In the present study, 89 porcine reproductive and respiratory syndrome virus (PRRSV) isolates in China during 2007 to 2012 were randomly selected from the GenBank genetic sequence database. Evolutionary characteristics of these isolates were analyzed based on the sequences of non-struc-tural protein 2 (Nsp2) and glycoprotein 5 (GP5). The genetic variations of the isolates were also compared with six representative strains. The results showed that a high degree of genetic diversity exists among the PRRSV population in China. Highly pathogenic PRRSV isolates, with a discon-tinuous deletion of a 30 amino acid residue in the Nsp2 region, remained the most dominant virus throughout 2007-2012 in China. Owing to the extensive use of representative vaccine strains, natu-ral recombination events occurred between strains. Three isolates-HH08, DY, and YN-2011-were more closely related to vaccine strains than the other isolates. Both YN-2011 and DY were the evolu-tionary products of recombination events between strains SP and CH-1R. The results of the present study provide useful information for the epidemiology of PRRSV as well as for vaccine development.

Objective:To explore the relationship between lower respiratory tract microflora and type of anti-tuberculosis immune response, clinical characteristics in patients with pulmonary tuberculosis (PT).Methods:The clinical data of 80 patients with PT and 80 patients with non-PT from January 2018 to March 2020 in the Second Hospital of Zhejiang Medical School of Changxing District were retrospectively analyzed. All patients were treated with bronchoalveolar lavage, the bronchoalveolar lavage fluid counts of Haemophilus, Neisser coccus, Streptococcus and Veillonella were detected by germiculture, and the bronchoalveolar lavage fluid expression levels of T-bet mRNA (Th1 immune response) and GATA-3 mRNA (Th2 immune response) was detected by real-time polymerase chain reaction. The clinical symptoms of PT were recorded. The correlation was analyzed by Pearson correlation analysis.Results:There were no statistical differences in bronchoalveolar lavage fluid Neisser coccus, Veillonella and Haemophilus between patients with PT and patients with non-PT ( P>0.05); the bronchoalveolar lavage fluid Streptococcus in patients with PT was significantly lower than that in patients with non-PT (630 ± 120 vs. 1 000 ± 330), and there was statistical difference ( P<0.05). There was no statistical difference in expression level of T-bet mRNA between patients with PT and patients with non-PT ( P>0.05); the expression level of GATA-3 mRNA in patients with PT was significantly lower that in patients with non-PT: (5.883 ± 1.864) ×10 4 vs. (3.997 ± 1.186) ×10 6, and there was statistical difference ( P<0.05). Pearson correlation analysis result showed that fever was positively correlated with bronchoalveolar lavage fluid Neisser coccus and Veillonella ( r = 0.402 and 0.566, P<0.01 or <0.05); proportion of tuberculosis foci to lung area was positively correlated with T-bet and GATA-3 mRNA ( r = 0.024 and 0.442, P<0.05), the body weight loss was positively correlated with T-bet mRNA ( r = 0.112, P<0.05); GATA-3 mRNA was positively correlated with bronchoalveolar lavage fluid Neisser coccus ( r =0.332, P<0.05), T-bet mRNA was positively correlated with bronchoalveolar lavage fluid Haemophilus ( r = 0.162, P<0.05). Conclusions:There is a significant correlation between the Th1/Th2 immune response type and the bronchoalveolar lavage fluid Haemophilus and Neisser coccus in patients with PT, and the fever symptoms is also significantly related to Neisser coccus and Veillonella. There is a certain correlation between weight loss and the quantitative results of proportion of tuberculosis foci to lung area and the type of immune response.