ABSTRACT
Objective: To investigate the role of CCR5 key residues as a co-recptor for the cellular entry of human immunodeficiency virus type I (HIV-I). Methods: Mutation of amino acids was introduced in different extracellular loops of CCR5 by site-directed mutagenesis technique, turning the non polar amino acids into polar ones, the non-hydrophilic into hydrophilic, and the aromatic into non-aromatic. The mutants of CCR5 were expressed in BamH I/Xho I and were allowed to bind with gp120, and the binding activity of the mutants was compared with that of wild-type CCR5. Results: The coreceptor activity of CCR5 was reduced greatly when Cys in the first extracellular loop was replaced by Tyr and Pro in the third extracellular loop was replaced by Ser. There was no obvious change in the coreceptor activity of CCR5 when other replacements were introduced. Conclusion: HIV-I virus needs receptor and co-receptor to achieve its cellular entry. CCR5 is a co-receptor and some of its extracellular loop amino acids are essential for gp120 recognition of HIV-I.
ABSTRACT
<p><b>AIM</b>To study the effect of prothymosin alpha (Pro T alpha) as a fusion protein on secretion of IFN-gamma, IFN-alpha and TNF-alpha in vitro.</p><p><b>METHODS</b>The in vitro study was carried out on the culture of splenocytes, splenic and peritoneal macrophages isolated from Balb/c mice. Splenocytes were incubated with various concentrations of Pro T alpha (1 x 10(-7)-1 x 10(-10) mol.L-1) with or without Con A (5 micrograms.mL-1) for 72 h. Splenic and peritoneal macrophages were respectively treated with Pro T alpha (1 x 10(-7)-1 x 10(-10) mol.L-1) in the presence of LPS (10 micrograms.mL-1) for 24 h. Then IFN-gamma, IFN-alpha and TNF-alpha levels in the supernatant were detected by ELISA.</p><p><b>RESULTS</b>Pro T alpha (1 x 10(-7) mol.L-1) was found to obviously increase IFN-gamma level (P < 0.05) in the supernatant of splenocytes compared with the control group. Moreover, Pro T alpha (1 x 10(-7) mol.L-1) significantly induced the secretion of IFN-alpha (P < 0.01) and TNF-alpha (P < 0.01) in splenic and peritoneal macrophages.</p><p><b>CONCLUSION</b>In vitro, Pro T alpha could increase the secretion of IFN-gamma, IFN-alpha and TNF-alpha.</p>