDLV121 causes no visible histopathological lesions in target organs in association with restricted viral replication and unique cytokine response

Abstract

The live equine infectious anemia virus (EIAV) vaccine strain EIAVDLV121 was developed by in vitro attenuation of a virulent strain, EIAVLN40, in the 1970s, and it has been demonstrated to induce protective immunity under laboratory and natural EIAV infection conditions. The detailed biological features of this attenuated virus remain to be further investigated. Experimental inoculation with EIAVDLV121 did not result in clinical symptoms even with immunosuppressive treatment in our previous studies. Here, we further investigated whether the replication of the vaccine strain EIAVDLV121 in experimentally infected horses causes histopathological lesions to develop in the targeted organs. Both the lungs and the spleen have been demonstrated to support EIAV replication. By evaluating the gross macroscopic and histological changes, we found that EIAVDLV121 did not cause detectable histopathological lesions and that it replicated several hundred times more slowly than its parental virulent strain, EIAVLN40, in tissues. Immunochemical assays of these tissues indicated that the primary target cells of EIAVDLV121 were monocytes/macrophages, but that EIAVLN40 also infected alveolar epithelial cells and vascular endothelial cells. In addition, both of these viral strains promoted the up- and down-regulation of the expression of various cytokines and chemokines, implicating the potential involvement of these cellular factors in the pathological outcomes of EIAV infection and host immune responses. Taken together, these results demonstrate that the EIAV vaccine strain does not cause obvious histopathological lesions or clinical symptoms and that it induces a unique cytokine response profile. These features are considered essential for EIAVDLV121 to function as an effective live vaccine.

Attenuation of Equine Lentivirus Alters Mitochondrial Protein Expression Profile from Inflammation to Apoptosis

“…Our previous research found that EIAV DLV34 can induce a host inflammatory storm to cause severe pathological injury but that EIAV DLV121 can induce only a weak inflammatory response. In addition, the apoptosis induced in eMDMs infected with EIAV DLV121 was significantly higher than that induced in eMDMs infected with EIAV DLV34 (4,5). This finding suggests that the host cellular inflammatory responses and apoptosis are closely related to EIAV pathogenicity and the protective mechanisms of the attenuated vaccine.…”

Anticipation of the entry and spread of Equine Infectious Anemia in Horses in Indonesia

“…Lebih lanjut Ma et al (2011) melaporkan bahwa vaksin hidup yang telah dilemahkan dinilai sangat efektif untuk mencegah penyakit, terutama saat terjadi wabah. Penelitian yang telah dilakukan oleh Liu et al (2016), menunjukkan bahwa virus strain yang digunakan pada vaksin EIA mampu memberikan proteksi yang optimum, dan tidak menimbulkan lesi pada organ kuda secara histologi.…”