Generation and Efficacy of Two Chimeric Viruses Derived from GPEVaccine Strain as Classical Swine Fever Vaccine Candidates.

Abstract

A previous study proved that vGPEmainly maintains the properties of classical swine fever (CSF) virus, which is comparable to the GPEvaccine seed and is a potentially valuable backbone for developing a CSF marker vaccine. Chimeric viruses were constructed based on an infectious cDNA clone derived from the live attenuated GPEvaccine strain as novel CSF vaccine candidates that potentially meet the concept of differentiating infected from vaccinated animals (DIVA) by substituting the glycoprotein Eof the GPEvaccine strain with the corresponding region of non-CSF pestiviruses, either pronghorn antelope pestivirus (PAPeV) or Phocoena pestivirus (PhoPeV). High viral growth and genetic stability after serial passages of the chimeric viruses, namely vGPE/PAPeV Eand vGPE/PhoPeV E, were confirmed in vitro. In vivo investigation revealed that two chimeric viruses had comparable immunogenicity and safety profiles to the vGPEvaccine strain. Vaccination at a dose of 10TCIDwith either vGPE/PAPeV Eor vGPE/PhoPeV Econferred complete protection for pigs against the CSF virus challenge in the early stage of immunization. In conclusion, the characteristics of vGPE/PAPeV Eand vGPE/PhoPeV Eaffirmed their properties, as the vGPEvaccine strain, positioning them as ideal candidates for future development of a CSF marker vaccine.