Location: Foreign Animal Disease Research
Project Number: 3022-32000-063-044-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2025
End Date: Jun 30, 2027
Objective:
The objectives of this agreement is the evaluation of the effects of vaccination with the ARS developed African Swine Fever (ASF) ASFV-G-DI177L strain on the reproductive capacity of sows at reproductive age as well as the efficacy of vaccination in protecting these animals against the infection with the parental virulent field strain. The potential negative effect of ASF live attenuated vaccines in the reproductive performance of sows have been one of the major problems in extending the massive use of these commercial vaccines in the field. The expected results will have high significance in understanding protective mechanism and the reproductive impact induced by ASFV-G-DI177L and other live attenuated ASFV vaccines.
Approach:
Recombinant ASFV-G-D177L is a rationally developed African Swine Fever Virus (ASFV) live attenuated vaccine that has been approved for commercial production by the government of Vietnam. ASFV-G-D177L is a live attenuated virus developed by genetic manipulation of the highly virulent ASFV Georgia 2010 (ASFV-G) isolate (genotype II). ASFV-G-D177L has been shown to be safe and efficacious in inducing solid protection against the virulent parental virus ASFV-G as well as another derivative virus isolated in Vietnam in 2019. There is a lack of data on the effect of vaccination with recombinant ASFV live attenuated vaccines (LAV) on the reproductive fitness of sows at reproductive age and the survival of their piglets. The purpose of this project is to analyze the effect of vaccination and challenge on the number of piglets a sow produces per cycle and the growth and survival of the litter after vaccination and/or challenge. Fifteen sows at reproductive age will be artificially inseminated (AI) in a first reproductive cycle to evaluate their production capacity (number of piglets and health status after birth) and be randomized in the three groups of 5 animals. Group 1 and Group 2 sows will be vaccinated twice, 28 days apart, and 21 to 28 days after the last boost they will be AI in a second reproductive cycle. Group 2 sows will be challenged with the parental virulent strain ASFV-G at the midterm of pregnancy (around 60 days after AI) to evaluate sow and piglet survival and growth. A third group of 5 sows (Group 3) will be used as controls of production with no intervention apart from mock-vaccinations and mock-challenge at the same time as the treatment groups. Two pigs will be used as a challenge control group to ensure the potency of the challenge material. Sow and pig clinical signs associated with vaccination and challenge will be monitored daily, together with survival curves for all the groups of animals and their litters. The presence of protection and growth curves (piglets) in each of the groups will be monitored after the vaccination and/or challenge. Virological and immunological parameters will also be evaluated in the vaccinated/challenged animals to support the analysis of the presence/absence of protection after virus inoculation (either vaccine or challenge).