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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #243512
Title: Vaccine Efficacy of Porcine Reproductive and Respiratory Syndrome Virus Chimeras

Author
item ELLINGSON, JOSHUA - Iowa State University
item WANG, YUE - University Of Minnesota
item LAYTON, SARAH - Boehringer Ingelheim
item CIACCI-ZANELLA, JANICE - Labex - Embrapa
item ROOF, MICHAEL - Boehringer Ingelheim
item Faaberg, Kay

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/25/2009
Publication Date: 3/19/2010
Citation: Ellingson, J.S., Wang, Y., Layton, S., Ciacci-Zanella, J., Roof, M.B., Faaberg, K.S. 2010. Vaccine Efficacy of Porcine Reproductive and Respiratory Syndrome Virus Chimeras. Vaccine. 28(14):2679-2686.

Interpretive Summary: Porcine reproductive and respiratory syndrome virus (PRRSV) is the foremost infectious disease of swine in the United States. One area of study is the development of newer, more effective vaccines that will provide greater protection from reinfection with the same or different viral strains. Infectious cDNA clones of PRRSV, which can represent chimeras or site-specific changes that may potentially increase the immune response and may also have specifically engineered deletions and/or insertions to provide markers for vaccine identification, is one approach to solving this PRRSV vaccination problem. In this manuscript, we studied six infectious viruses made from synthetic genomes of two PRRSV strains and their ability to induce host immunity and to protect against infection with a third strain of PRRSV.

Technical Abstract: The vaccine efficacy of five chimeras and a deletion mutant engineered from two PRRSV type 2 strain viral clones that differed by 14.3% on a nucleotide basis was examined by challenge with type 2 strain JA-142. The appearance of antibodies and virus characterization revealed regions of the genome that could influence PRRSV replication in vivo. Swine growth, clinical symptoms and lung lesions were also monitored. Average daily weight gain was negatively and directly impacted by some vaccines, and after challenge, vaccination with different constructs led to variable weight gain. We also found that only two published chimeras and one in which strain MN184 ORF5-6 was placed on the background of Ingelvac® PRRS MLV were able to prevent lung consolidation to a similar extent as traditionally prepared cell-passaged attenuated vaccines. The study suggested that only specific chimeras can attenuate clinical symptoms in swine and that attenuation cannot be directly linked to primary virus replication. Additionally, a broad deletion of a region of strain MN184 nsp2 was not sufficient to reduce the pathogenicity of that strain, or serve as an adequate vaccine against heterologous challenge with strain JA142.