No abstract

DNA vaccines expressing the envelope (Env) of the human immunodeficiency virus type 1 (HIV-1) have been relatively ineffective at generating high-titer, long-lasting, neutralizing antibodies. In this study, DNA vaccines were constructed to express the gp120 subunit of Env from the isolate HIV-1 R2 using both wild-type and codon-optimized gene sequences. Three copies of the murine C3d were added to the carboxyl terminus to enhance the immunogenicity of the expressed fusion protein.Mice (BALB/c) vaccinated with DNA plasmid expressing the gp120 R2 using codon-optimized Env sequences elicited high-titer anti-Env antibodies regardless of conjugation to C3d. In contrast, only mice vaccinated with DNA using wild-type gp120 R2 sequences fused to mC3d 3 , had detectable antiEnv antibodies. Interestingly, mice vaccinated with DNA expressing gp120 R2 from codon-optimized sequences elicited antibodies that neutralized both homologous and heterologous HIV-1 isolates. To determine if the unique sequence found in the crown of the V3 loop of the Env R2 was responsible for the elicitation of the cross-clade neutralizing antibodies, the codons encoding for the Pro-Met (amino acids 313-314) were introduced into the sequences encoding the gp120 ADA (R5) or gp120 89.6 (R5X4). Mice vaccinated with gp120 ADA -mC3d 3 -DNA with the Pro-Met mutation had antibodies that neutralized HIV-1 infection, but not the gp120 89.6 -mC3d 3 -DNA. Therefore, the use of the unique sequences in the Env R2 introduced into an R5 tropic envelope, in conjunction with C3d fusion, was effective at broadening the number of viruses that could be neutralized. However, the introduction of this same sequence into an R5X4-tropic envelope was ineffective in eliciting improved cross-clade neutralizing antibodies.

DNA vaccines expressing the envelope (Env) of the human immunodeficiency virus type 1 (HIV-1) have been relatively ineffective at generating high-titer, long-lasting, neutralizing antibodies. In this study, DNA vaccines were constructed to express the gp120 subunit of Env from the isolate HIV-1 R2 using both wild-type and codon-optimized gene sequences. Three copies of the murine C3d were added to the carboxyl terminus to enhance the immunogenicity of the expressed fusion protein. Mice (BALB/c) vaccinated with DNA plasmid expressing the gp120 R2 using codon-optimized Env sequences elicited high-titer anti-Env antibodies regardless of conjugation to C3d. In contrast, only mice vaccinated with DNA using wild-type gp120 R2 sequences fused to mC3d 3 , had detectable anti-Env antibodies. Interestingly, mice vaccinated with DNA expressing gp120 R2 from codon-optimized sequences elicited antibodies that neutralized both homologous and heterologous HIV-1 isolates. To determine if the unique sequence found in the crown of the V3 loop of the Env R2 was responsible for the elicitation of the cross-clade neutralizing antibodies, the codons encoding for the Pro-Met (amino acids 313-314) were introduced into the sequences encoding the gp120 ADA (R5) or gp120 89.6 (R5X4). Mice vaccinated with gp120 ADA-mC3d 3-DNA with the Pro-Met mutation had antibodies that neutralized HIV-1 infection, but not the gp120 89.6-mC3d 3-DNA. Therefore, the use of the unique sequences in the Env R2 introduced into an R5 tropic envelope, in conjunction with C3d fusion, was effective at broadening the number of viruses that could be neutralized. However, the introduction of this same sequence into an R5X4-tropic envelope was ineffective in eliciting improved cross-clade neutralizing antibodies.

No abstract