Positive selection and differential selective pressure analyses were carried out to study Haemagglutinin (HA) genes of H9N2 influenza viruses from different hosts in this paper. Results showed that, although most positions in HAs were under neutral or purifying evolution, a few positions located in the antigenic regions and receptor binding sites were subject to positive selection and some of them were even positively selected at the population level. In addition, there were always some positions differentially selected for viruses from different hosts. Both selection pressure working on HA codons and positions differentially selected might account for the extension of the host range and adaptations to different hosts of H9N2 influenza viruses.

Human enterovirus 71 viruses have been long circulating throughout the world. In this study, we performed a positive selection analysis of the VP1 genes of capsid proteins from Enterovirus 71 viruses. Our results showed that although most sites were under negative or neutral evolution, four positions of the VP1 genes were under positive selection pressure. This might account for the spread and frequent outbreaks of the viruses and the enhanced neurovirulence. In particular, position 98 might be involved in neutralizing antibodies, modulating the virus-receptor interaction and enhancing the virulence of the viruses. Moreover, both positions 145 and 241 might correlate to determine the receptor specificity. However, these positions did not display much difference in amino acid polymorphism. In addition, no position in the VP1 genes of viruses isolated from China was under positive selection.

Objective To investigate the effects of selenium supplement on atherogenesis and endothelial function in ApoE-knockout mice fed high fat diet.Methods ApoE-knockout mice fed with selenium-deficient and high fat diet were randomly allocated into 3 groups based on random number table including control group (not supplied with sodium selenite,n =10),low dosage selenium supplement group (supplied water with 0.1 mg/L sodium selenite,n =10) and high dosage selenium supplement group (supplied water with 0.2 mg/L sodium selenite,n =10).After 15 weeks,the following values were measured:the concentrations of selenium in heart and liver,the levels of serum lipid,the parameters of antioxidant function including activities of superoxide dismutase(SOD) and glutathion peroxidase (GSH-Px) and malondialdehyde (MDA) level in serum,the parameters of endothelial function including serum nitric oxide (NO),endothelin 1(ET-1),and vascular endothelial growth factor (VEGF) levels,and ET-1 and VEGF levels in aorta roots.The atherosclerotic lesions in aorta roots were analyzed with oil red O staining.Results (1) The selenium concentrations in heart and liver were significantly higher in high dosage and low dosage selenium supplement groups compared to control group (both P ＜ 0.05).(2) The levels of triglyceride,total cholesterol,low density lipoprotein cholesterol,very low density lipoprotein cholesterol and high-density lipoprotein cholesterol were similar among groups (all P ＞ 0.05).(3) The activity levels of serum SOD were significantly higher in low dosage ((113.8 ± 12.5) U/ml) and high dosage selenium supplement group ((152.3 ± 11.3) U/ml) compared to control group ((90.7 ± 10.7) U/ml,all P ＜ 0.05).The activity levels of serum GSH-Px were significantly higher in low dosage ((53.9 ± 7.2) U/ml) and high dosage ((69.6 ± 8.7) U/ml) selenium supplement groups than that of control group ((36.4 ± 5.6) U/ml,all P ＜0.05).The serum MDA levels in low dosage ((4.73 ± 1.05) nmol/ml) and high dosage ((4.13 ± 1.21)nmol/ml) selenium supplement groups were significantly lower than that of control group ((5.97 ± 1.08) nmol/ml,all P ＜ 0.05).(4) The serum NO concentrations in low dosage ((61.5 ± 12.8) μmol/L) and high dosage ((79.0 ± 14.6) μmol/L) selenium supplement groups were significantly higher than that of control group((42.7 ± 9.1) μmol/L,all P ＜ 0.05).The concentrations of serum ET-1 in low dosage ((52.8 ±6.3)ng/L)and high dosage ((46.3 ±4.7)ng/L)selenium supplement groups were significantly lower than that of control group((72.2±6.3)ng/L,P ＜ O.05).The concentrations of serum VEGF in low dosage ((97.4 ± 16.5) ng/L) and high dosage ((83.5 ± 22.0) ng/L) selenium supplement groups were significantly lower than that of control group((125.8 ± 18.6) ng/L,P ＜0.05).The expression levels of ET-1 and VEGF in aorta roots among low dosage and high dosage selenium supplement groups were significantly lower compared to control group (all P ＜ 0.05).(5) The plaque area of aorta roots in low dosage ((0.95 ± 0.19)× 105 μm2) and high dosage selenium supplement ((0.75 ± 0.15) × 105 μm2) groups were significantly smaller than that of control group ((1.13 ± 0.23) × 105 μm2),and the plaque area in high dosage selenium supplement group was significantly smaller than in low dosage selenium supplement group (P ＜ 0.05).Conclusion Supplement of selenium can attenuate atherogenesis in ApoE-knockout mice fed high fat diet,which is possibly mediated via reducing lipid peroxidation and improving endothelial functions.