ABSTRACT
ObjectiveTo clarify the influence of human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein 120 V4 region with mutations at amino acid locuses on its abilities to enter target cells.Methods Based on the facts that ADA strains was a CCR5-tropic strain,only had the ability to infect CCR5 cells; that HXB2 strains was a CXCR4-tropic strain,only had the ability to infect CXCR4 cells,serial glycoprotein 120 mutants with alanine substitution in V4 region of ADA and HXB2 strains,were constructed by overlaping PCR.Eukaryotic expression vectors of mutants and expression vectors of HIV framework gene with luciferase reporter gene were cotransfected into eukaryotic cells to produce pseudoviruse.Concentration of HIV-1 gag P24 in pseudoviruses was detected by enzyme-linked immunosorbent assay(ELISA).U87.CD4.CCR5 and U87.CD4.CXCR4 cells were infected with 20 and 40 ng pseudoviruses,with wild ADA and HXB2 strains as control groups,respectively.The ability to infect cells of pseudovirus of each mutant with HIV-1 V4- region mutated at amine acid locuses 386-417 was measured by detecting the luciferase activity (relative light unit,RLU).ResultsTen mutants with alanine substitution in V4 region of HIV-1 ADA and HXB2 strains were successfully constructed,respectively.Mutants of pseudoviruse with 20 ng and 40 ng at locuses 389-391 and 414-417 with alanine substitution of V4 region in both ADA and HXB2 strains lost completely the abilities to enter CCR5 and CXCR4 expressing cells[ (0 ± 0)％].It was found that introduction of alanine to ADAs 400-403 and ADAs 408-410 increased the ability to infect cells to (124 ± 35)％,(182 ± 29)％ and (127 ± 8)％,( 134 ± 16)％ with pseudoviruse of 20 ng and 40 ng,respectively.Likewise,the ability to infect CXCR4 expressing cells also increased to (144 ± 42 )％ and (121 ± 18 )％ with pseudoviruse of 20 ng and 40 ng,respectively by introduction of alanine to HXB2s 395-397.However,other mutants in V4 region of ADA and HXB2 only maintained partial entry abilities( 15％- 84％).ConclusionsMutants of V4 region of HIV-1 envelope glycoprotein 120 with alanine substitution at locuses 389-391 and 414-417 in both ADA and HXB2 strains have been constructed successfully.They completely lost the ability to enter target cells.