Live attenuated classical swine fever vaccine based in genetic manipulation of a putative fusion peptide area in the virus structural glycoprotein E2

Inventors

Borca, Manuel V. • Gladue, Douglas P. • Holinka-Patterson, Lauren G. • O'Donnell, Vivian • Nieva, Jose

Assignees

UNIVERSIDAD DEL PAIS VASCO/EUSKAL HERRIKO UNIBERTSITATEA (UPV-EHU) • Euskal Herriko Unibertsitatea • University of Connecticut • US Department of Agriculture USDA

Abstract

The role of a specific E2 region containing a putative fusion peptide (FP) sequence was evaluated. FPs critically contribute to the interaction between proteins and the membrane system of the host cell. Reverse genetics utilizing a full-length infectious clone of the highly virulent CSFV strain Brescia (BICv) was used to evaluate how amino acid substitutions within this region of E2 may affect replication of BICv in cell cultures and affect virus virulence in swine. Interestingly, mutated virus FPi.c was completely attenuated when inoculated intranasally at a dose of 105 TCID50 in swine. Importantly, animals infected with FPi.c virus were protected against the virulent challenge with Brescia virus at 3 and 28 days after vaccination. Protection was evidenced by absence of clinical signs related with CSF as well as the absence of viremia produced by the challenge virulent virus.

Core Innovation

This invention relates to the construction of a recombinant Classical Swine Fever Virus (CSFV) live attenuated candidate strain vaccine, named FPi.c. The FPi.c virus contains mutations in three amino acid residues within the fusion peptide (FP) region of the CSFV E2 glycoprotein, specifically amino acids 869-878, resulting in the substitutions W871T, W875D, and V878T. The alteration of these amino acids affects the virus's ability to replicate and cause disease in swine.

Classical swine fever (CSF) is a highly contagious disease of swine caused by CSFV, an enveloped RNA virus encoding several structural proteins including the essential glycoprotein E2. The fusion peptide region of E2 plays a critical role in the interaction between viral proteins and the host cell membrane, facilitating viral entry. Modifications in this E2 region have a significant impact on the virulence of CSFV. The present invention aims to exploit this fact by genetically manipulating the putative fusion peptide area to attenuate the virus.

The mutated FPi.c virus was completely attenuated when inoculated intranasally in swine and was able to protect animals from a subsequent challenge with the virulent Brescia strain at both 3 and 28 days after vaccination. Protection was demonstrated by the absence of clinical signs of CSF and absence of viremia following challenge. Thus, the invention provides a rationally designed live attenuated CSFV vaccine that inhibits the fusion protein region's interaction with the host cell membrane, offering effective protection against classical swine fever.

Claims Coverage

The patent contains one independent claim focusing on the recombinant CSFV mutant virus and independent method claims related to vaccination. The main inventive features involve the specific mutations in the fusion peptide region and the use as a live attenuated vaccine.

The claims cover the novel mutant CSFV with specific fusion peptide mutations, its use in vaccine compositions, and methods for immunization against classical swine fever, establishing the recombinant virus as an effective live attenuated vaccine strain.

Stated Advantages

Documented Applications