Comparison of genomic homology among the highly virulent field HP-PRRSV strains isolated from 2009 to 2014 and the PRRSV strains of commercial vaccines

Abstract

Three genetic fragments including NSP2, ORF5 and ORF7 of 36 field HP-PRRSV strains isolated during 2009-2014 from several provinces were sequenced and analyzed on genetic similarity in comparison with the commercial vaccine strains. At ORF5, field HP-PRRSV strains having the nucleotide/amino acid similarity level in comparison with those of the vaccine strains: JXA1-R, P129 Fostera, ATCC VR-2332 Ingelvac, Resp Ingelvac PRRS, BCL-PS 100, Amervac PRRS and Porcilis PRRS decreased gradually: 86.8-99.7/84.0-99.5, 89.0-93.8/83.2-96.9, 84.1-98.8/88.1-92.1, 83.7-98.8/83.8-97.4, 83.3-98.5/81.4-96.9, 42.6-46.2/46.8-51.1 and 42.3-45.5/42.3-47.7 respectively. At ORF7, field HP-PRRSV strains havingthe nucleotide homology level in comparison with those of the vaccine strains: JXA1-R, P129 Fostera, ATCC VR-2332 Ingelvac, Resp Ingelvac PRRS, Amervac PRRS and Porcilis PRRS decreased gradually: 91.1-99.7/94.7-99.1, 90.3-95.6/94.7-99.9, 90.6-99.7/94.7-99.9, 90.6-99.7/94.7-99.9, 41.9-46.0/52.8-55.8 and 42.3-46.1/52.8-56.9 respectively. The highly genetic diversity among the field isolates basing on ORF5 and ORF7 analysis led on large variation of homology in comparison with the current commercial vaccine strains.