Location: Foreign Animal Disease Research2010 Annual Report
1a. Objectives (from AD-416)
Classical Swine Fever Virus (CSFV) is a highly contagious disease affecting swine world-wide. CSFV control methods include prophylactic vaccination or eradication in the event of an outbreak. Disease-free countries do not allow the use of currently available live attenuated virues (LAVs) as tools to control disease. Use of current LAV also does not allow for the differentiation of infected animals from vaccinated animals (DIVA) after application. ARS, PIADC has developed an experimental LAV marker vaccine strain (FlagT4) which serves as a positive marker and produces complete protection against CSFV strain Brescia. The objectives of this project are 1. Produce and evaluate FlagT4 master seed stock and determine efficacy and minimal dose response. 2. Develop and optimize a rapid molecular test to differentiate between FlatT4 and wild type viruses and develop companion serological and genetic DIVA tests. 3. Identify cellular proteins that interact with CSFV proteins and construct genetically modified viruses lacking this interaction. These viruses will be evaluated for their ability to induce disease and induce protection in swine against CSFV.
1b. Approach (from AD-416)
Objective 1: FlagT4 master seed stock will be produced and evaluated for revision to virulence in swine. Safety data will be developed for use of the vaccine off-PIAC. Efficacy testing and minimal dose response challenge testing will be conducted. Determine the efficacy and minimal protective dose of FlagT4 master seed stock in challenge studies. Objective 2: Develop and optimize a rapid molecular test (RT-PCR) to differentiate FlagT4 vaccinated from wild-type viruses. Develop serological and genetic companion tests compatible with FlagT4. Objective 3: Identify cellular proteins that physically interact with CSFV proteins. Determine the residues in the viral proteins that are important for interaction with cellular proteins. Construct and characterize mutant viruses harboring genetically modified binding motifs. Viruses presenting complete attenuation will be assessed as potential vaccine strains and bioprophylactic.
3. Progress Report
The objective of this collaborative research agreement is to conduct safety testing of Classical Swine Fever FlagT4 vaccine (CSF FlagT4v) and determine protection levels and correlating doses. Although FlagT4v meets the entry level criteria for the early development stage, the vaccine is considered a Select Agent by USDA APHIS. Exclusion from the Select Agent list is a requirement for the National Veterinary Stockpile, would accelerate product development, and is the first Go/No Go decision point for this vaccine candidate. 1. Assessment of FlagT4v as vaccine candidate. 2. A request for exclusion from federal select agent regulations of classical swine fever virus, strain FlagT4v, was filed. 3. Test viral-vectored vaccine. Proof-of-concept safety and efficacy studies were completed using adenovirus-vectored experimental vaccine: Recombinant adenovirus harboring different versions of the CSFV structural protein E2 gene have been designed and developed. To date, no technology has been transferred. No publications related with this project have been produced. This project was monitored through email and telephone exchange as well interaction with DHS S&T personnel stationed at PIADC.