#04-174

Complete

Date Full Report Received

11/03/2006

Date Abstract Report Received

11/03/2006

Investigation

Institution:
Primary Investigator:

One of the major obstacles for PRRSV control is the significant variability of this virus in the field. Such variability of PRRSV is expressed at the level of the genetic information of the strains ( commonly detected in the diagnostic labs by PCR followed by gp5 sequencing) and also, and most importantly, in the antigenic( structural proteins)make-up of the PRRSV strains which determines the strain’s ability to induce specific protective immunity in the pig. There is a significant need for typing and classifying PRRSV strains by some means different than the genetic sequencing now in use. The possibility of having a typing system based, rather than in genetic sequencing, in the distinct ability of strains for inducing similar or different immune responses is a very senseful way to classify and group the large universe of PRRSV strains circulating in the field. To our knowledge this project is the first attempt worldwide to apply such a typing system for PRRSV. Using a system of reference antisera that we designed under the assumption that the main PRRSV glycoprotein 5 of PRRSV plays a central role in antigenic diversity and neutralizing activity of PRRSV we were unable to type 50 % of the samples analyzed. While the typing done so far is incomplete, the results obtained, when joined with sequencing studies currently ongoing under different collaborative projects with SDSU and ISU should shed light on the role of specific structural genes of PRRSV in cross-neutralization , typing and probably cross protection. Such information could then be used to increase the number of reference antisera to be incorporated in our library so to maximize the number of “typable” isolates. Likewise, a closer analysis of some strains with anomalous reactivity detected by this research should teach us about the possibility of occurrence of inter-typic recombinants ( i.e PRRSV strains originated by crossing of Euro X U.S. types) that may be occurring in the field. This latter information is also crucial for PRRSV control, as there is ample evidence for the simultaneous circulation of both serotypes within the same geographic areas of the US. For further information please contact: Fernando A. Osorio, University of Nebraska-Lincoln, fosorio@unl.edu, phone: 402-472-7809