Effect of Splice Site Mutation. (A) Analysis of splicing in splice site mutation vectors. RNA from 293T cells transfected with the relevant vector, pcDNA3.1tat101ml and pHCMVrevmlwhv  was reverse transcribed and PCR was used to amplify spliced transcripts as described in Methods. The brackets indicate the mutation of the major and minor splice donor sites present in each vector. SDm, pHIV-1SDmSE; SDm2, pHIV-1SDm2SE; SDm2.1, pHIV-1SDm2.1SE; SDm2.2, pHIV-1SDm2.2SE; SDm2.3, pHIV-12.3SE; SDm2.4, pHIV-1SDm2.4SE. (B) Vector titres using 0.125 ug vector per well (see Materials and methods for details). *All SDm2 variants, with the exception of SDm2.1, had significantly higher titres than the parental vector, SDm (ANOVA/Holm-Sidak, p < 0.01). In addition, SDm2, SDm2.2, SDm2.3 and SDm2.4 all had significantly higher titres than SDm2.1 (ANOVA/Holm-Sidak, p < 0.01). All results are presented as Mean ± SD (n = 6).