These results were not unexpected since hydrophilic amino acid sequences are likely to be exposed on the surface of the protein and thus may be more easily recognized by B-lymphocytes. A previous report has also demonstrated the occurrence of a cluster of B-cell epitopes in Nsp2 of an EUtype PRRSV isolate and a north America PRRSV isolate, NVSL 97-7895 strain [33, 48]. Conclusions In conclusion, this study presented detailed molecular and

phylogenetic analyses for seven field isolates of PRRSV from China. The collected results revealed that the highly pathogenic PRRSV variants with the 30-aa deletion in Nsp2 were still the dominating viruses in China. The genetic diversity of PRRSV strain existed in the field in China. These PLX4032 research buy results might be useful for the origin and genetic diversity of PRRSV Chinese isolates and the development of vaccine candidates in the future. Methods Cell culture and viruses Swine Alveolar Macrophages (SAM) were obtained from about 4 week-old pigs as previously described [49]. The cells were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum and antibiotics (25 U/ml penicillin, 25 μg/ml streptomycin,

40 μg/ml gentamicin, 25 μg/ml neomycin and 300 U/ml polymyxin). Monkey kidney cell line, MARC-145 [50], was cultured in Eagle’s minimum essential medium supplemented with 5% Dibutyryl-cAMP fetal bovine serum. Infectious PRRSV, LS-4, HM-1, HQ-5, GCH-3, GC-2, HQ-6 and ST-7 strains from Shijiazhuang of Hebei province (Additional

file 10), were isolated in our laboratory at National Center of Wildlife Born Diseases, by inoculation of the sera or the tissue homogenates into SAM or MARC-145 cells. RNA extraction, reverse transcriptase PCR (RT-PCR) and nucleotide sequencing RNAs were extracted from 200 μl of the culture supernatant of the PRRSV-infected SAM or MARC-145 cells using QIAamp® viral RNA mini kit (Qiagen) according to the manufacturer’s Acadesine purchase recommendation. Alanine-glyoxylate transaminase Each target gene was amplified using QIAGEN® One-Step RT-PCR kit (Qiagen). PCR and sequencing primers were shown as Table 1. The PCR reactions were done in a total volume of 25 μl containing 1 ng of the extracted cDNA,,200 μM of each (dNTP) (TakaRa), 1 × PCR buffer (TakaRa), 3.0 mM MgCl2, and 2.5 U of Taq polymerase(TakaRa). The PCR conditions were set as initial denaturation step at 94°C for 3 min followed by 40 cycles, each consisted of denaturation step at 94°C for 1 min, annealing step at 55°C for 1 min and elongation step at 72°C for 2 min, a final extensition at 72°C for 10 min was included. Size of amplicons was verified by agarose gel electrophoresis in TAE buffer using known standards. PCR products were purified using QIAquick® PCR purification kit (Qiagen) and submitted to Invitrogen for sequencing.