Abstract:
Recombinant glycoproteins of gp120 were successfully produced by prokaryote
and eukaryote systems to use as immunogen for studying function and immunogenicity of
HIV-1 envelope. Two pairs of HIV-1 isolates (M46PC & M46SC and F36PC & F36VC)
from blood and genital fluid of infected individuals were used in this study. The biotype of
M46PC and F36PC were SI/T tropic while the biotype of M46SC and F36VC were
NSI/M tropic. The data analysis supported the compartmentalization of HIV-1 CRF01_AE
that there is no correlation between viruses in blood and genital fluid in the following
features; biotypes, envelope nucleotide sequence of viruses.
With the different phenotype of paired HIV-1 isolates, only one paired isolate
(F36PC & F36VC) was expressed in both expression systems. The production of
rgp120F36PC/E.coli, rgp120F36VC/E.coli, rgp120F36PC/mammalian and rgp120F-
36VC/mammalian were 1.0, 1.2, 0.3 and 0.5 mg/ml, respectively. Antibody response of
rgp120F36VC was higher than rgp120F36PC with statistical significantly. To gain insight
to epitopes response of rgp120F36VC and rgp120F36PC, peptide ELISA was performed.
The result showed that only V2 epitope exhibited response. But there were no evidence to
prove the cause of difference between rgp120F36VC and rgp120F36PC on antibody
response because immunogenic epitope was the same. This might suggest that antibody
response to rgp120F36VC and rgp120F36PC were conformational dependent. To study
the effect for conformation changing on antibody response, V3 deletion was suggested.
Production of rgp120F36PC/?V3/E.coli, rgp120F36VC/?V3/E.coli,
rgp120F36PC/?V3/mammalian and rgp120F-36VC/?V3/-mammalian were 1.5, 1.7, 0.4
and 0.7 mg/ml, respectively. The deletion of V3 looped affected by increasing production
of recombinant protein. While the deletion did not effect any change in structure because
the level of antibody response was the same as wild type. Moreover, the prediction of
three dimensions of wild type F36PC and wild type F36VC were found b-strands at the tip
of V3 wild type F36VC isolates. So the mutation at subregion of V3 might affect the
structure of gp120 and lead to change the level of antibody response
The deletion of V3 from gp120 could alter immunogen but the antibody response
did not different from wild type. One approach to change the structure of gp120 was
subregion V3 mutation or combining variable loop deletion with the removal of
glycosylation sites.