Classical swine fever virus replicon particles lacking the E^rnsgene: a potential marker vaccine for intradermal application

Abstract

-Classical swine fever virus replicon particles (CSF-VRP) deficient for E rns were evaluated as a non-transmissible marker vaccine. A cDNA clone of CSFV strain Alfort/187 was used to obtain a replication-competent mutant genome (replicon) lacking the sequence encoding the 227 amino acids of the glycoprotein E rns (A187delE rns ). For packaging of A187delE rns into virus particles, porcine kidney cell lines constitutively expressing E rns of CSFV were established. The rescued VRP were infectious in cell culture but did not yield infectious progeny virus. Single intradermal vaccination of two pigs with 10 7 TCID 50 of VRP A187delE rns elicited neutralizing antibodies, anti-E2 antibodies, and cellular immune responses determined by an increase of IFN-γ producing cells. No anti-E rns antibodies were detected in the vaccinees confirming that this vaccine represents a negative marker vaccine allowing differentiation between infected and vaccinated animals. The two pigs were protected against lethal challenge with the highly virulent CSFV strain Eystrup. In contrast, oral immunization resulted in only partial protection, and neither CSFV-specific antibodies nor stimulated T-cells were found before challenge. These data represent a good basis for more extended vaccination/challenge trials including larger numbers of animals as well as more thorough analysis of virus shedding using sentinel animals to monitor horizontal spread of the challenge virus.pestivirus / classical swine fever virus / E rns / replicon / marker vaccine

The Molecular Biology of Pestiviruses

“…An interesting approach combining the advantages of killed and live vaccine is the use of autonomous replicons for immunization. Different replicon vaccine candidates have been established for BVDV and CSFV (Frey et al, 2006;Maurer, Stettler, Ruggli, Hofmann, & Tratschin, 2005;Reimann et al, 2007;van Gennip, Bouma, van Rijn, Widjojoatmodjo, & Moormann, 2002;Widjojoatmodjo et al, 2000). All of them contain deletions of essential sequences so that their propagation requires in trans-complementation.…”

“…Thus, the trigger for the immune system is probably not very strong. Nevertheless, induction of protective immunity has been successfully demonstrated in stringent challenge models in several cases (Frey et al, 2006;Loy et al, 2013;Maurer et al, 2005;Sun et al, 2011;Yang et al, 2012;Zemke, Koenig, Mischkale, Reimann, & Beer, 2010). However, it is not yet clear whether a single vaccination with a replicon can consistently prevent fetal infection in a pregnant animal.…”

Functional RNA Delivery Targeted to Dendritic Cells By Synthetic Nanoparticles

“…Following transfection of a DC line, this replicon efficiently induced cytotoxic immunity. Frey et al [112] and Suter et al [113] employed VRP based on the classical swine fever virus genome, demonstrating that a single inoculation was efficient at inducing both humoral and cellular immunity. Flavivirus replicons, such as those derived from West Nile fever virus, have been modified to deliver genes of dengue virus type 2 [114].…”

Basic Science Paves the Way to Novel Safe and Effective Pestivirus Vaccines

“…These approaches are based on establishing autonomous replicons by deleting sequences from viral genomes. Several such putative replicon vaccines have been established for BVDV and CSFV [78,[107][108][109][110]. In all of these recombinant viruses, essential sequences were deleted from the genomes so that the vaccine candidates can only be propagated when the proteins encoded by the deleted sequences are provided in trans.…”