A Novel Recombinant Peste des Petits Ruminants-Canine Adenovirus Vaccine Elicits Long-Lasting Neutralizing Antibody Response against PPR in Goats

Junling Qin,Geng Huang,Chengyu Wang,Xianzhu Xia,Yuwei Gao,Hainan Huang,Xiaoqiang Hou,Na Feng,Songtao Yang,Yang Ruan,Tiecheng Wang,Eric A Weaver

doi:10.1371/journal.pone.0037170

Abstract

BackgroundPeste des petits ruminants (PPR) is a highly contagious infectious disease of goats, sheep and small wild ruminant species with high morbidity and mortality rates. The Peste des petits ruminants virus (PPRV) expresses a hemagglutinin (H) glycoprotein on its outer envelope that is crucial for viral attachment to host cells and represents a key antigen for inducing the host immune response.Methodology/Principal FindingsTo determine whether H can be exploited to generate an effective PPRV vaccine, a replication-competent recombinant canine adenovirus type-2 (CAV-2) expressing the H gene of PPRV (China/Tibet strain) was constructed by the in vitro ligation method. The H expression cassette, including the human cytomegalovirus (hCMV) promoter/enhancer and the BGH early mRNA polyadenylation signal, was inserted into the SspI site of the E3 region, which is not essential for proliferation of CAV-2. Infectious recombinant rCAV-2-PPRV-H virus was generated in transfected MDCK cells and used to immunize goats. All vaccinated animals produced antibodies upon primary injection that were effective in neutralizing PPRV in vitro. Higher antibody titer was obtained following booster inoculation, and the antibody was detectable in goats for at least seven months. No serious recombinant virus-related adverse effect was observed in immunized animals and no adenovirus could be isolated from the urine or feces of vaccinated animals. Results showed that the recombinant virus was safe and could stimulate a long-lasting immune response in goats.Conclusions/SignificanceThis strategy not only provides an effective PPR vaccine candidate for goats but may be a valuable mean by which to differentiate infected from vaccinated animals (the so-called DIVA approach).

Highlights

Peste des petits ruminants (PPR) is an acute and highly contagious disease of small ruminants, affecting goats and sheep
The identification of the plasmid pVAX-H, pVAXDE3-H and pPolyII-canine adenovirus (CAV)-DE3-H by restriction endonuclease digestion confirmed that the H gene and its expression cassette were included in the recombinant virus
A canine adenovirus type-2 (CAV-2) expression vector with a deleted E3 has some advantageous features for gene delivery applications: it replicates efficiently to high titers, provides large cloning space, permits the expression of recombinant proteins in most mammalian cell lines and tissues, and accurately expresses and modifies recombinant proteins

Summary

Introduction

Peste des petits ruminants (PPR) is an acute and highly contagious disease of small ruminants, affecting goats and sheep. The disease may resolve after a prolonged convalescent period, but more frequently leads to death [1]. PPR was first described in 1942 in Cote d’Ivoire as a fatal disease of small ruminants that resembled rinderpest of cattle. PPR is responsible for significant economic losses in goats and sheep productivity in the endemic regions. Peste des petits ruminants (PPR) is a highly contagious infectious disease of goats, sheep and small wild ruminant species with high morbidity and mortality rates. The Peste des petits ruminants virus (PPRV) expresses a hemagglutinin (H) glycoprotein on its outer envelope that is crucial for viral attachment to host cells and represents a key antigen for inducing the host immune response

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Conclusion