Self-assembly and release of peste des petits ruminants virus-like particles in an insect cell-baculovirus system and their immunogenicity in mice and goats.

Wenchao Li,Hongyan Jin,Chenghuai Yang,Wenquan Wang,Zhanzhong Zhao,Gang Li,Junping Li,Xiukun Sui,Tetsuro Ikegami

doi:10.1371/journal.pone.0104791

Abstract

Peste des petits ruminants (PPR) is an acute, febrile, viral disease of small ruminants that has a significant economic impact. For many viral diseases, vaccination with virus-like particles (VLPs) has shown considerable promise as a prophylactic approach; however, the processes of assembly and release of peste des petits ruminants virus (PPRV) VLPs are not well characterized, and their immunogenicity in the host is unknown. In this study, VLPs of PPRV were generated in a baculovirus system through simultaneous expression of PPRV matrix (M) protein and hemaglutin in (H) or fusion (F) protein. The released VLPs showed morphology similar to that of the native virus particles. Subcutaneous injection of these VLPs (PPRV-H, PPRV-F) into mice and goats elicited PPRV-specific IgG production, increased the levels of virus neutralizing antibodies, and promoted lymphocyte proliferation. Without adjuvants, the immune response induced by the PPRV-H VLPs was comparable to that obtained using equivalent amounts of PPRV vaccine. Thus, our results demonstrated that VLPs containing PPRV M protein and H or F protein are potential “differentiating infected from vaccinated animals” (DIVA) vaccine candidates for the surveillance and eradication of PPR.

Highlights

Peste des petits ruminants (PPR) is a highly contagious and economically important viral disease of domestic and some wild small ruminants, and in particular, of goats and sheep
Electron microscopic examination of negatively stained samples revealed that both peste des petits ruminants virus (PPRV)-H and PPRV-F virus-like particles (VLPs) showed spherical shapes, with spikes on their surfaces, and with a diameter of approximately 80– 100 nm, which is similar to the morphology and size of native PPRV particles propagated in Vero cells(Fig.2E–G).An ultrathin section of Sf21 insect cells infected with recombinant baculoviruses (rBVs) at 48-h post-infection was investigated, revealing VLPs with a diameter of approximately 100 nm budding from the plasma membrane, and some spikeless VLPs distributed throughout the cytoplasm(Fig. 2B–C)
PBS = phosphate-buffered saline, as negative control; PPRV = Peste des petits virus; VLP = virus-like particles. *Different superscript letters indicate that the differences were significant (p,0.05), same superscript letters indicate that the differences were not significant (p.0.05).. doi:10.1371/journal.pone.0104791.t003

Summary

Introduction

Peste des petits ruminants (PPR) is a highly contagious and economically important viral disease of domestic and some wild small ruminants, and in particular, of goats and sheep. The disease is characterized by severe pyrexia, oculonasal discharges, necrotizing and erosive stomatitis, enteritis, and pneumonia. It was first described in the Ivory Coast, West Africa, but has become wide-spread in sub-Saharan Africa, Arabia, the Middle East, Southwest Asia, India, and other countries[1]. PPR outbreaks can cause severe economic losses, because they often result in high morbidity and mortality; development of an effective vaccine for the prevention and control of PPR is important

Methods

Results

Conclusion