To monitor genetic variation of porcine reproductive and respiratory syndrome virus (PRRSV),RT-PCR was used to identify a sample suspected of PRRSV infection.A PRRSV named SC-GY strain was obtained,and its Nsp2,ORF5 and ORF3 genes were used for sequence alignment and phylogenetic tree construction.The results showed that SC-GY strain is highly pathogenic PRRSV American variant strains with Nsp2 gene discontinuous deletion of 30 amino acids,ORF3 gene aa17 a serine (S) insert.Comparing to VR2332,CH-1a,JXA1,HUN4,NADC30,HENAN-XINX and SC2012,the Nsp2,ORF5 and ORF3 of SC-GY shared 70.3％-97.9％,82.4％-97.6％ and 83.1％-98.2％ of nucleotide similarity,and 62.3％-96.3％,78.0％-95.7％ and 81.6％-96.5％ of deduced amino acid similarity;and compared to LV they shared only 18.9％,60.8％ and 63.7％ of nucleotide similarity,and 14.0％,54.9％ and 57.2％ of deduced amino acid similarity.The phylogenetic tree revealed that the SC-GY formed independent small branches although it belonged to the same subgroup as highly pathogenic PRRSV strains.The results showed that in high frequency live vaccine immunization of currently PRRSV,the gene of PRRSV epidemic strain is still in constant variation.Vaccination of live PRRSV vaccines should be reduced and surveillance of PRRSV strains should be enhanced.

Objective:To evaluate the safety and efficacy of the treatment for oppressive spinal by microwave ablation combined with percutaneous fixation and open decompression.Methods:From January 2015 to September 2018, 20 patients with 26 spinal metastatic were treated with microwave ablation combined with percutaneous fixation and open decompression, including 13 males and 7 females with an average age of 43.85±18.67 years (range, 16-79 years). The locations of the lesions included: 9 in the thoracic, 11 in the lumbar. The tumors' type: myeloma 2 cases, leukemia 1 case, liver cancer 4 cases, osteosarcoma 2 cases, lung cancer 5 cases, kidney cancer 1 case, esophagus cancer 1case, cervical cancer 1 case, intestinal cancer 1 case, prostate cancer 1 case, adenoid cystic cancer 1case. Preoperatively all the patients suffered with the local pain and the spinal cord or nerve root compression symptoms. All 20 cases were examined with CT or MRI to determine the lesions and the sizes of metastasis, as well as to evaluate the ablation zone. The entry of the pedicle screws were performed by Wiltse method through paravertebral muscles. After that the lesions were treated with partial resection for decompression of spinal cord or nerve root, and followed with microwave ablation at the metastasis site. Thermometer was used to monitor the temperature at the central and posterior edges of the vertebral body. The surrounding important tissue were cooled by ice saline. 13 patients were performed with vertebroplasty for enhancement the intensity of the vertebral body. The visual analogue scale (VAS) score was used to evaluate the effect of pain relief after surgery. The postoperative neurological function and performance status were evaluated using Frankel grading and Eastern Cooperative Oncology Group (ECOG).Results:Each lesion was heated for 5.43±2.07 min (range, 3-10 min). The power of microwave ablation was 40-60 W. The mean blood loss during operation was 852.50±514.40 ml (range, 100-1 700 ml). The mean operating time was 4.11±0.99 h (range, 2.5-6.0 h). The temperature inside the lesion was 70-85 ℃. The temperature of the surrounding tissue was maintained at<43 ℃ by repeated frozen saline flush. All cases were followed up for 8.45±2.01 months (range, 6-14 months) without any recurrence. The VAS score of the 20 patients at 48 h, 1 month, 3 months and 6 months after operation were 1.55±1.23, 2.70±0.87, 2.40±1.14 and 3.05±1.00 points, which were all statistically lowerthan the preoperative score 5.95±1.18 ( P<0.05). The Frankel grading of 14 patients had at least one grade improvement 6 months after operation. There were 8 patients shown markedly improved ECOG score 6 months after surgery. Only one case suffered from reduced myodynamiaof lower limb and covered in one month after system treatment. Conclusion:The microwave ablation combined with percutaneous fixation and open decompression could resolve the spinal and nerve compression, relieve the pain in metastatic spinal oppression, reconstruct the stability, and improve the quality of lives, which is a safe and effective palliative surgical method.

Objective:To analyze the prognostic factors and evaluate the accuracy of existing survival prediction models in patients with lung cancer-derived spinal metastases who have undergone open surgery.Methods:According to the inclusion criteria, the data of 76 patients with spinal metastasis of lung cancer who underwent open surgery in the department of Orthopedics in Guangdong Provincial People's Hospital were collected from January 2019 to November 2021. The relationship between the number of bone metastasis, pathological type, visceral metastasis, epidermal growth factor receptor mutation, serum alkaline phosphatase (ALP), hemoglobin (Hb), Frankel grade and postoperative survival time in 76 cases was analyzed by Cox logical regression analysis and Kaplan-Meier method to determine the potential prognostic factors. The accuracy of Tomita score, Tokuhashi revised score, Katagiri New score, New England Spinal Metastasis Score score (NESMS) and Skeletal Oncology Research Group (SORG) machine learning algorithm in predicting postoperative survival time was verified by drawing receiver operating characteristic (ROC) curve.Results:The median follow-up time of the patients was 18.0 months (2.3-36.0 months). The median survival time was 12.6 months [95% CI (10.8, 14.4)]. The survival rates at 6 and 12 months after operation were 71.6% and 52.0%, respectively. Multivariate regression analysis showed that ALP [ HR=0.23, 95% CI (0.11, 0.48), P<0.001], Hb [ HR=4.48, 95% CI (2.07, 9.70), P< 0.001] and EGFR mutation [ HR=2.22, 95% CI (1.04, 4.76), P=0.040] were independent predictors of prognosis. The accuracy of Tomita score, Tokuhashi revised score (2005), Katagiri New score and NESMS score in predicting 1-year mortality was 58.7%, 65.7%, 70.5% and 65% respectively, and the accuracy in predicting 6-month mortality was 63.7%, 62.2%, 61.2% and 56.8% respectively. The accuracy of SORG machine learning algorithm in predicting 1-year and 90 d mortality was 81.1%, 67.5%, respectively. Conclusion:No EGFR mutation, ALP>164 U/L and Hb≤125 g/L were risk factors affecting the survival of patients with spinal metastasis of lung cancer. SORG machine learning algorithm has good accuracy in predicting the postoperative survival rate of patients with lung cancer spinal metastasis.