Development of an experimental inactivated PRRSV vaccine that induces virus-neutralizing antibodies

Merijn Vanhee; Peter L. Delputte; Iris Delrue; Marc F. Geldhof; Hans J. Nauwynck

doi:doi:10.1051/vetres/2009046

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Volume 40 / No 6 (November-December 2009)

Vet. Res., 40 6 (2009) 63

Abstract

Open Access

Issue		Vet. Res. Volume 40, Number 6, November-December 2009


Number of page(s)		15
DOI		https://doi.org/10.1051/vetres/2009046
Published online		13 August 2009
How to cite this article		Vet. Res. (2009) 40:63

How to cite this article: Vet. Res. (2009) 40:63
DOI: 10.1051/vetres/2009046

Development of an experimental inactivated PRRSV vaccine that induces virus-neutralizing antibodies

Merijn Vanhee, Peter L. Delputte, Iris Delrue, Marc F. Geldhof and Hans J. Nauwynck

Laboratory of Virology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium

Received 16 January 2009; accepted 11 August 2009; published online 13 August 2009

Abstract - Porcine reproductive and respiratory syndrome virus (PRRSV) can induce reproductive disorders and is involved in the porcine respiratory disease complex, causing tremendous economic losses to the swine industry. Inactivated PRRSV vaccines are preferred over attenuated vaccines because of their safety and flexibility towards emerging virus strains, but the efficacy of current inactivated PRRSV vaccines is questionable. In this study, experimental inactivated PRRSV vaccines were developed, based on two formerly optimized inactivation procedures: UV irradiation and treatment with binary ethylenimine (BEI). In a first experiment, it was shown that vaccination with UV- or BEI-inactivated virus in combination with Incomplete Freund's Adjuvant induced virus-specific antibodies and strongly primed the virus-neutralizing (VN) antibody response. Subsequently, the influence of adjuvants on the immunogenicity of neutralizing epitopes on the inactivated virus was investigated. It was shown that vaccination with BEI-inactivated virus in combination with a commercial oil-in-water adjuvant induced high titers (3.4 log²) of VN antibodies in 6/6 pigs, instead of only priming the neutralizing antibody response. After challenge, neutralizing antibody titers in these vaccinated animals rose to a mean value of 5.5 log², and the duration of the viremia was reduced to an average of 1 week. This study shows that, by the use of an optimized inactivation procedure and a suitable adjuvant, inactivated PRRSV vaccines can be developed that induce VN antibodies and offer partial protection upon challenge.