Isolation and characterization of the gene ORF5 of porcine reproductive and respiratory syndrome (PRRS) virus in Mexico

Abstract

THE PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME (PRRS) REPRESENTS A MAJOR MENACE TO THE NATIONAL AND INTERNATIONAL PORCINE INDUSTRY. THE VIRUS GENETICS AND ANTIGENIC PROPERTIES, AS WELL AS ITS CAPACITY TO MODULATE THE IMMUNE SYSTEM, HAVE MADE IT DIF- FICULT TO CONTROL THIS VIRUS. IN MEXICO, AS IN THE REST OF WORLD, THE DISEASE PRODUCES IMPORTANT ECONOMIC LOSSES IN THE PORCINE INDUSTRY. THIS STUDY DESCRIBES THE ISOLATION AND CHARACTERIZATION OF PRRS VIRUS OBTAINED FROM PIGS OF A FARM LOCATED IN SONORA, MEXICO. THE ISOLATED VIRUS WAS IDENTIFIED BY NESTED RT-PCR OF THE ORF-6 GENE, AND BY CYTOPATHIC EFFECT IN MARC -145 CELLS. THE ISOLATED VIRUS WAS INOCULATED IN NEGATIVE PIGS WHICH BECAME VIREMIC AND PRODUCED ANTIBODIES AND MONONUCLEAR CELL (MNC) RESPONSE AFTER INOCULATION. IN ORDER TO ESTABLISH THE GENOTYPE OF THE ISOLATED VIRUS, THE SEQUENCE OF THE GENE ORF-5 WAS DETERMINED, AND IT WAS 88% AND 87 % SIMILAR TO THE AMERICAN VIRUS (VR-2332) AND THE MODIFIED LIVE VIRUS (MLV) VACCINE, RESPECTIVELY. THESE STUDIES ARE BASIC FOR THE DEVELOPMENT OF STRATEGIES ORIENTED TO CONTROL THIS DISEASE IN MEXICO.