Vaccination with Recombinant Adenoviruses Expressing the Peste des Petits Ruminants Virus F or H Proteins Overcomes Viral Immunosuppression and Induces Protective Immunity against PPRV Challenge in Sheep

et al. (2014) Vaccination with Recombinant Adenoviruses Expressing the Peste des Petits Ruminants Virus F or H Proteins Overcomes Viral Immunosuppression and Induces Protective Immunity against PPRV Challenge in Sheep. PLoS ONE 9(7): e101226. doi:10. 1371/journal.pone.0101226 Vaccination with Recombinant Adenoviruses Expressing the Peste des Petits Ruminants Virus F or H Proteins Overcomes Viral Immunosuppression and Induces Protective Immunity against PPRV Challenge in Sheep Jose M. Rojas 0 He ctor Moreno 0 Fe lix Valca rcel 0 Lourdes Pen a 0 Noem Sevilla 0 Vero nica Martn 0 Mauricio Martins Rodrigues, Federal University of Sao Paulo, Brazil 0 Centro de Investigacio n en Sanidad Animal (CISA-INIA), Instituto Nacional de Investigacio n y Tecnolog a Agraria y Alimentaria , Valdeolmos, Madrid , Spain Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants caused by the Morbillivirus peste des petits ruminants virus (PPRV). Two recombinant replication-defective human adenoviruses serotype 5 (Ad5) expressing either the highly immunogenic fusion protein (F) or hemagglutinin protein (H) from PPRV were used to vaccinate sheep by intramuscular inoculation. Both recombinant adenovirus vaccines elicited PPRV-specific B- and T-cell responses. Thus, neutralizing antibodies were detected in sera from immunized sheep. In addition, we detected a significant antigen specific T-cell response in vaccinated sheep against two different PPRV strains, indicating that the vaccine induced heterologous T cell responses. Importantly, no clinical signs and undetectable virus shedding were observed after virulent PPRV challenge in vaccinated sheep. These vaccines also overcame the T cell immunosuppression induced by PPRV in control animals. The results indicate that these adenovirus constructs could be a promising alternative to current vaccine strategies for the development of PPRV DIVA vaccines. Current address; Centro Nacional de Biotecnologa (CNB-CSIC); Campus Universidad Auto noma de Madrid; Cantoblanco; Madrid; Spain - Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files. Funding: This work was funded by grant numbers RyC-2010-06516 and AGL-2011-25025 (VM); AGL2009-07353 (NS) and RTA2010-00094-C03-03 (FV) from Ministerio de Ciencia e Innovacio n (http://www.mineco.gob.es/portal/site/mineco/idi) and 228394-NADIR Integrating Activities 7th EU program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Peste des petits ruminants (PPR) is a very important and contagious disease of small ruminants, mainly sheep and goats, notifiable to the World Organization for the Animal Health (OIE). The disease is endemic in Asia, the Middle East and Africa, and is spreading to other countries, as evidenced by the recent outbreak declared in December 2013 in China. It causes significant economical losses in endemic regions. Clinically PPR may vary from acute infection with severe clinical disease and death to mild, with little or no visible clinical signs. Acute infection may include severe pyrexia [41.041.3uC] with affected animals often becoming restless, having a dull coat, dry muzzle, catarrhal inflammation of the ocular and nasal mucosa, diarrhoea, enteritis, pneumonia and loss of appetite [1]. The mortality rate is comprised between 5080% in the acute cases [2]. The eradication in 2001 of the closely related Rinderpest Virus (RPV) has increased the global interest in PPRV because of its emergence and has highlighted the necessity to develop specific strategies for its surveillance and prevention through vaccination [3]. The causal agent, Peste des petits ruminants virus (PPRV), belongs to the genus Morbillivirus, in the family Paramyxoviridae. There is only a single serotype of PPRV but it is genetically grouped into four distinct lineages (1, 2, 3 and 4) on the basis of partial sequence analysis of fusion protein (F) gene [4,5,6]. PPRV is an enveloped negative single strand RNA virus with two external glycoproteins, F and hemagglutinin (H), associated with the envelope [7]. These represent key antigens for triggering an effective protective immune response. PPRV is a lymphotropic virus, causing leucopenia and a generalized immunosuppression [3]. Current PPRV vaccines [8] are based on live virus attenuated by serial passage in Vero cells of various PPRV strains (Nigeria 75/1 [9,10], Sungri96, Arasur87 and Coimbatore97 [11]) and they are extensively used in countries where PPRV is endemic [12]. Single immunization with live PPRV vaccines has been able to maintain protective levels of serum antibody for up to three years. Although effective, an important drawback of this vaccine is that vaccinated animals cannot be differentiated from infected animals, affecting control and regulatory measures against the disease. They are also thermosensitive and require an efficacious cold chain to remain active, which is an important practical problem, more so in developing countries and warm climates, where the disease is more prevalent. Different research groups are focused on developing thermoresistant live attenuated vaccines to overcome the obstacles posed by having to maintain the cold chain for vaccine distribution [13]. Several strategies that allow the expression of the F and/or H proteins of PPRV using different vectors, including recombinant adenoviral [14,15] or poxviral vectors [16,17], and chimeric RPV [18,19] have been shown to induce long lasting neutralizing antibody responses against PPRV in goats as well as partial or total protection against disease in some cases. Adenoviruses have proved excellent candidates as vaccine delivery vehicles [20,21] due to their genetic stability, safety [14] and the strong immune response they generate [9,10,22,23,24]. Furthermore, they can be easily produced in large quantities and their structural characteristics make them amenable to distribution in hot climates areas, like Africa and Asia, where PPRV is currently a major threat. Previously, we have generated two recombinant adenoviruses expressing the F or H proteins from PPRV and demonstrated that they induce specific PPRV neutralizing antibodies as well as cellular immune responses to PPRV in mice [25]. In the present study, protective immune response to these two recombinant adenoviruses was evaluated in sheep. PPRV-specific B- and T- cell responses were induced by both recombinant vaccines and protected sheep against virulent challenge. These vaccines overcame the T cell immunosuppression observed in infected animals. These adenovirus constructs are a promising alternative to current vaccine strategies for the development of PPRV DIVA vaccines. Material and Methods Cells an (...truncated)