Heterologous Protection

Ingelvac PRRS® vaccines:
proven cross protection against homologous and heterologous challenge


Porcine reproductive and respiratory syndrome (PRRS) is quick to mutate, and many strains currently exist in the field. It is important to remember that the degree of gene sequence homology between the infective virus strain and the vaccine strain is not a good indicator of vaccine efficacy.1 Ingelvac PRRS® vaccines have demonstrated cross protection against both homologous and heterologous challenges. Additionally, Boehringer Ingelheim Vetmedica, Inc. has four published research trials investigating the effectiveness of Ingelvac PRRS® MLV vaccine against various field strains.2,3,4,5

Figure 1 shows a dendrogram of known reference PRRS virus strains, Ingelvac PRRS® vaccine strain and the recent challenge strains tested. Table 1 shows the homology matrix between 8 recent wild-type isolates and Ingelvac PRRS® vaccines. Field strains tested varied from 100–86 percent homologous to Ingelvac PRRS® MLV vaccine.

Table 1

Ingelvac PRRS® vaccines have demonstrated cross protection against heterologous challenges. Recently tested isolates vary as much as 14 percent in relation to vaccine strains. Boehringer Ingelheim Vetmedica, Inc. continues to evaluate the efficacy of Ingelvac PRRS® vaccines against the most current field strains of PRRS. Our goal is to provide you with the most up-to-date information possible so you can feel confident in the PRRS control strategy being implemented on your farms.

References
  1. Opriessnig T, Pallarés FJ, Halbur PG, et al. Genomic homology of ORF 5 gene sequence between modified-live vaccine virus and porcine reproductive and respiratory syndrome virus challenge isolates is not predictive of vaccine efficacy. J Swine Health Prod 2004;13:246–253.
  2. Roof M, et al. Efficacy of modified-live virus porcine reproductive and respiratory virus vaccines against heterologous respiratory challenge. 2003, IPVS, P117.
  3. Jordan D, Layton S, Philips R, Genzow M. Modified- live PRRS vaccination provides heterologous protection against virulent 1-18-2 challenge. Leman Conference, 2009.
  4. Karriker L, et al. Meta-analysis of 16 modified-live PRRS vaccination challenge studies. International Symposium of Emerging and Reemerging Swine Diseases, 2007.
  5. Patterson A, Victoria J, Jordan D, et al. Modified-live PRRSv vaccination is efficacious following challenge with eight genetically diverse PRRSv isolates. Leman Conference, 2013.