Early and Solid Protection Afforded by the Thiverval Vaccine Provides Novel Vaccination Alternatives Against Classical Swine Fever Virus.

Yaneysis Lamothe-Reyes,Mònica Alberch,José Alejandro Bohórquez,Marta Pérez-Simó,Llilianne Ganges,Rosa Rosell,Miaomiao Wang

doi:10.3390/vaccines9050464

Abstract

Classical swine fever virus (CSFV) remains a challenge for the porcine industry. Inefficient vaccination programs in some endemic areas may have contributed to the emergence of low and moderate virulence CSFV variants. This work aimed to expand and update the information about the safety and efficacy of the CSFV Thiverval-strain vaccine. Two groups of pigs were vaccinated, and a contact and control groups were also included. Animals were challenged with a highly virulent CSFV strain at 21- or 5-days post vaccination (dpv). The vaccine induced rapid and strong IFN-α response, mainly in the 5-day immunized group, and no vaccine virus transmission was detected. Vaccinated pigs showed humoral response against CSFV E2 and Erns glycoproteins, with neutralising activity, starting at 14 days post vaccination (dpv). Strong clinical protection was afforded in all the vaccinated pigs as early as 5 dpv. The vaccine controlled viral replication after challenge, showing efficient virological protection in the 21-day immunized pigs despite being housed with animals excreting high CSFV titres. These results demonstrate the high efficacy of the Thiverval strain against CSFV replication. Its early protection capacity makes it a useful alternative for emergency vaccination and a consistent tool for CSFV control worldwide.

Highlights

Classical swine fever (CSF) is a highly contagious disease that affects domestic pigs and wild boars
CSF poses a threat for the pig industry from sanitary and economic points of view, and its notification is mandatory to the World Health Organization for animal health (OIE) [1,2,3]
CSF virus (CSFV) E2 specific antibodies were determined in sera samples using a commercial ELISA kit (IDEXX Laboratories, Liebfeld, Switzerland)

Summary

Introduction

Classical swine fever (CSF) is a highly contagious disease that affects domestic pigs and wild boars. The viral genome, of around 12.3 Kb of length, codifies for a unique polyprotein that after proteolytic processing yields mature non-structural and structural proteins [4,5]. The disease has been successfully eradicated in North America, Oceania, and a large part of the European Union [7]. Despite the implementation of extensive eradication programs, CSF remains endemic in Asia, South and Central America, and the Caribbean [7]. The risk for CSFV re-emergence remains high, as shown by the recent outbreaks in countries including Korea, Colombia, Russia, Brazil, and even Japan, some of which had been CSF-free for decades [8,9]

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