| Summary: | 碩士 === 國立屏東科技大學 === 獸醫學系所 === 97 === Outbreaks of a severe form of porcine reproductive and respiratory syndrome (PRRS), have occurred in pig herds in China since June, 2006. The infection of this highly pathogenic PRRS virus (PRRSV) resulted in 100% morbidity and 25–50% mortality. The clinical signs include high fever ( 40–42℃), respiratory distress, dyspnoea and erythematous blanching rash. Whole-genome analysis showed that a unique molecular hallmark in these viral isolates, namely a discontinuous deletions of 1 and 29 amino acids in nonstructural protein 2 (NSP2) corresponding to positions 480 and 531–559 of strain VR-2332, respectively, was observed. These unique molecular indicators in NSP2 are only found in highly pathogenic PRRSV isolates, implying that they can be used as a novel marker for the differential detection of PRRSV strains with different degree of virulence. In order to prevent the invasion of this highly pathogenic PRRSV into pig herds in Taiwan, we established an RT-PCR with primers 2691F and 3060R that amplified 347 bps and 560 bps products of Taiwanese PRRSV isolated during 2007-2008 and 2004-2006, respectively. Using the same primer pair, a 470 bps of amplification product for highly pathogenic PRRSV should be obtained as calculated by the published gene sequence. According to the sizes of amplification products, differential diagnosis can be achieved among these three PRRSV strains. So far, no highly pathogenic PRRSV has been diagnosed in pigs in Taiwan.
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